Trace Element Analysis of Industrial Wastewater and Sewage ......Sewage Analysis 12/13/2010 21. When applied to trace element analysis of fresh water and sewage samples, TXRF offers

Trace Element Analysis of Industrial Wastewater and Sewage with TXRF and ICP-MS

Bruker AXS – Madison, WI

Bruker CAD – Fremont, CA

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Welcome

Today’s Topics

• Introduction to TXRF

• Why wait for sample prep

• Application studies

• Sewage Analysis• Industrial Wastewater

• Introduction to ICP-MS

• Operation of Bruker ICP-MS

• Wastewater analysis

• Interactive Q & A

Speakers

Mike Beauchaine Business Development TXRFMadison, Wisconsin

Andrew TomsICP-MS SpecialistMilton, Ontario

Introduction to TXRF

Mike Beauchaine

Principles X-ray fluorescence (XRF) spectroscopy

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1. An X-ray quantum hits an inner shell electron in a (sample) atom. The electron is removed leaving the atom in an excited state

2. The missing inner shell electron is replaced by an electron from an outer shell

3. The energy difference between the inner and outer shell is balanced by the emission of a photon (fluorescence radiation)

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Principles X-ray fluorescence (XRF) spectroscopy

• The energy, and therefore the wavelength, of the X-ray fluorescence radiation is characteristic for the different chemical elements.

QUALITATIVE ANALYSIS

• The intensity of the X-ray fluorescence radiation is, in first approximation, proportional to the element concentration.

QUANTITATIVE ANALYSIS

Low Z High Z

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Principles X-ray fluorescence (XRF) spectroscopy

“Common” XRF optics

Beam angle: 45o / 45o

X-ray tube

Sample

Detector

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Principles of total reflection X-ray fluorescence (TXRF) spectroscopy

Typical instrument design of a TXRF spectrometer

Beam angle: 0o / 90o

X-ray tube

Detector

Sample carrier

Monochromator

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Principles of total reflection X-ray fluorescence spectroscopy

• No scattering Detection limits down monochromated X-rays to 0.1 ppb

• Versatile with regard Measurement of liquidsto sample type suspension, powders

etc.

• Sample amount Low µg or µl range

• Prepared as thin films Matrix effect are inconsequential

Features and benefits of TXRF

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Principles of total reflection X-ray fluorescence spectroscopy

• The S2 PICOFOX detects elements from Na(11) to U(92)

• The element sensitivities depend on the atomic number

• The sensitivity factors are calibrated ex works

• Sensitivities will differ based on the tube

Element sensitivity

L-linesK-lines

Atomic number

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The TXRF spectrometerS2 PICOFOX

Benchtop TXRF spectrometer: S2 PICOFOX

• Metal-ceramic X-ray tube• Mo anode

• air-cooled• optionally other tubes available

• Multilayer monochromator

• XFlash® Silicon Drift Detector• thermoelectrically cooled

• ≤149 eV @ MnKα 100 kcps

• Automatic version• 25-sample magazine

Please use your mouse to answer the question to the right of your screen:

Audience Poll

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What would you most like to improve upon regarding your

current analysis?

Speed of measurement

Accuracy

Sensitivity

Sample prep

Cost-of-ownership

Ease-of-use

Application studiesSewage Analysis

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Application studiesSewage Analysis

• Control of threshold values of heavy metals in sewage per 40 CFR 503.13:

• Dried sewage samples

• Sample prep

• Dilution (raw sewage sludge)

• Filtration and separate analysis of filtrate possible

• Internal standardization

• Preparation – homogenization

• Apply 10 µl of sample to carrier

• Vacuum dry or heat

• Measurement

• Measurement time of 1000 s

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• fill powder in mortar

• grind carefully

• weigh about 20-50 mg

• transfer to vial

Solid materials are ground to fine particle size and resuspended for direct analysis without digestion

Sample preparation of filtrates, soils, and solids

Application studiesSample preparation for rapid screening

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Application studiesSample preparation for rapid screening

• suspend in detergent solution• add standard

• homogenize• pipette on carrier

Application studiesSewage Analysis

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• Calculated detection limits in mg/l of common elements measured at 1000 s at 3σ in control solution, sewage, and raw sewage.

• Exceeds threshold values for Cr, Mn, Fe,Co, Ni, Cu, Zn, Se, Ba, and Pb

• Good correspondence with ICP-OES withthe added benefits of TXRF

Application studiesIndustrial Effluents

• Effluent analysis of heavy metals from tanning leather process:

• Raw sewage samples

• Sample prep

• Internal standardization (Yttrium)

• Preparation – homogenization

• Apply 10 µl of sample to carrier

• Vacuum dry or heat

• Measurement

• Measurement time of 1000 s

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Sample preparationLiquid samples

You‘ll need just a few steps for the preparation of liquid samples

• fill sample in micro tube

• add internal standard

• homogenize

• pipette on carrier

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Sample preparationFinal steps

• dry by heat / vacuum• load the instrument

• start data acquisition

Application studiesIndustrial Effluents

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• Level of Detection was well below limit value

• Level of Detection only showed slight improvement with Microwave Digestion

• Analyzed using W tube for 1000 s

• Little required sample prep and low cost of ownership

• Complementary tool to digestion techniques such as ICP-MS for industrial treatment plants

• Concentrations expressed as mg/L• Concentration limits for heavy metals in industrial wastewater effluents according to the regulation from the Catalonia Water Agency (Spain) and calculated detection limits from the analysis of the waste-water reference material SPS-WW2 by TXRF

* Acknowledgments to E. Margui – Institute of Earth Sciences Barcelona, Spain

Application studiesSewage Analysis

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When applied to trace element analysis of fresh water and sewage samples, TXRF offers the following benefits:

• Flexibility with regard to sample type• Raw sewage

• Industrial wastewater and effluents

• Contaminated soils• Filtered sewage

• Fresh water

• Sewage filtrates

• Easy multi-element analysis without external calibration – Allows for prescreening of unknown samples prior to ICP-MS

• Low maintenance costs

• Small size of the system (mobile use)

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ConclusionTXRF vs. AAS/ICP-OES

• Small footprint/portable

• Microgram sample size

• % to ppb levels

• Single std. calibration

• Low maintenance

• Non-destructive

• Short learning curve

• Fast sample prep

• Large, fixed installation

• Milligram sample size

• ppm to sub-ppb levels

• Multi-standard calibration

• High maintenance

• Destructive

• Long learning curve

• Laborious sample prep

TXRF AAS / ICP-OES

Summary

Introduction to ICP-MS

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Andrew Toms

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ICP-MS Overview

• Very high sensitivity and low background

• Low DLs <1 ppt for some elements in solution

• Large linear dynamic range (9 orders)

• Few spectral interferences

• Simple spectra produced

• Isotopic analysis capability

• Routine trace element analysis

• (ppb and below)

• Rapid multi-element analysis

• Wide range of elements (>75)

• Analysis of a wide variety of sample types

• Simple sample preparation

• Wide variety of sample introduction options

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Elemental Analysis by Mass Spectrometry

Atomic Number

The number of protons in the nucleus of the atom

Also the number of electrons in a ground state (electrically neutral) atom

Isotopes

Atoms of elements which have the same number of electrons and protons but different numbers of neutrons

Mass Number - common ICP-MS terminology

The total number of protons and neutrons in the nucleus of a particular isotope

AMU

Atomic Mass Unit - the mass of a proton or neutron

The two isotopes of boron shown here will have different masses but will otherwise be essentially identical in their chemical properties

Mass Number

Atomic NumberB11

5B10

5

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Element Isotopes in ICP-MS

Example: Nickel

58Ni 60Ni 61Ni 62Ni 64Ni

No. of protons (p+) 28 28 28 28 28

No. of electrons (e-) 28 28 28 28 28

No. of neutrons (n) 30 32 33 34 36

Atomic mass (p+ + n) 58 60 61 62 63

Atomic number (p+) 28 28 28 28 28

Natural abundance 68.1% 26.2% 1.14% 3.63% 0.93%

Atomic weight 58.69

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ICP-ES Spectrum for Ni

Many emission lines for Ni

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ICP-MS Spectrum for Ni

Five stable isotopes of Ni

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Extent of Ionization in Argon Plasma

H HeLi Be B C N O F NeNa Mg Al Si P S Cl ArK Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I XeCs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At RnFr Ra Ac

Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb LuTh Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lw

>80% 50-10%80-50% <10%

Calculated values of degree of ionization of M+ and M+2 (T=7500K, ne = 1e15cm-3 ) * Houk 1986

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ICP-MS System Summary

• Sample nebulized (aerosol) in spray chamber

• Argon transports sample and sustains plasma

• RF generator supplies energy to induction coil

• Sample atomized and ionized in the plasma

• Ions are transmitted through the interface, most of the gas removed

• Collision/reaction technology applied to minimize interferences (some instruments)

• Ions are focused into mass analyzer

• Quadrupole filters the ions by mass

• Detector counts the ions

Distance fromload coil

Initial Radiation Zone

Plasma Tail

Plasma Gas

Induction Zone

ICP-MS Sampling Position

Preheating Zone

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Nebulizer Gas + Sample Aerosol

Auxiliary Gas

The Inductively Coupled Plasma

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Recombination Ionization Atomization Vaporization

Oxides Ions Atoms Gas Solid Liquid

Sampleaerosol

M(H20)+ X-MXnMXMXM+MO+

Processes in the Plasma

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Plasma RF System

Solid state 27‐MHz RF generator

Microprocessor‐controlled impedance matching network

Interlaced Load Coils 

• High coupling efficiency for the utmost in plasma stability

• Allows unshielded cool plasma operation

Computer‐controlled XYZ alignment

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The ICP in operation

• RF-induced plasma operating at ~5000K

• Hot enough to ionize almost every element in the periodic table

• Argon used because of suitable ionization properties

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Interface and Ion Mirror

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Common ICP-MS analytesand their common interferences

Analyte Interferences

40Ca 40Ar

51V 35Cl16O

52Cr 40Ar12C, 35Cl16O1H, 36Ar16O

53Cr 40Ar13C, 37Cl16O

56Fe 40Ar16O, 40Ca16O

75As 40Ar35Cl

78Se 40Ar38Ar

80Se 40Ar40Ar

Bruker’s Answer?

The Collision/Reaction Interface (CRI)

H2 gas injected to react with Ar+ and ArX+

molecular ions

He gas used to separate other interferences using Kinetic Energy Discrimination (KED)

Implementation of the CRI

The best conditions (high plasma density and high temperature) for collisions and reactions are found in the aperture of the skimmer .   

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Ions are more affected by the alternating RF field. Will drift until it finds itself in stronger and stronger regions of field. It will quickly collide with an electrode and disappear.

Not affected much by the alternating field, but will gradually drift in the constant (DC) part of the field. The alternating field is not strong enough to drag it back as it wanders, so it also collides with an electrode, and is lost.

An ion of the correct mass/charge ratio is stable in the quadrupole field and reaches the end, where it can be detected.

Too Light -

Too Heavy -

Just “Right” -

The Quadrupole in operation

Extended Dynamic Range Detector

Adjustment of gain applied to control dynode provides attenuation of final output signal

ControlSection

Signal Output

QuadrupoleGain

Control

Ion to e-Conversion

Amplification

+e- e-

e-e-e-

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109 Linear Range

10 ppt -> 1000 ppm Tl205

R2 = 0.999999

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Trace Elements:0.01 – 5 ppb Selenium

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Major elements:0.1 ppb – 100 ppm Mg

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Sewage and WastewaterAnalysis by ICP-MS

• ICP-MS is less tolerant of samples with high dissolved solids.

• Cloudy/murky solutions should be dissolved/digested/filtered.

• Highly concentrated solutions can also be diluted – automated online dilution is optional

• ICP-MS is highly automated, and can run 100’s to 1000’s of samples unattended, every day

Application Notes ready to go

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Any Questions?

Please type in questions you may have for either of our speakers in the Q&A paneland then click Send.

Q & A

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