EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

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FGD ICP/MS SOP: Inductively Coupled Plasma Mass Spectrometry for 

Trace Element Analysis in Flue Gas Desulfurization Wastewaters 

1.0 Scope and Application

1.1 This document describes procedures used to measure elements in Flue Gas 

Desulfurization (FGD) wastewaters. Inductively coupled plasma-mass 

spectrometry (ICP/MS), as described in EPA Methods 200.8 and 1638, was used 

with a collision cell to mitigate the effects of interferences in the samples. These 

procedures are intended for use by analysts experienced with applying ICP/MS to 

complex wastewater samples. 

1.2 These procedures are applicable to the analysis of acid digested FGD wastewater, 

and have been evaluated for the analysis of 13 elements of interest. These are Al, 

As, Cd, Cr, Cu, Pb, Mn, Ni, Se, Ag, Tl, V and Zn. Additional elements may be 

included provided that the performance criteria presented in Sections 9 and 12 are 

met. 

1.3 Flue Gas Desulfurization wastewaters frequently have very high levels of calcium, 

sodium, magnesium, manganese, chloride and sulfate (up to thousands of ppm). 

The use of instrument configurations and/or accessories designed to 

accommodate samples with high dissolved solids levels is highly recommended. 

2.0 Summary

2.1 Aqueous samples, digestates, or leachates are nebulized into a spray chamber 

where a stream of argon carries the sample aerosol through the quartz torch and 

injects it into an RF plasma. There the sample is decomposed and desolvated. 

2.2 The ions produced are entrained in the plasma gas and by means of a watercooled, differentially pumped interface, introduced into a high-vacuum chamber 

that houses a quadrupole mass spectrometer capable of providing a resolution 

better than or equal to 0.9 amu peak width at 10% of the peak height. The ions 

are separated according to their mass-to-charge ratio and measured with a 

detector, such as an electron multiplier. 

2.3 A collision/reaction cell utilizing He and (optionally) H2 gases is used to remove 

molecular interferences. 

2.4 Interferences not eliminated by the collision/reaction cell must be assessed and 

valid corrections applied, or the data flagged to indicate problems. Interference 

correction must include compensation for interferences not removed by the 

collision / reaction cell. Recommended elemental equations are listed in 

Attachment 1. Use of the internal standard technique is required to compensate 

for suppressions and enhancements caused by sample matrices. 

3.0 Definitions

3.1 Batch – A group of samples which behave similarly with respect to the sampling or 

the testing procedures being employed and which are processed as a unit. For 

QC purposes, if the number of samples in a group is greater than 20, then each 

group of 20 samples or less will all be handled as a separate batch 
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3.2 Dissolved Metals - Those elements which pass through a 0.45-μm membrane 

filter (sample is acidified after filtration). 

3.3 Suspended Metals - Those elements which are retained by a 0.45-μm membrane 

filter. 

3.4 Total Recoverable Metals - The concentration determined on an unfiltered 

sample following treatment with hot, diluted mineral acids, as described in this 

procedure 

3.5 Instrument Detection Limit (IDL) - See Section 12.2 

3.6 Sensitivity - The slope of the analytical curve (i.e., the functional relationship 

between raw instrument signal and the concentration). 

3.7 Tuning Solution - This is a multi-element solution containing analytes which are 

representative of the entire mass range capable of being scanned by the 

instrument. It is used to optimize the sensitivity of the instrument and to verify the 

mass resolution meets method criteria. 

3.8 Initial Calibration Verification / Quality Control Standard (ICV/QCS) - A multielement standard of known concentrations prepared to verify instrument 

calibration. This solution must be an independent standard prepared near the midpoint of the calibration curve, and at a concentration other than that used for 

instrument calibration. 

3.9 Continuing Calibration Verification (CCV). - A multi-element standard of known 

concentrations prepared to monitor and verify the instrument daily continuing 

performance. 

3.10 Laboratory Control Sample / Laboratory Fortified Blank (LCS/LFB) - A multielement standard of known concentrations that is carried through the entire 

sample preparation and analysis procedure. This solution is used to verify method 

performance in an ideal sample matrix. 

3.11 Reagent Blank - High purity (> 18 megohm-cm) water containing the same acid 

matrix as the calibration standards that is carried through the entire digestion 

process. The reagent blank is used to determine the concentrations of trace 

metals in the reagents used to prepare and analyze the samples. 

3.12 Calibration Blank - High purity (> 18 megohm- cm) water acidified with the same 

acid concentrations present in the standards and samples. Also referred to as the 

Initial Calibration Blank (ICB) and Continuing Calibration Blank (CCB). 

3.13 Method Detection Limit (MDL) – Refers to the instructions in Appendix B to 40 

CFR Part 136. Also see Section 12.1 of this document. The MDL is determined 

from analysis of a sample in a given matrix containing the analyte. 

3.14 Individual FGD Interference Check solutions – Single element solutions at 

concentrations similar to those found in flue gas desulfurization wastewaters. 

3.15 Synthetic FGD wastewater – A mixed solution of elements at typical 

concentrations found in flue gas desulfurization wastewaters. 
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4.0 Interferences

4.1 Isobaric Interferences 

Isobaric interferences in the ICP/MS are caused by isotopes of different elements 

forming ions with the same nominal mass-to-charge ratio (m/z). The 

recommended ions used for the elements in this procedure do not have elemental 

isobaric interferences, except for a very small interference from krypton on 78Se, 

which can be avoided by using argon free of krypton. 

4.2 Isobaric Molecular 

• Isobaric molecular interferences are caused by ions consisting of more 

than one atom. These molecular interferences are minimized by use of the 

collision cell utilizing He and/or H2 gases. Common examples are potential 

interferences from 40Ar35Cl or 40Ca35Cl on 75As, or 35Cl16O on 51V, or 40Ar12C 

on 52Cr. Collision cell interference removal works both by causing the 

interfering molecular ion to dissociate and by reducing the kinetic energy of 

the ion. The latter is termed Kinetic Energy Discrimination (KED), and is the 

primary mechanism for interference removal. Polyatomic ions are larger 

than elemental ions and so collide with the helium atoms in the collision cell 

more frequently than the smaller elemental ions. Each collision reduces the 

energy of the ion, so the molecular ions lose energy more quickly. At the 

end of the collision cell there is a positive voltage plate that prevents 

passage of the now low energy molecular ions. Since the molecular ions do 

not reach the detector, the interference is eliminated. 

4.3 Doubly Charged Ion Interferences 

Doubly charged elemental ions are possible in cases where the second ionization 

potential of the element is significantly below the fist ionization potential for argon 

(15.7eV). If a doubly charged ion is formed, it will cause a response at half of its 

elemental mass, potentially causing an interference. Fortunately, most elements 

have high enough second ionization potentials that formation of doubly charged 

ions is not an issue. For the target analytes in this procedure, a significant potential 

for interference is from 150Nd and 150Dy (potential interference on 75As and from 

156Gd (potential interference on 78Se). To check for these potential interferences, 

monitor the response for mass 150 and 156. If the cps for these masses is > 5 

times the cps for the quantitation limit for arsenic (in the case of mass 150) or 

selenium (in the case of mass 156) an interference is possible. In this case 

analyze a 100ppb standard of Nd and Dy (if mass 150 is observed) or Gd (if mass 

156 is observed) and measure the response at 150 and 75 (or 156 and 78). This 

ratio can then be used to create an interference correction equation. For example, 

if the response for a 100ppb Gd standard at mass 156 is 10,000 cps, and the 

observed response for the same standard at mass 78 is 1,000 counts, then the 

equation for 78Se would be: 

78Se = 78Se – (156Gd/10) 

4.4 Physical Interferences 

• Physical interferences are associated with the transport and nebulization 

process. Internal standards are used to compensate for these types of 

interferences. 

• Internal standards should be added at a level to give approximately 50,000 

- 800,000 counts of raw signal intensity. The mass of the internal standard 
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should ideally be within 50 amu of the mass of the measured analyte. 

Consideration should also be given to matching internal standards to 

analytes with similar ionization potentials. 

• Matrix effects are monitored by comparing the internal standard intensity in 

the sample to the internal standard intensity of the calibration blank. The 

internal standards must be between 60% and 125% of the calibration 

blank. If they are outside this window the sample is diluted by a factor of 2 

(1:1) and is reanalyzed. 

• Memory effects are dependent on the relative concentration differences 

between samples and/or standards which are analyzed sequentially. The 

rinse period between samples must be long enough to eliminate significant 

memory interference (see section 10.3.6). 

5.0 Safety 

This procedure may involve hazardous material, operations and equipment. This 

procedure does not purport to address all of the safety problems associated with its use. It 

is the responsibility of the user of the method to follow appropriate safety, waste disposal 

and health practices under the assumption that all samples and reagents are potentially 

hazardous. Safety glasses, gloves, lab coats and closed-toe, nonabsorbent shoes are 

required. 

5.1 Specific Safety Concerns or Requirements 

5.1.1 Eye protection that satisfies ANSI Z87.1, laboratory coat, and 

nonpowdered nitrile or latex gloves must be worn while handling 

samples, standards, solvents, and reagents. Disposable gloves that 

have been contaminated must be removed and discarded; nondisposable gloves must be cleaned immediately. 

5.1.2 The ICP plasma emits strong UV light and is harmful to vision. All 

analysts must avoid looking directly at the plasma. The RF Generator 

produces strong radio frequency waves, most of which are unshielded. 

People with pacemakers should not go near the instrument while in 

operation. 

5.2 Primary Materials Used 

The following is a list of the materials used in this method, which have a serious or 

significant hazard rating. Note: This list does not include all materials used in 

the method. The table contains a summary of the primary hazards listed in 

the MSDS for each of the materials listed in the table. 
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Material (1) Hazards Exposure 

Limit (2) Signs and Symptoms of Exposure 

Nitric Acid Corrosive 

Oxidizer 

Poison 

2 ppmTWA 

4 ppmSTEL 

Nitric acid is extremely hazardous; it is corrosive, reactive, 

an oxidizer, and a poison. Inhalation of vapors can cause 

breathing difficulties and lead to pneumonia and pulmonary 

edema, which may be fatal. Other symptoms may include 

coughing, choking, and irritation of the nose, throat, and 

respiratory tract. Can cause redness, pain, and severe skin 

burns. Concentrated solutions cause deep ulcers and stain 

skin a yellow or yellow-brown color. Vapors are irritating and 

may cause damage to the eyes. Contact may cause severe 

burns and permanent eye damage. 

Material (1) Hazards Exposure 

Limit (2) Signs and Symptoms of Exposure 

Hydrochloric 

Acid 

Corrosive 

Poison 

5 ppmCeiling Inhalation of vapors can cause coughing, choking, 

inflammation of the nose, throat, and upper respiratory tract, 

and in severe cases, pulmonary edema, circulatory failure, 

and death. Can cause redness, pain, and severe skin burns. 

Vapors are irritating and may cause damage to the eyes. 

Contact may cause severe burns and permanent eye 

damage. 

1 – Always add acid to water to prevent violent reactions. 

2 – Exposure limit refers to the OSHA regulatory exposure limit. 

6.0 Equipment and Supplies

6.1 Instrumentation 

• Inductively Coupled Plasma Mass Spectrometer (ICP/MS) capable of providing 

resolution, less than or equal to 0.9 amu at 10% peak height from 6-253 amu and 

1.0 amu at 5% peak height from 6-253 amu with a data system that allows 

corrections for isobaric interferences and the application of the internal standard 

technique. The ICP/MS must be equipped with a collision cell for the removal of 

molecular interferences. This procedure was developed using an Agilent 7500 or 

7700 instrument equipped with a high matrix interface. The interface extends the 

amounts of total dissolved solids that may be measured into the percent 

concentration range. Any collision cell instrumentation that meets the 

specifications in this procedure may be used. 

• A discrete sample introduction system enables the use of only the exact amount 

of sample volume required for data acquisition. 

• Accessories and configuration that are designed to accommodate samples with 

high levels of dissolved solids should be used. 

• This sampling system results in less matrix being deposited in the system during 

analysis and minimizes the rinse times normally needed for difficult matrices. 

• Autosampler with autosampler tubes. 

• Appropriate water cooling device. 

• Block digester with tubes. 

6.2 Supplies 

• Argon gas: High purity grade (99.99%). 
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• Helium gas: High purity grade (99.99%). 

• Hydrogen gas: High purity grade (99.99%). 

• Calibrated automatic pipettes or Class A glass volumetric pipettes. 

7.0 Reagents and Standards

7.1 Storage and Shelf-Life 

7.1.1 All standards must be stored in glass, FEP fluorocarbon or previously 

unused polyethylene or polypropylene bottles. Standards stored at 

concentrations as received from the vendor and mid-level dilutions must 

be replaced prior to the expiration date assigned by the vendor. If no 

expiration date is provided, the stocks and mid-level standards may be 

stored for up to one year. They must be replaced sooner if verification 

from an independent source indicates a problem (See section 10.3.5 for 

initial calibration verification acceptance criteria). 

7.1.2 Working standards, i.e., all standards at concentrations ready to analyze 

on the ICP/MS (all except tuning mixes, ICSA and ICSAB mixes, which 

are received at ready-to-use concentrations), are prepared fresh daily. 

7.2 Standards

7.2.1 Tuning Solution, 10 ppb 

The tuning solution stock is purchased as a custom multi-element mix. 

The concentrations of the constituents are shown in Attachment 5. 

Prepare the Tuning Solution as detailed below. 

• Obtain a clean 100 mL volumetric flask. 

• Place 50 mL of reagent water and 2 mL of conc. HNO3 and 0.5 

mL of conc. HCl in the flask. 

• Swirl to mix. 

• Pipet 0.1mL of the Tuning Solution Stock into the flask 

• Dilute to volume with reagent water. Stopper and mix. 

7.2.2 PA Tuning Solution 

The dual detector solution may be commercially purchased as a custom 

multi-element mix. 

Prepare the PA Tuning Solution as detailed below. 

• Add approximately 50 mL of the 2% HNO3 / 0.5% HCl to a 100 

mL volumetric flask. 

• Prepare at a concentration recommended by the instrument 

manufacturer. 

7.2.3 Calibration Standards 

Stock calibration standards are purchased as custom multi-element 

mixes or as single element solutions. Each day of analysis, the 

standards are diluted to working levels using 2% nitric acid and 0.5% HCl 

acid matrix. Suggested concentrations are given in Attachment 8, but the 

laboratory may adjust calibration standard concentrations as appropriate 
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for the instrument and samples. At a minimum, a 3 point curve must be 

used. 

7.2.4 Individual FGD Interference check solutions. 

7.2.4.1 All individual FGD interference check solutions should be made 

up in the same acid matrix as the calibration standards. 

7.2.4.2 Chloride, 10,000 mg/L 

7.2.4.3 Calcium, 5,000 mg/L 

7.2.4.4 Sulfate, 4,000 mg/L 

7.2.4.5 Magnesium, 3,000 mg/L 

7.2.4.6 Sodium, 2,000 mg/L 

7.2.4.7 Boron 500 mg/L 

7.2.4.8 Iron 500 mg/L

7.2.4.9 Nitrate 250 mg/L 

7.2.4.10 Manganese 200 mg/L 

7.2.4.11 Bromide 100 mg/L 

7.2.4.12 Fluoride 100 mg/L 

7.2.4.13 Selenium 20 mg/L

7.2.4.14 Vanadium 10 mg/L

7.2.4.15 Zinc 2 mg/L

7.2.4.16 Chromium 1 mg/L

7.2.4.17 Copper 1 mg/L

7.2.5 Mixed Interference Check Solution (Synthetic FGD Wastewater) 

7.2.5.1 Chloride, 5,000 mg/L 

7.2.5.2 Calcium, 2,000 mg/L 

7.2.5.3 Magnesium, 1,000 mg/L 

7.2.5.4 Sulfate, 2,000 mg/L 

7.2.5.5 Sodium, 1,000 mg/L 

7.2.5.6 Butanol, 2000ppm 

7.2.6 Initial Calibration Verification (ICV) Standard 

The ICV stock is from a source different than the source for the 

calibration standards. Each day of analysis, the ICV standard is 

prepared in 2% HNO3 and 0.5 % HCl acid to the concentrations shown in 

Attachment 8. 
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7.2.7 Continuing Calibration Verification (CCV) Standard 

The CCV is prepared from the same source as the calibration standards. 

The CCV standards are prepared fresh each day of analysis in 2% 

HNO3/0.5% HCl. The concentrations are shown in Attachment 8. 

Prepare the Working CCV as detailed below. 

• Dilute by 2X a known volume of the Working Calibration Standard 

in the 2% HNO3 / 0.5% HCl acid matrix. 

7.2.8 Spiking Stock Solution 

The spike stock solution is prepared from the same stocks as the 

calibration standards using the 2% HNO3 / 0.5% HCl acid matrix. Spike 

concentrations are listed in Attachment 8. 

7.3 Reagents

7.3.1 Reagent Water - ASTM Type I or equivalent for the elements of interest, 

generated using an ion-exchange water polishing system capable of 

achieving 18.0 megohm-cm.

7.3.2 Blank Matrix 2% HNO3 and 0.5% HCl. 

8.0 Sample Collection, Preservation, Shipment and Storage

Sample container, preservation techniques and holding times may vary and are dependent 

on sample matrix, method of choice, regulatory compliance, and/or specific contract or client 

requests. Listed below are the holding times and the references that include preservation 

requirements. 

Matrix Sample 

Container 

Min. Sample 

Size Preservation Holding Time Reference 

Waters HDPE 50 mLs HNO3, pH < 2 180 Days 40 CFR Part 136.3

Soils Glass or 

HDPE 

4 oz Cool 4 + 2oC 180 Days N/A 

9.0 Quality Control 

9.1 Quality control requirements are also summarized in Attachment 7. 

9.2 Ongoing data quality checks are compared with established performance criteria 

to determine if the results of analyses meet the performance characteristics of the 

method. Any QC result that fails to meet control criteria must be documented. 

9.3 Individual interference check solutions 

The individual interference check solutions listed in section 7.2.6 are analyzed 

prior to initiating sample analysis, and at least once per quarter while FGD 

wastewaters are being analyzed, and after any major changes to instrument 

operating conditions. Concentrations of target elements observed should be less 

than their reporting limits. In some cases it may not be possible to obtain 

interference check solutions that are completely free of contamination. In this case, 

results up to 5X the reporting limit are acceptable if it is possible to demonstrate 

that the isotopic ratios correspond to natural abundances. For example, the natural 
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abundances of zinc isotopes are Zn64 48.6%; Zn66 27.9%; Zn67 4.1%; Zn68 18.8%; 

Zn70 0.6%. The measured ratios are not expected to be exact, especially for low 

abundance isotopes, and some isotope may be masked by other elements in the 

solution, (for example Zn70 in the above example will be masked by Ge70) but it 

must be possible to explain the observed ratios. Because Arsenic, Manganese 

and Aluminum are monoisotopic, this demonstration is not possible and the level 

of interference observed must be less than the reporting limit. 

9.4 Synthetic FGD interference check solution 

The synthetic FGD matrix solution listed in section 7.2.7 is analyzed prior to 

initiating sample analysis, and at least once per day (immediately after calibration) 

while FGD wastewaters are being analyzed, and after any major changes to 

instrument operating conditions. Internal standard recovery must meet method 

criteria (Section 9.9) and concentrations of target elements observed should be 

less than their reporting limits. In some cases it may not be possible to obtain 

interference check solutions that are completely free of contamination. In this case, 

results up to 5X the reporting limit are acceptable if it is possible to demonstrate 

that the isotopic ratios correspond to natural abundances. For example, the natural 

abundances of zinc isotopes are Zn64 48.6%; Zn66 27.9%; Zn67 4.1%; Zn68 18.8%; 

Zn70 0.6%. The measured ratios are not expected to be exact, and some isotopes 

may be masked by other elements in the solution, (for example Zn70 in the above 

example will be masked by Ge70) but it must be possible to explain the observed 

ratios. Because Arsenic, Manganese and Aluminum are monoisotopic, this 

demonstration is not possible, and the level of interference observed must be less 

than the reporting limit. 

If the Synthetic FGD solution has to be diluted in order to analyze it 

effectively on the ICP/MS, then all samples and QC (including the MDL 

replicates) must be diluted by at least the same factor. 

9.4.1 Laboratory fortified Synthetic FGD solution 

The synthetic FGD solution is spiked with 40ppb of each of the target 

elements (400ppb for zinc and 4000ppb for aluminum) and analyzed 

once per day, immediately after the synthetic FGD check in section 9.4. 

All target elements must be recovered within 70-130% of the true value. 

If the Laboratory Fortified Synthetic FGD solution has to be diluted 

in order to analyze it effectively on the ICP/MS, then all samples and 

QC (including the MDL replicates) must be diluted by at least the 

same factor. 

9.5 Linear range determination 

The linear range for each element is determined prior to initiating sample analysis 

and at least once per year thereafter. The linear range must also be determined 

subsequent to changes that will have a major effect on instrument sensitivity, such 

as changing the detector. The linear range is established using a single element 

standard at the desired linear range. The result of the analysis must be within 10% 

of the true value. 

9.6 Method Blank / Laboratory Reagent Blank (MB/LRB) 

The method blank consists of reagent water that has been processed in the same 

manner as the samples. One method blank must be processed with each preparation 

batch. 

Acceptance Criteria: Method blank results are acceptable if the concentration 

for each analyte of interest is less than the reporting limit. 
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Corrective Action: If the method blank does not meet the acceptance criteria, 

the source of contamination should be investigated to 

determine if the problem can be minimized or eliminated. 

Samples associated with the contaminated blank shall be 

reprocessed for analysis, or under the following 

circumstances, may be reported as qualified (qualifier 

flags or narrative comments must be included on report): 

• The same analyte was not detected in the 

associated samples; 

• The method blank concentration is less than 1/10 of 

the measured concentration of any sample in the 

batch; 

• The method blank concentration is less than 1/10 the 

specified regulatory limit; or 

• The analyte is a common laboratory contaminant 

(copper, iron, lead, calcium, magnesium, potassium, 

sodium, or zinc) less than 2 times the RL. Note that 

some programs do not recognize common lab 

contaminants. 

If the above criteria are not met and reanalysis is not 

possible, then the sample data must be qualified. This 

anomaly must be addressed in the project narrative and 

the client must be notified. 

9.7 Laboratory Control Sample / Laboratory Fortified Blank (LCS/LFB) 

The LCS consists of reagent water that is spiked with the analytes of interest as 

summarized in Attachment 8. One LCS must be processed (digestion and analysis) 

for each preparation batch. 

Acceptance Criteria: LCS control limits are based on three standard deviations 

of past laboratory results. These limits are not to exceed 

85-115% recovery. The control limits are maintained in a 

LIMS or other appropriate system. 

Corrective Action: If the LCS % recovery falls outside of the control limits for 

any analyte, that analyte is judged to be out of control. All 

associated samples must be reprocessed for analysis. 

One possible exception is a recovery for a given element 

above the upper control limit with no detection for the 

same element in the samples. 

9.8 Matrix Spike / Matrix Spike Duplicate / Laboratory Fortified Sample Matrix / 

Laboratory Fortified Matrix Duplicate (MS/MSD/LFSM/LFMD) 

MS is prepared by taking a second aliquot of a selected sample and spiking it with 

the analytes of interest as summarized in Attachment 8. An MSD is prepared by 

taking a third aliquot of a selected sample and spiking it with the analytes of interest 

as summarized in Attachment 8. The MS and MSD are processed in the same 

manner as the samples. One MS/MSD pair must be processed every 10 samples. 

Acceptance Criteria: Control limits are based on three standard deviations of 

past laboratory results. These limits are not to exceed 70-

130% recovery, and 20% relative percent difference 
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(RPD). The control limits are maintained in the LIMS 

system. If the sample concentration for a specific analyte 

in the sample selected for spiking is greater than the 

concentration added by the spike, then recovery accuracy 

will be reduced. In this case a dilution test may be 

performed. A 1:5 dilution should agree within 20% of the 

original determination. If not, a physical or chemical 

interference is suspected, and must be discussed in the 

sample narrative. 

Corrective Action: If MS/MSD results and any applicable 

dilution tests do not meet the acceptance criteria and all 

other quality control criteria have been met, then a matrix 

interference is suspected. Failed matrix spikes are 

flagged, and are discussed in the final report case 

narrative. 

9.9 Internal Standards Evaluation for Samples 

The internal standards in samples must be between 60 and 125% of the intensity in 

the calibration blank. If the sample intensities fall outside this range, the calibration 

blank is reanalyzed to confirm the instrument has not drifted out of control. If the 

criteria is met, the sample is diluted by a factor of 2 (1:1) and reanalyzed. IS limits 

and corrective actions for standards and blanks are described in Section 10. 

10.0 Procedure

10.1 One-time procedural variations are allowed only if deemed necessary in the 

professional judgment of the supervisor to accommodate variation in sample 

matrix, radioactivity, chemistry, sample size, or other parameters. Any variation in 

procedure shall be completely documented. Any unauthorized deviations from this 

procedure must also be documented as a nonconformance, with a cause and 

corrective action described. 

10.2 Sample Preparation 

10.2.1 EPA Method 1638 was used as the reference for the digestion of the 

samples in which Section 12.2.8 describes Closed Vessel digestion. 

10.2.2 Transfer a 50mL (+/- 0.5mL) aliquot from a well mixed acid preserved 

sample to a 50mL digestion tube. 

10.2.3 Add 0.5mL of concentrated nitric acid and 0.25 mL hydrochloric acid. 

10.2.4 Spike the LCS and MS/MSD samples per spiking protocols. 

10.2.5 The total volume of the solution in the tube is now greater than 50 mLs. 

The final volume will be 50 ml following the procedure to eliminate the 

discrepancy in the initial and final volumes. 

10.2.6 Tightly cap each digestion vessel. 

10.2.7 Place the digestion tube into a block digester adjusted to achieve a 

temperature of approximately 85o

C. 

10.2.8 Heat for 2 hours after 85o

C is obtained. 

10.2.9 Remove from the block and allow to cool. 
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10.3 Calibration 

10.3.1 Instrument Start Up 

Set up the instrument according to manufacturer’s operating instructions. 

Allow the instrument to become thermally stable for at least 30 minutes 

before tuning. 

10.3.2 Instrument Tuning / Mass Calibration 

Tune the instrument with a solution containing elements representing all of 

the mass regions of interest. The relative standard deviations must be less 

than 5% for a minimum of 4 integrations of the solution. Mass calibration 

and resolution checks using the tuning solution must be completed at the 

beginning of every day. 

Mass Calibration Check – The mass calibration results must be within 

0.1 amu from the true value. If this criterion is 

not met, the mass calibration must be 

adjusted before running samples. 

Mass Resolution Check - The resolution must be verified to be less than 

0.9 amu full width at 10% peak height. 

10.3.3 Mass 75 interference check 

The counts per second for mass 75 must be less than 10 when the blank 

matrix (2% nitric acid / 0.5% hydrochloric acid) is infused (using the 

collision gas mode used for arsenic). CPS > 10 under these conditions 

indicates that the collision cell is not effectively removing molecular 

interferences (in this case Ar40Cl35). 

10.3.4 Initial Calibration 

The ICP/MS is calibrated each day of operation using a blank and at 

least 3 standards (see Section 7.2.3). Report the average of at least 

three integrations. 

The validity of the calibration is determined by the subsequent calibration 

verifications, which are performed at concentrations as described in the 

next sections. 

10.3.5 Second-Source Initial Calibration Verification (ICV) 

A 40 μg/L / 4,000 ug/L ICV standard (see Section 7.2.8) is analyzed 

immediately after the initial calibration. This is a standard obtained from 

a different vendor than the standard used for calibration. This analysis 

also satisfies the Method 200.8 requirement for a Quality Check Standard 

(QCS). 

Acceptance Criteria: The ICV recovery must be within 90-110%. 

Additionally, the internal standard recoveries for 

200.8 must fall between 60 and 125% of true 

values. The ICV can be reanalyzed, but must be 

successful twice in succession or corrective 

action must be taken. 

Corrective Action: If the ICV results are outside of the acceptance 

limits, investigate the accuracy of the standards, 

correct as necessary, and recalibrate.
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10.3.6 Calibration Blank 

Checks for the memory effects described at Section 4.4 may be 

accomplished by analysis of an initial calibration blank (ICB) after the 

ICV. Continuing calibration blanks (CCBs) are analyzed after each 

continuing calibration verification. 

Acceptance Criteria: Results for the calibration blanks must be less 

than the RL. 

Corrective Action: If the calibration blank exceeds acceptance 

limits, then the possibility of instrument 

contamination should be examined, particularly 

the possibility of carry-over from high level 

samples. The blank can be reanalyzed, and if 

successful, analysis can continue. However, 

samples tested after high-level samples should 

be retested. If the reanalysis is not successful, 

then the analysis should be terminated. After the 

problem is corrected, recalibrate and reanalyze 

all samples tested since the last acceptable CCB. 

10.3.7 Reporting Limit (RL) Verification Standard 

An independent standard is analyzed after the ICV to monitor the lab’s 

ability to produce reliable results at RL-level concentrations. The RL 

verification standard is analyzed after the daily ICB. 

Acceptance Criteria: For project reporting limits at or above two times 

the MDL, the results should be within 50% of the 

expected value. Some programs may require 

tighter control, in which case the RLs will need to 

be three or more times the MDL concentration. 

Corrective Action: If the RL verification fails to meet acceptance 

limits, data for the associated samples must be 

assessed. For example, if the results are high, 

consider blank contamination, and if the results 

are low, consider MDL verifications. At a 

minimum, sample results must be qualified in the 

final report.

10.3.8 Continuing Calibration Verification (CCV) Standard 

A 50 μg/L CCV standard is analyzed after every set of ten samples and 

at the end of the analytical sequence. 

Acceptance Criteria: The CCV recovery must be within 85-115%. In 

addition, the IS recovery must be within 60-

125%. If CCV results are not within these limits, 

the CCV can be reanalyzed, but it must be 

successful twice in succession or further 

corrective action must be taken. 

Corrective Action: If the CCV fails acceptance criteria, then the 

analysis should be terminated. Recalibrate and 

reanalyze all samples tested since the last 

acceptable CCB. 
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 14 of 25

10.4 Sample Analysis 

10.4.1 Report the average of at least three integrations for all field and QC 

samples analyzed. 

10.4.2 Flush the system with the rinse blank for at least 30 seconds between 

samples and standards during the analytical run. Evaluate the 

effectiveness of this time and increase the flush time, if needed. 

10.4.3 It may be valuable to monitor additional isotopes for elements that are 

potentially susceptible to interferences. In particular, monitoring additional 

isotopes for selenium may help data analysis. 

10.4.4 Dilute and reanalyze samples that are more concentrated than the 

highest calibration standard for an analyte or specific isotope of interest. 

No analyte may be reported from an analysis of a diluted sample in which 

the analyte concentration is less than 5 times the RL. 

The analytical run sequence should be performed as follows to meet all 

quality control criteria: 

Instrument initialization 

Warm-up 

Tune instrument 

Perform mass calibration 

Perform resolution check 

Validate tuning criteria 

Calibration blank 

Calibration standard 1 

Calibration standard 2 

Calibration standard 3

ICV 

ICB 

RL verification standard 

CCV 

CCB 

10 Samples (which can include all sample types) 

CCV 

CCB 

11.0 Calculations / Data Reduction

11.1 LCS percent recoveries are calculated according to the equation:

11.2 ICV percent recoveries are calculated according to the equation:

100%

ICV True Value

ICV Found Value % ⎟×

⎠

⎞ ⎜

⎝

⎛ R =

100%

LCSTrue Value

LCS Found Value - LRB Found Value % ⎟×

⎠

⎞ ⎜

⎝

⎛ R =
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 15 of 25

11.3 CCV percent recoveries are calculated according to the equation:

11.4 Matrix Spike Recoveries are calculated according to the following equation:

Where: 

SSR = Spike Sample Result 

SR = Sample Result 

SA = Spike Added 

NOTE: When the sample concentration is less than the detection limit, use SR = 0 

for the purpose of calculating %R. 

11.5 The relative percent difference (RPD) between sample duplicates is 

calculated according to the following equation:

 

Where: 

DU1 = Sample result 

DU2 = Sample duplicate result 

11.6 The final concentration for an aqueous sample is calculated as follows:

2

1 Result ( g/L) VC ×V × D

μ =

Where: 

C = Concentration from instrument readout, ppb 

D = Instrument dilution factor 

V1 = Final volume in liters after sample preparation 

V2 = Initial volume of sample digested in liters 

100%

CCV True Value

CCV Found Value % ⎟×

⎠

⎞ ⎜

⎝

⎛ R =

100%

SA

SSR - SR % ⎟×

⎠

⎞ ⎜

⎝

⎛ R =

( ) 100

1 2 2

1

/ 1 2/

×

⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡

+

− = DU DUDU DU RPD
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 16 of 25

12.0 Method Performance 

12.1 Method Detection Limit Study (MDL) 

An initial method detection limit study must be performed on each instrument 

before samples can be analyzed. MDL studies are conducted annually as follows: 

• Prepare seven samples at three to five times the estimated MDL concentration. 

The MDL samples are prepared in the Synthetic FGD wastewater matrix and in 

reagent water. 

• Prepare and analyze the MDL standards as described in Section 10. 

• Calculate the average concentration found in μg/L, and the standard deviation 

of the concentration(s) in μg/L, for each analyte. 

• The MDL is calculated as Students t for the 99th percentile times the standard 

deviation of the MDL replicate results, following the procedure at 40CFR Part 

136, Appendix B. 

NOTE1: Perform the MDL study in the synthetic FGD wastewater 

matrix. Spiking this matrix provides detection limits that 

are better matched to the complex matrix typical of FGD 

wastewater. These limits can be significantly higher than 

those obtained in a reagent water matrix. In some cases (zinc 

in particular), the level of contamination in the synthetic 

FGD solution may be high enough to result in somewhat 

elevated MDLs. 

NOTE2: An FGD-MDL may be less than the MDL observed in method 

blanks. If this occurs frequently, the FGD-MDL should be 

elevated to the mean of the method blanks plus the Student t 

factor times the standard deviation of the method blanks. 

12.2 Instrument Detection Limit Study 

Instrument detection limit (IDL) studies are conducted quarterly for each 

instrument and each mass used for analysis. 

• Prepare ten blanks. 

• Analyze the IDL blanks on three non-consecutive days. 

• The IDL is equal to three times the standard deviation of the blank results.

12.3 Demonstration of Capabilities

All personnel are required to perform an initial demonstration of proficiency (IDOC) 

on the instrument they will be using for analysis prior to testing samples. On-going 

proficiency must be demonstrated annually. IDOCs and on-going proficiency 

demonstrations are conducted as follows. 

Four aliquots of the ICV are analyzed using the same instrumental conditions and 

procedures used to analyze samples. The analyst must employ ICV’s from four 

distinct analytical sequences. Using these four ICV’s demonstrates the analyst’s 

ability to optimize and calibrate the instrument and to prepare analytical solutions. 

Calculate the average recovery and standard deviation of the recovery for each 

analyte of interest. 
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 17 of 25

• If any analyte does not meet the acceptance criteria, (85-115% recovery, 

unless other criteria are established) the test must be repeated. Only those 

analytes that did not meet criteria in the first test need to be evaluated. 

Repeated failure for any analyte indicates the need for the laboratory to 

evaluate the analytical procedure and take corrective action. 

12.4 Training Requirements 

12.4.1 Each analyst performing the method must complete a demonstration of 

capability (DOC) by successfully preparing and/or analyzing four 

consecutive LCSs, or a blind performance evaluation (PE) sample, or 

other acceptable QC samples. Analysts who continue to perform the 

method must successfully complete a demonstration of capability 

annually. 

13.0 Pollution Control 

13.1.1 For information about pollution prevention that may be applicable to 

laboratory operations, consult “Less is Better: Laboratory Chemical 

Management for Waste Reduction” available from the American 

Chemical Society’s Department of Government Relations and Science 

Policy, 1155 16th Street N.W., Washington, D.C., 20036, or online at 

http://www.ups.edu/x7432.xml. 

14.0 Waste Management

All waste must be disposed of in accordance with Federal, State, and local 

regulations. 

15.0 References / Cross-References

15.1 EPA Method 200.8, “Determination of Trace Elements in Waters and Wastes 

by Inductively Coupled Plasma - Mass Spectrometry”, Revision 5.4, EMMC 

Version. 

15.2 EPA Method 1638, “Determination of Trace Elements in Ambient Waters by 

Inductively Coupled Plasma – Mass Spectrometry, January 1996 

16.0 Attachments

Attachment 1: Recommended Elemental Equations 

Attachment 2: Internal Standards and Corresponding Metals 

Attachment 3: Sample Preservation and Holding Times 

Attachment 4: Suggested Mass Choices 

Attachment 5: Tuning Solution 

Attachment 6: Suggested Tuning and Response Factor Criteria 

Attachment 7: Summary of Quality Control Requirements 

Attachment 8: Calibration, Calibration Verification, and Spike Concentrations 
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 18 of 25

Attachment 1 

Recommended Elemental Equations 

Element 

Isobaric 

Correction Mathematical Equation 

Pb None (1.0000)(208M) + (1.0000)(207M) + 

(1.0000)(206M) 

6Li Li (natural) (1.0000)(6M) - (0.0813)(7M) 

In Sn (1.0000)(115M) - (0.0149)(118M) 

The 6

Li correction equation is only needed if 6Li is used as an internal standard for low mass 

elements. 

Attachment 2: Internal Standards and Corresponding Metals 

Internal Std. Associated elements1,2

Sc Na, Mg, Al, K, Ca, V, Cr, Mn 

Ge Fe, Ni, Cu, Zn, As, Se 

In Ag, Cd 

Ho Tl, Pb 

Footnote: (1) Na, Mg, K, Ca and Fe are included in the synthetic FGD wastewater but 

their analytical determination is optional – the interferences caused by these elements is 

more important than the determination of their exact concentration. 

(2) Other internal standards may be used. For example, 6

Li, Ga, Rh, Bi, Ho and Tb may 

be considered for use as internal standards. 
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 19 of 25

Attachment 3: Sample Preservation and Holding Times 

Measurement 

Parameter

Container (1) Preservative (2) Maximum Holding 

Time (3)

Waters: 

Metals (4) P,G HNO3 to pH < 2 6 months 

Soils/Sediments/Wastes: 

The preservation required for soil/sediment/waste samples is maintenance at 4°C ( ± 2°C) 

until digestion. 

Footnotes: (1) Polyethylene (P) or glass (G). 

 (2) Sample preservation is performed by the sampler immediately upon 

sample collection or shipped to the laboratory unpreserved for preservation 

at the laboratory. 

 (3) Samples must be analyzed as soon as possible after collection. The times 

listed are the maximum times that sample may be held before analysis and 

still considered valid. Holding times are calculated from the date when the 

sample was collected. 

 (4) Samples are filtered immediately on-site by the sampler before adding 

preservative for dissolved elements. 
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 20 of 25

Attachment 4: Suggested Mass Choices 

Masses listed indicate the masses which have the most impact on data quality and the elemental 

equations used to collect the data. 

Mass Element of Interest Analysis mode 

27 Aluminum No gas 

75 Arsenic He 

111 Cadmium He 

52 Chromium He 

63 Copper He 

208, 207, 206 Lead No gas or He 

24 Magnesium No gas 

55 Manganese He 

60 Nickel He 

39 Potassium No gas or He 

78 Selenium He (H2) 

107 Silver He 

23 Sodium No gas or He 

205 Thallium No gas or He 

51 Vanadium He 

66 Zinc He 

NOTE: It is strongly recommended that elements other than those of interest be 

monitored to indicate other potential molecular interferences which could 

affect the data quality. 
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 21 of 25

Attachment 5: Tuning Solution 

A tuning solution containing elements representing all of the mass regions of interest must be 

analyzed. Below are two groups of suggested solutions which cover a typical mass calibration 

range. 

Method 200.8 

Element Concentration (μg/L) 

Mg 10 

Rh 10 

Ba 10 

Be 10 

U 10 

Ce 10 

Y 10 

Pb 10 

Li 10 

Co 10 

In 10 

Tl 10 
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 22 of 25

Attachment 6: Suggested Tuning and Response Factor Criteria 

No Gas Mode

Li7 >2000cps 

Tl205 >3000cps 

CeO/Ce 156/140 1% 

Ce++/Ce+ 70/140 <3% 

He Mode:

ArAr 78 2-3 counts/sec 

ArCl 75 2-3 counts/sec 
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 23 of 25

Attachment 7: Summary of Quality Control Requirements 

QC Parameter Frequency* Acceptance Criteria Corrective Action 

ICV/QCS Beginning of every 

analytical run. 

90 - 110% recovery. 

200.8 IS, 60-125% rec. 

Terminate analysis; 

correct the problem; 

recalibrate. 

ICB/CCB Immediately after each 

ICV. 

The result is < RL 

200.8 IS, 60-125% rec. 

Terminate analysis; 

correct the problem; 

recalibrate. 

Synthetic FGD 

interference check 

Prior to initiating 

analysis and at least 

quarterly. 

Result for target 

elements is < RL, 

unless actual presence 

of target element can 

be demonstrated, in 

which case result is < 

5X RL. 

Correct the problem 

prior to sample 

analysis. 

Individual element 

interference checks 

Prior to initiating 

analysis and at least 

quarterly. 

Result for target 

elements is < RL, 

unless actual presence 

of target element can 

be demonstrated, in 

which case result is < 

5X RL. 

Correct the problem 

prior to sample 

analysis. 

CCV Beginning and end of 

run and every 10 

samples OR every 2 

hours, whichever is 

more frequent. 

Beginning and end of 

each lot. 

90 - 110% recovery. 

IS, 60-125% rec. 

If unacceptable, 

terminate analysis; 

correct the problem; 

recalibrate the 

instrument, reverify 

calibration and rerun 

all samples since the 

last acceptable CCV. 

CCB Immediately following 

each CCV. 

The result must be < 

RL 

200.8 IS, 60-125% rec. 

If unacceptable, 

terminate analysis; 

correct the problem 

recalibrate the 

instrument, reverify 

calibration and rerun 

all samples since the 

last acceptable CCB. 
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 24 of 25

Attachment 7: Summary of Quality Control Requirements (continued) 

QC Parameter Frequency* Acceptance Criteria Corrective Action 

Method 

Blank/Laboratory 

Reagent Blank 

One per lot of 20 field 

samples or fewer. 

The result must be 

less than the RL. 

Sample results greater 

than 10x the blank 

concentration or 

samples for which the 

contaminant is < RL, 

do not require 

redigestion or 

reanalysis. 

Re-run once. If > than 

the RL, Redigest and 

reanalyze samples. 

Note exceptions under 

criteria section. 

See Section 9.4 for 

additional 

requirements. 

Matrix 

Spike/Laboratory 

Fortified Matrix 

One every ten samples 

or fewer. 

Must be within 

laboratory control 

limits. 

See section 9.6 for 

additional 

requirements. 
EPA Office of Water May 20, 2010 

Engineering & Analysis Division 

Page No.: 25 of 25

Attachment 8: Calibration, Calibration Verification, and Spike Concentrations 

Element 

Initial Calibration 

(μg/L) 

ICV 

(μg/L)

CCV 

(μg/L)

LCS

(μg/L)

MS/MSD 

(μg/L)

Aluminum 100, 1,000, 10,000 4000 5000 4000 4000 

Arsenic 1, 10, 100 40 50 40 40 

Cadmium 1, 10, 100 40 50 40 40 

Chromium 1, 10, 100 40 50 40 40 

Copper 1, 10, 100 40 50 40 40 

Lead 1, 10, 100 40 50 40 40 

Manganese 1, 10, 100 40 50 40 40 

Nickel 1, 10, 100 40 50 40 40 

Selenium 1, 10, 100 40 50 40 40 

Silver 1, 10, 100 40 50 40 40 

Thallium 1, 10, 100 40 50 40 40 

Vanadium 1, 10, 100 40 50 40 40 

Zinc 1, 10, 100 40 50 40 40 

Additional elements may be included in the calibration solution at the above levels. 

Levels may be adjusted to meet specific requirements. 

####