-
Journal of Automatic Chemistry, Vol. 13, No. 2 (March-April
1991), pp. 59-79
Pittcon Abstracts (1991)
Speciation studies of selenium and arsenic byreversed-phase
high-performance liquid chroma-tography, employing hydride
generation and induc-tively coupled plasma mass spectrometric
detection
W. Charles Story, E. Hywel Evans, Douglas T. Heitkemper
andJoseph A. Caruso (Department of Chemistry, University
ofCincinnati, Mail Loc. 172, Cincinnati, OH 45221-0172;National
Forensic Chemistry Center, U.S. Food and DrugAdministration, 1141
Central Parkway, Cincinnati, OH 45202)
Different forms of metals and metalloids have varyingdegrees of
toxicity in biological systems. Because of this,there has been an
increase in the research focused on thespeciation of metals at
trace levels. Plasma mass spec-trometric detection of hydride
species has been estab-lished as a viable technique for the
determination of thesespecies at trace levels. One problem with the
determi-nation of arsenic by plasma mass spectrometry is
thepossibility of interference from the formation of ArC1+.Since
many naturally occurring samples contain chloride,direct
nebulization of the sample will introduce chlorideto the plasma. A
possible solution to this problem is theuse of hydride generation
to convert the arsenic to avolatile form coupled with separation
from the chlorideusing a membrane gas liquid separator of the type
usedpreviously.
The effectiveness of using hydride generation and themembrane
separator in reducing the ArC1+ interferenceon the detection of
arsenic was presented. A high-performance liquid chromatographic
separation ofseveral arsenic and selenium species demonstrate
thesimultaneous detection and speciation of these twoelements using
hydride generation to increase the sensi-tivity. Figures of merit
were discussed, along with thepertinent experimental details.
Addition of molecular gases to Ar gas flow for thereduction of
polyatomic ion interferences on arsenicand selenium in inductively
coupled plasma massspectrometry
Jiansheng Wang, E. Hywel Evans and Joseph A. Caruso(Department
of Chemistry, M. L. 172, University of Cincinnati,OH 45221)
Due to its sensitivity and multi-element capability,Inductively
Coupled Plasma Mass Spectrometry (ICP-MS) has developed into a very
powerful technique for thedetermination of trace elements. However,
the choice ofhydrochloric acid for sample dissolution, or a
highconcentration of chloride in sample, makes it almostimpossible
to determine arsenic or selenium because ofinterferences caused by
75ArCl+ on 75As+, 76ArAr+ on76Se+, 77ArCl+ on 77Se+ and 78ArAr+ on
78Se.
Different methods, such as co-precipitation of
chlorides,chromatographic de-salting, alternative sample
prep-aration procedures and addition ofmolecular gases to
thecentral channel Ar gas flow have been used to overcomethese
polyatomic interferences.
In this study, the effects of addition of molecular gasessuch as
nitrogen to the central channel, the coolant andthe auxiliary flows
have been investigated. A standardreference material and real
fusion samples containing ahigh concentration ofHCL have been
studied. The effectsof the addition of molecular gases to Ar flows
onpolyatomic arsenic and selenium were shown.
Vapour generation techniques to measure arsenic byatomic
fluorescence
P. B. Stockwell (P. S. Analytical Ltd, B4 Chaucer BusinessPark,
Kemsing, Sevenoaks, Kent TN15 6QY, UK; L. C. Ebdonand Warren Corns,
Polytechnic South West, Drake Circus,Plymouth PL4 8AA, UK); and K.
C. Thompson (YorkshireWater Enterprises Ltd, Charlotte Road,
Sheffield $2 4EQ, UK)Vapour generation techniques have proved
immenselyvaluable when measuring environmentally importantelements
at the levels present by existing techniques.Sensitivity
improvements of500 times are not uncommonfor such measurements when
linked to AtomicAbsorption and Inductively Coupled
PlasmaSpectroscopy. Recently Stockwell et al. have
describedadditional benefits of coupling such simple
preparativetechniques to atomic fluoresence. A specific
systemdesigned for mercury analysis provides simple instrumen-tal
systems which can measure reliably down to few partsper
trillion.
The determination of arsenic by hydride generationatomic
fluorescence spectrometry using both non-dispersive and dispersive
systems is well established.However, to date, there is no
commercially availableinstrumentation for this technique, this is
largely due tothe lack of reliable high intensity sources.
The paper described the use of a boosted dischargehollow cathode
lamp to excite arsenic atoms obtainedfrom various designs of atom
cells. The relative advan-tages and disadvantages of using
dispersive and non-dispersive systems will also be discussed.
Applications of environmental interest were describedwith
validation using a wide range of certified referencematerials at
different levels, a fully atomated system wasalso described in
detail.
59
-
Pittcon Abstracts (1991)
Determination of tin using hydride AAS includingflow injection
analysis (FIA) and trapping in agraphite furnace
Zhang Li, Susan Mclntosh, Glen Carnrick and Walter Slavin(The
Perkin-Elmer Corporation, 761 Main Avenue, Norwalk,CT
06859-0237)The determination of tin at ultratrace levels is
veryimportant because the metal has an important environ-mental
role even at very low levels. There is littleinformation in the
literature on the tin determination asthe hydride, although it has
been reported as difficultbecause the hydride is reported to be
unstable.
The hydride method provides the opportunity to measurevery low
concentrations of Sn and, at the same time, toseparate the element
from potential interferences. Thesimplicity and convenience of flow
injection analysis(FIA) has been used to explore the parameters of
the Sndetermination as the hydride.
Still greater concentration sensitivity was found bytrapping the
Sn hydride in a warm graphite furnace, andthen atomizing the Sn
using conventional STPF con-ditions for Sn. The characteristic mass
for Sn in pg by thisprocedure was the same as when solutions
containing Snwere analysed in the furnace but large volumes of
samplecan be analysed. Interferences were small using
furnacetrapping.
The detection limit was 7 ng/1 for a 10-ml sample,probably the
best instrumental, non-laser, detection limitever reported for Sn.
The analytical precision was 3 to 5%RSD at ng of Sn. Inter-element
interferences wereinvestigated. The recommended method has
beenapplied to the analysis of Steel, River Sediment andOrchard
Leaves and Bovine Liver Standard ReferenceMaterials, SRM’s and this
data was presented.
The rapid determination of traces of selenium andtellurium in
copper electrolytes
John Bozic, R. L Ethier, J. M. Balleny (INCO Limited,
CentralProcess Technology, Copper Cliff, Ontario, POM 1NO,
Canada)INCO Limited is a major producer ofhigh quality
coppercathodes, using both electrorefining and
electrowinningprocesses at its Copper Cliff Copper Refinery.
For process control purposes, and to ensure productquality, the
rapid determination of Se and Te levels incopper electrolytes down
to sub parts-per-million levelsis very important. Traditional
procedures have reliedupon separation of the analytes by
distillation, co-precipitation, solvent extraction, etc. prior to
spectro-photometric measurement. Such procedures are slow
andlabour-intensive. The authors investigated the capabilityof a
number of modern instrumental analysis techniquesto determine Se
and Te in the difficult matrix containing,for example, 200
g/1H:SO4, 100 g/1Cu, and 10 g/1Ni, Co.
6O
Direct ICP-AES and DCP-AES procedures lacked suf-ficient
sensitivity and suffered from major inter-elementinterferences.
Flame AAS with deuterium arc back-ground correction was also
insensitive.
Anodic stripping voltammetry was found to be impracti-cal due to
interferences from organic additives present inthe
electrolytes.
Electrothermal Zeeman AAS and polarized flameZeeman AAS were
both found to be capable of providingprecise and accurate Se and Te
analyses with minimalsample treatment. For routine analysis the
latter pro-cedure is favoured.
Te is measured using an air-acetylene flame, while
anargon-hydrogen-air flame is used for Se. Matrix matchedstandards
are essential. Details of analytical proceduresand comparisons
between methods were presented andapplications of polarized flame
Zeeman AAS to otherdifficult matrices were outlined.
Determination of hydride-forming elements ’inmetals by flow
injection atomic absorption spec-trometry with on-line matrix
isolation
S. G. Offley and N. J. Seare (Department of Chemistry,University
of Technology, Loughborough, LeicestershireLEll 3TU, UK); J. F.
Tyson (Department of Chemistry,University ofMassachusetts, Amherst,
MA 01003); and H.A.B.Kibble (Philips Scientific, York Street,
Cambridge CB1 2PX,UK)
Although the determination of elements such as As andSe by the
generation of the volatile hydride withsubsequent atomization in a
tube furnace is a maturetechnique, there are a number of
limitations to theprocedure. These arise principally from the
nature of thematrix components. Determinations of trace elements
intransition metals are particularly difficult due to
theinvolvement of the matrix element in a competingreaction with
the reductant (borohydride) and thesubsequent reaction of the
determinands with the reac-tion products.
This work described the application of a continuous flowmanifold
which removes the matrix element from theanalyte solution by
retention on a cation exchangecolumn. The resulting solution flows
through the loop ofaflow injection (FI) valve and a discrete volume
is injectedinto a FI manifold in which it is merged with streams
ofacid, borohydride and argon prior to separation of thevapor in a
glass U-tube device. This novel flow injectionmanifold design
allows independent optimization of thematrix isolation and hydride
generation chemistries. Thevarious operations may be fully
automated, includingthat of column regeneration.
-
Pittcon Abstracts (1991)
Optimization of the FI manifold for the determination ofSe was
carried out using an alternating variable method.Optimum
sensitivity was determined to be dependent notonly on reagent
concentration but also on the totalreagent flow rate in the
manifold. Optimization ofsensitivity for interference tolerance for
both copper andnickel was achieved through maximizing the total
reagentflow rate (15 ml min-1). Reducing the injection volumewas
observed to increase the interference tolerance.
The accurate analysis of two standard reference coppermaterials
(BAM 361 and NIST 454) was carried outcontaining 30 and 479 mg kg-1
Se(IV) respectively.throughput of 17 h-1 was possible with column
regen-eration after each sample (triplicate injections of
eachsample). A characteristic concentration of 1"0 ppb wasachieved
with an RSD of 1"5% (10 ppb, N 12).
The FI manifold has also been optimized for thedetermination of
As(III). Performance was observed tobe significantly affected by
the condition ofthe silica tube-in-flame atomizer. Conditioning
procedures were investi-gated. Investigation was made into the
interferencetolerance of the system for Ni, Cu, Co(II),
Sn(II),Sb(III) and Se(IV). Incorporation of an in-line mem-brane
filter was observed to eliminate interferencememory effects
associated with high concentrations ofCuand Ni and improve the
precision.
Determination of As, Sb, and Se with electrothermalvaporization
into a helium microwave-inducedplasma
Jorge Alvarado andJon W. Carna.han (Department of
Chemistry,Northern Illinois University, DeKalb, IL
60115)Electrothermal vaporization (ETV) has been shown to bean
excellent method for the introduction of aqueoussamples into helium
microwave-induced plasmas (He-MIP). In a comparison study of ETV
and ultrasonicnebulization (USN), Wu and Carnahan have shown theETV
to exhibit superior Cland Br detection limits by twoorders of
magnitude. The authors have shown similarbehavior for the analysis
of As, Sb, and Se.
For this study, the sample introduction system consists ofa
carbon cup type electrothermal vaporizer coated withtantalum in a
glass chamber. A secondary pyrex vaporrestriction device is used to
enhance the efficiency ofsample transport to the plasma.
Detection limits obtained with ETV (15 btl sample) andUSN,
respectively, were: SB, 0"008 mg/1 and 0"098 mg/1at 259"805nm; Se,
0"122 mg/1 and 13"2 mg/1 at203"985 nm; and As, 0"015 mg/1 and 0"750
mg/1 at234"984 nm. To obtain the best detection limits
nickelnitrate and lead nitrate were used as matrix modifiers.
Linear responses of three orders of magnitude wereobtained for
each element.
Simultaneous ICP-AES determination of As, Sb, andSe by
hydride-generation sample introduction
L. 21. Prell, 21. D. Lindner, V. A. Letourneau, and D. E.
Dobb(Lockheed Engineering and Sciences Company, 1050 E.
FlamingoRd., Las Vegas, NV 89119), and T. A. Hinners (US
EPA,Environmental Monitoring Systems Laboratory, 944 E. Harmon,Las
Vegas, NV 89119)The multi-element capability of ICP-AES has not
beenrealized for low level As, Sb, and Se determinations.Pneumatic
nebulization alone does not provide enoughsensitivity for these
elements. However, hydride-generation (HG) sample introduction
greatly improvesICP-AES sensitivity for these elements. To optimize
thissensitivity, Hg sample introduction requires conversionof
analyte species to their most efficient hydride-formingoxidation
states. Presently, HG techniques for As and Sbrequire the addition
ofKI to form the + 3 oxidation state.However, KI reduces Se to its
elemental form, which doesnot form hydrides. Selenium’s most
efficient hydride-forming oxidation state is +4, which is attained
by highconcentrations (20%) of HCL. Since the conditions forHG
differ between Se and the As/Sb pair, analyses ofthese elements
were historically performed separately.However, there is no need to
separate the analyses oncethe hydrides are formed. Thus, a
continuous-flow hydridegenerator, which splits the sample flow into
two reactionstreams, was used for simultaneous determination of
allthree elements. One reaction stream (3"0 ml/min) washeated to 70
C and mixed directly with 0"28 ml/min of0" 1% NaBH4. This allowed
the selenium hydride to form.The other reaction stream (3"0 ml/min)
was heated to70 C and mixed with 0"42 ml/min of 1% KI before it
wasmixed with 0"28 ml/min of 0"1% NaBH4. This allowedthe As and Sb
to form hydrides. The streams were thencombined and introduced into
a Hildebrand-grid nebu-lizer and water-jacketed Scott Spray chamber
chilled toC. This combination served as a highly efficient gas-
liquid separator. The argon carrier gas pressure was 10psi (100
ml/min), which was too low to cause nebuliz-ation of the aqueous
phase that is laden with salts. Withthe Hildebrand-grid nebulizer,
a significant mist is notobserved unless the pressure is greater
than 40 psi. Theanalytical figures of merit were evaluated using an
ARL3560 mini-torch ICP-AES with synthetic solutions anddigests of
NIST Fly Ash and NIST River Sediment. Therelative standard
deviation was 1"5% for As and Sb, and5% for Se. The detection
limits (DLs) were 0"8 tg/1 for Asand Sb and 5 btg/1 for Se. The Se
DL was not affected bythe compromise HG conditions used for the
otheranalytes. The linear range extended to 100 tg/1 for allthree
elements. Above the 100 btg/1 level, pneumaticnebulization provides
sufficient sensitivity. The devel-oped analytical procedure is a
candidate method forapproval by the US EPA.
Notice: Although the research described in this articlehad been
supported by the United States Environmental
61
-
Pittcon Abstracts (1991)
Protection Agency, it has not been subject to Agencyreview and
therefore does not necessarily reflect the viewof the Agency and no
official endorsement should beinferred. Mention oftrade names or
commercial productsdoes not constitute endorsement or
recommendation foruse.
A practical approach to automated ultra-low levelmercury
determinations
Doug Shrader and Johnathan Moffett (Varian OpticalSpectroscopy
Instruments, 201 Hansen Court, Suite 108, WoodDale, IL 60191)A
continuous flow cold vapor generator (VGA-76) is.capable of routine
detection limits of 0"2 btg/1 by atomicabsorption. Increasingly,
legislation around the world isspecifying mercury levels to be
measured at sub-ppblevels. European regulations require
measurements to bemade at 0"05 btg/1. This implies that a system
should beable to measure to an order of magnitude lower than0.2
btg.
For a number of reasons, atomic absorption is the logicalchoice
to measure at these ultra-low levels. These includeits excellent
sensitivity, adaptation to routine measure-ment and
cost-effectiveness.
The ease with which gold can form an amalgam withmercury
suggests a method to improve sensitivity. A goldcollecting surface
can be inserted into the mercury vaporflow. After a suitable
collection time, the adsorbedmercury can be quickly released by
electrical heating ofthe gold collector. This gives an enhanced
transientmercury signal. This study shows that the enhancementis
directly proportional to collection time. Calibrationcurves are
linear up to a mass of mercury equivalent to100 ng and absorbances
of about 1"0.
In routine accurate measurements of sub-ppb levels ofmercury,
several analytical challenges present them-selves. For instance,
reagent contamination alone isfrequently greater than 0"05 btg/1.
Technical problemsand their resolution were discussed. These
includeminimization ofextraneous mercury being trapped on
thecollector, interaction with an automatic sampler andvarious
atomization cell designs.
The determination of tin in complex environmentalsamples by
hydride generation atomic absorptionspectroscopy
Cindy Beach and Doug Shrader (Varian Optical
SpectroscopyInstruments, 201 Hansen Court, Wood Dale, IL 60191)
Hydride generation AA techniques are used routinely forthe
determination of As, Se, and Sb in environmentalsamples. Advantages
include high sensitivity, simplicity,and relative freedom from
interferences. Tin can also bedetermined by hydride generation,
however, current
62
methodology suffiers from severe difficulties. Theseinclude pH
dependency, potential contamination prob-lems poor standard
stability, and severe metalinterferences.
This paper described the development of a relativelysimple tin
hydride generation AA method that eliminatesthese problems. In this
study difficult environmentalsample were analysed for tin by
continuous flow hydridegeneration. Continuous flow designs greatly
reduceanalysis time as well as improve precision and allow
forautomation. Various masking or complexing agents havebeen found
to be extremely beneficial, not only in theelimination of metal
interferences as reported by others,but also in significant
improvements in sensitivity,precision and stability. A surprising
aspect of the methodwas little pH dependency. Standards and
samplescontained 1% HNO3 at a pH of
-
Pittcon Abstracts (1991)
executed via programmable logic controllers on thefactory
floor.
Automated flow-through microwave digestion foron-line sample
preparation and inductively coupledplasma spectrometry
Ramon M. Barnes and Laura J. Martines (University
ofMassachusetts, Department of Chemistry, Lederle GRC
Towers,Amherst, MA 01003-0035)Innovative sample preparation for
accurate elementaldeterminations, especially with inductively
coupledplasma spectrometry, has been stimulated by the
avail-ability of commercial microwave digestion devices thatprovide
benefits compared to conventional open beaker,hot plate digestions.
Closed and open vessel microwaveoven digestions are effective
techniques that improveprecision and accuracy, reduce
contamination, andincrease sample throughput. One practical
limitationresults from the sealing of closed vessels and the
insertionof vessels into the microwave oven. The combination
ofmicrowave digestion and flow techniques was firstreported by
Burguera et al., and has subsequently beeninvestigated by others.
Continuous or stopped-flowonline microwave digestion can increase
sample through-put and extend sample handling automation.
A commercial laboratory microwave oven is available(Prolabo
A300) with the capability to perform automateddigestions by
utilizing microprocessor control and amechanical arm. The microwave
energy in this oven isfocused in a small cavity. In one approach to
combinemicrowave digestion with sample flow techniques, thesample
tubing is placed in the digestion cavity. As thesample and acid are
pumped through the tubing insidethe cavity, the microwave energy
can heat the acid andcontrolled sample digestion can occur.
Several experimental considerations must be made forthe
practical development of this approach. The acidstype and volume,
use offlowing streams and stopped flowtechniques, settling of
solids from the reaction solution,control ofreaction pressure, and
formation ofgas bubblesare some of these considerations. These
effects and theanalytical characteristics of flow-through
microwavedigestion techniques will be described. An expert
systemthat helps to select the digestion parameters can
beinterfaced with the flow-through system to enhanceautomation of
the digestion methods development.
Sample preparation of oxide materials using thepulverizing,
pelletizing and fusion method underroutine conditions in fully
automatic systems
G. Hawickhorst (HERZOG Maschinenfabrik GmbH, P. O. Box2329,
D-4500 Osnabriick, Germany)Almost 15 years ago the first
installations of fullyautomatic sample preparation systems based on
pulveriz-ing and pelletizing had been established in the cement
industry. The first systems based on the fusion techniquehave
been installed during the last few years.
With improved speed, performance and reliability of thethird
generation of those systems, entry was made in steelplant-, mining-
and other laboratories.
The advances in electronics and robotics gave thenecessary tools
to automate the fusion process. Thisprocess is much more sensitive
to trouble-causing effectssuch as dust, vibration etc. than the
pulverizing andpelletizing process.
The fused bead eliminates several negative effects in thesample
(mineralogical, particle size, etc.), but on theother hand there is
the danger ofcracking ofthe glass diskdue to internal stress.
Beside the analytical requirements these facts also have tobe
taken ito account when deciding which method to usefor fully
automatic on-line systems under routine con-ditions for process
control.
With both systems there is enough experience available tojudge
in which field of application which system willpromise the best
success concerning analytical results,speed, lowest maintainance
cost, and reliability.
Layouts of existing installations were shown and thelatest
experiences with installations in various industrieswere
reported.
The adaptation of FIA for the determination ofphosphate in
phosphate ore
Franklin E. Patrick and John E. Gibson (IMC
FertilizerIncorporated, P.O. Box 876, Bartow, FL 33830)IMC
Fertilizer is the world’s largest private producer ofphosphate
rock. As such, the capability for rapid andaccurate determinations
ofphosphate in phosphatic ore iscrucial. In the authors’ lab, the
following criteria havebeen designated as necessary to provide this
capability:
(1) Throughput of at least 60 samples/hour.(2) A range from 10
to 1500 mg P205/1.(3) Relative standard deviation of less than 0"5%
at
the upper end of the range.
These criteria reduced the number of possible analysersto a
select few. The Tecator 5010 FIA Analyzer wasevaluated and was
found acceptable.
The Tecator 5010 Analyzer is an automated flowinjection
instrument interfaced with a personal computerusing the
manufacturer provided software, SuperFlow II.The standard
molybdo-vanadate procedure as describedin the AOAC Officiall
Methods of Analysis was adapted tothe instrument. This paper
reported on the manifoldconfiguration, flow rates, and other
considerations
63
-
Pittcon Abstracts (1991)
necessary to run this method on the analyser and meet
thestringent analytical requirements. Calibration is accom-plished
by analysing phosphate rock standards coveringthe range encountered
in digested rock samples. Datafrom these standards are processed
using a polynomialcurve fitting routine to obtain a calibration
curve thataccurately fits the non-linear absorbance versus
concent-ration relationship.
Data from the Tecator Analyzer compared favorablywith data from
three different instruments: an air-segmented continuous flow
analyser, a discrete volumeautomated batch analyser, and an ICP.
The throughputof the system is 90 samples/hour. A standard
deviation of4.0 mg P205/1 was established for samples at the
higherend of the cencentration range.
The module design of the analyser was also an
importantconsideration. There are currently three analysers at
twoseparate locations and there are plans to add another oneat a
third location. The flexibility offered by the designallows
components to be swapped if needed to reducedown time.
A practical system approach to NIR industrialprocess
analysis
Barry Read (Bran + Luebbe Analyzing Technologies, Inc,
103Fairview Park Drive, Elmsford, NY 10523)Successful
implementation of spectroscopic analysis inthe process control
environment requires knowledge ofthe physical and chemical
properties of the constituent tobe analysed, as well as its
corresponding matrix.
In addition to the fundamental spectrochemistry, theproper
sensor must be selected for the application toensure accurate and
reliable data collection. Next,sample handling techniques must be
optimized for thesensor and the individual process environment.
Once these factors have been solved, data acquisition,process
equipment interface and integration of theexisting automation
processes is required before thesystem can be truly considered as
an in-line sensor.
The implementation strategy used in placing nearinfrared sensors
into the process environment werediscussed with some real world
examples of theseprojects.
Flexible sample and data handling systems for thedetermination
of total nitrogen sulphur
John S. Crnko, Dewey Smith and Mike Martin (AntekInstruments,
Inc. 300 Bammel Westfield Rd., Houston, TX77090)Sampling and
analytical techniques for the new totalnitrogen and total sulphur
analyser were presented.Descriptions of the various equipment used
to eliminate
64
or minimize sample preparation for many differentsample types
were included. New data handling systemswith customized software
are utilized in a stand aloneintegration system, a personal
computer or as an on-board function of the Antek Analyzers. All of
thesesystems can be used in both manual and autosamplermodes.
The ability to analyse solids, liquids, and gases by using
asingle pyrotube configuration is highlighted. Also a newmore
efficient inlet oven for solid materials will bedescribed.
Data generated using a new autosampler for solidsmaterials and a
new gas sample injection system areincluded.
Examples of operational characteristics are illustrated toshow
peak integration flexibility, data archival, reportformats, quality
assurance measures and ease of use.
All system descriptions are accompanied by applicationdata
including measurement at ppb levels for bothnitrogen and sulphur.
Materials analysed include bothorganic and inorganic matrices such
as petroleumproducts, polyolefins, petrochemicals, and
agricuturalproducts.
The use of automated gravimetric techniques forenhanced
analytical precision
Brian G. Lightbody and Sally D. Dowling @mark
Corporation,Hopkinton, MA 0178)The use of automated equipment for
routine samplepreparation is growing, however, it is important
tomaintain a high level of control to maintain assayprecision.
Recent developments in automated works-tations have resulted in
capability to use an on-board 4-place analytical balance to monitor
the progress of thesample prep process. This paper discussed
severaltechniques built into the automated instrumentationwhich use
analytical balance results to help ensure theprecision and
integrity of the analytical process. Someexamples are as
follows:
(1) The use ofconcentrate weight to calculate and adda diluent
during automated dilutions.
(2) The use of sample weight to calculate and add aproportional
amount of solvent.
() The use of sample weight to calculate and add aproportional
amount of internal standard.
(4) The monitoring of the weight of all reagentadditions to
ensure adequate system performance.
-
Pittcon Abstracts (1991)
Continuous monitoring of personal exposure
Eirik Nordheim and Helge Nes*
(AluminiumindustriensMiljosekretariat, Sigurd Syrs gate 4, N-0273
Oslo 2, Norway;*Elkem Aluminium Mosjoen, P.O. Box 348, N-8651
Mosjoen,Norway)Industrial hygiene monitoring of personal exposure
istraditionally carried out with sampling equipment likefilters,
impinger or adsorbent tube connected to asampling pump or
alternatively spot sample with hand-held adsorbent tubes. The
latter type gives a crudeestimate of short-time exposure while the
first type givesan average exposure over the time period measured.
Inaddition the result of the measurement is quite often
notavailable for some time due to time-consuming labora-tory
analysis. For some specific applications directreading instruments
or dosimeters are now available, butmost of them do still have a
fairly limited application dueto lack of continuous recording
capacity.
Recently, lightweight dataloggers which are batteryoperated and
with large datastorage capacity havestarted appearing on the
market. These are flexibleinstruments with several input ports and
capable ofrecording signals from a wide variety of sensors.
In the Norwegian aluminium industry the authors haveover the
last years tested out the use of a specificdatalogger with 42 K
storage capacity and 16 channels.This has been used together with
sensors for CO, SO2,respirable dust, static magnetic fields, body
vibration,body temperature, pulse, skin temperature etc.
For most of these factors recordings have been made atone second
intervals over an 8-hour shift period, giving acontinuous record of
exposure during a work period. Thedatalogger will thus give
information about averageexposure over a selected time period and,
since time isalso recorded continuously, be able to show
short-timehigh exposure peaks with exact time when these
occurred.For the purpose of health related monitoring these
areoften of more interest than the 8-hour average exposure.
The datalogger is connected to a PC after use for transferof
data, complete printout and graphical presentation.This can be done
immediately after the measurement isfinished. The operator who has
carried the equipment,may be given a graph showing his exposure
that daywhile he is still at work.
This lecture gave a complete description to the equip-ment,
together with examples from actual monitoring inaluminium smelters,
and also discussed the advantages ofthis type of monitoring in
relation to employee health.
Laboratory automation occurring at municipalwastewater treatment
plants
Gregory A. Zelinka (Madison Metropolitan Sewerage District,1610
Moorland Road, Madison, WI 53713)Because of operational, liability,
or permit requirements,today’s municipal wastewater treatment
plants arerequired to analyse a variety of sample matrices for
a
complex set ofchemical and biological parameters. Thesematrices
include: soil, plant tissue, ground water, surfacewater, and
industrial wastes, as well as the moretraditional municipal
wastewater and sludges. Thechemical parameters involve nutrients,
metals, andorganics, many existing at concentrations equal to
orbelow current method detection limits. To meet thesenew and
changing demands as well as keep up with theever increasing sample
load, it had become necessry forwastewater treatment plants to
automate as much of theroutine chemistry as possible. This paper
discussed one ofthe ways Madison Metropolitan Sewerage District
hasattempted to automate its analytical workload.
One of the major areas intially examined was automatingour
solids and nitrogen procedures. Measurements forsolids have been
enhanced by coupling an electronicbalance to a PC-based
spreadsheet. This has reduced thetedium of recording weighings by
hand, sped-up thecalculations, and minimized the data handling
errors.Nitrogen (NH3 & TKN) analyses have been automatedby
switching analytical methods from a Macro Kjeldahlmethod to a
Semi-Automated method utilizing anAutoanalyzer. This has not only
saved analytical time,but also energy and reagents as well.
A second area examined was the addition ofautosamplersand timers
to two of GCs, an IC, and an AA. Thisaddition has allowed these
instruments to operateunattended beyond regular working hours or
over theweekend.
Data acquisition is being accomplished by dedicated
PCsdistributed throughout the lab and through the use
ofstandardized data acquisition software. The authors arecurrently
able to track the analog output from AAs,Autoanalyzer, IC, and GCs
with a single vendor’ssoftware.
Data quantitation utilizes a series ofspecialized
programswritten in a compiled basic, which meets
specificquantitation requirements and allows for custom
reportgeneration.
Quality assurance data is either automatically extractedand
calculated (from the custom report format) or amanually entered
into a daily QA report which flagscontrol limit exceedances and
facilitates monthly andquarterly report summaries.
An automated, small-volume, block-digester pro-cedure for the
high-speed, simultaneous determi-nation of total Kjeldahl nitrogen
and total phosphor-us in water samples
Charles J. Patton (U.S. Geological Survey, National WaterQuality
Laboratory, 5293 Ward Road, Arvada, CO 80002)About 20 000 surface
and ground water samples areanalysed for total Kjeldahl nitrogen
(TKN) and totalphosphorus (TP) at the US Geological Survey
National
65
-
Pittcon Abstracts (1991)
Water Quality Laboratory (NWQL) each year. Recentestimates
indicating that sample loads for TKN and TPwill double by 1993 have
spurred efforts to streamline allsteps of these lengthy and labor
intensive tests.Significant improvement in processing rates for
pre- andpost-digestion sample preparation, sample digestion,
anddetermination of ammonium and orthophosphate ions indiluted
digests have been achieved for these determi-nations relative to
current NWQL procedures.
The NWQL currently uses two different digestionprocedures- a
Kjeldahl, block digestion proceduresimilar to US Environmental
Protection Agency (EPA)method 351.2, and an acid/persulfate,
autoclave diges-tion procedure, similar to EPA method 365.1 for
TKNand TP determinations, respectively. By determining TPin TKN
digests, as per EPA method 365.4, samplepreparation time is halved.
Time required for thedigestion step was reduced from four hours to
one byhalving sample and reagent volumes as per Jirka et al.Using
syringe pump-based dispenser/diluter modules toautomate pre- and
post-digestion sample preparationpermits these operations to be
performed at rates ofabout100 samples hr-1, which is comparable to
the rates atwhich ammonium and orthophosphate ions in dilutedTKN
and TP digests can be determined using third-generation continuous
flow analysers.
In addition to increased production capacity, benefitsafforded
by this approach include decreased exposure ofanalysts to caustic
and toxic materials, lower reagent andreagent preparation costs,
and lower costs associatedwith proper disposal of caustic and toxic
wastes resultingfrom these tests.
Selecting a continuous flow analyser for the analysisof sludge
and industrial waste effluents
Shirley Arment and R. B. Roy (ALPKEM Corporation, 14625S.E. 82nd
Drive, Clackamas, OR 97015)
Both air segmented (e.g. AAII and RFA) and nonseg-mented (FIA)
continuous flow analysers are available forthe analysis of sludges
and industrial waste effluents. Inrecent years the originally
introduced CFA Technology,such as that of the AAII, have undergone
muchimprovement both in mechanical designs and incorpora-tion of
computer capabilities.
For instance, the RFA (Rapid Flow Analysis) system wasdevloped
to use glassware with reduced internal diam-eter, electronic timing
of the segmentation gas, peckingsampler and ’gated’ detector which
needs no debubblingof air in the flowcell. Thus, the system
provides fasterthroughput and low consumption of reagents, which
inturn, reduced the cost of reagent and waste disposal.
FIA (Flow Injection Analysis) systems have similarfeatures as
the RFA except the FIA does not require airbubbles to separate
samples. Both RFA and FIA haveimproved analytical performances in
comparison to AAII
66
systems. Unlike AAII systems, attainment of a steadystate to
analyse sample is not required in both RFA andFIA systems. Sample
analysis rates well over 100 samplesper hour are easily
achieved.
The advantages and limitations of continuous flowanalytical
systems which are currently used in municipalarid industrial
laboratories were presented. In addition,performance data which
will review design aspects ofALPKEM RFA systems, and, show
applications demon-strating their various capabilities for
environmentalanalysis were discussed.
Ammonia and total Kjeldahl nitrogen determi-nations using fast
distillations and gas diffusion
Bernard Bubnis (Novatek, 10 West Rose Avenue, Oxford,OH 45056),
andJurgen Moller (Tecator AB, Hoganas, Sweden)Automated procedures
for measuring ammonia and totalKjeldahl nitrogen (TKN) have been
comparativelytested against a currently accepted EPA method.
Three test procedures for measuring ammonia and TKNhave
undergone the Alternate Test Procedure (ATP)outlined in the
protocol of 20 June 1990. The methodsare: automated steam
distillation followed .bYNesslerization, automated steam
distillation with titri-metric detection and the automated Flow
InjectionAnalysis (FIA) gas diffusion procedure. All TKN meth-ods
used aluminium block digestion for samplepre-treatment.
Final effluent samples obtained from ten sites represent-ing the
top five SIC classifications for each parameterwere tested by each
of the three methods. Data indicatethat fast steam distillation
gives results which areaccurate and more precise than the accepted
method.Further, the steam distillation process proved to be
lesstime consuming and easier to operate even whencompared to the
ammonia electrode method.
The FIA gas diffusion procedure also showed improvedresults in
addition to having an ammonia methoddetection limit (MDL) of 0.01
mg/1. The automated FIAmethod was straight forward and
uncomplicated givingresults in 70 seconds.
Data for each of the procedures were presented. Themethod
approval process was discussed and outlined inrelation to the
submitted ammonia and TKNmethodologies.
Automated inorganic ion analyses for wastewater,sludge and stack
gas incineration
Aldo Conetta (Bran + Luebbe Analyzing Technologies, Inc.,
103Fairview Park Drive, Elmsford, NY 10523-1500)Both Federal and
State EPA Agencies are mandatingincreased analytical testing for
inorganic analytes.Knowing the level of contamination will often
dictate the
-
Pittcon Abstracts (1991)
best remedial action required for cleanup. The end resultis to
significantly reduce contamination to the nation’swaterways, soils
and air for a healthier environment.
There is no sample matrix that is immune from thesemandates,
and, as each year passes, the number oforganic and inorganic
analytes being added to thehazardous waste list is increasing. For
example, the USEPA Contact Laboratory Program has realized
anapproximately 500-fold increase in analytical testing inthe past
decade. In addition, there are approximately3000 private
laboratories involved in all aspects ofenvironmental testing.
Automation for the environmental laboratory
throughinstrumentation is the only alternative to meet
analyticaldemands and still maintain a favorable cost/benefit
ratio.Placements of such instrumentation have exceeded onebillion
dollars per year worldwide.
Analytical instrumentation- Analytical instrumentation canbe
categorized in many ways. However, with respect toenvironmental
analyses a logical approach would be asfollows:
Laboratory analysers
On-line process analyser
Stack gas analysers
The one common thread for each of these analysers isautomation.
A review of analytical instrumentationcurrently available, coupled
with specific applicationswas presented.
Fast automated multi-element elemental analysis ofsludges and
effluents using a new sequential atomicabsorption spectrometer
William Batie and A. E. Bernhard (Analyte Corp., 910 ChevyWay,
Medford, OR 97504)Over the past 10 years there has been a barrage
ofpublications and papers extolling the desirability ofmethods
alternative to Atomic Absorption Spectrometry(AAS) for the analysis
of metals in sludge and effluents.Despite this, and the advantage
of being essentially asingle element technique, AAS continues to be
widelyused for this application because of its simplicity
ofoperation and relative freedom from interferences com-pared to
emission techniques.
Attempts have been made to automate AA resulting inthe
capabilities of analysing up to eight elements in anumber of
samples, one element at a time. This meansthat the analysis of the
first sample of a group of samplesis not complete until the last
sample has been analysed.In addition, 8 elements are insufficient
for this appli-cation, requiring operator intervention to change
HCLs.
A new AA spectrometer, the ANALYTE 16, providesfully automatic
analysis of up to 24 elements in a single
pass on a sample at the rate of 10 elements per minute.This is
achieved through use ofa 16 hollow cathode lamp(HCL) turret which
selects elements, one at a time, with aspeed of second. During the
time the carousel isselecting a new HCL, the grating drives to the
properwavelength and the bandwidth is changed appropriately.
This novel instrument, and its use and capabilities for
fastautomated analysis of sludges and effluents, werediscussed.
Automated air analysis of volatile organic com-pounds on a new
intermediate polar phase
R. P. M. Dooper, D. Zwiep (Chrompack Inc., 1130 Route
202,Raritan, NJ 08869); and H.J. Th. Bloemen (National
InstituteofPublic Health and Environmental Protection, P. O. Box 1,
3720BA Bilthoven, The Netherlands)In recent years interest in air
analysis has grown rapidly,especially for such volatile organics as
ozone precursors.Automation of these analyses, usually done by
capillarygas chromatography, is possible nowadays. To improvethe
reliability of these analyses, identification of thecompounds of
interest on two columns with differentstationary phases often used.
The most commonly usedstationary phase is a 100% polymethyl
silicone phase.
The best choice of a second column is one with a polaritybetween
5% phenyl/95% methyl silicone and an OV-17type of phase.
This new phase has been developed. The phase is highlyinert and
chemically bonded. Also, the phase is especiallyuseful in ECD
applications.
Automation of the USEPA’s contract laboratoryprogram
requirements of the determination of 15elements in a variety of
environmental samples byinductively coupled Plasma Optical
EmissionSpectrometry (ICP-OES)
Geoff Tyler, Flay Finotello and Tran Nham (Varian
OpticalSpectroscopy Instruments, 201 Hansen Court, Suite 108,
WoodDale, IL 60191)
The requirement for strict quality control and qualityassurance
in the analysis ofenvironmental samples is nowwell established and
fully documented by theEnvironmental Protection Agency (EPA)
ContractLaboratory Program (CLP). This need to ensure thevalidity
and security of analytical data has increased thenumber of quality
control test solutions required to beanalysed.
This paper presented a Quality Control Protocol (QCP)software
package designed for automation of sampleanalysis, QC testing,
implementation of QC test failureactions and results reporting
conforming to USEPA’s
67
-
Pittcon Abstracts (1991)
CLP requirements for ICP-OES. Comparison of detec-tion and
interference data with EPA recommendationsshows that the package is
applicable to a variety ofenvironmental samples including
wastewaters, potablewaters, effluents and acid rain. Alternative
elementalwavelengths providing higher analytical performance
isrecommended. The screening of sulphur in environmen-tal samples
ICP-OES was also proposed.
Analytical performance of an automatic samplepreparation system
for atomic absorptionspectrophotometry
,James A. Gaunt (Department of Civil and
ConstructionEngineering, 123 Town Engineering Building, Iowa
StateUniversity, Ames, IA 50011)Preparation of samples for analysis
by atomic absorptionspectrophotometry (AAS) frequently requires
dilution,addition of matrix modifiers, and preparation of a rangeof
calibration standards. Use of an automatic samplepreparation system
(prep station) can significantlydecrease the time required for
these activities.
The subject of this investigation was a PS-150 PrepStation used
with an ISC-150 Intelligent SampleChanger and a TJA Smith-Hieftje
12 AA/AESpectrophotometer (all components supplied by ThermoJarrell
Ash Corporation, 8 E. Forge Parkway, Franklin,MA 02038). Soon after
the PS-150 Prep Station wasplaced in routine service, a quality
assurance auditsuggested that a study of the analytical performance
ofthe prep station would be appropriate.
The gross volumetric accuracy of the prep station wastested by
weighing distilled water delivered into taredsample tubes using the
following protocol: 2"0 ml sampleuptake (SU), 1"0 ml matrix
modifier (MM), 5"0 ml finalvolume (FV). The average weight
delivered was 4.9900 g(s 0"0131, RSD 0"263%, N 12).
The sample dilution and matrix modifier and matrixmodifier
functions were tested by using known concen-trations of Cu++ as the
’sample’ or the ’matrix modifier’in several different protocols so
that the preparedsolutions should have contained exactly 0"500
mg/1. Sixreplicates of each solution were prepared and
subse-quently analysed using flame AAS. Recoveries of Cu++were
between 99% adn 102% for dilution ratios of 2x,5 x, 10 x and 20 x.
A matrix modifier dilution ratio of50x(SU=2.0, MM=0.1, FV 5.0 ml
resulted in a recoveryof 108% (0"538 mg/1 Cu++).
The standard preparation function was tested by prepar-ing six
replicate sets of standards for both Ca++ and
++Cu using the prep station and analysing them by flameAAS
calibrated with manually prepared standards. Theresults were as
follows:
Theo. mg/l Ca 2"00 4"00 6"00 8.00 10"00Mean 2"72 4"62 6’83 8’82
10"83
0"06 0"27 0"29 0"38 0"42Recovery (%) 136 116 114 110 108Dilution
ratio 50x 25x 16"7x 12.5x 10x
68
Theo. mg/1 Cu 0"200 0"400 0’600 0"800 1"000Mean 0"200 0"405
0"637 0’881
0"001 0’004 0’003 0"009 0"003Recovery (%) 100 101 106 110
103Dilution ratio 50x 25x 16"7x 12"5x 10x
The PS-150 Prep Station is a statisfactory instrument
forpreparing samples for analysis by AAS provided that thedilution
ratio of sample or matrix modifier is not greaterthan 20x (i.e.,
uptake 0"3 ml, final volume 6’0 ml).However, it does not appear to
be a reliable instrumentfor preparing calibration standards.
Automatic continuous on-line analysis of haloformsin drinking
water using process GC with electroncapture detection
Matthew Przybyciel (ES Industries, 8 S. Maple Avenue,Marlton, NJ
08053)Haloforms have been shown to be chlorination by-products of
municipal water supplies. Possible haloformcontamination have
raised concerns over drinking waterquality and has left to
increased manual sampling foranalysis. Unfortunately, manual
sampling may not occurat frequent enough intervals to detect
problems. Inaddition, manual sampling is extremely labour
intensiveand is prone to operator error.
The continuous automatic analysis ofwater using processGC with
flame ionization detection has been commer-cially available for
several years. The detection for manyhaloforms are in the 5-20 ppb
range using this type ofinstrumentation. The levels are achieved
using a con-tinuous sparging technique along with the process GC.
Inorder to achieve lower levels ofdetection for the haloformsusing
this type of instrumentation, electron capturedetection will be
required. Historically, electron capturedetectors have not been
stable or reliable enough for usein continuous automated
instrumentation, however, theelectron capture detector used in this
study has beenspecially adopted for use in continuous
operation.
In this paper the continuous detection of the haloforms atlevels
less than ppb was shown. In addition, long termstability,
reproducibility, cycle time and reliability of theinstrumentation
was discussed.
Automated pre- and post-column reaction/detectionsystems in
column liquid chromatography andcapillary gas chromatography
H. Lingeman, U. A. Th. Brinkman and E. A. Hogendoorn2(Department
of Analytical Chemistry, Free University, DeBoelelaan 1083, 1081 HV
Amsterdam, The Netherlands;2National Institute of Public Health and
EnvironmentalProtection, P.O. Box 1, 3720 BA Bilthoven, The
Netherlands)In spite of the fact that column liquid
chromatography(CLC) and capillary gas chromatography (CGC)
are(becoming) mature analytical techniques, selectivity and
-
Pittcon Abstracts (1991)
sensitivity are still not always sufficient when solutes
inrelatively complex matrices (e.g. biological, environmen-tal,
food and fodder) should be determined. One of thepossibilities to
overcome this limitation is the use of achemical reaction/detection
(derivatization) procedure.These reactions can be performed in
several modes:before, during and after the separation and in an
on-lineand off-line mode with CLC.
However, for routine analyses automation is one of thekey
parameters, which means that on-line methods arepreferred over
time-consuming and laborious off-lineprocedures.
Nowadays, a number of sample processors andcontinuous-flow
systems are available allowing the auto-mation of pre- as well as
post-column reaction/detectionand sample preparation
techniques.
In this presentation the automated pre-column phase-transfer
catalysed dansylation of phenolic steroids inplasma using a Model
231-401 sample processor, theautomated on-line pre-column dialysis
and concentra-tion of benzodiazepine containing samples using
acontinuous-flow system (ASTED), the combination ofanon-line
post-column derivatization and on-line pre-column dialysis
procedure of the determination ofsulfonamides in food products, and
a clean-up anddetection system for the determination ofpolar
pesticidesin aqueous samples using automated (ASPEC)
ion-pairderivatization with pentafluorbenzylbromide and capill-ary
gas chromatography with electrochemical detectionwas discussed.
Analytical variables (e.g. reproducibility,
repeatability,throughput, detection limits) of the different
methodswere compared.
On-line analysis of moving solids by transientinfrared
spectroscopy
Roger Jones and John McClelland (Center for AdvancedTechnology
Development and Ames Laboratory-USDOE, IowaState University, Ames,
IA 50011)
Industry requires methods to quantitatively and
non-destructively analyse solid materials in real time as theymove
along a production line. Transient InfraredSpectroscopy (TIRS) can
provide such analyses. InTIRS a thin layer of the sample material
is transientlyheated or cooled, usually by a gas jet, as it passes
throughthe field ofview of an infrared spectrometer. This
surfacelayer is spectroscopically different from the bulk of
thematerial, and it may be analysed separately from thebulk. If the
layer is heated, it acts as a thin emissionsource with much less
self-absorption than is characteris-tic of thick emission sources.
If the layer is cooled, it actsas a thin absorption sample through
which blackbodyemission from the bulk of the sample passes on its
way tothe spectrometer. In both cases, the layer is thin enoughthat
saturation is reduced sufficiently for quantitativeanalysis.
A protype industrial-site instrument is presently beingdeveloped
for on-site test and demonstration. It is basedon a Bomem MB-100
FTIR spectrometer fitted withspecial sampling optics. A commercial
hot-air tool with amodified nozzle is used as the surface-heating
source. Theproperties and performance of the prototype
werediscussed.
Laboratory results demonstrating some of the specialproperties
of TIRS were also covered. TIRS can be donewith only moderately hot
(below 100 C) or cold (above-50 C) gas jets, as long as the heating
or cooling is rapidenough to create a suitably thin transient
layer. Theperformance at various jet temperatures will be
pre-sented. As the figure below demonstrates, the morpho-logy of
non-isotropic materials can be determined byusing
polarization-sensitive detection. Depth profilingcan be performed
by controlling the thickness of thethermally altered layer at the
time of observation. Thefreedom ofTIRS from interference effects
(fringes) whenthe sample material is thin and has parallel sides
was alsoshown.
Determination of vitamin C content in pharaceuti-cals via
flow-injection chemiluminescence detection
John Vicars and Chu-Ngi Ho (Department of Chemistry, Box
23,350A, East Tennessee State University,Johnson City,
TN37614)Because of the nutritive and other perceived health valueof
vitamin C, commercial sources of the vitamin arenumerous and
availability abundant. Because of itsimportance, many methods have
been developed for thedetermination ofvitamin C in all sorts
ofsamples rangingfrom pharmaceuticals, agricultural and food
products tobiological fluids. The methods include classical
titri-metry, ultra-violet and visible absorption,
luminescencespectrometry and high performance liquid
chromato-graphic separation.
The authors have developed and implemented a simpleand rapid
flow injection system coupled with chemi-luminescence (CL)
detection to analyse pharmaceuticalsamples for the amount of
vitamin C present. The CLsystem utilized is that of peroxyoxalate
employingbis(trichlorophenyl)peroxyoxalate (TCPO). The vitaminC in
different samples is reacted with a given fixedamount ofhydrogen
peroxide in the presence ofCu(II) ascatalyst. Imidazole which
catalyses the CL reaction isadded to the solution. The excess
hydrogen peroxide canthen react with TCPO to produce the CL using
peryleneas fluorophore. The TCPO and perylene are premixedand
pumped into a flow system. The vitamin C andexcess hydrogen
peroxide incubation mixture is injectedthrough a 20 btl Rheodyne
injector loop into the flowstream. The reaction to produce CL takes
place in theflow and the signal is detected in a homemade flow
cellplaced in front of a photomultiplier tube. The TCPO andperylene
are made in methylacetate while the reactionmixture is entirely
aqueous. There does not seem to beany mixing problem at all. In
this presentation, the
69
-
Pittcon Abstracts (1991)
procedure, optimization of the solvents used, flow rate,and
concentration of different reagents, data and theresults obtained
were discussed.
Extending the capabilities of flame atomic absorp-tion
spectrometry with on-line sample treatment
S. R. Bysouth, J. F. Tyson, E. Debrah, T.J. Gluodenis andR. M.
Larue (Department of Chemistry, University ofMassachusetts,
Amherst, MA 01003)
Many of the limitations to the performance of flameatomic
absorption spectrometry (FAAS) can beaccounted for by (a)
shortcomings in the nebulization andatomization processes and (b)
interference effects due tomatrix components. For a number of
years, research inthe authors’ group has been directed towards
overcomingthese limitations by the use of continuous-flow and
flowinjection procedures ofsample handling. Three uses havebeen
made of these techniques: (i) separation of theanalyte from its
matrix, (ii) preconcentration of theanalyte and (iii) generation of
volatile analyte species.Examples of recent work in each of these
areas werepresented to illustrate the potential of on-line,
sampletreatment procedures. The determination of trace ele-ments in
silver as silver chloride with on-line filtrationprovides an
example of the first procedure where thematrix is removed. The
alternative version of this system,where the analyte is
precipitated, was demonstrated forthe on-line preconcentration of
copper as the hydroxideas an example of the second procedure.
On-line gener-ation of a volatile metal complex where the complex
issubsequently extracted into supercritical or liquid carbondioxide
before direct introduction to the atomizerinvolves all three
procedures. Vaporization of the carbondioxide carrier stream can be
achieved using a simpleheated restrictor. This device has been
shown to producecalibration curves with sensitivities comparable to
thatobtained with continuous nebulization, when only 20of a
solution of the complex in a solvent is injected.Results of the
investigation of the separation of thecomplex from the aqueous
phase by solid phase extrac-tion or precipitation followed by
re-dissolution in carbondioxide and direct liquid-liquid extraction
werepresented.
The extension of such procedures for use in conjunctionwith
electrothermal atomization AAS were alsodiscussed.
Method studies in ambient air analyses
Dick Siscanaw (US EPA, Region 1 Laboratory, 60 Westview
St.,Lexington, MA 02173); Hui Wang and Delon Maas (Roy F.Weston,
Inc., Landmark One, 1 Van de Graaft Dr., Burlington,MA 01803)In
environmental laboratories, most of the work hashistorically been
water, soil, and drum samples. Now
7O
measurements for organic air toxics are increasinglybeing
requested. The authors’ load has more thandoubled in the past three
years. For air, the laboratoryfaces a variety of situations which
have different dataquality objectives and require different
methodologies.For example, an emergency is treated differently from
anambient air study at a superfund site.
Five years ago, most of the authors’ air analyses were
foremergencies and an occasional site investigation. Theportable
gas chromatograph was used approximately90% of the time. The
remaining techniques were theTedlar bags, color detector tubes, and
NIOSH methods.These techniques are still used today. The
practicalquantitation levels (PQLs) ranged from 10 ppb for
thevolatile aromatics to ppm. This was relatively high forsome
ambient site investigations.
In 1986, Region started measuring the volatile organicsusing the
Spherocarb and Tenax solid adsorbents, EPAmethods T01 and T02. A
measured volume of air isdrawn through the trap, typically 5-20 1,
which is laterthermally desorbed into the gas
chromatograph/massspectrometer (GC/MS). Our PQLs dropped by 50
ppt.Last year, the laboratory expanded its air program toinclude
the SUMMA passivated canister, EPA methodT014. In this method, 500
ml is drawn into the GC/MS.for analysis. QLs for the canister is
approximately2 ppb.
This presentation focused on experiences with thesemethods and
the modifications made. The subjectsincluded are field analyses and
screening, varioussamplers (sector sampler), quality control
(replicates,back-up, and distributive samples), cleaning
apparatus,and the preparation of our standards.
Automatic perimeter monitoring ofairborne organiccompounds at a
superfund remediation site utilizinga gas chromatograph equipped
with a multipointsampling system
Amos Linenberg (Sentex Sensing Technology Inc., 553 BroadAvenue,
Ridgefield, NJ 07657)Since the US National Priority list for the
clean-up of thenation’s most highly contaminated sites has been
created,EPA has established funding priorities and made
theadvancement of sites to the construction phase a maingoal of the
EPA Superfund Program.
Many of thse sites are located near residential areas,therefore,
it is necessary to determine the identity andquantity of the
pollutants that escape the confines of theremediation site.
Usually, this is accomplished byobtaining samples at various
locations along the peri-meter of the site and transporting the
samples to a centrallaboratory for analysis. This procedure is time
consum-ing, and often leads to inaccurate results due to loss
ofsample during transportation.
-
Pittcon Abstracts (1991)
A monitoring system based on an automatic multipointhas
chromatograph has been installed at a landfill, whichis ranked
among the top Superfund sites on the NationalPriority list.
This system automatically draws ambient air samplesfrom 16
different sampling points along the perimeter,injects each sample
into the gas chromatograph, performsthe analysis, and stores the
data on a computer disk. Thefrequency and order in which each site
is sampled isoperator controlled.
A specially developed software program enables theoperation of
the system, as well as obtaining parametersand retrieval of data
from a remote location through theuse of a second computer and a
modem.
The description of the operation of the system, its
set-up,configuration and performance was discussed.
Alternate sampling strategies for ICP-MS
R. C. Hutton, D. Gregson (VG Elemental Limited, Ion Path,Road
Three, Winsford, Cheshire CW7 3BX, UK); W. Vogel,J. D. Steiner, A.
Eastgate (ARL, En Vallaire, CH-1024Ecublens, Switzerland)The
analytical potentials ofICP-MS have been expandedby the capability
of utilizing a variety of sampleintroduction techniques. To date in
commercial terms,both laser ablation and electrothermal
vaporization areavailable.
There are, however, still many other sampling techniqueswhich
can further enhance analysis by ICP-MS. Save forthe use of
ultrasonics, the solutions nebulizer has notundergone any
significant technical advancement, yetthis area is a key to
analytical performance.
A nebulization system which effectively removes 99% ofall
solvent and enhances ICP-MS sensitivity by up to 40 xhas been
developed. The applications for this device forthe analysis of high
purity reagents will be discussed.
Analysis of metal samples can be carried out byLA-ICP-MS.
However, there are application areas wherelaser technology may be
too sophisticated and expensive.Preliminary results from the
coupling of a conductivesolids nebulizer customized for ICP-MS was
described.In particular, the performance in a metals process
controlenvironment was evaluated.
Automated analysis of industrial waste effluentsusing
photo-oxidation with ultraviolet radiation
R. B. Roy, John Swanson and Shirley Arment (ALPKEMCorporation,
14625 S.E. 82nd Drive, Clackamas, OR 97015)Industrial waste
effluents are analysed to (i) determinethe compliance of
wastewaters, (ii) estimate the toxiceffects ofwaste discharges, and
(iii) evaluate the pretreat-ment requirements for reuse of
water.
Most frequently, organic carbon, chemical oxygendemand,
nitrogen, phosphorous, cyanide and chromiumare determined in a wide
variety of industrial wasteeffluents. For the measurement of these
parameters,samples are oxidized using either wet chemical
oxidationsor ultraviolet-promoted photo-oxidation procedures.
Theresulting breakdown products, such CO2 and NH3, aredetermined to
establish organic carbon and nitrogencontents, respectively,
present in the samples.
The ultraviolet-promoted oxidations are simple andavoid problems
which are associated with wet chemicaloxidations and combustion
procedures. Photo-oxidationprocedures are also used to clean up
colored samples forthe measurement of metal ions.
In this presentation, the application of
UV-promotedphoto-oxidation procedures used for the measurement
oforganic and inorganic materials present in a wide varietyofwaste
effluents were highlighted. In addition, selectionof experimental
conditions, interferences encounteredand their elimination were
presented.
Automated analysis of reducing sugars in fermen-tation broth
R. B. Roy, Shirley Arment and John Swanson (ALPKEMCorporation,
14625 S.E. 82nd Drive, Clackamas, OR 97015)
Various sugars, molasses and corn syrups are used ascarbon
source for the growth ofmicroorganisms in a widevariety of
industrial fermentation processes. Measure-ment of reducing sugars
ensures the microbial growthand product formation during the
operations ofindustrialfermenters.
The fermentation broth consists of insoluble, gelatinousbiomass,
the nutrient fluid, and the soluble metabolitesresulting from the
fermentation operation. Due to thepresence of polysaccharide
materials in biomass, thefermentation broths are, usually, viscous
and sticky.Samples are diluted as filtered prior to analysis.
Usually, manual colorimetric, liquid and gas chromato-graphic
procedures are used for the determination ofreducing sugars from
fermentation broths. For rapid andreliable analysis of reducing
sugars, an automatedmethod using an ALPKEM RFA system was
developed.Samples are dialysed and the dialysates are reacted
withalkaline potassium ferricyanide. The decrease in ab-sorbance,
which is proportional to the amount ofreducing sugars, is measured
at 420 nm.
The results obtained using the RFA system compare wellwith
standard manual methods. The method is sensitiveand can be used to
determine reducing sugar content of awide variety of fermentation
broths. In addition, theprocedure developed has the potential for
on-line moni-toring of reducing sugar contents present in
fermentersand/or bioreactors. Thus, ALPKEM RFA system could
71
-
Pittcon Abstracts 1991)
be used as a part ofclosed loop system in which the outputfrom
the analyser could be used to automatically controlreducing sugar
variations in fermenters. Technical detailsneeded in the
transportation of samples to the RFAsystem were also discussed.
Total cyanide analysis by manual standard methodsand automated
Kelada method, comparative studyand data evaluation
Nabih P. Kelada (Head of Methodology & Toxic
Substances,Metropolitan Water Reclamation District of Greater
Chicago);R & D Egan (550 S. Meacham Rd., Schaumburg, IL
60193);and Cecil Lue-Hing (Director of R & D Dept.,
MetropolitanWater Reclamation Distriuct of Greater Chicago)An
automated method for total cyanide has beendeveloped (20
samples/h). In addition to the Bran Lube(Technicon Industrial
Systems) AutoAnalyzer IImodules for segmented flow, the system
utilized two newautomated units, for ultraviolet (UV) irradiation
and forcontinuous thin film distillation. The UV irradiation
isperformed in alkaline medium and Pyrex sample coil,thus the
strong cyanide complexes (Fe and Co) areeffectively broken down and
measured colorimetrically,but not thiocyanate.
The automated Kelada Method is making good progressfor
acceptance by the American Society for Testing andMaterials (ASTM).
The round robin study for per-formance evaluation has been
completed successfully andgave about 5% coefficient of variation,
and 90-100%spike recovery for most sample matrixes. The method,
asfound by the participants, is applicable to water,wastewater
(effluent, raw sewage and sludge) andindustrial discharges.
Eventually this method will replacethe present ASTM D-4374 for
automated total cyanide.
The present USEPA approved Method 335-2 (same asStandard Method
412-B and ASTM D-2036-A) is timeconsuming ( 11/2 h/sample), has
wide variability andfrequently subjected to thiocyanate
interference. An indepth study was conducted to compare the
manualapproved method with this auomated method. Samplesanalysed
were collected from sewage treatment plants(for National Discharge
Elimination System, NPDES),and other cases as stated by regulations
40 CFR(aluminum forming, coil coating, electroplating, organicand
inorganic chemicals, iron and steel, metal manufac-turing and
powders, and petroleum industries). Spikesincluded simple and
strong complex cyanides (100-5,000zg/1). Results obtained by both
methods show that theyare comparable. However, other than being
free fromthiocyanate interference, the automated Kelada
Methodconsistently gave far better detection limit (0.5
btg/1),precision, accuracy and spike recovery. Representativedata
were presented.
72
Water quality control via on-line total organiccarbon
determination
Steve H. Vien, Connie M. Courtney, Walt W. Henslee, andJohn M.
Leach (Dow Chemical USA, Analytical & EngineeringSciences,
Freeport, TX 77541)The analysis of total organic carbon (TOC) is
importantto assess the water quality in a water treatment
facilityand in chemical processes which do not tolerate highorganic
content. In addition, TOC analysis of theincoming stream in a water
treatment plant helps pro-tect microorganisms from organic shock. A
compositesampling technique followed by laboratory analysis
ofthedaily composite sample is commonly used. This methodis
generally too slow to respond to plant upsets.
An on-line TOC analyser has been recently evaluated inthe
authors’ laboratory and on a process stream. Thisinstrument makes
use of the low temperature catalytic airoxidation process to
oxidize organics. The instrumentfeatures a unique variable sample
volume injection andmulti-ranging system which eliminates the need
forsample dilution. Sampling cycles for as short as 3 minutescan be
achieved. The principle of operation, analyticalperformance of the
instrument, and the results of fieldapplications were
presented.
An automatic method to measure agglomerated anddispersed
particle size and size distribution
Jason Ruan (Reichhold Chemicals, Inc. P.O. Drawer ’K’, Dover,DE
19903)
Dozens of methods for measuring particle size distribu-tion
(PSD) have been developed in the past decades.Among them,
microscopic techniques are still the mostreliable and are the
industry standard. The drawback ofthese techniques, however, is
that they are slow andtedious. Though much progress has been made
since theadvent of the image analyser, they have not
beensuccessfully applied to resolve agglomerated particles.Even the
very sophisticated systems with the de-agglomeration feature can
only analyse very narrowdistribution and barely touching
particles.
A method has been developed for measuring agglomer-ated, as well
as dispersed, PSD from electron micro-graphs. The chord lengths of
horizontal lines scannedthrough the micrographs are measured. The
chorddistribution is converted to PSD as if all particles
weredeagglomerated. A mathematical procedure has beenderived for
converting chord distribution, g(1), to PSD,F(x). Non-linear
Gaussian regression curve fitting wasalso applied.
The technique has been verified by computer simulationand
implemented on a variety of latex samples. They allshow that this
technique gives excellent representation ofthe actual particle size
distribution. The whole process iscompletely automated and takes
less than a minuteinstead of several hours. This method is
specially
-
Pittcon Abstracts (1991)
designed to resolve agglomerated particles, but it is
alsoapplicable to micrographs offracture surface for the core-shell
structure and/or solid foam analysis.
Automated sample handling and quantitation inlubricant
analysis
Jay R. Powell and David A. C. Compton (Bio-Rad, DigilabDivision,
237 Putnam Ave., Cambridge, MA 02139)The analysis of lubrication
oils for wear metals by atomicspectroscopy and oil additive
depletion, breakdown andcontamination by infrared spectroscopy has
been a longestablished technique in this field. The analysis of
wearmetals by atomic spectroscopy lends itself to automationeasily
because oftwo major factors. First, the quantitativeanalysis is
relatively simple, because atomic absor.ption ofa given metal will
most often follow a linear Beer’s law fit,or an easily corrected
deviation. Second, the relativelyviscous oil can be easily diluted
with a solvent such askerosene in order to permit aspiration into
the flame orplasma, with the dilution ratio determined by the use
ofan internal standard. By contrast, creating an automatedsystem
for the analysis of lubricants by infrared spec-troscopy has been
much more difficult. Quantitativeanalysis of these fluids is
complicated, due to the complexnature of these fluids in terms of
both the number ofcomponents and interactions between all the
compo-nents. Recent advances in multivariate quantitativetechniques
has some promise in overcoming thesedifficulties. In addition,
sample handling is complicatedby the fact that no dilution solvent
exists that is soluble inthe oil and is infrared inactive. This
requires that thesample be transported neat to the sample cell,
with a non-interfering solvent used to clean the cell and
transportsystem between samples. Here, the design of an auto-mated
infrared lubricant analysis system was discussed,dealing with both
a comparison of classical quantitativetechniques to multivariate
techniques, and how compo-nent architecture can affect sample
handling and trans-port in a commercial system.
Designing optimized industrial process analysersfor closed loop
control
Hanno Kellner, Gerd Popp and Uwe Grummisch (Bran + LuebbeGmbH,
Postfach 1360, Werkstrasse 4, D 2000, Norderstedt,Germany)
Until now the day-to-day application of near infra-redhas been
primarily focused on laboratory and ’at-line’analysis. However, the
benefits of this technology aremost dramatically realized when the
analysis takes placedirectly in the process line.
Process conditions vary from explosion proof environ-ments in
the chemical industry to clean-in-place environ-ments in the food
and pharmaceutical industries.Therefore, installation of near
infra-red analysersrequires optimization of both the analyser
design and the
sampling interface. Different approaches will be dis-cussed
including filter based systems and fiber opticbased scanning
systems.
Full closed loop process control is achievable when
thisanalysing approach is combined with precision dosingsystems,
weighing electronics and process control units.Real world examples
from various types of industry wereincluded in the paper.
On-line multiparameter process analysis utilizingflow injection
procedures
Paul Karges and Karl G. Schick (EppendorfNorth America, Inc.,545
Science Drive, Madison, WI 53711)Process analysers must be rugged
and dependable.Versatility is usually not as important.
Sometimes,however, novel chemistries can be combined with
appro-priate hardware to satisfy the requirements for rugged-ness
and yet are simple enough so that two parameterscan be measured
dependably. Two multi-parameter FlowInjection Analysis (FIA)
methods were described, both ofwhich use a single wavelength
colorimetric detector and asingle manifold.
The first application determines acidity (up to 25 ppmHC1) and
basicity (to 40 ppm KOH) of a complexorganic matrix, 70% of which
is toluene. Bromocresolpurple indicator dissolved in 1-butanol is
used as thecarrier. A colorimeter operating at 600 nm is used as
thedetector. When the carrier is properly adjusted, anincrease in
the carrier absorbance is proportional to theconcentration
ofpotassium hydroxide while a decrease inabsorbance is proportional
to the concentration ofhydrochloric acid.
The second application consists of the measurement ofthe
concentration of zinc sulphite (0"1-6%) and sul-phuric acid (2-9%)
in a synthetic fibers plant. For thisapplication the normal FIA
mixing coil is replaced withan exponential dilution chamber
followed by a color-imeter operating at 540 nm. A three-way
solenoid valvealternatively switches between the zinc carrier,
whichconsists of xylenol orange dissolved in a mixed
buffersolution, and the acid carrier, which consists of the
samebuffer containing a methyl orange indicator.
An explanation of the exponential dilution chamber,along with a
description of how the technique ofelectronic dilution was used to
extend the range of thezinc sulphate analysis, was given.
Automated real-time response surface mapping forcontinuous flow
systems
Peter D. Wentzell and Nils G. Sundin (Trace Analysis
ResearchCentre, Department ofChemistry, Dalhousie University,
Halifax,Nova Scotia, Canada B3H 4J3)The development of continuous
flow methods of analysisoften requires the optimization ofnumerous
experimentalparameters. Because of the complex interactions
among
73
-
Pittcon Abstracts (1991)
these variables, empirical optimization strategies, such asthe
simplex method, are usually preferred when theprimary objective is
to obtain the optimal operatingconditions. If the objective is to
obtain a better under-standing of variable interactions, however,
systematicresponse surface mapping (i.e. response vs.
experimentalvariables) with an appropriate experimental design
ismore useful. One way to perform both of these tasksefficiently
and reliably is through the use of a computer-controlled continuous
flow apparatus. In this talk, theimplementation of a highly
automated continuous flowsystem constructed in our laboratory was
discussed.
One of the drawbacks to existing response surfacemethods is that
they are normally carried out off-line, i.e.after all experiments
are complete and the apparatus hasbeen shut down. While this
permits fairly comprehensivedata analysis, it eliminates any kind
of immediateexperimental feedback. The authors have
developedsoftware which allows three-dimensional response sur-face
maps to be viewed while the experiments are inprogress. This
provides some distinct advantages, par-ticularly for investigating
noisy, suspicious, or unusualregions of the surface. Also, since
the time lag betweenexperiments is small, conditions are more
reproducible.The details of this approach were illustrated through
itsapplication to a hydride generation/atomic absorptionsystem for
the determination of arsenic.
Response surface display methods employ several strat-egies, all
of which possess certain advantages whenapplied to experimental
systems. The most basic methodis the generation of ’stick plots’ in
which the data aredisplayed as vertical lines in a 2-dimensional
projection ofa 3-dimensional space. This has the advantage
ofproviding a true representation of the measurements, butgives a
poor perspective on the overall shape of thesurface and is not as
visually pleasing as the morecommon ’wire frame’ representations.
The generation ofwire frame surfaces or topographical maps requires
thatthe data be modelled however, and this always runs therisk of
imposing artificial structure on the data.Polynomial modeling and
triangulation with simple orcomplex interpolation are the most
common approachescurrently used. Because the ideal rnodeling
methoddepends on the nature of the chernical data set, theautomated
system developed in our lab makes a variety oftechniques available.
This permits more thorough exam-ination ofvariable interactions
while the experiment is inprogress. Methods for improving the
efficiency of themapping procedure through alternatives in
experimentaldesign have also been considered.
On-line process analyser for chemically boundnitrogen and sulfur
compounds
James S. Wreyford (Antek Instruments, Inc., 300 BammelWestfield
Road, Houston, TX 77090)Bench top analyses of nitrogen compounds by
pyro-chemiluminescent nitrogen specific detector and
sulfurcompounds by pyrofluorescent sulfur system have been
74
successfully utilized in various academic and
industriallaboratories for several years. The need for
on-linenitrogen and/or sulfur analyses in the industrial food
andchemical processing plants and refineries prompteddevelopment of
an on-line process system using con-tinuous flow and/or discreet
sampling techniques.
The analytical techniques, sensitivity, as well as linearityand
repeatability of response were discussed for water,liquid
hydrocarbons, and gas applications.
A new method for chromium determination inchrome-phosphate
treatment on aluminum surface
Richard F. Puchyr and Ravi Raja (American National CanCompany,
433 N. Northwest Highway, Barrington, IL 60010)The passivation of
the surface ofaluminum coils used forproduction of food cans is
crucial for good adhesionbetween the aluminum and the organic
coating applied tothe metal surface. A chrome-phosphate chemical
treat-ment is applied to aluminum coils for this purpose.Chromiun
content seems to be the most important factorthat determines the
adhesion.
There are methods using X-ray fluorescence spec-troscopy to
determine the amount of treatment onaluminum coils, but all require
known aluminum platestandards. There has not been an established
method todetermine the amount of chromium in the treatment onan
aluminum surface. Since different aluminum suppliersuse different
formulations, the same weight of treatmentfrom two suppliers may
not have the same chromiumcontent. Therefore, it is important that
there is a methodto determine the chromium content itselfwhen no
knownplate standards are available. Once the chromiumcontent is
known the chemical treatment levels canreadily be determined by any
supplier.
The authors have developed a method for this purpose.This method
uses a combination of atomic absorptionand direct reading emission
spectroscopic techniques.The method consists of removing the
treatment usinghydrochloric acid and determining the chromium
contentin the acid solution by an atomic absorption procedure.
Asmall amount of chromium in the aluminum that isusually removed
with the chromium treatment con-tributes to the chromium content
determined by AA. Acorrection for this is made by determining the
alloychemistry of the coil by a Direct Reader emissionspectrometer
and compensating for the chromium con-tribution from the alloy that
dissolved into the acidsolution.
As an offshoot of this method, the authors have alsoderived a
fast indirect method for determining the relativetreatment levels
on the aluminum coil by using a DirectReader emission spectrometer,
using known standards.
-
Pittcon Abstracts 1991)
The automation ofan atomic absorption spectometerfor on-stream
analysis of total iron in zinc sulphatesolutions
Michael Knowles, Fred Delles (Varian Optical
SectroscopyInstruments, 201 Hansen Court, Suite 108, Wood Dale,
IL60191); D. L. Hoobin (Vrian Pty. Ltd., 11-13 Palmer Court,Mount
Waverley, Victoria3071, Australia); B. R. Champion andM.J. Howell
(Pasminco Metals-EZ, GPO Box 377D, Hobart,Tasmania 7001,
Australia)
This paper described the design of an automated on-stream
analysis system for the determination of total ironin zinc sulphate
solutions. The Pasminco Metals-EZNeutral Leaching Plant removes
iron from zinc plantelectrolyte by leaching impure zinc oxide with
acidicspent electrolyte. An iron dosing solution is supplied tothe
plant to maintain the Fe(III) concentration at thedesired
level.
A fully automated system was described which isprogrammed to
periodically sample plant solution andprepare the sample for
analysis by an autotitrator forFe(II) and an atomic absorption
spectrometer (AAS) fortotal iron. The Fe(III) level is calculated
as the differenceand is used to control the flow ofiron dosing
solution. TheAAS has provision for user written software for
instru-ment control via a GP10 communications utility, whichhandles
up to 12 digital outputs and 14 digital inputs, 2RS232C ports and
an HP-GPIB port. An Opto 22 solidstate Input/Output (I/O) interface
was assembled toactivate the flame and the stream selector system
duringeach analysis.
Other I/Os synchronize and advise analyser status to
theplant-wide Taylor MOD 300 Distributed Control System(DCS).
Customized software had been prepared for theAAS system to control
the analysis and to allow theprogramming of additional VDU displays
and compu-tations and for the computed results to be sent to theMOD
300 DCS via an RS232C data link.
Aspects of the system design and implementation werediscussed,
including the software design approach, thedetails of the analysis
and aspects of interfacing andsafety.
Intelligent automated laboratory systems
H. M. Kingston, F. ’A. Settle,* M. A. Pleva,** P.J. Walter;G. W.
Krarner and L. B. Jassie (Consortium on AutomatedAnalytical
Laboratory Systems (CAALS), National Institute ofStandards and
Technology, Center for Analytical Chemistry,Inorganic Analytical
Research Division, Gaithersburg, MD20899; * Department of
Chemistry, Virginia Military Institute,Lexington, VA 24450; **
Department of Chemistry, Washingtonand Lee University, Lexington,
VA 24450)Industrial and government operations both dependheavily
upon the analytical laboratory for chemicalmeasurements. These
measurements provide criticalfeedback in research, acceptance
testing, environmental
quality, and quality assurance. The field of chemicalanalysis
has become instrument based and is now capableof being integrated
into an autoInated laboratoryenvironment. Integrating
instrumentation into analyticalsystems that automate complete
analyses is difficult dueto incompatibilities in hardware,
software, and sampletransport. Several key issues have been
identified that willhave a positive effect on the development
ofmore efficientinstrumentation in the automated laboratory.
Theseissues include instrument modularity, intelligence,
com-munication, and integration and must be addressed toprovide the
highest level of sophistication for thelaboratory.
The National Institute of Standards and Technology(NIST) has
,joined with US industry to form theConsortium on Automated
Analytical LaboratorySystems (CAALS). The Consortium seeks to
acceleratethe development of automated analysis methods andsystems,
to improve efficiency and data quality, and topromote
transferability of analytical methods.
The automated systems developed will integrate chemi-cal
analysis expertise (intelligence), provide recom-Inended methods
for utilizing modular analytical instru-mentation, and incorporate
quality assurance proceduresinto the automated methods.
The first component of the system, an automatedmicrowave
decomposition station, has been developed. Itcan be controlled by a
prototype expert system that isbeing developed to assist the
analyst in establishingprocedures for nicrowave dissolution. The
entire systemwill consist of three modula designed components.
Thesecomponents represent fundamental steps in inorganicanalysis,
specifically analysis release, separation anddetection. The
specific modules that will be combined toperform these functions
are microwave decomposition,chelation chromatography, and ICP-OES
and/or MS.The system was discussed emphasizing
intelligentcontrol.
Intelligent, automated laboratory systems
Frank A. Settle,,Jr (Department of Chemistry, Virginia
MilitaryInstitute, Lexington, VA 24450)
Although many laboratories have dmnonstrated that theautomation
of one or two steps of an analytical methodcan improve both the
quantity and quality of results, fewmethods have been totally
automated. Critical problemareas in implementing automated methods
are methoddevelopment and method validation. The resourcesrequired
for automation are often lacking in laboratorieswhere automation is
needed most. Once an automatedmethod has been validated it can be
transferred electron-ically among laboratories with identical
automationcomponents.
An intelligent laboratory system to expedite the
design,optimization, validation and transfer of automatedanalytical
methods was described. This system
75
-
Pittcon Abstracts (1991)
integrates existing software for experimental design,statistical
analysis, expert system development andlaboratory automation with
the components required forsample preparation and analyte
measurement. Althoughmost ofthe components are commercially
available, it hasbeen necessary to develop programs to facilitate
com-munication among components.
The hardware and software components should becompatible and
interchangeable to facilitate efficientconfiguration, optimization
and transfer of automatedmethods. The preliminary results from
colorimetricdeterminations oforthophosphates in water samples
werepresented.
This work was funded in part by NSF Grant #CHE-.8805930, Zymark
Corporation and a grant from the VMIFoundation.
Flow injection analysis of glutamate with a gluta-mate oxidase
reactor and acridinium ester chemi-luminescence detection
Maureen Stuever Kaltenbach and Mark A. Arnol