trace metals epa 200 8 nov 07

7/31/2019 Trace Metals EPA 200 8 Nov 07

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Analysis of Trace and Non-Trace Elements inWaters and Wastes by EPA Method 200.8

Written by: Eric D. DoddsApproved by: Dr. John M. Kennish

Applied Science, Engineering, and Technology LaboratoryUniversity of Alaska Anchorage

Revised: by Birgit Hagedorn November 2007Analysis of Trace and Non-Trace Elements in

Waters and Wastes by EPA Method 200.8


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Analysis of Elements by EPA 200.8 1

Application and Methodology

Based on EPA method 200.8, the analytical methods described here allowfor the quantitaion of dissolved or total elements in samples such as ground

waters, surface waters, and drinking water. Total recoverable elements in wastewaters, sludges, and soils may also be determined. Analysis of appropriatelyprepared samples is conducted by inductively coupled plasma massspectrometry (ICP-MS). The analytes shown in Table I constitute the usual suiteof trace elements included in method 200.8 analyses; however, additional non-trace elements (such as calcium, iron, magnesium, potassium, sodium) may bedetermined in aqueous matrices as appropriate.

Table I. Typical suite of elements determined byEPA Method 200.8.

Element Name ElementSymbol

LOD

Aluminum Al 0.8Antimony Sb 1.5

Arsenic As 0.5

Barium Ba 0.7

Beryllium Be 0.04

Cadmium Cd 0.5

Chromium Cr 0.8

Cobalt Co 2.0

Copper Cu 1.5

Lead Pb 0.4

Manganese Mn 1.4

Mercury Hg

Molybdenum Mo 0.8

Nickel Ni 0.8Selenium Se 0.8

Silver Ag 0.8

Thallium Tl 1.0

Thorium Th 0.8

Uranium U 0.8

Vanadium V 1.0

Trace ElementsEPA 200.8 Validated

Zinc Zn 0.7

Calcium Ca 70

Iron Fe 20

Magnesium Mg 20

Potassium K 30

Non-Trace Elements

Sodium Na 26

University of Alaska Anchorage (ASET)


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Reagents, Solutions, and Standards

All solutions prepared for use in this method must be stored inpolyethylene containers the use of glassware is not acceptable. The usefullifetime of these solutions is no more than about one week.

Analytical grade deionized water (DI H2O). Must have a resistivity of 17.518.5M/cm.

Concentrated nitric acid (HNO3). Trace metals analysis grade.

Diluent solution. Must contain 1.0 % concentrated HNO3 by volume. Combine100 mL trace metals analysis grade concentrated HNO3 in several liters of DIH2O, and bring to a total final volume of 10 L with DI H2O. Mix thoroughly.

ICP-MS tuning solution. Contains 10 ppb Li, Y, Ce, Tl, and Co for instrumenttuning and verification of performance. Mixed from single element standards of

1000 ppm concentration: Preparation of stock solution: Pipette 1 mL of eachelement solution into 100 mL volumetric flask and fill with 1% HNO 3 diluent.Preparation of tuning solution: Pipette 1 mL of stock solution in 1000 mL flaskand fill with 1% HNO3 diluent.

Multi-element primary standard mixture. Contains Fe, K, Ca, Na, and Mgat 1000 ppm and Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, Se, Tl,V, Zn, Th, and U at 10 ppm. Available from Agilent, item number 5183-4688.

Single-element primary standards. If elements in addition to thosecontained in the multi-element primary standard are to be determined, working

standard solutions may be supplemented with single-element standards toproduce the desired concentrations. Single-element standards of suitable qualityfor plasma methods are available from a variety of sources.

Internal standards (ISTD) primary standard mixture. Contains Li6, Sc, Ge,Y, In, Tb, and Bi at 10 ppm for use as internal standards. Available from Agilent,item number 5183-4680.

Working ISTD solution. To prepare the working internal standards solution(1 ppm each IS), add 10 mL IS primary standard mixture to approximately 50 mLdiluent solution and dilute to a total final volume of 100 mL with diluent solution.

Erbium primary standard. Contains Er at 1 ppm for use as a dilutionstandard. Available from Agilent, item number G1820-60372.

Working erbium solution. To prepare the working dilution standard solution(50 ppb Er), add 12.5 mL 1 ppm Er to approximately 100 mL diluent solution anddilute to a total final volume of 250 mL with diluent solution.



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Calibration standards. To prepare initial calibration (ICAL) solutions,specific volumes of the multi-element primary standard mixture are diluted withdiluent solution. The required volumes of multi-element primary standard mixturefor preparation of a standard set of ICAL solutions is given below (Table II),followed by the resultant concentration of all analytes at each calibration level

(Table III). If additional elements are desired, single-element standards must beused to supplement the preparations described below. In order to obtain theconcentrations listed in Table III, the total final volume of each solution must be250.0 mL. If any of the elements are expected to exceed the calibration rangegiven below, additional levels may be used in order to span the necessary rangeof concentrations using the multi-element or single-element standards asappropriate.

Table II. Preparation of ICAL standards.

LevelVolume, primarystandard mixture

( L)1 0.0

2 5.0

3 10.0

4 50.0

5 100.0

6 500.0

7 1000.0

Table III. Typical ICAL Levels.

Concentration (ppb) of Analyte at ICAL Level:Analyte(s) 1 2 3 4 5 6 7

Fe, K, Ca, Na, and Mg Blank 50 100 500.0 1,000.0 5,000.0 10,000

Ag, Al, As, Ba, Be, Cd,Co, Cr, Cu, Mn, Mo, Ni,Pb, Sb, Se, Tl, V, Zn,Th, and U

Blank 0.5 1.0 5 10.0

50.0 100.0

Sample Collection, Preparation, and Storage

Samples must be collected and stored at all times in polyethylenecontainers. For the determination of dissolved elements in water, the sample

must first be 0.45 m filtered, then preserved with 1.0% concentrated HNO3 by

volume (0.5 % concentrated HCl is only added if Ag is of interest). For thedetermination of total recoverable elements in water, unfiltered samples are to beacidified with HNO3 as described above. In all cases, the pH of the samplesshould be verified to be less than 2.0 prior to analysis. The holding time forproperly preserved aqueous samples is 6 months.



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Solid samples require no form of preservation. Any solid material to be

processed for total recoverable elements should be stored at 4C at all times. Noholding times have been established for solid samples.

More detailed procedures for treatment of water samples as well as

protocols for digestion of solid materials are available in EPA Method 200.8.

Daily Procedures for Instrument Setup

Prior to operating the ICP-MS, the following steps must be performed on adaily basis. These steps assume that the instrument hardware and software isconfigured for the 200.8 ICP-MS application. If the configuration is set for anotherapplication (i.e., LC-ICP-MS), see Appendix A for detailed instructions regardingsetup of the hardware and software for the 200.8 ICP-MS application.

1. Replace all peristaltic pump tubing. When ready for analysis, clamp the

tubing in place on the pumps. Place the lines for uptake of diluent andinternal standard solutions into the appropriate vessels (refer toAppendix B for a detailed diagram of the tubing configuration).

2. Ensure that there is sufficient argon and helium supply.

3. Verify that the hydrogen generator is functioning properly.

4. Turn the chiller unit on prior to igniting the plasma.

5. Verify that all waste lines are in place, and empty waste reservoirs if

needed.

6. Verify that ventilation is operating properly prior to igniting the plasma.

7. On the Agilent ICP-MS ChemStation software, enter the ICP-MS Top,and open the Instrument Control window. Click Plasma On.

8. Once the Plasma started check if Ar tank pressure and Ar carrier gaspressure have the right value. The values correspond to the usednebulizer and can be found in the Hardware Manual book. Adjust thepressure by opening or closing the regulation valve at the Ar-tank.

9. Once the plasma parameters have reached their setpoints, theinstrument control window can be closed. Ensure that the 200.8

method (2008.M) is loaded (Method Load and run method). Next,enter the tune menu, and perform a sensitivity check of each of thethree tune files utilized by the acquisition method (i.e., h2aset.U,

heaset.U, and normaset.U). Once a tune file is loaded, use the ALS Go To command to send the autosampler probe to a vessel



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containing tuning solution. Go to ISIS Prerun, allow time for thesolution to reach the plasma, and start acquisition. Compare theresponses to those in the ICP-MS reference notebook.

10. Perform a pulse to analog (P/A) factor tuning for each tune step as

follows:

Insert tubing into the ISTD solution.

Go to tuning modenormal

Go to Tune P/A Factor and Load Masses from AcquisitionMethod delete all elements except for: Na, Mg, Li, K, Sc, Y, Ge, In,Bi,

Using the ALS Go To command, send the autosampler probe toICAL level 2 (0.5 ppb) and start P/A factor, If sensitivity is too low forP/A factors use calibration solution 3

Go to Tune P/A Factor and Load Masses from AcquisitionMethod delete all elements except for: Be, Al, Mn, Co, Y, Tl, Th, U

Using the ALS Go To command, send the autosampler probe toICAL level 6 (50 ppb), check box for insert values and start P/Afactor.

Go to Tune P/A Factor and Load Masses from AcquisitionMethod delete all elements except for: Ni, Zn, As, Se, Mo, Ag, Cd,Sb, Ba, Pb, and all elements that had too low sensitivity withcalibration solution 6.

Using the ALS Go To command, send the autosampler probe toICAL level 7 (100 ppb) check box for insert values and start P/Afactor.

Go to tuning mode H2Go to Tune P/A Factor and Load Masses from AcquisitionMethod delete all elements except for: Ca, Fe, Ge, Y, Se, Sc

Using the ALS Go To command, send the autosampler probe toICAL level 3and start P/A factor

Go to Tune P/A Factor and Load Masses from AcquisitionMethod delete all elements except for: Cr, Cu

Using the ALS Go To command, send the autosampler probe toICAL level 7and start P/A factor, check box for insert values

Go to tuning mode He

Go to Tune P/A Factor and Load Masses from AcquisitionMethod delete all elements except for: Ge, V, As, Se, Y

Using the ALS Go To command, send the autosampler probe toICAL level 7and start P/A factor



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Usually only Be, Zn, As, Se and Ba have too low sensitivity all otherelements should express a value


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Table IV outlines the tune step in which each element is acquired, whichisotope is acquired (if applicable), and internal standard element and isotopebeing utilized for that analyte. In addition, Tables V-IX outline the remainingacquisition parameters and instrument settings applied during this analysis.

Table IV. Tune step and internal standardm/z for each analyte m/z.

Analyte / m/z IS / m/z Tune StepBe / 9 Li / 6 3 (Normal)

Na / 23 Y / 89 3 (Normal)

Mg / 24 Y / 89 3 (Normal)

Al / 27 Y / 89 3 (Normal)

K / 39 Y / 89 3 (Normal)

Ca / 40 Sc / 45 1 (H2)

V / 51 Sc / 45 2 (He)

Cr / 52 Sc / 45 1 (H2)

Mn / 55 Y / 89 3 (Normal)

Fe / 56 Y / 89 1 (H2)

Co / 59 Y / 89 3 (Normal)Ni / 60 Y / 89 3 (Normal)Cu / 63 Y / 89 1 (H2)

Zn / 66 Y / 89 3 (Normal)

As / 75 Y / 89 3 (Normal)Se / 77 Y / 89 3 (Normal)Se / 78 Y / 89 1 (H2)

Mo / 98 Y / 89 3 (Normal)

Ag / 107 In / 115 3 (Normal)

Cd / 114 In / 115 3 (Normal)

Sb / 121 In / 115 3 (Normal)

Ba / 137 In / 115 3 (Normal)

Tl / 205 Bi / 209 3 (Normal)

Pb / 208 Bi / 209 3 (Normal)Th / 232 Bi / 209 3 (Normal)

U / 238 Bi / 209 3 (Normal)

Table V. Interference equations.

Mass Equation6 (6)*1 (7)*0.0813

115 (115)*1 (118)*0.0149

208 (208)*1 + (207)*1 + (206)*1

Table VI. Acquisition parameters.

Acquisition mode Spectrum multi-tune

Peak pattern Full quantNumber of points per mass 3

Integration time per point 0.10 secNumber of repetitions 3

Total acquisition time 168 secDetector Auto (P/A)

Stabilization time, tune step 1 (tune file: mt_h2.u) 30 sec

Stabilization time, tune step 2 (tune file: mt_he.u) 30 sec

Stabilization time, tune step 3 (tune file: mt_norm.u) 5 sec



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Table VII. ISIS peristaltic pump program.

Uptake speed 0.70 rps

Uptake time 20 sec

Stabilization time (undiluted) 40 secBefore Acquisition

Stabilization time (diluted) 70 sec

Rinse speed 0.05 rpsRinse time (sample) 5 secAfter Acquisition

(probe rinse) Rinse tine (standard) 5 secRinse vial 1

Uptake speed 0.70

Uptake time 60 sec

Stabilization speed 0.02 rps

After Acquisition(rinse)

Stabilization time 0 sec

Table VIII. ISIS autodilution settings.Dilution factor 20

Correction On (periodic mode)Std element 166 amu

Online IS element 159 amuDilute all samples Off

Table IX. Plasma conditions.

RF power 1500 W

S/C Temperature 2C

Carrier gas flow 1.00 L / min

Makeup gas flow 0.42 L / min

Peri pump speed 0.10 rps

Sample depth 8.4 mm

Torch H x.x mmTorch V x.x mm

Quality Control

Internal standard performance. The response of each internal standard ismonitored throughout all standard, analysis, and quality control samples. Theinitial response in counts per second (cps) for each IS is established whenanalyzing the calibration blank. All subsequent cps values for each IS must bewithin the range of 60% - 125% of the initial baseline value. If this condition is notsatisfied, the elements quantitated using that IS may not be reported unless the

sample is reanalyzed with satisfactory IS recovery.

Continuing calibration verification (CCV). For every ten samples, a CCV isanalyzed in order to verify the integrity of the instrument calibration. The CCVmay be prepared by adding 1.25 mL of the multi-element primary standardmixture to approximately 100 mL diluent solution and dilute to a total final volumeof 250 mL with diluent solution. This results in a concentration of 5000 ppb in Fe,K, Ca, Na, and Mg and a concentration of 50 ppb in Ag, Al, As, Ba, Be, Cd, Co,



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Cr, Cu, Mn, Mo, Ni, Pb, Sb, Se, Tl, V, Zn, Th, and U. The analytical result forconcentration of each element in the CCV must be within 85% - 115% of theactual value. If this condition is not satisfied, the failing element(s) may not bereported in the affected samples. If reanalysis of the CCV does not producesatisfactory results, recalibration may be necessary. Once satisfactory

performance of the CCV is achieved, any affected samples may be reanalyzed.

Overall performance verification. An international standard for trace metalsin water (NIST 1643) is measured undiluted to verify the overall performance ofthe trace metal analysis. This performance is tested once a month. The recoveryof the standard must be between 85% to 115% for environmental analysis.

Table x: True and measured values for the NIST standard 1643

Element concentration Measured n=4 Dev

g/kg g/kg %

Ag 7.6 8.4 11

Al 52.0 51.8 0As 26.7 26.0 -3

Ba 148.0 145.2 -2

Be 34.9 34.0 -3

Cd 22.8 22.5 -1

Co 20.3 20.5 1

Cr 38.6 34.3 -11

Cu 85.2 84.3 -1

Fe 34.3 42.3 23

K 994.0 1035.1 4

Mn 121.5 123.7 2

Mo 46.8 46.8 0

Ni 27.4 27.8 1

Pb 27.9 27.7 -1

Sb 13.8 14.4 5

Se 22.0 18.8 -14

Th Nd

Tl Nd

U Nd

V 13.0 13.5 4

Zn 53.2 52.1 -2

mg/kg mg/kg

Ca 7.0 6.8 3

Mg 5.8 5.9 2

Na 29.4 30.3 3

Continuing calibration blank (CCB). For every ten samples, a CCBconsisting of unsupplemented diluent solution is analyzed in order to determinethe presence or absence of unacceptable carryover. If the analytical resultobtained for a CCB is greater than 0.5 ppb for trace elements or 50 ppb for non-trace elements, the affected elements may not be quantitated. Reanalysis of the



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CCB should be performed after rinsing the system with DI H2O. Samples may bereanalyzed after acceptable blank levels have been attained.

Calibration range exceeded. If any element in a sample is found to exceedthe range of calibration, the sample is to be diluted into the appropriate range

and reanalyzed. This may be accomplished by automated means using theAgilent 7500c ICP-MS integrated sample introduction system (ISIS). When asample result is greater than a used defined maximum (i.e., the concentration ofthe highest ICAL level), the sample is subjected to online ISIS dilution by a factorof twenty and reanalyzed. The original concentration is the calculated andreported using an exact dilution factor established by analyzing a 50 ppb erbiumsolution at undiluted and diluted levels. The exact dilution factor (DF) is given by:

))(Tb(Er

))(Tb(ErDF

UD

DU=

Where ErU is the undiluted cps of erbium (m/z 166), TbD is the diluted cps of theinternal standard terbium (m/z 159), ErD is the diluted cps of erbium, and TbU isthe undiluted cps of terbium. If autodilution fails to bring the analyteconcentrations into the appropriate range, the result is reported as being greaterthan the limit of calibration. In order to obtain a result, manual dilution accordingto the judgment of the analyst may be required.

ReferencesEPA Method 200.8, Revision 5.4, U.S. Environmental Protection Agency,Cincinnati, OH, 1994.



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Appendix A

Changing the Hardware and Software

Configuration to ICP-MS from LC-ICP-MS

The ICP-MS system may also be utilized in tandem with LC to performmetals speciation analyses such as arsenic speciation (see ASET arsenicspeciation protocol). When the instrument is being routinely utilized in differentapplications, the analyst will be required to modify certain hardware and softwareconfigurations in order to change from one application to the next. This appendixsummarizes the changeover procedures to ICP-MS from LC-ICP-MS.

To change from LC-ICP-MS to ICP-MS:

Hardware

Plug the serial cable from the ISIS communications box into the remoteport on the lower left corner of the ICP-MS rear panel. Turn the ISIS box on.

Carefully remove the concentric nebulizer and attached tubing from thespray chamber interface, and replace with the standard Babbington nebulizerand associated plumbing (see Appendix B for the full tubing configuration). Beespecially sure that the nebulizer is fully seated and well sealed and that themakeup gas and carrier gas lines are properly attached.

Software

Enter the configuration panel. Under Remote Start, select Dont Use.Under Sample Introduction, set the type to ISIS, and set the ISIS Applicationto Autodilution. On the Autosampler menu, select the ASX500. Next to theautosampler drop-down menu, click Setup. The ID for Racks 1, 2, 3, and 4should be set for 21, 60, 60, and 60, respectively. Click OK. Next, click onMiscellaneous, and change the Remote Shutdown to Standard. Once thesechanges are complete, click Save (if you do not click Save, your changes willnot be made!).



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Appendix B

Tubing and Hardware Configuration for Autodilution with ISIS

Provided by Emmett Soffey, Agilent Technologies

ISIS #1 ISIS #2

ASX-500

Diluent

Large WasteContainer

ISTD

Nebulizer

1 2

3 3

4

5

6

13

7 8

9

10

11

12

1mm 2 Stop Tygon (See note for Item 1&2)

1.0 or 0.89mm 3 Stop Tygon (See note for Item 7)

0.19 or 0.25mm 3 Stop Tygon(See note for Item 8)

0.5mm ID Teflon

0.3 or 0.5 mm ID Teflon

2mm ID Teflon for Drain

The teflon tubing incorporated into the flow paths from

both the ASX-500 and Diluent should be 0.5 mm up to

this point. At some sites customers have installed

0.8mm tubing between item 6 and 13 in order to

minimize backpressure during rapid uptake.

Items 7 and 8 refer to peri pump

tubing on channels 1&2 of the 7500

peri pump or channel 1&2 of peripump #1 on the 4500.

**The peri pump tubing

connected to the spray

The teflon tubing

downstream of this point

may be 0.3 or 0.5 mm

tubing. See explanation

below.

chamber drain has been

omitted from this diagram.

2mm Teflon drain tube

Tubing and Hardware Configuration for

Autodilution with ISIS

1.0 or 0.89 mm 3 stop tygon.

Trim this tubing so that only

two stops remain with tubing

extending ~3/4 inch beyondstops.

Denotes sections of

teflon tubing that

should be as short

as possible.

1 mm 2stop

tygon. Trim ~ 1

inch from stops.

0.25mm 3 stop

tygon tubing

1mm 2

stop tygon.


trace metals epa 200 8 nov 07

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