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Chern. Anal. (Warsaw), 46,305 (2001) REVIEW
MicrowaveInduced. Plasma Emission Spectrometryfor Environmental
Analysis. A Review*
by Krzysztof Jankowski
Department o/Analytical Chel11istry, Facultyo/Chemistry,
Technical University o/Warsaw,3 Noakowskiego Str., 00-664 Warszawa,
Poland
Key words: microwave induced plasma, environmental analysis,
speciation
Microwave induced plasma is included among the new generation of
spectrochemicalexcitation sources, which in therecent twenty years
considerably broadened the possibil-ities of trace analysis and
speciation studies. Analytical problemsconnected with
envi-ronmental control and protection are the main field of
applications ofatomic emissionspectrometry with the use ofmicrowave
plasma(MIP-AES). A critical evaluation oftheusability ofthe MIP-AES
method for multi-element analysis ofenvironmental samplesis
presented. The analytical performance of this method considering
various sample in-troduction techniques is shown. Examples of
application of microwave. plasma. in theanalysis ofspecific
environmental materials and also in speciation studies oftoxic
heavymetal compounds are described.
Mikrofalowo indukowana plazma jest zaliczana do
spektrochemicznych zr6del wzbu-dzenia nowej generacji, kt6re w
ostatnich dwudziestu latach znacznie poszerzyly mozli-wosci analizy
sladowej i badania specjacji.G16wnym obszarem zastosowan
emisyjnejspektrometri( atomowej z uzyciem plazmy mikrofalowej
(MIP-AES) s~ zagadnieniaanalityczne zwictzane z kontrol~ i ochron'l
srodowiska. Przedstawiono krytyczn~ ocen~przydatnosci metody
MIP-AES do analizy wielopierwiastkowej pr6bek srodowisko-wych.
Zaprezentowano charakterystyk~ analityczn~ tej metody uwzgl~dniaj~c
r6znetechniki wprowadzania pr6bek do plazmy. Opisano przyklady
zastosowania plazmymikrofalowejw analizie konkretnych materia16w
srodowiskowych, a takze w badaniachspecjacji toksycznych
zwi~zk6wmetali ci~zkich.
*Presented at the VI Polish Conference on Analytical Chemistry,
9-14 July, 2000, Gliwice, Poland.
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306 K. Jankowski
Atomic spectrOlTIetry based on absorption or emission of
electromagnetic radia-tion by the atomized sample or on
fluorescence are widely applied in environmentalstudies [1-3].
Among them, plasma atomic emission spectrometry plays an
importantrole. This method, due to high sensitivity and
specificity, and first of all versatilityand possibility of
multielement analysis, is one of the lTIOst effective methods
inchemical analysis. Due to the possibility of simultaneous
determination ofmany ele-lnents and efficiency reaching several
tens of determinations per hour, it is appropri-ate for monitoring
the environment. A broad linear dynamic range for a large numberof
elernents, enables silnultaneous determination of analytes at the
ultra and microtrace level. Plasma sources ar~ characterized by
high excitation efficiency, and atsame time by high stability,
which results in a very sensitive and precise
anal.yticalmethod.
Inductively coupled plasma atomic emission spectrometry
(ICP-AES) is knownas a reliable and rapid method for multielement
analysis, due to low detection limits,and appropriate, for the
determination of practically all elements in environmentalsamples
[4,5]. A different mechanism of the sample excitation
inmicrowaveplaslnabased on Penning ionization with argon or helium
metastables provides favorableconditions for the determination
ofnon-metals, such as sulfur, nitrogen, phosphorus,chlorine and
fluorine. In this sense ICP and MIP may be treated as
supplementingeach other. There are reports on devices equipped
simultaneously in both types ofplasma [6,7]. An important
disadvantage having an essential effect on the extent ofapplication
of lnicrowave plasma is the lack of commercially available
instrumentsequipped with this excitation source. An apparatus
ofHewlett-Packard in which MIPwas used as a universal and very
sensitive detector in gas chromatography is an ex-emption here
[8-11].
A great progress occurred in recent years in the field on
Inicrowave inducedplasma [12-14] .• With the' aid of MIP over 70
elements at the trace level (detectionlimit 0.1 to 1000 ppb) can be
determined. The ability to detect halogens at the ppblevel under
the conditions of chromatographic analysis is a unique feature of
heliummicrowave plasma in comparison to other types ofplasma.
Microwave plasma can besustained in various gases such as argon,
helium, nitrogen [15,16], air [16],oxygen[17], carbon dioxide [18],
both under normal as well as reduced pressure, whichbroadens the
possibility ofselecting appropriate measuring conditions and
permits toanalyze samples of various origin, both inorganic and
organic. The simplicity in de-sign ofMIP sources and low use
ofenergy and gas are decisive for the low apparatusand operating
costs ofMIP in comparison with other plasma excitation sources.
Analytical problems connected with the environment control and
protection arethe main field of applications of the atomic emission
spectrometry with microwaveplasma (MIP-AES). It finds application
in the analysis of air and drinking water, soiland sediments, and
also of biological materials. By selecting an appropriate
experi-Inental setup the MIP-AES can be utilized for the
determination ofthe total content ofelements in a sample [12],
identification and determination of various chemical
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Microwave induced plas111a emission spectroT11etry 307
forlTIsofone elelnent [11], or finally to deterlnine the
structure ofmacrolnolecules ofnatural origin [19].
MIP exhibits the greatest analytical possibilities as coupled
with salnple intro-duction techniques, which assure separation
ofthe analyte froin the matrix and its in-troduction to plaslna in
the forin of vapour. The number of applications of thehyphenated
technique GC-MIP-AES in trace. analysis of real materials .and
spe-ciation studies •rapidly increases [20,21]. Considerable
analytical possibilities areprovided by coupling MIP with
the.hydride generation [22] or electrotherlnal vapor-ization
[23].
The lhnitations oflnicrowave plasma are connected mainly with
the instability ofthe discharge caused by the introduction of the
salnple lnaterial. It was found thatInaxilnuln lIng Inin-1
ofthematerial canbe introducedinto the plasma [24]. In recentyears
several original resonator designs improving the MIP performance
have beenproposed. The improved versions ofBeenakker's cavity
[25,26], sufratons [27], Mi-crowave Plaslna Torch [28], or TE IOI
rectangular cavity [29,30] perinit obtaining astable discharge even
when introducing arelatively large ainount ofthe sample (val-ues
froln? to 200 lng Inin-1 of water have been reported)
[17,26,31l
Recently an increasing nUlnber ofMIP application in the analysis
of agricultural[32,33], clinical [35,36] and industrial materials
[37-39] are noted.
BASIC ASPECTS OF MIP-AES APPLICATION
The MIPcould be used as a source of sample excitation and atomic
einission forthe Inultielement analysis, where depending on the
form ofth.e sainple studied, vari-ous ways ofits introdllction are
applied. In the second group ofapplication, MIP as at-oinizer, was
applied in atoinic absorption spectrometry [40-42], atomic
fluorescence[43-46] and especially Inass spectrometry [47-49]. The
application of low-energylnicrowave piasina for fragmentation of
large organic molecules in order to studytheir structure bY.Inass
spectrometry [50] is an interesting example.
An ilnportant advantageofMIP-AES is its compatibility with
various salnple in-troduction techniques. The operating parameters
of microwave excitation sources,and especially the gas and analyte
flow rates are similar to those applied in varioustypes of
chrolnatography, hydride generation, graphite furnace, or flow
injectionanalysis. Especially GC-MIP has an established position in
trace analysis andspeciation studies [51-54]. This technique is
utilized for the analysis oftrace ainountsof organic cOlnpounds
containing heteroatoms, such as N, S, CI, Br, F, P, Si
andorganometallic cOlnpounds [10,11]. High sensitivity and
selectivity of detectiontakes advantage ofhigh resolution ofthe
chromatographic separation. For lnany ele-mentsthe pg S-1 detection
is achieved, and defined as the absolute detection lilnit di-vided
by the elelneni peak half width. Absolute detection lilnit is
defined as thealnountofeleluent (in pg) introduced on the .gas
chromatographic coltunn, which pro-
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308 K. Jankowski
duces an output signal equal to twice the background noise. The
atomic emissionspectroinetry with Inicrowave piasina was applied
also as a detection method in liquidchroinatography [55-59],
capillary electrophoresis [60] and flow injection analysis[61].
Gas sainpies are introduced to the piasina after mixing with the
piasina gas[62-64]. The deterinination ofnitrogen, oxygen,
hydrogen, heliuln, krypton, amiTIO-nia, water vapour, carbon oxide
and organic gases in argon can be an exainple. Thegas sample was
introduced directly to the piasina gas streaITI by Ineans of a
syringe.The detection lilnits permit direct analysis of argon of
5.5 N purity.
The analysis of liquid sainpies introduced by nebulization.is
carried out Inainlyfor aqueous solutions [26,65,66]. However, the
direct introduction of aqueous-organic [67] or organic [25, 61]
solutions to the microwave piasina have also been re-ported. In the
case ofsolid or liquid samples often conversion ofthe eleinent
detectedto a volatile forin is applied, sOlnetilnes achieving also
separation of the analyte froinother cOlnponents of the sample.
Such techniques cover electrotherinal vaporization[23,68],
especially irivolving a graphite furnace, hydride generation
[22,69-71], coldvapour generation for Inercury [72,73] and other
Inethods consisting in convertingthe detected eleinent into
volatile halogens [74], carbonyls [45,75] or Inetal chelates[76],
and in the case of non-InetaIs into volatile cOlnpounds such as
chlorine, hydro-gen brolnide, sulfur dioxide or hydrogen sulfide
[77-79].
Various sample introduction techniques are applied, in which no
chemical modi-fication of the salnple occurs. Spark generation [37]
or laser ablation [80] were usedfor the vaporization of solid
salnples. Gelhausen and Carnahan [81] analysed coalsalnples by
direct powder inj ection into He-MIP. Matusiewicz and Sturgeon [82]
usedpneulnatic nebulization for slurry introduction of finely
ground biological referenceInaterial dispersed in 10% nitric acid.
Laylnan and Hieftje [83] suggested a Inicro arcfor the vaporization
of salnples. A 0.1 to 40 f.ll salnple of the solution was placed
onthe cathode, the solvent was evaporated, and the residue was
atomized by an arc dis-charge.
Plaslna sources show variation with respect to the sainple
excitation. The ICP is avery efficient excitation source, which
leads to a very rich spectrlun, including in-tense ionic lines of
many elements. The ICP spectrum is similar to that forlned in
aspark discharge. However, the MIP spectrlun is siInilar to the arc
spectruln with an ex-cess of atolnic lines and relatively slnall
nUlnber of intense lines for particular ele-Inents, due to the
slnaller excitation energy. The following order can be proposed
inrespect of the degree of ionization:
spark> ICP» MIP ~ ncp > arc
Basic studies ofMIP spectra are still randoln and incolnplete
[13, 66,84]. Spectraof a large group of eleinents excited in MIP
have been recorded and the Inost intenselines have been chosen
[85]. On the basis of data collected in Table 1 essential
differ-
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Microwave induced plasl'rla elnission spectro111etry 309
ences between Ar-MIP and Ar-ICP can be noticed. The ion lines
ofTI and V,whichin ICP are the Inost intense lines ofthese
elements, were not found in MIP. The inten-sity ofthe ion lines
oiCd, Co, Cr, Hg, In, Mn, Ni, Pb and Pt is also Inuchsmaller inMIP
than that in ICP [86,87]. For 18 of 50 elements presented an
atoinic line is themost sensitive in MIP whereas the ionic one in
ICP. However, for 20 of the eleinentsexactly the saIne line is
reported as the Inost sensitive in MIP and ICP. ForAs, C, Ga,In,
Mn, as, Pb, Re and V the Inost sensitive atoinic line in MIP is
attributed to a transi-tion of lower energy than in ICP.
Table 1. The most intense atom and ion lines of some eletnents
in the Ar-MIP and Ar-ICP (190-800 nn1)[13,85-88]; n.f. - not found;
the most intense line of each element in MIP and ICP is
underlined.
MIP-AES ICP-AES
Elelnent Atom line Ion line Atom line Ion linenm nn1 nn1 nm
Ag 328.07 n.f. 328.07 243.78
Al 396.15 n.f 309.27 281.62
As 234.98 n.f. 193.70 n.f.
Au 242.80 208.21 242.80 208.21
B 249.77 n.f. 249.77 n.f.
Ba 553.55 455.40 553.55 455.40
Be 234.86 313.04 234.86 313.04
Bi 223.06 n.f. 223.06 190.24
Br 635.07* 470.49*
C 247.86 n.f. 193.09 n.f.
Ca 422.67 393.37 422.67 393.37
Cd 228.80 226.50 228.80 214.44
CI 725.67* 479.45* 725.67
Co 240.73 238.89 240.73 238.89
Cr 425.43 205.55 357.87 205.55
Cs 455.53 452.67 455.53 452.67
Cu 327.40 213.60 324.75 224.70
F 685.60* n.f. 685.60 n.f.
Fe 248.33 238.21 302.05 259.94
Ga 417.21 209.13 294.36 209.13
Hg 253.65 194.23 253.65 194.23
206.24 516.12* 206.24
In 451.13 230.69 325.61 230.69
K 766.49 n.f. 766.49 n.f.Li 670.78 n.f. 670.78 n.f.
Mg 285.21 279.55 285.21 279.55
Mn 403.08 257.61 279.48 257.61
1\10 379.83 ,,){V'l (\') 379.83 202.03L.VL,.V:J
Na 589.00 n.f. 589.00 288.11
Ni 232.00 231.60 232.00 221.65
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310 K. Jankowski
Table 1 (continued)
Os 375.25 228.24 222.80 225.59
P 213.61 n.f. 213.61 n.f.
Pb 405.78 220.35 217.00 220.35
Pd 340.46 n.f. 340.46 229.65
Pt 265.94 214.42 204.94 214.42
Re 229.45 227.53 204.91 197.31
Rh 343.49 n.f. 343.49 233.48
Ru 372.80 240.27 349.89 240.27
S 217.05* 545.39* 545.39
Sb 206.83 n.f. 206.83 n.f.
Se 196.03 n.f. 196.03 n.f.
Si 251.61 n.f. 251.61 n.f.
Sn 235.48 190.00 235.48 190.00
Sr 460.73 407.77 460.73 407.77
Te 214.28 n.f. 214.28 n.f.
Ti 365.35 334.90 363.55 334.90
TI 535.05 n.f. 276.79 190.86
V 437.92 n.f. 292.36 309.31
Zn 213.86 202.55 213.86 202.55
Zr 360.12 339.20 360.12 343.82
*data for helium plasma [89].
The lnost sensitive lines ofelements in the MIP spectra cover a
broad range ofUVand VIS. However, in ICP a majority of intense
emission lines is placed in the UV.Thus, lnicrowave plasma could be
a modern excitation source recommended for qual-itative analysis,
since in comparison with ICP spectral interferences are much
lessprobable. An essentiallilnitation in the application of the MIP
is that SOlne intenselines ofAI, Be, Bi, Cd, Ti and V overlap
intense OH bands, especially in the 306-320nm range.
For analytical purposes low temperature plasmas (up to 10000 K)
are utilized.MIP is definitely a plasma not in local thermodynamic
equilibrium, and a consider-able difference between the electron
temperature and that ofthe gas can occur. Condi-tions favorable for
the occurrence of various chemical reactions exist in this type
ofplasma. The excitation mechanisms in MIP are not yet sufficiently
known. The mainrole is attributed to collisions with high energy
electrons and Penning ionization in-volving argon or heliuln atolns
in the metastable state.
Chelnical interferences are connected with the fact that the
analyte excitation isaccolnpanied by reactions involving other
components ofthe salnple. The decrease inthe calcium elnission in
the presence ofphosphates [26] or alluninum [90] is a classi-cal
exalnple of chemical interferences due to the forlnation
ofrefractory cOlnpounds.This type ofinterferences can be eliminated
in Iv1IP by the addition ofa spectral buffer[91].
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Microwave induced plasT11a emission spectroT11etry 311
Alkali Inetals, usually present in environmental sainples, cause
a positive Inatrixeffect, which leads to an improvement of
analytical performance of MIP-AES forInanyeleinents [87]. An
additional increase in einission is observed in the presence
ofchlorides, owing to the formation· of volatile chlorides of the
elements determined[87,92]. A very large increase in emission can
be observed for someelelnents(1 OOO-fold forMn [93]) when thermal
vaporization is used as the method ofsampleintroduction to MIP.
Despite the occurrence of a clear matrix effect from such ele-ments
as sodium,. potassium, calcilun or InagnesiuIn, the application of
the Ina-trix-lnatching Inethod is sufficient for assuring good
accuracy and precision of thedeterlninations in the analysis of
environinental sainples.
ANALYTICAL PERFORMANCE OF THE MIP-AES
The .detection lilnit (DL) for individual elementsin the MIP-AES
depend to agreat extent on the sample introduction technique
applied. Table 2 summarizes DL forselected elements using solution
nebulization. It is. generally assumed that in atoinicelnission the
best detection liInits are achieved for ICP, as MIP and DCP offer
smallersensitivity, whereas FAAS is in many cases the least
sensitive method.
The DL for 31 elements by the MIP-AES have been determined [86].
A greatersensitivity ofthe MIP-AES in cOlnparison to that for
ICP-AES was found for Ag, Cd,K, Li, Na, P, Pb and Sb. The detection
limits for AI, Be, Se, As,Cu, Fe, Zn and Bi inMIP and ICP are
comparable, and for the others Inuchbetter perforinance is
providedby ICP. This concerns especially the determination ofmetals
forining in plasma stableoxides, e.g. W, Mo, .Zr andTi.
Table 2. Comparison of detection limits by various spectroscopic
techniques with solution nebulization;MIP - argon microwave induced
plasma [12,13], CMP -argon capacitively coupled microwaveplasma
[12,13], Iep - argon inductively coupled plasma [88],.DCP - argon
direct current plasn1a[94,95], MINDAP -lnicrowave induced nitrogen
discharge plasma [15], FAAS - flame aton1icabsorption spectron1etry
[96].
ElementDetection limit, ng mr l
MIP CMP ICP DCP MINDAP FAAS
Ag 3 470 7 2
Al 24 500 23 15 13 20
As 30 53 150
B 10 4.8 10 6000
Ba 16 500 1,3 15 10
Ca 0.7 2 0.2 0.5 1.2 1
Cd 0.12 6 2.5 1.7 2
Cr 10 9 6 1 3Cu 9 10 5.4 1
Fe 8 150 4.6 5 280 10
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312 K. Jankowski
Table 2 (continued)
K 2 40 10 5.4 1
Mg 0.6 2 0.15 0.1 13 0.1
Mn 6 8 1.4 2 2
Na 1 1 29 0.29 0.2
Ni 35 20 10 1 5.3 2
P 90 76 100
Pb 10 10 42 13 84 10
Ti 6 4 3.8 90
V
Zn
20
10
50
200
5
1.8 4
47
120
20
1
MIP-AES with the electrothermal vaporization is a useful and
sensitive Inethodfor the analysis ofinicro-sainpies. The fact that
the sample reaches the piasina zone asa vapour, and even partially
atomized, which reinarkably facilitates its excitation, isan
essential advantage ofthis Inethod ofsample introduction. In Table
3 are presentedthe DL for SOlne elementsachieved under various
measurement conditions and usingvarious techniques of
electrothermal vaporization including graphite rod, graphitefurnace
and heated graphite atomizer, and reviewed by Carey and Caruso
[23].
Table 3. Comparison of absolute detection limits by various
spectroscopic techniques with electrothenllalvaporization [23,96]
(in pg).
Elelllent ETV-MIP-AES ETV-ICP-AES GF-AAS
Al - 0.5 .. 400 1
As 120-300000 60-2000 8
Ca 3850 1-600 1
Cd 0.2 1-600 0.1
Cu 30-900 1.5-500 0.5
Fe 500-11000 10-100 1
Hg 6-100 4-200 5-90
Ni 110-3800 27-485 5
P 660-5000 100-2000 -
Pb 120 4-650 0.7
Se 140-250 - 20-60
Zn 400-500 0.6-800 0.1
In the cOlnbination of the hydride generation technique (HG)
with MIP a lilnitedainount of the sainple Inaterial is introduced
into the piasina in the gas forin. More-over, the use of relatively
sinallplasma gas flow causes sinall dilution of the sampleand
prolongs the tilne ofits residence in the piasina zone. The
exceptionally low back-ground level is an additional advantage. As
shown in Table 4 cOlnparable detectionlimits for As, Ge, Sb, Se,
and Sn are obtained with various spectroscopic techniquesbased on
MIP or ICP. Fricke et at. [97] deterinined nanograin alnounts
ofelelnents ap-plying hydride generation, cold trap
preconcentration and gas chroinatography.
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Microwave induced plasnla enu'ssion spectronletry 313
Bulska et 'al. [69]ilnproved· the analytical performance of
HG-MIP. by on-linepreconcentration of As, Sb and Se hydrides by hot
graphite furnace trapping (GFT)and subsequent evaporization
oftheanalyteinto the helium plaslna.
Table 4. COlnparison of detection limits (ng mr l ) by various
atomic emission spectrometry systen1sutilized MIP or ICP with
hydride generation [22,69,97].
Element HG-MIP HG-ICP HG~GFT-MIP HG-GC-MIP HG-GC-ICP
1
0.8
()QV.V0.35
0.15
0.5
1.25
2
0.12
0.14
0.031.4
Se
Sn
As 0.3 0.06 0.08
Ge 0.04 0.06
Sb 6.1 0.18
Coupling of MIP-AES with .gas chromatography is a unique.
hyphenated tech-nique with a possibility of simultaneous
multielement detection of the cOlnpoundsseparated [8-11,52,98]. The
Inicrowave plaslna detector (MPD) belongs to the Inostsensitive
detectors now used in gas chromatography. ·Especially
heliulnplaslna ischaracterized by great sensitivity, both with
respect tOlnetals and non-lnetals.Asshown in Table 5, for many
elements the DL do not exceed several pg S-l. TheGC-MPD could be
used for the identification ofall organic cOlnpounds present in
thesalnple on the basis of the carbon concentration Ineasurelnent
and individual reten-tion times, identification of selected classes
of cOlnpounds, e.g. halogen derivativeson the basis of the
heteroatomelnission measurement, speciation studies
ofdifferentcOlnpounds of one element or determination of the
chemicalcolnpositionof com-pounds on the basis of deterlnination of
the elelnent ratio of several basic elelnents[99,100].
Table S.Analytical perforn1ance of the microwave plasma detector
MPD (He-MIP-AES), [11,52].
ElementDetection limit,
Selectivity ElementDetection limit,
Selectivitypg S-I pg S-1
C 0.2 1 F 8.5 3500
H 2.2 6000 CI 16 2400
0 75 25000 Br 10 1400
N 7.0 6000 I 21 5000
P 1.5 25000 Fe 0.3 280000
S 1.7 150000 I-Ig 0.6 77000
As 6.5 47000 Pb 0.17 25000
Se 5.3 10900 Sn 1.6 36000
Si 9.3 1600 V 4.0 --
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314 K. Jankowski
For the GC-MIP and other techniques ofgaseous salnple
introduction a linear an-alytical graph extends to four or five
orders of lnagnitude. However,. for MIP-AESwith solution
nebulization this range is narrower due to full load of plasma. Ng
andShen [101] achieved a linear dynamic range for several elelnents
deterinined in syn-thetic ocean water in the range from 0.01 to 100
lng 1-1. Silnilar results were achievedfor several elements
analyzed in fresh water [86]. Some elelnents (Au, Ca, Cd, Cu,Zn)
yield instrumental responses linear over two orders of magnitude
due to self-absorption effects [65,86].
In order to deterll1ine the accuracy of the ~v1IP-AESmethod, the
analysis ofcerti-fied reference lnaterials was carried out,
especially of vegetable and anilnal origin[29,30,34,102], and also
using synthetic salnples corresponding to natural salnples[65,86].
In general, the results obtained were in good agreelnent with the
certifiedvalues. However, lnatrix effects were observed in SOlne
cases and additional analyti-cal procedures were applied, including
addition of chelnical modifier [29] or separa-tion of the analytes
[102].
In reviews concerning plasma emission spectrometry a comment
could be foundthat MIP is characterized by poor precision
oflneasurement owing to the lilnited sta-bility of the microwave
discharge [94]. However, during the recent years
technicalilnprovelnents brought an increase in the precision of
lneasurements [12,13,30] . Theshort-term precision calculated for
standard solutions of several elelnents (Ag, Ca,Cd, P, Pd, Zn) was
froln 0.6 to 1.1% at the analyte concentration at the lng 1-1 level
andfroin 1.5 to 2.0% at l-lg 1-1 level. The long-term precision
lneasured for Zn and P solu-tions was 1.8 and 3.0% respectively
[103]. Good precision of measurelnents wasachieved not only for
standard solutions of elelnents, but also for real salnples,
e.g.river water and fresh water [86] as well as synthetic ocean
water [65,101].
AI1 evaluation of the MIP-AES lnethod with respect to the lnost
popular instru-lnentallnethods can be found in some reviews
[30,104,105].
AIR ANALYSIS BY MIP-AES
MIP is a promising excitation source for Inonitoring air and
exhaust gas, even dueto the possibility of obtaining air Inicrowave
piasina. Sielnens et al. [38] studied theMIP-AES for the monitoring
of trace amounts of lnercury in flue gases using anon-Inixed
argon-nitrogen discharge. The DL was 8 J.lg In-3 ofHg in nitrogen,
whichis sufficient for carrying out on-line monitoring ofmercury
for environmental protec-tion. Verlnaak et at. [106] utilized air
MIP for the detection of the gaseous lead in ex-haust gases. The
gas sample was introduced directly to the plaslna. Denkhaus et
at.[64] deterlnined lnolecular nitrogen in natural gases by direct
introduction ofthe san1-pIe into the low-pressure MIP. The emitted
radiation was directed to the lnonochro-Inator by fiber optics.
Linear response ofnitrogen emission was obtained in the rangeof
0-14% (v/v), and theDL was 0.01 ppIn (v/v).
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Microwave induced plasma elnission spectrOl1'letry 315
Another method of analyzing gaseous .products .consists in
injecting a definedvolume to the plasma gas stream. Serravalo and
Risby [107] studied the determina-tion of vinyl chloride
concentration in air by means of He-MIP under reduced pres-sure on
the basis of the chlorine emission· for the 479.45·nITI line. The
DL for vinylchloride was 300 ppm.
The determination ofsulfurin the form ofhydrogen sulfide or
sulfur dioxide in airwas studied by Taylor et al. [108]. They
injected to plasma up to·l Oml ofthesainplestudied. Air, helium and
argonplasinas were studied and the best analytical perfor-mance
\vas achieved for the latter: DL 0.2 flg ofsulfur and linear
response from 100 to500 ppm.
BaUlnann and HeUlnann [78] determined organobromine compounds,
hydrogenbromide and tetraalkyllead in exhaust .gases. Hydrogen
bromide was preliminaryconverted into 2-bromocyclohexanol. Then
organobroinine compounds were ad-sorbed on Tenax GC and the lead
compound on Porapak N forpreconcentration andliberated by Ineans
ofthermal desorptionto the GC-MIP-AES system. The contentsofthe
compounds studied in theexhaust gases was froin several to several
hundred IJg m-3.
Realner et al. [109] studied the content of the total gaseous
lead (TGL) and totalparticle lead (TPL) in exhaust gases, tunnel
air and lab air. The sample was transferredthrough a system in
which particulate lead was collected on a filter and gaseous leadon
an appropriate adsorbent. The compounds deterinined were released
by means ofafreeze-drying system to the GC-MIP-AES instruinent.
TGLandTPL contents lnea-sured were 20-1000 and 1000-55000 ng Pb
m-3, respectively.
ANALYSIS OF WATER AND WASTE-WATER
Determination of metals and metalloids
Deterinination of impurities, for which the maximum adinissible
concentration(MAC) non-toxic for live organisms was established, is
essential in water analysis.Special monitoril)g programs and
normalized analytical procedures utilizing effi-cient instrumental
methods have been elaborated in order to obtain comprehensive
in-forlnation on environinent pollution over large regions
[110-114].
A comprehensive evaluation of the usability of the MIP-AESmethod
for themulti-element analysis ofnatural waters [86] has been
carried out on the basis of theprocedure of determining 31 trace
and main elements by the ICP-AES method rec-ommended by
international regulations [110]. The analytical lines and
correspondingdetection limits for these elements determined by the
MIP-AES in water have beenproposed. Relatively low DL are achieved,
especially for alkali and alkali earth met-als. The accuracy and
precision of analysis of impurities in water by the MIP-AESwas
evaluated on the basis of the results obtained for two reference
materials: syn-thetic river water and drinking water. For the Inain
elements and a majority oftrace el~
-
316 K. Jankowski
ements a good correlation with the certified data was achieved.
Matrix effects wereobserved when determining some elements in the
synthetic river water sample due tothe presence ofeasily ionizable
elements and concomitant anions. For chromium andlnanganese an over
two-fold increase in the DL was found in the presence of a
matrix(Ca, Na, Mg, Cl) in comparison with the results obtained for
standard solutions. Silni-lar improvements in the DL were obtained
for Ca, Cr, Mn, Ni, Pb and Zn when analyz-ing samples of water from
deep water intakes, tap water, municipal waste water andtwo
extractants used for the separation of the bioavailable fraction of
heavy metals-trAm CAilc f11 "\1.LI. V~~~ ""V~.l.lJ l.l. ..L,./
J'
The MIP-AES with direct nebulization of solutions shows good
usability for en-vironmental water analysis. Although the detection
lilnits achieved are comparable tothose obtained in ICP for only
about 50% ofthe elements studied, both techniques ful-fill the
requirements of the EPA program to a silnilar extent. The DL
obtained by theMIP-AES method have been compared with the Contract
Required Detection Limits(CRDL) from the Environmental Protection
Agency (EPA) program SOW No. 788[114] and the maximum admissible
concentrations (MAC) for metals and non-metalsin ground waters
recomlnended by WHO. MIP fulfils the requirements of the
.EPAprograIn for 12 of 21 elements (ICP 15 of 21), and considering
the possibility of ap-plying the hydride generation technique this
number will rise to 17. From the compar-ison ofthe DL by the
MIP-AES and MAC values presented by WHO it appears that 7elements
of 15 can be determined with the lnethod described (11 when
including theHG-MIP) without the necessity of preconcentrating the
salnple components. It hasbeen proved that by lneans ofthe MIP-AES
Fe, Mn, Zn, eu, Pb, Cr, Na, K, Mg and Cacan be deterlnined on the
level, which in many cases is sufficient for the needs of atypical
monitoring of pollutants in water.
However, the preconcentration oftrace impurities is essential in
lnany cases. Kai-ser et al. [72] deterlnined nano and picogram
amounts oflnercury in air, water, soiland milk applying different
techniques ofpreconcentration and introduction ofthe el-elnent to
plasma. Volland et al. [116] isolated less than 0.1 ng of Cu, Zn,
Fe, Ni, Coand Bi frOln the solution during 1-2 h by lneans of
hydrodynalnic electrolysis. Agraphite tube was used as the cathode.
The ETV-MIP-AES system based on this tubewas constructed and
multi-element analysis was perforlned. DLs below 0.01 ppbwere
obtained.
The content of some lnetals and lnetalloids in water can be
determined by firstconverting theln into a volatile complex. Tahni
and Norvell [117] applied theGC-MIP-AES for the determination
ofarsenic and antimony in drinking and seawa-ter as well as orchard
leaves. The elements were precipitated with thionalid, and
thenconverted into triphenyl arsine and stibine treating with
phenyhnagnesium bromide.The compounds fOflned were extracted with
ether and separated on a chromato-graphic column. The absolute
detection limits were 20 pg for As and 50 pg for Sb,which
corresponded to 50 and 125 ng 1-1, respectively to their initial
concentrationsin water. The As and Sb content in the samples
studied was 0.0016-11 ppm and0.00042-3.2 ppm, respectively.
-
Microwave induced plas11'za emission spectro11'zetry 317
Skogerboe et at. [74] used an ETV-MIP-AES setupin which the
determined ele-ments were preliminary converted into volatile
chloride. The absolute detection lilll-its for Bi, Cd, Ge, Mo, Pb,
Sn and Zn were between 1 and.5 ng, and 0.1 ng for Tl. Themethod was
applied for the determination of cadmium and lead in the 1-2 ng
Illl-lrange·in water samples.
Lunzer et at. [118] used a continuous HG-MIP-AES system for
thedeterillina-tion ofarsenic, antilnonyand selenium. The detection
limits for As, Sb and Se were0.7,0.9 and 0.4 ng ml- I ,
respectively, and the precision ofdetermination was 3-4 %(RSD). The
matrix effects occurring when determining As in seawater were also
stud-ied.Bulskaet at. [119] determined below 0.1 mg 1-1 ofarsenic
and selenium in waterby preconcentration of the separated hydrides
in a graphite· furnace filled with spe-cially prepared vitreous
carbon and then introducing thereleased compounds to MIP.Earlier
Lichte and Skogerboe [120] determined 0.02-1.32 ppm As in water by
theHG-MIP-AES method.
Dietz et at. [121] determined arsenic, selenium, antimony by
HG-MIP-AES andIllercury by (cold vapour) CV-MIP-AES in river and
waste waters. The content oftheeleinents mentioned varied in the
3-150-J.lg 1-1 range and respective DLs froill 2 to .13J.lg 1-].
Noijri et at. [73] determined below 1 ng 1-1 of mercury in lake
water byCV-MIP-AES. The mercury vapour was preconcentrated by
collection on gold de-posited on a porous structure and then
therillally released to the plasma.
Tao et at. [122] deterinined berylliulll in lake water on a ng
1-] level byGC-MIP-AES. Berylliulll was preconcentrated by
extraction as acetylacetonate.The DL for Be was 0.33pg ml-1 ofwater
sample. A similar procedure was applied byTahni and Andren [123]
when analyzing selenium in different sainples originatingfroIn the
combustion ofcoal at steaInplant. Aftersainple digestion,selenium
was ex-tracted as a volatile complex (p-nitro-piaselenol). The Se
content in the analyzed ma-terials was from 0.05 to 10 J.lgg-I.
Madrid et at. [61] studied the FIA-MPT-AES system to
deterininecopper in sea-water. Sodiuln diethyldithiocarbamate as
the chelating agent and ·reversed-phasechroinatography microcolumn
were used for separation and preconcentration ofcop-per. The
detection limit for Cu was 0.16 ng 1-1.
Determination of non-metals
The determination of chloride, bromide, iodide [124], fluoride
[125J as well ascarbon, phosphorus and sulfur [126] in aqueous
solutions on the mg I-I level shouldbe mentioned among the
analytically important applications ofhelium MIP. Barnett[77], and
also Camuna et at. [127] determined Cl, Br and lin water
continuously gen-erating halogens and·hydrohalides, which were
introduced to MIP after separationfrom the aqueous phase. TheDL did
not exceed 0.5 mg 1-1.
Chiba et at. [128] determined fluoride in natural waters by
GC-MIP-AES afterextraction with toluene in the presence of
trimethylchlorosilane as the derivatizingagent.
TheDLof7.5pgs-1forFwasachieved.l.3 J.lgmr~l ofFinseawateralldO.l
J.lg
-
318 K. Jankowski
ml-1 in tap and pond water samples were determined. Haraguchi
[129] reported theDL of20 J.lg ml-1 for a similar analysis of
natural water.
Nakahara et al. [130] elaborated two analytical procedures for
the determinationof iodide in waters. The indirect method utilizes
the decrease ofinercury emission in-tensity in the presence of
iodide in highly acidic medium. In continuous flowCV-MIP-AES
systein the DL for iodine was 50 ng ml-1• The direct method
permitsthe determination of the iodide and iodate content in
seawater and brine after conver-sion into iodine [131,132]. The DL
was 2.3 ng ml-1 of iodine.
.AJvarado and Carnahan [133] determined some organic compounds
ofsulfur, ase.g. cysteine and menthionine, by converting them into
hydrogen sulfide, pre-concentration in a liquid nitrogen trap and
excitation in a He-MIP. Thus, they coulddetermine these compounds
in water on a J.lg 1-1 level. The DL for sulfur was 0.4 ppb.A
similar procedure was accepted by Nakahara et al. [79] when
determining below 1mg 1-1 ofsulfide in wastewater. However, when
determining the content ofsulfites inwine at the 100 J.lg ml-1
level they liberated them from the sample as S02. The detec-tion
lilnit was 0.13 ng ml-1 for sulfur generated as hydrogen sulfide
and 1.28 ng ml-1
as sulfur dioxide.Gebersmann et al. [134] separated volatile
organic sulfides and thiols by means
of purge-and-trap technique before deterinining their content in
lake water and sea-water as well as in four types ofbeer and coffee
by the GC-MIP-AES. Dimethyl sul-fide, carbon disulfide and
etanothiol were at the 3.5-50 ng 1-1 level calculated withrespect
to sulfur.
Mitchell at al. [135] applied the ETV-MIP-AES method for
determining in waterthe total organic carbon (TOC) and particulate
organic carbon (POC) at the lIng 1-1 level.The sample was placed in
a platinum boat, water was evaporated off and by applyingan
appropriate oxidizer and temperature program the particular
compounds deter-Inined were released.
GC-MIP-AES was applied for the analysis of water polluted with
halogen or-ganic compounds ofvarious classes [99,100]. Chibaand
Haraguchi [136] determinedtrihalomethanes in tap, river, sea and
pond waters at the 0.02-55 ng 1-1 level. Thecharacteristics of the
MPD for F, Cl, Br and I was as follows: detection limits 36, 32,28
and 6.7 pg S-1 and selectivity 820,1000,530 and 530, respectively.
Quhnby et al.[137] determined below 1 J.lg 1-1 of trihalomethanes
in drinking water by thepurge-and-trap technique. By means of the
purge-and-trap injection device Slaets etal. [138] determined
volatile haloganated organic compounds (VOC) containing CI,Br or I
in seawater at 0.05-15.28 J.lg 1-1 concentrations.
Turnes et al. [139] determined below 1 J.lg 1-1 ofchlorophenols
in drinking waterapplying the solid phase extraction (SPE) for
separation and preconcentration of theelements determined. The
analytical conditions of determining halogen derivativesofhumic and
fulvic acids in tap water were investigated by Quimby et al. [140].
Thepossibilities of separating and determining dioxins [141] and
poly(chlorinated bi-phenyls) [142] by means of GC-MIP-AES were also
studied.
-
Microwave inducedplasma emission spectroTnetry 319
Much attention is drawn toward the determination ofadsorbable
halogen organiccompounds (AOC). Koschuh et al. [143] separated AOe
'scontaining Cl and Br frominorganic chloride, concentrated on
activated carbon, and then subjected to pyrolysisand the released
compounds were absorbed by 0.1 mol 1-1 sodium hydroxide.
Afteroxidation to chlorine and bromine they introduced the
resultant to helium MIP.TheDL for Cl and Brwere 3 and 8 ng ml-] ,
respectively. Lehnert et al. [144] elaborated aspecial measuring
system for the determination ofAOC's utilizing preconcentrationon
activated charcoal and thermal desorption. The absolute detection
limit for .chlo-rine was 0.2 IJg.
ANALYSIS OF SOILS, SEDIMENTS AND BIOLOGICAL MATERIALS
The analysis ofcomplex materials such as soils or sediments is a
valuable sourceof information on the analytical performance of a
method. Although the nUlnber ofpublications concerning the
application of MIP-AES for the determination of totalcontent
ofelemental pollutants in this type ofmaterials are not too
numerous, it is re-markably supplemented by speciation studies
described in the next section.
Seeley at al. [145] performed simultaneous multielement
detection of7 elementsin sediments and coal by pyrolysis-gas
chromatography. Absolute detection lilnitsobtained withthe MPD for
Se, S, P, 0, N, As and C were 4, 10, 17, 300, 20, 3 and 0.2pg,.
respectively..Whenapplying the continuous HG-MIP-AES method, Ng et
al.[146] determined selenium in soil. The DL was 40 ng ml-1 Se.
Jin et al. [147] determined Ag, AU,Ge, Pb, Sn and Te in
sediments by means ofETV-MIP-AES. The sample was digested with
simultaneous removal ofsilica. Thesolution obtained was vaporized
from a tantalum filament loop. The DL was from 3 to147 pg. Ag, Sn
and Te were determined at the level of 0.1-5 J.lg g-l in sediments
withcertified values for the elements. Kawaguchi and Vallee [93]
determined picogralnsofzinc by vaporizing lnicrogram amounts
ofenzyme samples into a He-MIP. Barnett[148] determined nickel and
lead in animal bones·(reference material). The sampleswere digested
with sulfuric and nitric acids, and vaporized from a tantalum
ribbon.
The applicability ofthe GF-MIP-AES method in the analysis
ofbiological mate-rials for the content ofheavy metals has been
shown. Leis and Broekaert [34] as wellas Aziz etal. [149]
determined below O.lllg g-l ofCu, Fe, Mn, Pb andZnin
samplesofspinach, orchard leaves and bovine liver afteracid
digestion. In an other procedurethe powdered 2 mgsampleswere placed
directly in a furnace, the organic matrix wasremoved at lower
temperature, and then the elements determined were released
andintroduced to argon MIP.
Yang et al. [29] determined heavy metals in tea leafs and hUlnan
hairatthe J.lg 1-1level. The samples were digested in acids, and
then placed in a graphite furnace, add-ing palladium as the
chemical modifier. The atomized sample was introduced into aAr-MIP
(TE Iol resonator). When applying the standard addition method a
satisfac~
-
320 K. Jankowski
tory accuracy ofdeterminations was achieved for Ag, CU,Fe, Mn
and Pb. Heltai et al.[102] determined Fe, Cu and Zn in tomato and
orchard leaves and bovine liver. Mod-ified cellulose was added to
the digested samples and the elements determined wereseparated as
thiocarbamate complexes. Then, the elements were eluted by means
ofnitric acid and froln 5 to 50 J.lI of the solution obtained was
introduced to.a graphitefurnace coupled with a toroidal Ar-MIP.
Microwave plasma is readily utilized in environmental analysis
when coupledwith the hydride generation technique. Schickling et
al. [150] separated arsenic asi\sH3, concentrated with trapping in
a graphite furnace coated with platinuln, andthen thermally
vaporized and introduced to argon or helium MIP. From 0.05 to 10
J.lgg-l As were determined in citrus leaves, human hair, mussel
tissue and pig kidney.Nakahara and Takeuchi [151] applied
HG-MIP-AES with nitrogen plasma in theanalysis of arsenic in
seaweed and scallop. For this experimental setup a DL of 3.13ng
ml-1 and linear response of 10-5000 ng mg-1 were achieved.
De la Calle-Guntinas et al. [152] determined selenium present in
wheat asselenolnethionine by means ofthe GC-MIP-AES after
derivatization. The analyticalperformance ofFPD, MS and MIP-AES
detectors has been compared in this study.Absolute detection limits
for selenium were 0.9,0.015 and 0.78 ng, respectively.
The application ofcoupled techniques increases the possibilities
ofutilizing MIPin the analysis of cOlnplex lnaterials ofnatural
origin. Riviere et al. [153] studied thepossibility of applying a
surfatron for pesticide analysis by the CGC-MIP-AESmethod. Earlier
Bache and Lisk [32] determined picogram alnounts ofpesticides
con-taining sulfur, halogens or phosphorus in food products such as
wheat, potatoes, on-ions, carrots, cabbage, sugar beet, powdered
lnilk and chicken meat as well asherbicides containing iodine in
soil, wheat and oats samples [154]. The analysis ofpesticide
content in food was dealt with also by Wylie and Oguchi [155].
APPLICATION OF MIP-AES TO SPECIATION STUDIES
In recent years considerable progress occurred in the speciation
studies ofheavy~
metals and metalloids [11,21,156,157]. The appearance ofplasma
excitation sourcesand their application for multielelnent analysis
by lneans of atomic emission spec-trometry and mass spectrometry at
the ultra-trace level were one of the reasons per-mitting the
broadening of these studies. These lnethods in their essence
perlnit,however, the determination of only the total content of
elements in the sample stud-ied, but coupling with chrolnatographic
techniques afforded a very efficient tool forspeciation studies.
Due to the selectivity of the Atomic Emission Detector (AED),very
clear chromatograms are obtained even in the analysis of cOlnplex
environmen-tal samples. The elnission measurement at a wavelength
corresponding to the lnetalstudied causes that the detector records
only one, the required class of organic com-pounds.
-
Microwave induced plasma emission spectrometry 321
A large number ofpapers is concernedwiththe speciation
ofalkyltin compounds[158-162]. Liu et al. [33] elaborated the
conditions of extractive separation andspeciation analysis for 15
different alkyltin compounds which can occur in soil andsediments.
Rodriguez-Pereiro et al. [163] applied multi-capillary GC-MIP-AES
forspeciation studies ofalkyllead, alkylmercury and alkytin
compounds in different en-vironmental samples. The accuracy of the
Inethod was confirmed by carrying out theanalysis of tin compounds
in certified materials: sediment and fish
tissue.Szpunar-Lobinskaetat. [164] studied the speciationof tin
compounds inwater anddetermined 1O~140 ng I-I oftin as
111onobutyltin, 8-67 ng I-I as dibutyltin and 4-11 ng 1-]as
tributyltin. The cOlnpoundswere preconcentrated·on aSPE column and
on-linederivatizatizedby means oftetraethylborate prior to
introduction on the capillary col-umn.
Liu etal. [165] determined simultaneously organic tin, lead and
mercury COln-pounds in environmental salnples using capillary gas·
chromatographyCGC-MIP-AES.The calibration curves exhibited
lineritybetween 2.5-2500 ng Inl-1
forSn andPb,and 2.5-10000 ng ml-I for Hg.Mercury is the
secondlnetal often met in speciation studies [166,167]. Snell et
at.
[168] studied speciation of mercury in the natural gas
condensate using on-linepre-concentration by means ofcold vapor
generation or solid-phasernicro-extraction(SPME) and· GC-MIP-:-AES.
The DL fordimethylmercury was 0.24~g I-I and
formethyhnercuryandHg(II) 0.56 J.lg I-I.
Donaiset al. [169J applied the GC-MIP-AES method for speciation
studies oflnercury in various certified materials ofsea origin. The
samples ofsediments, crusta-ceansand fishtissues were first
subjected to solid-liquid extraction system. The
lner-cury·compounds in the aqueous phase were extracted with
toluene, and finally thetoluene extract was purified from high
molecular lnass compounds by means of gelchrolnatography. The
methylmercury content in the samples studied was from 0.6 ng r--
Ito 13 J.lg g-I ofHg, and the total mercury content was from 0.04
to 28 J.lg I-I. The DLfor mercury was O.lpg S-I.
When •studying the methylmercury content in fish tissue, Palmeri
and Leonel[17OJ applied a ml;llti-step procedure ofpreparing the
sample covering alkaline diges-tion, extraction and
derivatization·· with· sodium tetraphenylborate prior toGC-MIP-AES
determination. The DL ofMeHg was 0.1 J.lg g-I. The accuracy
ofde-termination was checked by means. of BCR CRM 464 (tuna fish)
and NRCCDORM-2 (dogfish lnuscle).certified reference
lnaterials.
Elnteborg etal.. [171] studied the speciation of mercury in
sediments by super-critical fluid extraction and GC-MIP-AES. They
determined from 8 to 40 ng g--I oflnethylmercury, while the content
of inorganic mercury in the samples was from 500to 2000 times
higher. The same group determined mercury compounds in natural
wa-ters, rich in humic acids [172]. Mercury was concentrated by
solid phase extractionon a column packed with a resin \vith DDTC
groups, followed by elution andderivatization of the cOlnpounds.
The content ofMeHg+ was 0.2__0.3 ng I-I, and that
,
-
322 K. Jankowski
of inorganic mercury 2-5 ng 1-1. Chiba et al. [173] studied the.
speciation ofHg com-pounds in seawater by means of GC-MIP-AES
achieving DL below 0.5 J.lg 1-1.
Mena et al. [174] applied the FIA-GC-MIP-AES system equipped
with micro-coluinn for preconcentration to deterinine Hg in canal
water. The content of organicmercury in different samples varied
from 40 to 160 ng 1-1 , and that of inorganic mer-cury froin 100 to
340 ng 1-1. Costa-Fernandez et al. [175] studied the speciation
ofHgand As in seawater, tap water and urine using a flow system.
The determined com-pounds were separated by high permeation liquid
chromatography, and then con-verted to volatile compounds. By the
HPLC-HG-:L\1IP-i\ES Inethod the DL for fOUforganoarsenic cOlnpounds
were from 1 to 6 ng ml- J, and by theHPLC-CV-MIP-AES Inethod 0.15
ng Inl-1 in the inorganic forin and 0.35 ng ml-1 ofmethylmercury
(calculated with respect to Hg) could be detected.
Lead is the third leading eleinent in speciation studies
[163,176], the alkyl com-pounds ofwhich are determined first of all
in places liable to the elnission ofvehicleexhaust gases. Reamer et
al. [109] determined 5 lead compounds in air and exhaustgases. A
sample of gas was transferred through a column packed with an
appropriateabsorbent. The liberated cOlnpounds were then
concentrated by cold trapping and de-termined by Ineans of the
GC-MIP-AES. The contents of particular alkyllead com-pounds varied
from 0.5 to 650 ng m-3.
Alkyllead compounds are sought in tap and rain waters [160,177].
LobinskiandAdams [178] determined four alkyllead cOlnpounds using
theirextractive separationas thiocarbainate complexes and
GC-MIP-AES. The content of particular com-pounds in water studied
was 0.3-1.7 ng 1-1. Wasik et al. [179] determined
alkylleadcompounds in tap water applying the derivatizating
reaction in situ. In the acetatebuffer medium of pH = 4 they added
tetrabutylammonium tetrabutylborate and ex-tracted the derivatized
alkyllead compounds with hexane. The DL for particularanalytes were
in the 43-83 pg 1-1 range. In a similar way Heisterkamp and
Adains[180] studied the speciation of lead in tap water and peat.
The content of individualalkyllead cOlnpounds in water did not
exceed 0.5 ng 1-1, and in peat 20-1500 pg gJ.The speciation studies
of lead in snow from Greenland carried out by Lobinski.et al.[181]
is a special case. A similar procedure has been applied as when
analyzing tapwater, but as Inuch as 1250-fold preconcentration of
the traces was necessary. Thelead compounds content in snow was
from 0.02 to 0.48 pg g-J.
De la Calle-Guntinas et al. [182] determined selenium(IV) and
selenium(VI) byIneans ofconversion ofselenium(IV) into volatile
diethylselenium, concentration bycold trapping and GC-MIP-AES.
Selenium(VI) was determined in river and mineralwaters at a level
below 1 J.lg 1-1 preceding the reaction of diethylselenium
formationby reduction to seleniuln(IV). Volatile organoselenium
compounds were determinedin lake water by the purge-and-trap
GC-MIP-AES. The DL for dimethyldiselenidewas 2 pg ml-1 [183].
-
Microwave induced plasma emission spectronletry
FINAL REMARKS
323
The MIP-AES is a usefultnethod for the trace analysis and
speciation studies inenvironmental samples. When coupled with
appropriate sample introduction tech-niques, such as electrothermal
vaporization, hydride generation, chetnical vapourgeneration or gas
chromatography, it is possible to determine a group of eletnents
atthe ngg-I level.The. possibilityofdetenllining traccamounts
ofnon-metals, al1dfirstof all of halogens is a characteristic
feature of He-MIP-AES. The determination oftrace amounts ofalkali
metals is the second attractive field
ofMIP-AESapplications.Moreover, satisfactory low detection limits
are achieved for tnetals of the group I band II b of the periodic
system and for elements forming volatile hydrides.
The versatility·ofthismethod and. compatibility of its operating
parameters withthe parameters of comtnonchromatographic
techniques,flowinjection analysis Orhydride generation tcchniqueare
of essentialimp()rtance for the positive evaluationof the method.
GC-MIP-AES is a technique of choice for studying the speciation
oforganometallic compounds in the environtnent.
REFERENCES
1. Sturgeon R.E., J Anal. At. Spectrorn., 13, 351 (1998).2. Cave
M.R., Butler 0., Cook J.M., Cresser M.S., Garden L.M., Holden A.J.
and Miles D.L.,.! Anal. At.
Spectroln., 15, 181 (2000)., 14, 279 (1999).3. Clement R.E.,
YangP.W. and .Koester C.I, Anal. Cheln., 71, 257R (1999).4. Caroli
S., Spectrochiln. Acta, Part B, 43,371 (1988).5.q[ficial Methods
ofAnalysiso,fthe Association o,fq[ficial AnalyticalChelnists,
[CunniffP., Ed.], 16th
edn., Association of Official Analytical Chemists, Arlington, VA
1995.6. Borer M.W. and Hieftje G.M.,.! Anal.. At. Spectroln., 8,
339 (1993).7. Douglas D.1., Quan E.S.K. and Smith R.G.,
Spectrochiln. Acta, Part B, 38, 39 (1983).8. Uden P.C.,.!
Chrolnatogr. A, 703, 393 (1995).9. Quimby B.D. and Sullivan J.I,
Anal. Chern., 62,1027,1034 (1990).
10. Bulska E.,.! Anal. At. Spectrorn., 7, 201 (1992).11.
Lobinski R. and Adams EC., Tr. Anal. Chern., 12,41
(1993).12.Croslyn A.E., Smith B.W.and Winefordner ID., CRC Crit.
Rev. Anal. Chern., 27,199 (1997).13. Jin Q., Duan Y. and Olivares
IA., Spectrochirn. Acta, Part B, 52, 131 (1997).14. Matousek IP.,
Orr B.. I. and SelbyM., Prog. Anal. Cheln., 7, 275 (1984).15.
Deutsch R.D., Keilsohn J.P. and Hieftje G.M., Appl. Spectrosc.,
39,531 (1985).16. Urh J.1. and Carnahan lW., Appl. Spectrosc., 40,
877(1986).17. Matusiewicz H., Spectrochiln. Acta, Part B, 47,1221
(1992).18. Riviere B., Mermet J.M. and Deruaz D.,.! Anal. At.
Spectrorn., 3, 551 (1988).19. Donard O.F.X. and Lobinski R.,.!
Anal. At. Spectrorn., 11, 871 (1996).20. Uden P.C., Cheln. Anal.
(N. Y), 131, 143 (1995).21. Lobinski R. and Adams EC.,
Spectrochiln. Acta, Part B, 52, 1865 (1997).22. Tao H. and Miyazaki
A., Anal. Sci., 7, 55 (1991).23. Carey J.M. and Caruso J.A., CRC
Crit. Rev. Anal. Cheln., 23, 397 (1992).24. Lichte F.E. and
Skogerboe R.K., Anal. Chern., 44, 1321 (1972).25. Perkins L.D. and
Long G.L.,Appl. Spectrosc., 43, 499(1989).26. Long G.L. and Perkins
L.D., Appl. Spectrosc., 41, 980 (1987).
-
324 K. Jankowski
27. Galante L.l, Selby M. and Hieftje G.M., Appl. Spectrosc.,
42, 559 (1988) ..28. Jin Q., Zhang H., Liang F. and Jin Q., J.
Anal. At. SpectroJn., 10,875 (1995).29. Yang l, Zhang l, Schickling
C. and Broekaert lA.C., SpectrochiJn. Acta, Part B, 51, 551
(1996).30. Jankowski K., Parosa R., Ramsza A. and Reszke E.,
Spectrochim. Acta, Part B, 54, 515 (1999).31. Winefordner J.D.,
Wagner II E.P. and Smith B.W., J. Anal. At. SpectroJn., 11,689
(1996).32. Bache C.A. and Lisk DJ., J. Assoc. qlf. Anal. Chen1.,
6,1246 (1967).33. Liu Y., Lopez-Avilla V., Alcaraz M. and Beckert
W.F., Anal. Chen1., 66, 3788 (1994).34. Broekaert lA.C. and Leis
F., Mikrochi111. Acta, II, 261 (1985).35. Drews W., Weber G. and
T6IgG., Anal. Chi/no Acta, 231, 265 (1990).36. Bulska E., Emteborg
H., Baxter D.C., Frech W., Ellingsen D. and Thomassen Y., Analyst,
117, 657
(1992).37. Pak Y.N. and Koirtyohann S.R., J. Anal. At.
Spectron1., 9, 1305 (1994).38. Siemens V., Harju T., Laitinen T.,
Larjava.K. and Broekaert J.A.C., FreseniusJ.Anal. CheJ11.,
351,11
(1995).39. Cerbus C.S. and Gluck S.l, Spectrochi/n. Acta, Part
B, 38, 387 (1983).40. Ng K.C., JensenR.S., Brechmann MJ. and Santos
W.C., Anal. Che111., 60, 2818 (1988).41. Duan Y., Li X. and Jin Q.,
J. Anal. At. Spectro111., 8, 1091 (1993).42. Zybin A.,
Schnurer-Patschan C. and Nielnax K., J. Anal. At. Spectron1., 10,
563 (1995).43. Perkins L.D. and Long G.L., Appl. Spectrosc.,
42,1285 (1988).44. Duan Y., Du X., Li Y. and Jin Q., Appl.
Spectrosc., 49, 1079 (1995).45. Rigin V., Anal. Chi/no Acta, 283,
895 (1993).46. Oki Y., Uda H., Honda C., Maeda M., Izumi l,
Morimoto T. and Tanoura M., Anal. Che111., 62, 680
(1990).47. Brown P.G., Davidson T.M. and Caruso lA., J. Anal.
At. Spectr0111., 3,763 (1988).48. Olson L.K. and Caruso lA.,
Spectrochi/n. Acta, Part B, 49, 7 (1994).49. Okamoto Y., J. Anal.
At. SpectroJn., 9, 745 (1994).50. Poussel E., Mermet J.M., Deruaz
D. and Beaugrand C., Anal. CheJn., 60, 923 (1988).51. Sullivan J.l,
Tr. Anal. Che111., 10, 23 (1991).52. Uden P.C., Tr. Anal. CheJn.,
6, 238 (1987).53. Chau Y.K. and Wong P.T.S., Fresenius J. Anal.
CheJn., 339, 640 (1991).54. Scott B.F. and Wylie P.L., Che111.
Plant Prot., 12, 33 (1995).55. Luffer D.R., Galante L.l, David
P.A., Novotny M. and Hieftje G.M., Anal. Chen1., 60, 1365
(1988).56. Webster G.K. and Carnahan J.W., Anal. CheJn., 64, 50
(1992).57. Zhang L., Carnahan lW., Winans R.E. and Neill P.H.,
Anal. Chem., 61, 895 (1989).58. Galante L.l, Wilson D.A. and
Hieftje G.M., Anal. Chi/no Acta, 215, 99 (1988).59. Kollotzek D.,
Oechsle D., Kaiser G., Tsch6pel P. and T61g G., Fresenius Z. Anal.
Chen1., 318, 485
(1984).60. Liu Y. and Lopez-Avila V., J High Resolut.
Chromatogr., 16,717 (1993).61. Madrid Y., Wu M., Jin Q. and Hieftje
G.M., Anal. Chim. Acta, 277,1 (1993).62. Broida H.P. and Chapnlan
M.W., Anal. CheJn., 30, 2049 (1958).63. Mc Kenna M., Marr I.L,
Cresser M.S. and Lam E., Spectrochim. Acta, Part B, 41, 669
(1986).64. Denkhaus E., Golloch A. and Ku H.M., Fresenius J Anal.
CheJn., 353,156 (1995).65. Brown P.G., Haas D.L., Workman lM.,
Caruso J.A. and Fricke F.L., Anal. Cheln., 59, 1433 (1987).66.
Skogerboe R.K. and Coleman G.N., Anal. Chern., 48, 611A (1976).67.
Ng K.C. and Culp R.C., Appl. Spectrosc., 51, 1447 (1997).68.
Matusiewicz H., SpectrochiJ11. Acta Rev., 13,47 (1990).69. Bulska
E., Broekaert J.A.C., Tsch6pel P. and T6lg G., Anal. Chi/no Acta,
276, 377 (1993).70. Barnett N.W., Spectrochi/n. Acta, Part B, 42,
859 (1987).71. Pereiro R., Wu M., Broekaert lA.C. and Hieftje G.M.,
Spectrochi/n. Acta, Part B, 49, 59 (1994).72. Kaiser G., G6tz D.,
Schoch P. and T61g G., Talanta, 22, 889 (1975).73. Nojiri Y.,
Otsuki A. and Fuwa K., Anal. Chem., 58,544 (1986).74. Skogerboe
R.K., Dick D.L., Pavlica D.A. and Lichte F.E., Anal. CheJ11., 47,
568 (1975).75. Drews W., Weber G. and T61g G., Fresenius Z. Anal.
Cheln., 332, 862 (1989).76. Dagnall R.M., West T.S. and Whitehead
P., Analyst, 98, 647 (1973).77. Barnett N.W., J. Anal. At.
SpectroJn., 3, 969 (1988).
-
Microwave induced plasma elnission spectrolnetry 325
78. Baumann H. and Heumann K.G., Fresenius Z.. Anal.. Cheln.,
327, 186 (1987).79. Nakahara T., Mori T., Morimoto S. and Ishikawa
H., Spectrochiln. Acta, Part B, 50, 393 (1995).80. Uebbing J.,
Ciocan A. and Niemax K., Spectrochiln. Acta, PartB, 47, 601, 611
(1992).81. Gehlhausen lM. and Carnahan lW., Anal. Chent., 63, 2430
(1991).82. MatusiewiczH. and SturgeonR.E., Spectrochiln.Acta, Part
B, 48, 723 (1993).83. LaymanL.R. and Hieftje G.M., Anal.Chent., 47,
194 (1975).84. Beenakker C.I.M., Bosman B. and Boumans P.W.lM.,
SpectrochiTn. Acta, Part B, 33, 373 (1978).85. JankowskiK.,
RamszaA., StarskiL. and Waszkiewicz A., TheMIP spectrul1tatlas,
unpublished data.86. Jankowski K., J. Anal. At. Spectroln., 14,
1419 (1999).87. Jankowski K. and DregerM., J. Anal. At..
Spectront.,.15, 269(2000).88. Winge R.K., Peterson V.l and Fassel
V.A., Appl. Spectrosc., 33, 206 (1979).89. Tanabe K., Haraguchi H.
and Fuwa K., Spectrochi/n. Acta, Part B, 36, 119 (1981).90. Larson
G.F. and Fassel V.A., Anal.Cheln., 48,1161 (1976).91. Berman 1.0.
and Bostrum K., Anal. Chern., 51, 516(1979).92. Atsuya I.,
Kawaguchi H., VeillonC. and Vallee B.L., Anal.· Chent., 49, 1489
(1977).93. Kawaguchi H. and Vallee B.L., Anal. Cheln., 47,1029
(1975).94. Zander A.T., Anal. Chent., 58, 1139A (1986).95. Zander
A.T. andMillerM.H., Spectrochiln. Acta, Part B, 40, 1023 (1985).96.
Welz B., Atolnic AbsorptionSpectrontetry, Verlag Chemie,Weinheim
1985.97. Fricke F.L., Robbins w.n. and Caruso J.A., J. Assoc. o.ff
Anal. Chern., 61, 1118 (1978).98. Risby T.H. and Tahni Y., CRC
Crit. Rev. Anal. Chent., 14, 231 (1983).99. Rosenkranz B., Breer
C.B., Buscher W., Bettmer J. andCammann K., J. Anal. At.
Spectroln., 12, 993
(1997).100. Frischenschlager H., Peck Nt, Mittermayr C.,
Rosenberg E. and Grasserbauer M., Fresenius J. Anal.
Cheln., 357, 1133 (1997).101. Ng K.C. and Shen W.L., Anal.
Chern., 58,2084 (1986).102. Heltai G., BroekaertJ.A.C., Burba P.,
Leis F., Tsch6pel P. and T6lg G., Spectrochiln. Acta, Part B,
45,
857 (1990).103. Jankowski K., Karmasz D., Ramsza A. and Reszke
E., Spectrochiln. Acta, Part B, 52, 1813 (1997).104. Broekaert
lA.C. and T6lg G., Fresenius Z. Anal. Cheln., 326, 495 (1987).105.
Broekaert lA.C., Anal. Chi/no Acta, 196, 1 (1987).106. ·Vermaak H.,
Kujirai 0., Hanamura S. and Winefordner lD., Can. J. Spectrosc.,
31,95 (1986).107. Serravallo F.A. and Risby T.H., Anal. Cheln., 48,
673 (1976).108. •Taylor H.E., Gibson l.R. and Skogerboe R.K.,
Anal.Chem., 42, 1569 (1970).109. Reamer D.C., Zoller W.H. and
O'HaverT.C., Anal. Chent., 50,1449 (1978).110. Water quality - the
determination o.f33 elentents by ICP-AES, ISO 11885: 1996,
International Organiza-
tion for Standardization, 1996.Ill. Maier E.A., Tr. Anal.
Cheln., 10, 340 (1991).112. Quevauviller P., J. Anal.
At.Spectronl., 11, 1225 (1996).113. Inductively
CoupledPlaslna-AtolnicEmission SpectrOlnetric Method.for Trace
ElelnentAnalysiso.fWa-
ter and Wastes, Method 200.7, Environmental Protection Agency,
Federal Register 49 (209), 26 Octo-ber 1984,pp. 199-204.
114. Contract Laboratory Progranl Statement o.fWork.forlnorganic
Analysis, SOW No. 788, US Environ-mental Protection Agency,
Washington, DC, 1988.
115. Jankowski K, Microwave inducedplasnta as excitation
source.for spectrochenlical analysis - charac-terization and·
application,Habilitation, Publishing House of the Warsaw University
of Technol-ogy,Warsaw 2001 (in Polish).
116. Volland G., Tsch6pel P. and T6lg G., SpectrochiTn. Acta,
Part B, 36, 901 (1981).117. Talmi Y. and Norvell V.E., Anal.
Cheln., 47, 1510 (1975).118. Lunzer F., Pereiro-Garcia R.,
Bordel-Garcia N. and Sanz-Medel A., J. Anal. At. Spectro111., 10,
311
(1995).119. Bulska E., Beinrohr E., Tsch6pel P., Broekaert
J.A.C. and T6IgG., Cheln. Anal. (Warsaw), 41, 615
(1996).120. Lichte F.E. and Skogerboe R.K., Anal. Chenl., 44,
1480 (1972).121. Dietz C., Madrid Y., Camara C. and Quevauviller
P., J. Anal. At. Spectroin., 14, 1349 (1999).
-
326 K. Jankowski
122. Tao H., Miyazaki A. and Bansho K., Anal. Sci., 4, 299
(1988).123. Talmi Y. and Andren A.W., Cheln. Anal., 46, 2122
(1974).124. Michlewicz K.G. and Carnahan J.W., Anal. Cheln., 58,
3122 (1986).125. Gehlhausen J.M. and Carnahan J.W., Anal. Cheln.,
61,674 (1989).126. Wu M. and Carnahan J.W., J Anal. At. Spectroln.,
7,1249 (1992).127. Camuna F., Sanchez Uria J.E. and Sanz Medel A.,
Spectrochin1. Acta) Part B, 48, 1115 (1993).128. Chiba K., Yoshida
K., Tanabe K., Ozaki M., Haraguchi H., Winefordner J.D. and Fuwa
K., Anal. Chem.. ,
54, 761 (1982).129. Haraguchi H., Studies in Environ. Sci., 27,
31 (1988)..130. Nakahara T. and Wasa T., Microchern. J., 41,148
(1990).131. Nakahara T., Yamada S. and Wasa T., Appl. Spectrosc.,
45, 1561 (1991).132. Nakahara T~, Yamada S. and Wasa T~, Cheln.
Express., 6, 5 (1991).133. Alvarado J.S. and Carnahan J.W., Anal.
Chern., 65, 3295 (1993).134. Gerbersmann C., Lobiilski R. and Adams
F.C., Anal. Chi/no Acta, 316, 93 (1995).135. Mitchell G., Aldous
K.M. and Canelli E., Anal. Chern., 49, 1235 (1977).136. Chiba K.
and Haraguchi H., Anal. Chern., 55,1504 (1983).137. Quimby B.D.,
Delaney M.F., Uden P.C. and Barnes R.M., Anal. Chen1., 51, 875
(1979).138. Slaets S., Laturnus F. and Adams F.C., Fresenius J
Anal. Cheln., 363, 487 (1999).139. Turnes M.l., Rodriguez I.,
Mejuto M.C. and Cela R., J Chrornatogr. A, 683,21 (1994).140.
Quimby B.D., Delaney M.F., Uden P.C. and Barnes R.M., Anal. Chern.,
52, 259 (1980).141. Haas D.L. and Caruso J.A., Anal. Chern., 57,846
(1985).142. Hajslova J., Cuhra P., KempnyM., Poustka J., Holadova
K. and Kocourek V., J Chrornatogr. A, 699,
231 (1995).143. Koschuh B., Montes M., Camuna J.F., Pereira R.
and Sanz-Medel A., Mikrochiln. Acta, 129, 217
(1998).144. Lehnert H., Twiehaus T., Rieping D., Buscher W. and
Cammann K., Analyst, 123,637 (1998).145. Seeley J.A., Zeng Y., Uden
P.C., Eglinton T.l. and Ericson I., J Anal. At. Spectroln., 7, 979
(1992).146. Ng K.C., Xu X.X. and Brechmann M.J., Spectrosc. Lett.,
22,1251 (1989).147. Jin Q., Zhang H., YangW., Jin Q. and Shi Y.,
Talanta, 44,1605 (1997).148. Barnett N.W., Anal. Chiln. Acta, 198,
309 (1987).149. Aziz A., Broekaert J.A.C. and Leis F., Spectrochbn.
Acta) Part B, 37,381 (1982).150. Schickling C., Yang J. and
Broekaert J.A.C., J Anal. At. Spectroln., 11, 739 (1996).151.
Nakahara T. and Takeuchi N., Anal. Sci., 13, 13 (1997)..152.
Calle-Guntinas M.B. de la, Brunori C., Scerbo R., Chiavarini S.,
Quevauviller P., Adams F.C. and
Morabito R., J Anal. At. Spectroln., 12,1041 (1997).153. Riviere
B., Mermet I.M. and Deruaz D., J Anal. At. Spectrorn., 2,705
(1987).154. Bache C.A. and Lisk DJ., Anal. Chern., 38,785
(1966).155. Wylie P.L. and Oguchi R., J Chrornatogr., 517,131
(1990).156. Rodriguez Pereiro I., Schmitt V.O. and Lobiilski R.,
Anal. Chern., 69,4799 (1997).157. Ceulemans M. and Adams F.C., J
Anal. At. Spectroln., 11,201 (1996).158. Tutschku S., Mothes S. and
Dittrich K., J Chrornatogr. A, 683, 269(1994).159. Dirkx W.M.R.,
Lobiilski R. and Adams F.C., Anal. Sci., 9, 273 (1993).160.
Lobiilski R. and Adams F.C., Anal. Chiln. Acta, 262, 285
(1992).161. Lobiilski R., Dirkx W.M.R., Ceulemans M. and Adams
F.C., Anal. Chern., 64, 159 (1992).162. Szpunar J., Schmitt V.O.,
Lobiilski R. and Monod J.L., J Anal. At. Spectrorn., 11, 193
(1996).163. Rodriguez-Pereiro I., Wasik A. and Lobiilski R., Chern.
Anal. (Warsaw), 42,799 (1997).164. Szpunar-LobiilskaJ., Ceulemans
M., Lobiilski R. and Adams F.C., Anal. Chirn. Acta, 278,99
(1993).165. Liu Y., Lopez-Avilla V., Alcaraz M. and Beckert W.F., J
High Resolut. Chron1atogr., 17, 527 (1994).166. Gerbersmann C.,
Heisterkamp M., Adams F.C. and Broekaert J.A.C., Anal. Chiln.Acta,
350, 273
(1997).167. Carro-Diaz A.M., Lorenzo-Ferreira R.A. and
Cela-Torrijos R., J Chrornatogr. A, 683, 245 (1994).168. Snell
J.P., Frech W., and Thomassen, Analyst, 121, 1055 (1996).169.
Donais M.K., Uden P.C., Schantz M.M. and Wiese S.A., Anal. Chern.,
68, 3859 (1996).170. Palmeri H.E.L. and Leonel L.V., Fresenius J
Anal. Chern., 366, 466 (2000).
-
Microwave induced plasma emission spectrometry 327
171. Emteborg H., Bjorklund E., Odman E, Karlsson L., Mathiasson
L., FrechW. and Baxter D.C., Analyst,121,19 (1996).
172. Emteborg H., Baxter D.C., Sharp M. and Frech W., Analyst,
120, 69 (1995).173. Chiba K., Yoshida K., Tanabe K., Haraguchi H.
and Fuwa K., Anal. Chern., 55, 450 (1983).174. Mena M.L., Me Lead
C.W., Jones P., Withers A., Minganti V., Capelli R. and
Quevauviller P., Fresenius
J. Anal. Chern., 351, 456 (1995).175. Costa-Fernandez lM.,
Lunzer E,Pereiro-Garcia R., Sanz-Medel A. and Bordel-Garcia N., J.
Anal. At.
Spectrorn., 10, 1019 (1995).176. Szpunar-LobinskaJ., Ceulemans
M., Dirkx W.M.R., Witte C., Lobhlski R. and Adams F.C.,
Mikrochim.
Acta, 113, 287 (1994).177. Estes S.A., Uden P.C. and Barnes
R.M.,Anal. Chern., 53,1336 (1981).178. Lobiuski R. and Adams F.C.,
J. Anal. At. Spectrorn., 7, 987 (1992).179. Wasik A., Pereiro I.R.
and Lobiuski R., Spectrochirn. Acta, PartB, 53, 867(1998).180.
Heisterkamp M. and Adams F.C., Fresenius J. Anal. Chern., 362, 489
(1998).181. Lobiuski R., Boutron C.F., Candelone J.P., Hong S.,
Szpunar-Lobiuska J. and Adams F.C., Anal. Cheln.,
65, 2510 (1993).182. Calle-Guntinas M.B. de la, Lobiuski R. and
Adams EC., J. Anal. At. Spectrom., 10, 111 (1995).183..
Calle-Guntinas M.B. de la, Ceulemans M., Witte C., Lobiuski R. and
Adams EC., Mikrochirn. Acta,
120, 73 (1995).
ReceivedJuly 2000Accepted February 2001