EPA Office of Water December 2012

Engineering & Analysis Division

Page 1

Draft Procedure for Trace Element Analysis of Flue Gas 

Desulfurization Wastewaters Using Perkin Elmer NexION 300D

ICP-MS Collision/Reaction Cell Procedure

1.0

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

Desulfurization (FGD) wastewaters. One of the most widely used technologies for 

removing pollutants such as sulfur dioxide, from flue gas emissions produced by 

coal-fired power plants, is the limestone forced oxidation commonly known as flue 

gas desulfurization. This process employs gas scrubbers to spray limestone slurry 

over the flue gas to convert gaseous sulfur dioxide to calcium sulfate (gypsum). 

Many of the contaminants from the coal, limestone and make-up water are 

concentrated in the circulating water of the scrubbing system. So in order to maintain 

appropriate plant operating conditions, a constant purge stream of water containing 

these contaminants has to be discharged from the scrubbers. This purge stream is 

extremely acidic and saturated with high concentrations of gypsum, heavy metals, 

alkali earth metals, chlorides and dissolved organic compounds and after going 

through various treatment procedures it is discharged.

Introduction

1.2 State and Federal laws regulate the concentration of pollutants in FGD wastewater 

prior to discharge into the waterways and inductively coupled plasma-mass 

spectrometry (ICP-MS), as described in EPA Methods 200.8 and 1638, with addition 

of a Universal Cell TechnologyTM to mitigate the effects of interferences in the 

samples is used. The ICP-MS spectrometer with the Universal Cell can operate in 

reaction, collision and standard modes. The composition of Flue Gas 

Desulfurization wastewaters can vary significantly from plant to plant but almost 

always have very high levels of dissolved salts. The use of instrument configurations 

and/or accessories designed to accommodate samples with high dissolved solids 

levels is highly recommended. This method was developed on a Perkin Elmer 

NexION 300D ICP/MS using an Environmental Scientific SC-DX FAST Automated 

Sample Introduction System

1.3 The procedure described in this document is applicable to the analysis of aciddigested FGD wastewater, and has 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; see 

Attachment 1. Additional elements may be included provided that the performance 

criteria presented in Sections 9 and 12 are met.

1.4 As this procedure is written to address the very complex FGD wastewater matrix, it is 

also very capable of addressing less complex matrices such as drinking water, nonpotable water, and solids. The use of Universal Cell Technology is equally as 

effective for the interferences found in these matrices as it is in FGD wastewaters. 

Appropriate sample preparation steps and quality assurance practices for these 

sample types may be different than described herein.

2.0

2.1 The NexION 300D with the Universal Cell TechnologyTM (UCT) allows the analyst to

choose the most appropriate collision/reaction cell (CRC) conditions for each analyte 

in FGD wastewater samples, without any restrictions to the type of gases that can be 

used. The three modes of interference removal available in the NexION 300 are:

Hardware Description
EPA Office of Water December 2012

Engineering & Analysis Division

Page 2

Standard Mode: The cell is actively vented. This enables the instrument to be run in 

true standard mode, with the cell conditions optimized for maximum ion transition. For 

FGD wastewater samples, this mode is ideal for heavy metals like Pb and Tl, where 

there are very few polyatomic spectral interferences.

Collision Mode: In this mode, the instrument offers conventional collision cell capability 

with kinetic energy discrimination (KED). By using a non-reactive gas, such as helium, 

the collision mode with KED removes many of the simple solvent- and argon-based 

polyatomic spectral interferences. This makes it ideal for elements such as Co, Ni, Cu 

and Zn, which are prone to the larger cross-sectional polyatomic interferences to be 

concerned about.

Reaction Mode: A technique that offers the best available detection capability. This 

mode, known as DRC (Dynamic Reaction CellTM) technology, removes the majority of 

interferences with little or no loss of analyte sensitivity by using pure reaction gases like 

ammonia while not allowing any reaction byproducts to leave the cell which could cause 

further interferences. DRC technology features a scanning quadrupole with a bandpass 

that removes by-product reactions created in the Universal Cell. Therefore any reaction 

gas can be used and in its pure form. And by optimizing the cell’s quadrupole conditions, 

only the element of interest is allowed to pass through to the analyzing quadrupole. It is 

well recognized that ion-molecule reaction chemistry offers the very best performance 

for the reduction of polyatomic interferences. This would be the mode of choice for the 

lowest possible detection limits for elements such as Cr, V and Mn which are recognized 

as being the most difficult to determine in a complex FGD wastewater matrix.

The NexION also features a unique triple cone interface (TCI), which includes an 

additional hyper skimmer cone to tightly define and focus the ion beam entering the 

quadrupole ion deflector. All three cones can be quickly and easily removed, cleaned or 

replaced, which is particularly relevant for the analysis of FGD wastewaters that contain 

high levels of matrix components.

The highly focused ion beam then emerges from the TCI and enters a quadrupole ion 

deflector (QID), which is designed around a proprietary, miniaturized quadrupole. This 

filtering technology bends the ion beam 90 degrees, focusing those of a specified mass 

into the universal cell and discarding all neutral species into the turbo pump. The path 

through the quadrupole ion deflector is aligned with the tightly defined beam leaving the 

triple cone interface, which ensures that ions and neutral species never impact or 

degrade component surfaces within the cell, virtually eliminating the need for cleaning.

By removing the majority of particulates, neutrals and photons, this practical design 

significantly minimizes drift and delivers exceptional signal stability, even when running 

the most challenging FGD wastewater sample matrices.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 3

Figure 1. NexION schematic

2.2 The NexION 300 is 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/reaction cell for the removal of molecular interferences found in FGD 

wastewater samples. Any collision/reaction cell instrumentation that meets the 

specifications, and quality control requirements in this procedure may be used.

2.3 A NexION 300D ICP-MS (Perkin Elmer, Waltham, MA) coupled to an SC DX FAST 

(ESI, Omaha, NE) automated sample delivery system is used for this procedure. 

This delivery system is basically a rapid flow injection technique integrated into an 

autosampler, which significantly reduces the pre- and post-measurement times 

involved with delivering a new sample to and removing the previous sample from the 

ICP-MS. By optimizing these times, a significant improvement can be made in the 

sample throughput. The FAST portion of the delivery system uses a 6-port switching 

valve containing a Teflon sample loop. The sample loop is rapidly filled and 

evacuated with a vacuum pump and because the loop sits very close to the spray 

chamber, the time for the sample to be introduced is dramatically reduced. 

Equivalent autosamplers with rapid flow injection (a.k.a. switching valve) hardware is 

acceptable.

Figure 2. 6-Port valve schematic
EPA Office of Water December 2012

Engineering & Analysis Division

Page 4

Figure 3. SC DX FAST schematic

2.4 Digestates are nebulized in 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 desolvated and decomposed. An additional argon stream entering the 

spray chamber can by utilized for optional sample gas dilution instead of liquid 

dilution. The baffled, cyclonic spray chamber used in the SC DX FAST introduction 

system is Peltier-cooled to 2°C to ensure low oxides and greater stability of the 

instrument. The model PC3 Peltier chiller and spray chamber were used in this 

procedure, but equivalent chilled spray chambers are acceptable.

2.5 The ions produced are entrained in the plasma gas and by means of a water-cooled, 

differentially pumped interface, introduced into a high-vacuum chamber that houses 

a quadrupole ion deflector, a reaction/collision cell and 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-tocharge ratio and measured with a detector, such as an electron multiplier.

2.6 Universal Cell utilizing helium and/or reactive gases such as NH3 is used to remove 

molecular interferences. See Attachment 1 for recommended analyte masses and 

modes of operation.

2.7 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 2. Use of the 

internal standard technique is required to compensate for suppression and 

enhancement caused by sample matrices. Recommended internal standards are

listed in Attachment 3.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 5

3.0

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.

Definitions

3.2 Dissolved Metals - Those elements which pass through a 0.45-μm membrane filter 

(sample is acidified after filtration).

3.3 Total Recoverable Metals - The concentration determined on an unfiltered sample 

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

3.4 Instrument Detection Limit (IDL) - See Section 12.2.

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

between raw instrument signal and the concentration).

3.6 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.

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

This solution must be an independently prepared standard at a concentration level 

near the mid-point of the calibration curve.

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

concentrations prepared to monitor and verify the instrument daily continuing 

performance.

3.9 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.

3.10 Matrix Spike/Laboratory Fortified Sample (MS/LFS) – A sample to which known 

concentrations of the elements of interest are added. The fortified sample is taken 

through all preparation and analytical steps of the procedure. The results are used 

to determine the effect of the sample matrix on analyte recovery efficiency. 

3.11 Laboratory Reagent Blank/Method Blank (LRB/MB) – Reagent water containing 

the same acid matrix as the calibration standards that is carried through the entire 

digestion process. The method blank is used to determine the concentrations of 

trace metals in the reagents used to prepare and analyze the samples as well as the 

contribution of contamination from the digestion process.

3.12 Calibration Blank – Reagent 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 Reporting Limit (RL) – The minimum concentration that can be reported with a 

specified degree of confidence. The RL can be no lower than the concentration of 

the lowest initial calibration standard.

3.14 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.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 6

3.15 Individual FGD Interference Check Solutions – Single element solutions at 

concentrations similar to those found in flue gas desulfurization wastewaters.

3.16 Synthetic FGD Wastewater – A mixed solution of elements at typical concentrations 

found in flue gas desulfurization wastewaters.

4.0

4.1 Isobaric Interferences

Interferences

4.1.1 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).

4.1.2 Except for small interferences from Sn on In (In used as internal standard) 

and from Kr on 78Se, which can be avoided by using argon free of Kr, the 

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

elemental isobaric interferences.

4.2 Isobaric Molecular Interferences

4.2.1 Isobaric molecular interferences are caused by ions consisting of more than 

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

collision/reaction cell utilizing He, and/or NH3 gases. Common examples are 

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

40Ar12C on 52Cr.

4.2.2 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 usually 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. An energy barrier 

before the analyzing quadrupole prevents passage of the now low energy 

molecular ions.

4.2.3 Reaction mode works on the principle that the interfering molecular ion reacts 

with reactive gas (e.g., NH3) to form new ions of differing mass than the 

analyte isotope or by effecting charge transfer from the interfering molecular 

ion to form a neutral molecule.

4.3 Doubly Charged Ion Interferences

4.3.1 Doubly charged elemental ion interferences are possible in cases where the 

second ionization potential of the element is significantly below the first 

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 

interference. Fortunately, most elements have high enough second ionization 

potentials that formation of doubly charged ions is not an issue. Some double 

charged interferences may be removed in reaction mode by using NH3.

4.3.2 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), interference is 

possible. In this case, analyze a 100 ppb standard of Nd and Dy (if mass 150 
EPA Office of Water December 2012

Engineering & Analysis Division

Page 7

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. 

4.3.3 For example, if the response for a 100 ppb 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:

Se 78 = Se 78 − Gd 156

10

4.4 Physical Interferences

4.4.1 Physical interferences are associated with the transport and nebulization 

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

interferences.

4.4.2 Internal standards should be added at a level to give approximately 20,000 –

1,500,000 counts of raw signal intensity. The mass of the internal standard 

should ideally be within 50 amu of the mass of the measured analyte, but this 

is not mandatory with current instrumentation. Consideration should also be 

given to matching internal standards to analytes with similar ionization 

potentials.

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

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

internal standard responses must be between 60% and 125% of the intensity 

in the calibration blank. If they are outside this window the sample is diluted 

by a factor of 2 (1:1) and is reanalyzed.

4.4.4 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

This procedure involves hazardous materials, 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.

Safety

5.1 Specific Safety Concerns or Requirements

Eye protection that satisfies ANSI Z87.1, laboratory coat, and non-powdered nitrile 

gloves must be worn while handling samples, standards, solvents, and reagents. 

Disposable gloves that have been contaminated must be removed and discarded; 

non-disposable gloves must be cleaned immediately.

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 Table 1.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 8

Table 1. Primary Materials with a Serious or Significant Hazard Rating

Material1 Hazards Exposure 

Limit2 Signs and Symptoms of Exposure

Nitric Acid Corrosive

Oxidizer

Poison

2 ppm-TWA

4 ppm-STEL

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.

Hydrochloric 

Acid

Corrosive

Poison

5 ppm-Ceiling 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

6.1 Equipment

Equipment and Supplies

6.1.1 The discrete sample introduction system enables the use of only the exact 

amount of sample volume required for data acquisition. In this procedure, a 

1.5-mL volume was adequate to accommodate the necessary analysis time. 

The loop size can be modified to suit the analysis time as needed.

6.1.2 The sample introduction system also includes a PFA ST concentric nebulizer, 

2.0-mm quartz injector, and baffled cyclonic spray chamber with gas addition 

port (ESI, Omaha, NE), The spray chamber fits into the PC3 chiller described 

in Section 2.4. Other equivalent accessories and configurations that are 

designed to accommodate samples with high levels of dissolved solids may

be used.

6.1.3 PVC peristaltic pump tubing, orange-white, is used to produce a sample flow 

rate of 270 μL/min. This flow rate may be adjusted as necessary to optimize 

method conditions.

6.1.4 A mixing tee is used to blend in the internal standards after the peristaltic 

pump and before the nebulizer. The mixing tee can be used with or without 

the discreet sample introduction system. If used with the discreet sample 
EPA Office of Water December 2012

Engineering & Analysis Division

Page 9

intro system, the mixing tee is inserted after the 6-port valve. The peristaltic

pump tubing used for the internal standard solution is orange-white and when 

used in combination with orange-white pump tubing for the carrier solution or 

sample, creates a minimum dilution of approximately 8.1%. 

6.1.5 Automated sample dilution, liquid or gas, simplifies the dilution process and 

results in less matrix being deposited on the cones during analysis and 

minimizes the rinse times normally needed for difficult matrices. However, 

manual sample dilution is just as effective, albeit more labor intensive.

6.1.6 Autosampler with autosampler tubes.

6.1.7 Block digester with tubes.

6.2 Supplies

6.2.1 Argon gas: High purity grade (99.996%).

6.2.2 Helium gas: Ultra High purity grade (99.999%).

6.2.3 Ammonia gas, anhydrous: Ultra high purity grade (99.999%).

6.2.4 Calibrated automatic pipettes.

7.0

7.1 Storage and Shelf-Life

Reagents and Standards

7.1.1 Stock standards are purchased high purity grade solutions obtained from 

reputable commercial sources. Standard solutions must be traceable to 

national or international standards measurement, such as NIST. All standards 

must be stored in FEP fluorocarbon or previously unused polyethylene or 

polypropylene bottles at room temperature. 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, which are received at ready-to-use 

concentrations) are prepared fresh daily.

7.2 Standards

7.2.1 Tuning Solution, 1 ppb

The tuning solution may be purchased as a custom multi-element mix ready 

to use as is or prepared according to individual instrument manufacturer 

directions. The concentrations of the required elements for the NexION 300D 

ICP-MS are shown in Attachment 4 and the acceptance criteria are shown in 

Attachment 5.

7.2.2 Dual Detector Calibration Solution

7.2.2.1 The dual detector solution may be commercially purchased as a 

custom multi-element mix ready to use as is or prepared according 

to manufacturer’s recommendations. See Attachment 6.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 10

7.2.2.2 Alternative elements may be used that are more specific to the 

analytes being tested. Such solutions should contain elements at 

200 μg/L or other concentrations that accommodate the dual 

detector algorithm.

7.2.3 Calibration Standards

7.2.3.1 Stock calibration standards are purchased as custom multi-element 

mixes or as single element solutions. 

7.2.3.2 Each day of analysis, the standards are diluted to working levels 

using 2% HNO3 and 0.5% HCl matrix, to match the acid strength of 

the digestates. Suggested concentrations are given in Attachment 7, 

but the laboratory may adjust calibration standard concentrations as 

appropriate for the instrument and samples. At a minimum, a 3-point 

curve must be used.

7.2.4 Mixed Interference Check Solution (Synthetic FGD Wastewater)

7.2.4.1 The concentrations of the interferents below are representative of 

typical FGD field samples. If the samples are being diluted (liquid or 

gas) on-line, these concentrations must be used. However, if 

samples are diluted prior to analysis, the concentrations of the 

mixed interferent check solution may be reduced by the smallest 

dilution factor used on the FGD field samples. For example, if the 

field samples are diluted 1:10, then the Ca concentration would be 

200 mg/L.

7.2.4.2 The following solution is prepared in 1.6% HCl

Calcium, 2,000 mg/L

Magnesium, 1,000 mg/L

Sulfate, 2,000 mg/L

Sodium, 1,000 mg/L

1-Butanol, 2000 mg/L

7.2.5 Initial Calibration Verification (ICV) Standard

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

calibration standards.

7.2.5.2 Each day of analysis, the ICV standard is prepared in 2% HNO3 and 

0.5% HCl acid to the concentrations shown in Attachment 7.

7.2.6 Continuing Calibration Verification (CCV) Standard

7.2.6.1 The CCV standards are prepared from the same source as the 

calibration standards.

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

HNO3 and 0.5% HCl. The concentrations are shown in Attachment 

7. 

7.2.7 Internal Standards

Internal standards are required, and recommended isotopes are provided in 

Attachment 3. Inclusion of 10% methanol in the internal standard solution,

when added via the mixing tee, improves the count rate for those elements 
EPA Office of Water December 2012

Engineering & Analysis Division

Page 11

with high ionization potentials such as arsenic and selenium. A 10% 

methanol content in the internal standard solution will ultimately blend down 

to approximately 1% in the sample introduced into the spray chamber. 

7.2.8 Spiking Stock Solution

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

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

7.2.8.2 Spike concentrations are listed in Attachment 7. 

7.3 Reagents

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

of the elements of interest at the levels of interest. 

7.3.2 Blank Matrix - 2% HNO3 and 0.5% HCl.

7.3.3 Methanol – Semiconductor grade.

8.0

8.1 Table 2 lists the holding times and the references that include preservation 

requirements.

Sample Collection, Preservation, Shipment and Storage

8.2 Sample preservation is performed by the sampler immediately upon sample 

collection or shipped to the laboratory unpreserved for preservation at the laboratory. 

If preserved at the laboratory, then the sample must be held for at least 16 hours 

prior to digestion.

8.3 If dissolved elements are to be determined, the samples are immediately filtered 

through a 0.45-μm membrane filter on-site by the sampler before adding 

preservative.

Table 2. Holding Times

Matrix Sample 

Container

Minimum

Sample Size Preservation Holding Time Reference

FGD 

wastewater

HDPE or 

Glass

50 mL HNO3, pH < 2 180 Days 40 CFR Part 136.3

9.0

9.1 Quality control requirements are also summarized in Attachment 8.

Quality Control

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 Synthetic FGD Interference Check Solution

9.3.1 The synthetic FGD matrix solution listed in Section 7.2.4 is analyzed prior to 

initiating sample analysis. The synthetic FGD matrix solution must be 

analyzed at least once per day (immediately after calibration) while FGD 

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

operating conditions.

9.3.1.1 Internal standard recovery must meet method criteria (Section 9.7) 

and concentrations of target elements observed should be less than 

their reporting limits.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 12

9.3.1.2 In some cases it may not be possible to obtain interference check 

solutions that are completely free of contamination. In these cases, 

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 64Zn 48.6%; 66Zn 27.9%; 67Zn 4.1%; 68Zn 18.8%; 70Zn 0.6%. The 

measured ratios are not expected to be exact, especially for low 

abundance isotopes, and some isotopes may be masked by other 

elements in the solution, (for example 70Zn in the above example will 

be masked by 70Ge) but it must be possible to explain the observed 

ratios and clearly demonstrate that the observed contamination is 

not a result of polyatomic interferences. 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.

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

effectively on the ICP-MS (i.e., to meet all method criteria), then all 

samples and QC (including the MDL replicates) must be diluted by 

at least the same factor. Example FGD solution results are given in 

Attachment 9.

9.3.2 Laboratory Fortified Synthetic FGD solution

9.3.2.1 The synthetic FGD solution is spiked with 40 μg/L of each of the 

target elements (400 μg/L for zinc and 4000 μg/L for aluminum) and 

analyzed once per day, immediately after the synthetic FGD check 

in Section 9.3.1. All target elements must be recovered within 70-

130% of the spiked value. For other target elements that are 

routinely detected at concentrations significantly higher than 

100 μg/L, the spike concentrations may be elevated accordingly. 

Likewise, if zinc and aluminum are routinely detected at 

concentrations significantly lower than those above, the spike 

concentrations may be lowered accordingly. 

9.3.2.2 If the Laboratory Fortified Synthetic FGD solution has to be diluted 

in order to analyze it effectively on the ICP-MS (i.e., to meet all 

method criteria), then all samples and QC (including the MDL 

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

9.4 Method Blank (MB)

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. 

9.4.1 Acceptance Criteria: Method blank results are acceptable if the 

concentration for each analyte of interest is less than the reporting limit.

9.4.2 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):

9.4.2.1 The same analyte was not detected in the associated samples;
EPA Office of Water December 2012

Engineering & Analysis Division

Page 13

9.4.2.2 The method blank concentration is less than 1/10 of the measured 

concentration of any sample in the batch;

9.4.2.3 The method blank concentration is less than 1/10 the specified 

regulatory limit; or

9.4.2.4 The analyte is a common laboratory contaminant (copper, iron, lead, 

calcium, magnesium, potassium, sodium, or zinc) and is less than 2 

times the reporting limit. 

9.4.2.5 If the above criteria are not met and reanalysis is not possible, then 

the sample data must be qualified. This contamination must be 

addressed in the project narrative and the client must be notified.

9.5 Laboratory Control Sample (LCS) 

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

summarized in Attachment 7. One LCS must be processed (digestion and analysis) 

for each preparation batch.

9.5.1 Acceptance Criteria: LCS control limits should be 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. 

9.5.2 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 of at least those affected analytes. 

One possible exception is a recovery for a given element above the upper 

control limit with no associated detection for the same element in the 

samples.

9.6 Matrix Spike / Matrix Spike Duplicate (MS/MSD) 

9.6.1 The MS is prepared by taking a second aliquot of a selected sample and 

spiking it with the analytes of interest, as summarized in Attachment 7.

9.6.2 The MSD is prepared by taking a third aliquot of the selected sample and 

spiking it with the analytes of interest, as summarized in Attachment 7.

9.6.3 The MS and MSD are processed in the same manner as the samples. One 

MS/MSD pair must be processed every 10 samples.

9.6.3.1 Acceptance Criteria: Control limits should be based on three 

standard deviations of past laboratory results. These limits are not 

to exceed 70-130% recovery, and 20% relative percent difference 

(RPD). The control limits should be 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 may be reduced and the combined 

concentration may well exceed the calibration range. 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.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 14

The RPD is calculated as follows:

RPD = |C(MS) − C(MSD)|

1

2 [C(MS) + C(MSD)]

× 100%

Where C(MS) is the concentration observed in the MS

C(MSD) is the concentration observed in the MSD

9.6.3.2 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. When the concentration of any element in the 

selected sample is more than 5X the concentration of the spike 

concentration, then the acceptance criterion does not apply and the 

spike results should be flagged accordingly.

9.7 Internal Standard Evaluation for Samples

9.7.1 The internal standard (IS) responses in samples and QC (including the 

synthetic FGD solution) must be between 60 and 125% of the intensity in the 

calibration blank.

9.7.2 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

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

Dilution factors should increase as necessary until the IS response meets the 

acceptance criterion.

9.7.3 Corrective actions for standards and blanks are described in Section 10.

10.0

10.1 Procedural variations are allowed only if deemed necessary in the professional 

judgment of the laboratory director to accommodate variation in sample matrix, 

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

procedure shall be thoroughly documented and noted in the laboratory narrative. 

Any deviations from this procedure must also be documented as a nonconformance, 

with a cause and corrective action described.

Procedure

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 describes aqueous sample preparation.

10.2.2 Transfer a 50-mL (± 0.5 mL) aliquot from a well-mixed, acid-preserved 

sample to a 50-mL block digestion tube.

10.2.3 Add 1.0 mL of concentrated nitric acid and 0.25 mL concentrated hydrochloric 

acid. (If samples are received unpreserved, add 1% nitric acid and store for at 

least 16 hours before preparation). 

10.2.4 Prepare sample aliquots and spike the LCS and MS/MSD samples per 

spiking protocols.

10.2.5 Place a ribbed disposable watch glass over the digestion tube.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 15

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

temperature of approximately 85°C.

10.2.7 Heat for 2 hours after 85°C is obtained.

10.2.8 Remove the tubes from the block and allow to cool.

10.2.9 Add deionized water to digestates to bring them back to 50.0 mL.

10.3 Calibration

10.3.1 Instrument Start Up

10.3.1.1 Setup the instrument according to manufacturer’s operating 

instructions.

10.3.1.2 Allow the instrument to become thermally stable for at least 

30 minutes before tuning.

10.3.2 Instrument Tuning / Mass Calibration

10.3.2.1 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 

5 replicate integrations of the solution.

10.3.2.2 Perform mass calibration and resolution check using the tuning 

solution at a minimum of every two weeks.

10.3.2.2.1 Mass Calibration Check: The mass calibration results 

must be within 0.1 amu from the true value.

10.3.2.2.2 Mass Resolution Check: The resolution must be 

verified to be less than 0.9 amu full width at 10% peak 

height.

10.3.3 Dual Detector Calibration

10.3.3.1 The dual detector calibration allows the quantification of results 

using both the pulse mode and analog mode of the detector. 

Analysis of a multi-element standard at a concentration sufficient 

(e.g., 200 μg/L) to allow the detector to function in both modes 

allows the software to determine conversion factors. These 

conversion factors are used to quantify elements detected in the 

analog mode by converting the observed counts to equivalent pulse 

mode counts.

10.3.3.2 The dual detector calibration is only required for those isotopes that 

will trigger the analog mode of the detector (e.g., >2 million counts 

per second). Isotopes or elements that are known to always be 

present at count rates within pulse mode detection do not need to 

be included. Note that the dual detector calibration is specific to the 

isotopes and not necessarily the elements.

10.3.3.3 The dual detector calibration must be performed at least every 

month. The correlation coefficient (r2

) for each isotope must be 

>0.999. While there is no specific criterion for a minimum number of 

crossover points, it is recommended to have at least 10. The 

number of points can generally be increased by modifying the 

concentration of the affected element. Review of the count rate for 
EPA Office of Water December 2012

Engineering & Analysis Division

Page 16

the affected element will assist in determining if the element 

concentration should be increased or decreased from the default 

200 μg/L level.

10.3.4 Initial Calibration

10.3.4.1 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 replicate integrations.

10.3.4.2 The linearity of the initial calibration is assessed using a linear 

regression algorithm, based on the intensity counts of both the 

target elements and the internal standards. Calculate the correlation 

coefficient (r

2

) from the initial calibration. The calibration is 

sufficiently linear if r

2 ≥ 0.998. Elements not meeting this criterion 

are not valid and recalibration is required for at least those affected 

elements.

10.3.4.3 The ongoing validity of the calibration is determined by the 

subsequent calibration verifications, which are performed at 

concentrations and frequencies as described in the next sections.

10.3.5 Second-Source Initial Calibration Verification (ICV)

An ICV standard (see Attachment 7) is analyzed immediately after the initial 

calibration. This is a standard obtained preferably from a different vendor 

than the standard used for calibration but at a minimum must be a different lot 

number from the same vendor. 

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

Additionally, the internal standard responses must be between 60% 

and 125% of the intensity in the calibration blank. The ICV can be 

reanalyzed, but must be successful twice in succession or corrective 

action must be taken.

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

limits, investigate the accuracy of the standards, correct as 

necessary, and recalibrate.

10.3.6 Calibration Blank 

Checks for the memory effects described in Section 4.4 must be 

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

Continuing calibration blanks (CCBs) are analyzed immediately after each 

continuing calibration verification.

10.3.6.1 Acceptance Criteria: Results for the calibration blanks must be 

less than the RL. 

10.3.6.2 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 samples

containing high solids. 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.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 17

10.3.7 Reporting Limit (RL) Verification Standard

A standard (such as the low level calibration standard) is analyzed after the 

ICB to monitor the laboratory’s ability to produce reliable results at the 

reporting limit concentrations. The RL verification standard is analyzed after 

the daily ICB.

10.3.7.1 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. 

10.3.7.2 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 CCV standard (see Attachment 7) is analyzed after every set of ten 

samples and at the end of the analytical sequence.

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

In addition, the internal standard responses must be between 60% 

and 125% of the intensity in the calibration blank. 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.

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

analysis should be terminated. Recalibrate and reanalyze all 

samples tested since the last acceptable CCV.

10.4 Sample Analysis

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

samples analyzed.

10.4.2 Flush the system with a rinse solution between samples and standards during 

the analytical run. It is recommended that the rinse solution be the same as 

the matrix (i.e., 2% HNO3 and 0.5% HCl). If using a discreet analyzer or 

switching valve, the rinsing efficiency can be improved by rinsing the sample 

loop and valve as well as the sample line itself. Evaluate the effectiveness of 

this rinse 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 Where any target element is determined at a concentration exceeding the 

high calibration standard, those samples must be reanalyzed following 

dilution for at least those affected elements. The dilution factor must be 

sufficient to bring the target analyte to within the calibration range.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 18

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

quality control criteria:

Instrument initialization

Warm-up

Tune instrument

Perform mass calibration, when indicated

Perform resolution check, when indicated

Validate tuning criteria

Calibration blank

Calibration standards

ICV

ICB

RL verification standard

Synthetic FGD matrix 

Spiked synthetic FGD matrix

CCB (carryover check)

CCV

CCB

10 Samples 

Ending CCV 

Ending CCB

11.0

11.1 LCS percent recoveries are calculated according to the following equation:

Calculations/Data Reduction

%R = �

LCS Found Value

LCS True Value � × 100%

11.2 ICV percent recoveries are calculated according to the following equation:

%R = �

ICV Found Value

ICV True Value � × 100%

11.3 CCV percent recoveries are calculated according to the following equation:

%R = �

CCV Found Value

CCV True Value � × 100%

Repeat for all samples 

with 10% CCV/CCB 

frequency 
EPA Office of Water December 2012

Engineering & Analysis Division

Page 19

11.4 Matrix spike percent recoveries are calculated according to the following equation:

%R = �

SSR − SR

SA � × 100%

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:

RPD = |DU1 − DU2|

1

2 (DU1 + DU2)

× 100%

Where:

DU1 = Sample result

DU2 = Sample duplicate result

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

Result = C × V1 × D

V2

Where:

C = Concentration from instrument readout

D = Instrument dilution factor, where applicable

V1 = Final volume in milliliters after sample preparation

V2 = Initial volume of sample digested in milliliters

12.0

12.1 Method Detection Limit Study (MDL) 

Method Performance 

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

before samples can be analyzed. MDL studies are conducted annually per 

40 CFR Part 136, Appendix B. A summary of this procedure is as follows:

12.1.1.1 Prepare seven replicate samples at three to five times the estimated 

MDL concentration. The MDL samples are prepared in the Synthetic 

FGD wastewater matrix. The Synthetic FGD matrix may be diluted 

if it has previously been determined that the field samples require 

dilution to meet method criteria; see Section 9.3.

12.1.1.2 Prepare and analyze the MDL standards as described in Section 10, 

including the digestion procedure.

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

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

12.1.1.4 The MDL is calculated as Student’s t-value for the 99th percentile 

(3.143 for 7 replicates) times the standard deviation of the MDL 
EPA Office of Water December 2012

Engineering & Analysis Division

Page 20

replicate results, following the procedure at 40 CFR Part 136, 

Appendix B.

12.1.1.5 The calculated MDLs may not exceed the test concentrations used 

in the 7 samples nor may the test concentrations exceed the MDLs 

by more than a factor of 10. If either case is encountered, all 

elements affected must be prepared again at a more appropriate 

concentration.

12.1.1.6 Some elements may not require spiking if it has previously been 

determined that the Synthetic FGD matrix is contaminated and 

meets the criteria in Section 9.3, and the concentrations of the 

contaminants are within the acceptable range described in Section 

12.1.1.5.

NOTE: 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 wastewaters. 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. 

12.1.2 Example MDLs are given in Attachment 10.

12.2 Instrument Detection Limit Study

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

and each mass used for analysis.

12.2.1 Prepare ten blanks. 

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

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

12.3 Demonstration of Capabilities

12.3.1 All personnel are required to perform an initial demonstration of capability 

(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.

12.3.2 Analyst Instrument Proficiency - Four aliquots of the ICV are analyzed using 

the same instrumental conditions and procedures used to analyze samples. 

The analyst must employ ICVs from four distinct analytical sequences. Using 

these four ICVs 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.

12.3.2.1 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.

12.3.2.2 Repeated failure for any analyte indicates the need for the 

laboratory to evaluate the analytical procedure and take corrective 

action.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 21

12.3.3 Analyst Preparation Proficiency

12.3.3.1 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.

12.3.3.2 Analysts who continue to perform the method must successfully 

complete a demonstration of capability annually.

13.0

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 NW, Washington, DC, 20036, or online at 

Pollution Control 

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

14.0

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

Waste Management

15.0

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

Inductively Coupled Plasma - Mass Spectrometry,” Revision 5.4, 1994.

References

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

Inductively Coupled Plasma – Mass Spectrometry, January 1996.

15.3 This method was developed by PerkinElmer, Inc.

16.0

Attachment 1: Suggested Mass Choices

Attachments

Attachment 2: Recommended Elemental Equations

Attachment 3: Internal Standards and Corresponding Elements

Attachment 4: Tuning Solution

Attachment 5: Suggested Tuning and Response Factor Criteria

Attachment 6: Dual Detector Calibration Solution

Attachment 7: Calibration, Calibration Verification, and Spike Concentrations

Attachment 8: Summary of Quality Control Requirements

Attachment 9: Typical results for synthetic FGD solutions

Attachment 10: Typical Method Detection Limits
EPA Office of Water December 2012

Engineering & Analysis Division

Page 22

Attachment 1: Suggested Mass Choices and Analysis Mode

The isotope in bold is recommended as the most appropriate mass for quantitation. Additional 

masses listed are recommended for use as confirmation and to monitor for interferences. 

STD – Standard mode

He – Helium gas used in collision mode

NH3 – Ammonia gas used in reaction mode

Mass Element of 

Interest

Analysis 

Mode

27 Aluminum STD or He

75 Arsenic He

111, 114 Cadmium He

52, 53 Chromium NH3 or He

63, 65 Copper He

208, 207, 206 Lead STD

55 Manganese NH3 or STD

60, 62 Nickel He

78, 82 Selenium NH3 or He

107 Silver STD or He

205, 203 Thallium STD or He

51 Vanadium NH3 or 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.

Na, Mg, K, Ca and Fe are included in the synthetic FGD wastewater but 

their analytical determination is optional

Attachment 2: Recommended Elemental Equations

Element Isobaric Correction Mathematical Equation

Pb None (1.0000)(208M) + (1.0000)(207M) + (1.0000)(206M)

6

Li 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.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 23

Attachment 3: Internal Standards and Corresponding Elements

Internal Std. Associated elements1,2

Sc Na, Mg, Al, K, Ca

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

In V, Cr, Mn, Ag

In or Tb Tl, Pb

Footnotes:

(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 are 

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 Ir may 

be considered for use as internal standards.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 24

Attachment 4: Tuning Solution

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

analyzed. Below is a suggested solution covering a typical mass range for the NexION 300D. 

Instrument manufacturer recommendations should be followed for tuning solutions.

Element Concentration (μg/L)

Be 1

Ce 1

Fe 1

In 1

Li 1

Mg 1

Pb 1

U 1

Attachment 5: Suggested Tuning and Response Factor Criteria 

No Gas Mode

24Mg >20,000cps

115In >50,000cps

238U >40,000cps

220Background <1cps

CeO/Ce 156/140 <2.5%

Ce++/Ce+ 70/140 <3%
EPA Office of Water December 2012

Engineering & Analysis Division

Page 25

Attachment 6: Dual Detector Calibration Solution

A dual detector calibration solution containing elements representing all of the mass regions of 

interest must be analyzed. Below is a suggested solution covering a typical mass calibration 

range. Other elements can be added as needed. The concentrations used in the solution may 

be varied as necessary to accommodate the dual detector algorithms and the instrument 

sensitivity. Instrument manufacturer recommendations should be followed for tuning solutions.

Element Concentration (μg/L)

Ag 200

Al 200

As 200

Ca 200

Cd 200

Cr 200

Cu 200

Ge 200

In 200

K 200

Mg 200

Mn 200

Na 200

Ni 200

Pb 200

Sc 200

Se 200

Tb 200

Tl 200

V 200

Zn 200
EPA Office of Water December 2012

Engineering & Analysis Division

Page 26

Attachment 7: 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 – in particular, higher spiking levels for 

selenium and manganese may be needed to be able to reliably determine the spike above the 

sample concentration.

NOTE: The concentrations of elements in this table are intended to be the approximate 

concentrations supplied to the plasma. When the internal standards are added on-line 

through the use of a mixing tee, these concentrations should not be affected 

significantly. However, if it is determined that sample dilution is necessary to meet 

method criteria and this dilution is to be effected through the use of on-line dilutions 

with a mixing tee, the concentrations of the calibration standards and QC samples 

must be adjusted accordingly. In such cases, Silver may become unstable at higher 

dilutions and lower concentrations may be necessary.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 27

Attachment 8: Summary of Quality Control Requirements 

QC Parameter Frequency Acceptance Criteria Corrective Action

ICV/QCS Beginning of every 

analytical run.

90 - 110% recovery

IS, 60-125% of the intensity in 

calibration blank

Terminate analysis; correct 

the problem; recalibrate.

ICB/CCB Immediately after 

each ICV.

Result is < RL

IS, 60-125% of the intensity in 

calibration blank

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.

IS, 60-125% of the intensity in 

calibration blank

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.

IS, 60-125% of the intensity in 

calibration blank

Correct the problem prior 

to sample analysis.

CCV Beginning and end 

of run and every 10 

samples OR

85 - 115% recovery

every 

2 hours, whichever 

is more frequent. 

Beginning and end 

of each analytical 

sequence.

IS, 60-125% of the intensity in 

calibration blank

If unacceptable, terminate 

analysis; correct the 

problem; recalibrate the 

instrument, re-verify 

calibration and rerun all 

samples since the last 

acceptable CCV.

CCB Immediately 

following each 

CCV.

The result must be < RL

IS, 60-125% of the intensity in 

calibration blank

If unacceptable, terminate 

analysis; correct the 

problem, recalibrate the 

instrument, re-verify 

calibration and rerun all 

samples since the last 

acceptable CCB.

Method Blank/

Laboratory 

Reagent Blank

One per batch 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 re-digestion or reanalysis. 

Re-run once. If > than the 

RL, re-digest and 

reanalyze samples.

Note exceptions under 

criteria section.

See Section 9.4 for 

additional requirements.

LCS/LFB One per 

preparation batch 

of 20 samples or 

fewer

Not to exceed 85-115% recovery See Section 9.5

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 December 2012

Engineering & Analysis Division

Page 28

Attachment 9: Typical results for the synthetic FGD solution

Analyte

Synthetic FGD 

Solution A

Synthetic FGD 

Solution B

Synthetic FGD 

Solution C

Synthetic FGD 

Solution D

Synthetic FGD 

Solution E

Synthetic FGD 

Solution F

Spike Recovery 

Solution F

27Al 23.2 36.4 23.5 5.33 7.16 24.4 111%

51V 0.46 5.11 0.45 4.31 0.19 0.15 114%

52Cr 106 2.97 1.76 0.76 1.38 2.02 107%

55Mn 45.2 37.3 21.9 25.4 7.02 21.9 112%

60Ni 2.83 4.36 4.66 7.44 1.42 4.62 100%

63Cu 3.45 2.35 3.56 1.78 3.03 1.34 93.0%

66Zn 7.24 5.84 40.4 27.6 9.26 36.6 94.0%

75As 4.90 1.11 1.82 2.88 1.09 1.69 110%

78Se 10.6 3.10 4.00 4.21 3.04 6.48 108%

107Ag 0.53 0.22 1.36 2.33 0.31 0.02 90.0%

111Cd 1.00 3.25 2.85 3.92 0.11 1.93 107%

205Tl 0.31 0.19 1.28 0.94 0.05 0.10 103%

208Pb 2.05 1.36 5.30 9.23 5.37 4.17 94.2%

Note that these values are examples and not method requirements.

Synthetic FGD Solution F was spiked with 40 μg/L of all elements.
EPA Office of Water December 2012

Engineering & Analysis Division

Page 29

Attachment 10: Typical Method Detection Limits

Mass/Element Integration Time (sec) Mode Internal Standard MDL (μg/L)

27Al 0.5 STD Sc 0.54

51V 0.5 NH3 In 0.02

52Cr 0.5 NH3 In 0.09

55Mn 0.5 NH3 In 0.27

60Ni 0.5 He Ge 0.28

63Cu 0.5 He Ge 0.30

66Zn 0.5 He Ge 1.20

75As 1.5 He Ge 0.30

78Se 1.5 He Ge 1.01

107Ag 0.5 STD In 0.03

111Cd 0.5 He Ge 0.03

205Tl 0.5 STD In 0.01

208Pb 0.5 STD In 0.04

MDLs were determined in the synthetic FGD solution. Note that these values are examples, and 

not method requirements.

It should be noted that contamination present in the synthetic FGD solution may have a 

significant impact on the determination of MDL values. It may be impractical to spike the 

synthetic FGD solution for those elements that are already present at concentrations exceeding 

the 3-5 times estimated MDL value. It may also be problematic to determine an acceptable MDL 

for any element present in the synthetic FGD solution at a concentration that exceeds 10 times 

the calculated MDL.