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METHOD 6010D 

 INDUCTIVELY COUPLED PLASMA—OPTICAL EMISSION SPECTROMETRY

SW-846 is not intended to be an analytical training manual. Therefore, method procedures 

are written based on the assumption that they will be performed by analysts who are formally 

trained in at least the basic principles of chemical analysis and in the use of the subject 

technology. 

In addition, SW-846 methods, with the exception of required method use for the analysis of 

method-defined parameters, are intended to be guidance methods which contain general 

information on how to perform an analytical procedure or technique which a laboratory can use 

as a basic starting point for generating its own detailed standard operating procedure (SOP), 

either for its own general use or for a specific project application. The performance data 

included in this method are for guidance purposes only, and are not intended to be and must not 

be used as absolute quality control (QC) acceptance criteria for purposes of laboratory 

accreditation. 

1.0 SCOPE AND APPLICATION 

1.1 Inductively coupled plasma—optical emission spectrometry (ICP-OES) is a 

spectrometric technique used to determine trace elements in aqueous solutions. In ICP-OES, a 

sample solution is aspirated (i.e., nebulized) continuously into an inductively coupled, argonplasma discharge, where analytes of interest are converted to excited-state, gas-phase atoms or 

ions. As the excited-state atoms or ions return to their ground state, they emit energy in the form 

of light at wavelengths that are characteristic of each specific element. The intensity of the 

energy emitted at the chosen wavelength is proportional to the amount (concentration) of that 

element in the analyzed sample. Thus, by determining which wavelengths are emitted by a 

sample and their respective intensities, the elemental composition of the given sample relative to 

a reference standard may be quantified. For accurate results, direct ICP-OES analysis should 

be conducted on only relatively clean, aqueous matrices (e.g., pre-filtered groundwater 

samples). Other, more complex aqueous and/or solid samples need acid digestion prior to 

analysis; the analyst should insure that a sample digestion method is chosen that is appropriate 

for each analyte and the intended use of the data. Refer to Chapter Three for the appropriate 

digestion procedures. 
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The following RCRA analytes have been determined by this method: 

Element Symbol CASRNa Element Symbol CASRNa 

Aluminum Al 7429-90-5 Mercury* Hg 7439-97-6 

Antimony Sb 7440-36-0 Molybdenum Mo 7439-98-7 

Arsenic As 7440-38-2 Nickel Ni 7440-02-0 

Barium Ba 7440-39-3 Phosphorus P 7723-14-0 

Beryllium Be 7440-41-7 Potassium K 7440-09-7 

Boron B 7440-42-8 Selenium Se 7782-49-2 

Cadmium Cd 7440-43-9 Silica SiO2 7631-86-9 

Calcium Ca 7440-70-2 Silver Ag 7440-22-4 

Chromium Cr 7440-47-3 Sodium Na 7440-23-5 

Cobalt Co 7440-48-4 Strontium Sr 7440-24-6 

Copper Cu 7440-50-8 Thallium TI 7440-28-0 

Iron Fe 7439-89-6 Tin Sn 7440-31-5 

Lead Pb 7439-92-1 Titanium Ti 7440-32-6 

Lithium Li 7439-93-2 Vanadium V 7440-62-2 

Magnesium Mg 7439-95-4 Zinc Zn 7440-66-6 

Manganese Mn 7439-96-5 

aChemical Abstract Service Registry Number 

*NOTE: Mercury is not typically analyzed by this method and is not recommended for low-level 

quantitative analysis; however, this method can be used as a screening tool (e.g., prior to 

analysis by a low-level method when high concentrations of mercury are expected). 

CAUTION: Also note that mercury memory effects may result from the analysis of samples that 

contain high level Hg concentration. See Method 6020B Sections 7.20.11, 7.22.3, 

and 11.1 for guidance when analyzing for mercury. 

1.2 The table in Section 1.1 lists the elements for which this method has been 

validated. The sensitivity and the optimum and linear ranges for each element will vary with the 

wavelength, spectrometer, matrix, and operating conditions. Refer to the manufacturer’s 

instructions for recommended analytical wavelengths and estimated instrument detection limits 

(IDLs) for the elements in a clean aqueous matrix with insignificant background interferences. 

Other elements and matrices may be analyzed by this method if acceptable performance at the 

concentrations of interest is demonstrated (see Sec. 9.0). 

1.3 IDLs are necessarily instrument-specific. Therefore, if needed, an IDL must be 

determined through a separate experimental study for each instrument in a laboratory. IDLs 

should be established at minimum on an annual basis, for each matrix type analyzed and for 
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each preparatory/determinative method combination used (refer to Chapters One and Three for 

guidance). 

1.4 Analysts should clearly understand the data quality objectives (DQOs) prior to 

analysis. Before using the method for routine environmental analysis, analysts should document 

and have on file the necessary initial demonstration of performance (IDP) data, as described in 

Section 9.0. 

1.5 Use of this method is restricted to spectroscopists who are knowledgeable in the 

correction of the spectral, chemical, and physical interferences described in this method. 

1.6 Prior to employing this method, analysts are advised to consult the preparatory 

method for each type of procedure that may be employed in the overall analysis (e.g., Methods 

3005, 3010, 3015, 3031, 3040, 3050, 3051, 3052, 7000, and 6800) for additional information on 

QC procedures, development of QC acceptance criteria, calculations, and general guidance. 

Analysts also should consult the disclaimer statement at the front of the manual and the 

information in Chapter Two for guidance on the intended flexibility in the choice of methods, 

apparatus, materials, reagents, and supplies, and on the responsibilities of the analyst for 

demonstrating that the techniques employed are appropriate for the analytes of interest, in the 

matrix of interest, and at the levels of concern. 

In addition, analysts and data users are advised that, except where explicitly specified in a 

regulation, the use of SW-846 methods is not mandatory in response to Federal testing 

requirements. The information contained in this method is provided by EPA as guidance to be 

used by the analyst and the regulated community in making judgments necessary to generate 

results that meet the DQOs for the intended application. 

 1.7 This method is restricted to use by, or under supervision of, properly experienced 

and trained personnel. Each analyst must demonstrate the ability to generate acceptable results 

with this method. 

2.0 SUMMARY OF METHOD 

2.1 Prior to analysis, aqueous and solid samples are solubilized or digested using the 

appropriate sample preparation methods (see Chapter Three). When analyzing groundwater 

samples for dissolved constituents, acid digestion is not necessary, if the samples are filtered 

and acid-preserved prior to analysis (e.g., Methods 3005, 3010, 3015, 3031, 3050, 3051 and 

3052). Samples that are not digested necessitate the use of either an internal standard or 

should be matrix-matched with the standards. If using the former option, the instrument software 

should be programmed to correct for the intensity differences of the internal standard between 

samples and standards. 

 2.2 This method describes multi-element determinations by ICP-OES using sequential 

or simultaneous optical systems, and axial or radial viewing of the plasma. The ICP-OES 

instrument measures characteristic emission spectra by optical spectroscopy. Samples are 

nebulized and the resulting aerosol is transported to the plasma torch. Element-specific 

emission spectra are produced by a radio-frequency, inductively coupled plasma. The spectra 

are dispersed by a grating spectrometer, and the intensities of the emission lines are monitored 

by photosensitive devices. 
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 2.3 Background correction is necessary for trace element determination. Background 

emission must be measured adjacent to analyte lines on samples during analysis. The position 

selected for the background-intensity measurement, on either or both sides of the analytical line, 

will be determined by the complexity of the spectrum adjacent to the analyte line. The position 

used should be as free as possible from spectral interference and should reflect the same 

change in background intensity as that which occurs at the analyte wavelength being measured. 

 Background correction is not needed in cases of line broadening, where a background 

correction measurement would actually degrade the analytical result. Analysts should recognize 

the possibility of additional interferences, as identified in Sec. 4.0, and make appropriate 

corrections. Tests for the presence of additional interferences are described in Sec. 9.9. 

Alternatively, analysts may choose multivariate calibration methods, in which case, point 

selections for background correction are superfluous, since whole spectral regions are 

processed. 

3.0 DEFINITIONS 

 Refer to Chapter One, Chapter Three, and the manufacturer's instructions for definitions 

that may be relevant to this procedure. 

4.0 INTERFERENCES 

 Interferences can arise from a variety of sources and serve to diminish the bias and 

precision of analytical data, particularly when determining elements at trace levels. Interferences 

to ICP-OES have been studied in detail and are well understood. A summary of interferences to 

ICP-OES analysis as well as techniques to mitigate their effects on data are provided in the 

sections to follow. 

4.1 Spectral interferences can arise from several sources. Techniques to identify and 

compensate for spectral interferences are discussed below. 

 4.1.1 Background emission from continuous or recombination phenomena 

and/or stray light from the line emission of high concentration elements 

 4.1.1.1 Compensation for background emission and stray light can 

usually be conducted by subtracting the background emission determined through 

measurements obtained adjacent to the analyte wavelength peak. Spectral scans 

of samples or single-element solutions in the analyte regions may indicate when the 

use of alternate wavelengths is desirable because of severe spectral interference. 

These scans will also show whether the most appropriate estimate of the 

background emission is provided by an interpolation from measurements obtained 

on both sides of the wavelength peak, or by measured emission obtained only on 

one side. 

 The locations selected for the measurement of background intensity will 

be determined by the complexity of the spectrum adjacent to the wavelength peak. 

The locations used for routine measurement must be free of off-line spectral 

interference (interelement or molecular), or otherwise adequately corrected to 

reflect the same change in background intensity as that which occurs at the 
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wavelength peak. For multivariate methods using whole spectral regions, 

background scans should be included in the correction algorithm. Off-line spectral 

interferences are handled by including spectra on interfering species in the 

algorithm. 

 4.1.1.2 To determine the appropriate location for off-line background 

correction, the area adjacent to the wavelength on either side must be scanned, so 

that the apparent emission intensity from all other method analytes may be 

recorded. This spectral information must be documented and kept on file. The 

location selected for background correction must be either free of off-line interelement spectral interference or a computer routine must be used for automatic 

correction on all determinations. If a wavelength other than the recommended 

wavelength is used, the analyst must determine and document both the 

overlapping and nearby spectral interference effects from all method analytes and 

common elements and provide for their automatic correction on all analyses. Tests 

to determine spectral interference must be performed using analyte concentrations 

that will adequately describe the interference. Normally, 100-mg/L, single-element 

solutions are sufficient. However, for analytes such as iron, that may be found in 

the sample at high concentration, a more appropriate test would be to use a 

concentration near the upper limit of the analytical range (refer to Chapter Three for 

additional guidance). 

 4.1.2 Overlaps from the molecular spectra of the same target element may be 

avoided through the use of an alternate wavelength for quantitation. 

 4.1.3 Optical spectral-line overlaps between target elements 

 4.1.3.1 Interelement spectral overlaps are typically compensated 

through the use of equations that correct for interelement contributions. 

Instruments that use equations for interelement correction necessitate that 

interfering element(s) are analyzed at the same time as the target element(s) of 

interest. When operative and uncorrected, interelement interferences will produce 

false positive or positively biased determinations. However, if the interference 

affects the point selected for background correction, the resulting overcorrection will 

cause a negative bias. More extensive information on interferent effects at various 

wavelengths and resolutions is available in reference wavelength tables and books. 

 Analysts may apply interelement-correction equations determined on their 

instruments with tested concentration ranges to compensate (off-line or on-line) for 

the effects of interfering elements. Selected potential spectral interferences 

observed for the recommended wavelengths are given in Table 1. 

 4.1.3.2 For multivariate calibration methods that employ whole spectral 

regions, spectral interferences are handled by including spectra of the interfering 

elements in the calibration algorithm. The interferences listed in Table 1 are those 

that occur between method analytes. Only interferences of a direct overlap nature 

are shown. These overlaps were observed with a single instrument having a 

working resolution of 0.035 nm. 

 4.1.3.3 When using interelement-correction equations, the 

interference may be expressed as analyte concentration equivalents (i.e., false 

positive analyte concentrations) arising from 100 mg/L of the interference element. 
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For example, if As is to be determined at 193.696 nm in a sample containing 

approximately 10 mg/L of Al, according to Table 1, 100 mg/L of Al will yield a false 

positive signal equivalent to an As concentration of approximately 1.3 mg/L. 

Correspondingly, the presence of 10 mg/L of Al will result in a false positive signal 

for As equivalent to approximately 0.13 mg/L. The analyst is cautioned that 

alternate instruments may exhibit somewhat different levels of interference than 

those shown in Table 1. The interference effects must, therefore, be evaluated for 

each individual instrument, since the intensities will vary (see Sec. 4.1.3.5). It 

should also be noted that instruments using an Echelle grating are potentially 

subject to interferences from different diffraction orders. These potential 

interferences will not be listed in standard tables of emission lines and therefore 

careful evaluation of interelement corrections as described in Sec. 9.9.1 becomes 

even more vital. 

 4.1.3.4 Interelement corrections will vary for the same emission line 

among instruments because of differences in resolution. Such differences are 

determined by the grating, entrance and exit slit widths, and by the order of 

dispersion. Interelement corrections will also vary depending upon the choice of 

background correction points. Selecting a background correction point where an 

interfering emission line may appear should be avoided when practical. 

Interelement corrections that constitute a major portion of an emission signal may 

not yield accurate data. Analysts should continuously note that some samples may 

contain uncommon elements that could contribute spectral interferences. 

 4.1.3.5 As already noted (Sec. 4.1.3.3), the interelement effects must 

be evaluated for each individual instrument, whether configured as a sequential or 

simultaneous instrument. For each instrument, intensities will vary not only with 

optical resolution, but also with operating conditions (such as power, viewing height 

and argon-flow rate). When using the recommended wavelengths, the analyst 

must determine and document for each wavelength the effect from referenced 

interferences (Table 1) as well as any other suspected interferences that may be 

specific to the instrument or matrix. The analyst should utilize a computer routine 

for automatic correction on all analyses. 

 4.1.3.6 Analysts of sequential instruments must verify the absence of 

spectral interference by scanning over a range of 0.5 nm, centered on the 

wavelength of interest, for several samples. The range for lead, for example, would 

be from 220.6 - 220.1 nm. The procedure must be repeated whenever a new 

matrix is to be analyzed and when a new calibration curve using different 

instrumental conditions is to be prepared. Samples that show an elevated 

background emission across the range may be background-corrected by applying a 

correction factor equal to the emission adjacent to the line or at two points on either 

side of the line and interpolating between them. An alternate wavelength that does 

not exhibit a background shift or spectral overlap may also be used. 

 4.1.3.7 The accuracy of interelement corrections should be verified 

daily through the analysis of spectral-interference check (SIC) solutions. See Secs. 

7.12 and 9.9 for instructions on the preparation and use of SIC solutions. 
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 4.1.3.8 When interelement corrections are not used, the absence of 

interferences must be verified. Procedures for verifying the absence of 

interferences are given in sections 7.12 and 9.9. 

 

 4.2 Physical interferences are effects associated with the sample nebulization and 

transport processes. Changes in viscosity and surface tension can cause significant 

inaccuracies, especially in samples containing high dissolved solids or acid concentrations. If 

physical interferences are present, they must be reduced through (1) sample dilution, (2) the use 

of a peristaltic pump; (3) the use of an internal standard; or (4) the use of a high-solids nebulizer.

 

 Another problem that can occur, when high concentrations of dissolved solids are present, 

is salt buildup at the tip of the nebulizer, thus affecting aerosol flow rate and resulting in 

instrumental drift. Salt buildup can be controlled through (1) wetting the argon prior to 

nebulization; (2) use of a tip washer; (3) use of a high-solids nebulizer; or (4) sample dilution. 

Also, it has been reported that better control of the argon flow rate, especially to the nebulizer, 

improves instrument performance. This may be accomplished with the use of mass flow 

controllers. The tests described in Sec. 9.11 will help determine if a physical interference is 

present. 

 4.3 Chemical interferences include molecular compound formation, ionization effects, 

and solute vaporization effects. Normally, these effects are not significant with the ICP 

technique. However, if observed, they can be minimized by (1) careful selection of operating 

conditions (i.e., incident power, observation position, etc.); (2) buffering of the sample through 

matrix-matching; and (3) standard-addition procedures. Chemical interferences are highly 

dependent on matrix type and analyte. 

 4.3.1 The majority of interferences likely to be encountered when using this 

method can be managed successfully using the techniques discussed throughout Sec. 4.1. 

However, based on professional judgment, the method of standard additions may be 

useful when certain specific interferences are encountered. Refer to Method 7000 for a 

more detailed discussion on the use and application of the method of standard additions. 

 4.3.2 An alternative to the method of standard additions is the use of an internal 

standard(s). In the internal standard technique, one or more elements not found in the 

samples, and verified to not cause an interelement spectral interference, are added to the 

samples, calibration standards, and blanks. Yttrium or scandium is often used for this 

purpose. The concentration should be sufficient for optimum precision, but not so high as 

to alter the salt concentration of the matrix. The internal standard element intensity is used 

to ratio the analyte intensity signals for both calibration and quantitation. This technique is 

very useful in overcoming matrix interferences, particularly in high solids matrices. 

 4.4 Memory interferences result when analytes in a previous sample contribute to the 

intensity signals measured in a subsequent sample. Memory effects can result from sample 

deposition on the uptake tubing to the nebulizer and from the buildup of sample material in the 

plasma torch and spray chamber. The site where these effects occur is dependent on the 

element and can be minimized by flushing the system with a rinse blank between samples. The 

possibility of memory interferences should be considered within an analytical run. When 

recognized, suitable rinse times should be established to reduce them. The rinse times 

necessary for a particular element must be estimated prior to analysis. The estimation may be 

made by aspirating a standard containing the element(s) of interest at a concentration level that 

is ten times the typical or expected amount, or at the upper limit of the linear range. The 
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aspiration time for the rinse time-estimation standard should be the same as a normal sample 

analysis period, followed by analysis of the rinse blank at a series of designated intervals. The 

length of the rinse time necessary for reducing the analyte signal(s) to less than or equal to the 

IDL should be noted. A rinse period of at least 60-sec should be used between samples and 

standards until a more suitable rinse time can be established. If a memory interference is 

determined to be present, the sample must be reanalyzed following use of the newly established 

rinse period. Alternate rinse times may be established by the analyst based upon the projectspecific DQOs. 

 4.5 Analysts are advised that high salt concentrations can cause analyte signal 

suppressions and confuse interference tests. If the instrument does not display negative values, 

fortify the SIC check solution with the elements of interest at 0.5 - 1 mg/L and measure the 

added standard concentration accordingly. Concentrations should be within 20% of the true 

spiked concentration or dilution of the samples will be necessary. In the absence of measurable 

analyte, overcorrection could go undetected if a negative value is reported as zero. 

 4.6 The calibration blank (Sec. 7.11.2.1) may restrict the quantitation sensitivity, or 

otherwise degrade the precision and bias of the analysis. Chapter Three should be consulted 

for clean chemistry methods and procedures for reducing the magnitude and variability of the 

calibration blank. 

 4.7 Reagents and sample processing hardware may yield artifacts and/or interferences 

to sample analysis. All of these materials must be demonstrated to be free from interferences 

under the conditions of the analysis by analyzing method blanks. Specific selection of reagents 

may be necessary. Refer to each method to be used for specific guidance on QC procedures. 

5.0 SAFETY 

 5.1 This method does not address all safety issues associated with its use. The 

laboratory is responsible for maintaining a safe work environment and a current awareness file 

of OSHA regulations regarding the safe handling of the chemicals specified in this method. A 

reference file of material safety data sheets (MSDSs) should be available to all personnel 

involved in these analyses. 

 5.2 Concentrated nitric and hydrochloric acids are moderately toxic and extremely 

irritating to skin and mucus membranes. Use these reagents in a hood and if eye or skin contact 

occurs, flush with large volumes of water. Always wear safety glasses or a shield for eye 

protection when working with these reagents. 

 5.3 Hydrofluoric acid is a very toxic acid and penetrates the skin and tissues 

deeply if not treated immediately. Injury occurs in two stages: firstly, by hydration that 

induces tissue necrosis; and secondly, by penetration of fluoride ions deep into the tissue and 

thereby reacting with calcium. Boric acid and/or other complexing reagents and appropriate 

treatment agents should be administered immediately. 

WARNING: Consult appropriate safety literature for determining the proper protective eyewear, 

clothing and gloves to use when handling hydrofluoric acid. Always have 

appropriate treatment materials readily available prior to working with this 

acid. See Method 3052 for additional recommendations for handling hydrofluoric 

acid from a safety and an instrument standpoint. 
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 5.4 Many metal salts, such as those of osmium, are extremely toxic if inhaled or 

swallowed. 

WARNING: Exercise extreme care to ensure that samples and standards are handled safely 

and properly and that all exhaust gases are properly vented. Wash hands 

thoroughly after handling. 

6.0 EQUIPMENT AND SUPPLIES 

 6.1 Inductively coupled, argon-plasma, optical emission spectrometer 

 6.1.1 Computer-controlled, emission spectrometer with background correction 

capability 

 6.1.2 Radio-frequency generator - compliant with FCC regulations 

 6.1.3 Optional mass-flow controller for argon nebulizer-gas supply 

 6.1.4 Optional peristaltic pump 

 6.1.5 Optional autosampler 

 6.1.6 Argon gas supply - high purity 

 6.2 Volumetric flasks of suitable material composition, precision and accuracy 

 6.3 Volumetric pipets of suitable material composition, precision and accuracy 

 This section does not list all common laboratory ware (e.g., beakers) that might be used. 

7.0 REAGENTS AND STANDARDS 

7.1 Reagent-grade, and whenever necessary, ultra-high purity-grade chemicals, must 

be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the 

specifications of the Committee on Analytical Reagents of the American Chemical Society, 

where such specifications are available. Other grades may be used, provided it is first 

ascertained that the reagent is of sufficiently high purity to permit its use without lessening the 

accuracy of the determination. 

 7.2 Reagent water - Reagent water must be interference free. All references to water 

in this method refer to reagent water unless otherwise specified. 

 7.3 Hydrochloric acid (concentrated), HCl 

 7.4 Hydrochloric acid (50% [v/v]), HCl - Prepare by adding 500 mL concentrated HCl to 

400 mL water and diluting to 1 L. 

 
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 7.5 Hydrochloric acid (5% [v/v]), HCl - Prepare by adding 50 mL concentrated HCl to 

400 mL water and diluting to 1 L. 

 7.6 Nitric acid (concentrated), HNO3

 7.7 Nitric acid (50% [v/v]), HNO3 - Prepare by adding 500 mL concentrated HNO3 to 

400 mL water and diluting to 1 L. 

 7.8 Hydrofluoric acid (concentrated), HF - For use in matching the background matrices 

of the calibrations standards relative to those of the samples 

 7.9 Standard stock solutions — Purchase standard stock solutions from an appropriate 

commercial source. Otherwise, prepare them manually in the laboratory using only ultra, highpurity grade chemicals or metals (≥ 99.99% purity). When preparing them manually, except 

where specifically noted in the following sections, dry all metal salts for one hour at 105 ΕC 

prior to use. Replace stock standards when succeeding dilutions for the preparation of 

calibration standards cannot be verified 

CAUTION: Many metal salts are extremely toxic if inhaled or swallowed. Wash hands 

thoroughly after handling. 

NOTE: This section does not apply when analyzing samples prepared by Method 3040. 

NOTE: The mass of each analyte is expressed to four decimal places, since rounding to two 

decimal places can contribute up to 4% error for some compounds. 

 7.9.1 Aluminum standard stock solution (1000 μg/mL Al) - Prepare by dissolving 

exactly 1.000 g of aluminum metal in a beaker containing an acid mixture of 4.0 mL of 50% 

HCl and 1.0 mL of concentrated HNO3. Warm the beaker slowly to aid in dissolution of the 

metal. Afterwards, equilibrate the solution to ambient temperature. Add an additional 10.0 

mL of 50% HCl and dilute to volume in a 1-L volumetric flask with reagent water. 

 7.9.2 Antimony standard stock solution (1000 μg/mL Sb) - Prepare by dissolving 

exactly 2.6673 g of dried K(SbO)C4H4O6 in reagent water. Add 10 mL 50% HCl and dilute 

to volume in a 1-L volumetric flask with reagent water. 

 7.9.3 Arsenic standard stock solution (1000 μg/mL As) - Prepare by dissolving 

exactly 1.3203 g of dried As2O3 in 100 mL reagent water containing 0.4 g NaOH. Acidify 

the solution with 2 mL concentrated HNO3 and dilute to volume in a 1-L volumetric flask 

with reagent water. 

 7.9.4 Barium standard stock solution (1000 μg/mL Ba) - Prepare by dissolving 

exactly 1.5163 g BaCl2 (previously dried for two hours at 250 ΕC) in a mixture of 10 mL of 

reagent water and 1 mL 50% HCl. Add 10.0 mL 50% HCl and dilute to volume in a 1-L 

volumetric flask with reagent water. 

 7.9.5 Beryllium standard stock solution , (1000 μg/mL Be) - Prepare by 

dissolving exactly 19.6463 g of undried BeSO4•4H2O in reagent water Add 10.0 mL 

concentrated HNO3 and dilute to volume in a 1-L volumetric flask with reagent water. 

CAUTION: Drying of beryllium salts can lead to a toxic inhalation hazard. 
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 7.9.6 Boron standard stock solution (1000 μg/mL) - Prepare by dissolving 

exactly 5.716 g of undried, anhydrous H3BO3 in reagent water. Dilute to volume in a 1-L 

volumetric flask with reagent water. The use of a non-glass volumetric flask is 

recommended in order to avoid boron contamination from glassware. Transfer 

immediately to an appropriate container for storage. 

 7.9.7 Cadmium standard stock solution (1000 μg/mL Cd) - Prepare by 

dissolving exactly 1.1423 g CdO in a minimum amount of 50% HNO3. Apply heat to aid in 

dissolution. Following equilibration to ambient temperature, add 10.0 mL of concentrated 

HNO3 and dilute to volume in a 1-L volumetric flask with reagent water. 

 7.9.8 Calcium standard stock solution (1000 μg/mL Ca) - Prepare by 

suspending exactly 2.4969 g CaCO3 (previously dried for one hour at 180 ΕC) in reagent 

water. Dissolve cautiously with a minimum amount of 50% HNO3. Add 10.0 mL 

concentrated HNO3 and dilute to volume in a 1-L volumetric flask with reagent water. 

 7.9.9 Chromium standard stock solution (1000 μg/mL Cr) - Prepare by 

dissolving exactly 1.9231 g CrO3 in reagent water. Following dissolution, acidify the 

solution with 10 mL concentrated HNO3 and dilute to volume in a 1-L volumetric flask with 

reagent water. 

 7.9.10 Cobalt standard stock solution (1000 μg/mL Co) - Prepare by dissolving 

exactly 1.000 g of cobalt metal in a minimum amount of 50% HNO3. Add 10.0 mL 50% HCl 

and dilute to volume in a 1-L volumetric flask with reagent water. 

 7.9.11 Copper standard stock solution (1000 μg/mL Cu) - Prepare by dissolving 

exactly 1.2564 g CuO in a minimum amount of 50% HNO3. Add 10.0 mL concentrated 

HNO3 and dilute to volume in a 1-L volumetric flask with reagent water. 

 7.9.12 Iron standard stock solution (1000 μg/mL Fe) - Prepare by dissolving 

exactly 1.4298 g Fe2O3 in a warm mixture of 20 mL 50% HCl and 2 mL of concentrated 

HNO3. Following equilibration to ambient temperature, add an additional 5.0 mL of 

concentrated HNO3. Dilute the solution to volume in a 1-L volumetric flask with reagent 

water. 

 7.9.13 Lead standard stock solution (1000 μg/mL Pb) - Prepare by dissolving 

exactly 1.5985 g Pb(NO3)2 in a minimum amount of 50% HNO3. Add 10 mL 50% HNO3

and dilute to volume in a 1-L volumetric flask with reagent water. 

 7.9.14 Lithium standard stock solution (1000 μg/mL Li) - Prepare by dissolving 

exactly 5.3248 g lithium carbonate in a minimum amount of 50% HCl. Dilute to volume in a 

1-L volumetric flask with reagent water. 

 7.9.15 Magnesium standard stock solution (1000 μg/mL Mg) - Prepare by 

dissolving exactly 1.6584 g MgO in a minimum amount of 50% HNO3. Add 10.0 mL 50% 

HNO3 and dilute to volume in a 1-L volumetric flask with reagent water. 

 7.9.16 Manganese standard stock solution (1000 μg/mL Mn) - Prepare by 

dissolving exactly 1.000 g of manganese metal in an acid mixture of 10 mL concentrated 
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HCl and 1 mL concentrated HNO3. Dilute to volume in a 1-L volumetric flask with reagent 

water. 

 7.9.17 Mercury standard stock solution (1000 μg/mL Hg) - Prepare by dissolving 

exactly 1.354 g of undried HgCl2 in reagent water. Add 50.0 mL concentrated HNO3 and 

dilute to volume in 1-L volumetric flask with reagent water. 

CAUTION: Drying of mercury salts can lead to a toxic inhalation hazard. 

 7.9.18 Molybdenum standard stock solution (1000 μg/mL Mo) - Prepare by 

dissolving exactly 1.7325 g (NH4)6Mo7O24•4H2O in reagent water and dilute to volume in a 

1-L volumetric flask with reagent water. 

 7.9.19 Nickel standard stock solution (1000 μg/mL Ni) - Prepare by dissolving 

exactly 1.000 g of nickel metal in 10.0 mL of hot, concentrated HNO3. Following 

equilibration to ambient temperature, dilute the solution to volume in a 1-L volumetric flask 

with reagent water. 

 7.9.20 Phosphate standard stock solution (1000 μg/mL P) - Prepare by 

dissolving exactly 4.3937 g of anhydrous KH2PO4 in reagent water. Dilute to volume in a 

1-L volumetric flask with reagent water. 

 7.9.21 Potassium standard stock solution (1000 μg/mL K) - Prepare by dissolving 

exactly 1.9069 g KCl (dried to a constant weight at 110ΕC) in reagent water. Dilute to 

volume in a 1-L volumetric flask with reagent water. 

 7.9.22 Selenium standard stock solution (1000 μg/mL Se) - Prepare by dissolving 

exactly 1.6332 g of undried H2SeO3 in reagent water and dilute to volume in a 1-L 

volumetric flask with reagent water. 

 7.9.23 Silica standard stock solution (1000 μg/mL SiO2) - Prepare by dissolving 

exactly 2.964 g of undried (NH4)2SiF6 in 200 mL of 1:20 HCl. Heat solution to 85ΕC to aid 

in dissolution. After allowing the solution to equilibrate to ambient temperature, dilute to 

volume in a 1-L volumetric flask with reagent water. Transfer immediately to an 

appropriate container for storage. Protect standard from light during storage. 

 7.9.24 Silver standard stock solution (1000 μg/mL Ag) - Prepare by dissolving 

exactly 1.5748 g of AgNO3 in a reagent water mixture of 10 mL concentrated HNO3. Dilute 

to volume in a 1-L volumetric flask with reagent water. 

 7.9.25 Sodium standard stock solution (1000 μg/mL Na) - Prepare by dissolving 

exactly 2.5419 g of NaCl in reagent water. Add 10.0 mL of concentrated HNO3 and dilute 

to volume in a 1-L volumetric flask with reagent water. 

 7.9.26 Strontium standard stock solution (1000 μg/mL Sr) - Prepare by dissolving 

exactly 2.4154 g of Sr(NO3)2 in a 1-L volumetric flask containing 10 mL of concentrated 

HCl and 700 mL of reagent water. Dilute to volume with reagent water. 

 7.9.27 Thallium standard stock solution (1000 μg/mL Tl) - Prepare by dissolving 

exactly 1.3034 g TlNO3 in reagent water. Add 10.0 mL of concentrated HNO3 and dilute to 

volume in a 1-L volumetric flask with reagent water. 
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October 2012 

 7.9.28 Tin standard stock solution (1000 μg/mL Sn) - Prepare by dissolving 

exactly 1.000 g Sn shot in 200 mL of 50% HCl. Apply heat to aid in dissolution. After 

allowing the solution to equilibrate to ambient temperature, dilute to volume in a 1-L 

volumetric flask with 50% HCl. 

 7.9.29 Vanadium standard stock solution (1000 μg/mL V) - Prepare by dissolving 

exactly 2.2957 g NH4VO3 in a minimum amount of concentrated HNO3. Apply heat to aid 

in dissolution. After allowing the solution to equilibrate to ambient temperature, add 10.0 

mL of concentrated HNO3 and dilute to volume in a 1-L volumetric flask with reagent water. 

 7.9.30 Zinc standard stock solution (1000 μg/mL Zn) - Prepare by dissolving 

exactly 1.2447 g ZnO in a minimum amount of dilute HNO3. Add 10.0 mL of concentrated 

HNO3 and dilute to volume in a 1-L volumetric flask with reagent water. 

 7.9.31 Yttrium internal standard stock solution (1000 μg/mL Y) - Prepare by 

dissolving exactly 4.3081 g Y(NO3)3•6H2O in a minimum amount of concentrated HNO3. 

Add 10.0 mL concentrated HNO3 and dilute to volume in a 1-L volumetric flask with 

reagent water. 

 7.10 If the determination of one or more metals using a non-aqueous solvent is required, 

then all standards and quality control samples must be prepared on a weight/weight basis in the 

non-aqueous solvent since the density of non-aqueous solvents is not unity. Standards and 

quality control materials containing organometallic materials that are soluble in non-aqueous 

solvents are available from a variety of vendors. 

 7.11 Working-level standard solutions and blanks 

NOTE: Following the preparation of all intermediate- and working-level standard solutions, 

blanks, and QC standards (Sec. 9.0) immediately transfer to an appropriate container 

for storage. For all intermediate and working standards, especially low-level standards 

(i.e., < 1 μg/mL metal), the stability must be demonstrated prior to use. Working-level 

standards should be prepared as needed, recognizing the fact that low-level metal 

standards can degrade rapidly over time (Refer to Sec. 10.6 for guidance on 

determining the integrity of standards.) 

 7.11.1 Mixed-calibration standard solutions — Prepare by combining proper 

volumes of the standard stock solutions in 100-mL volumetric flasks. Add the appropriate 

types and volumes of acids so that the matrices of the standards are matched, relative to 

those of the sample digestates. Store all mixed-calibration standards in an appropriate 

container and protect from light. Prior to preparing the mixed standards, each standard 

stock solution should be analyzed, separately, in order to determine possible spectral 

interferences and/or the presence of impurities. Standards which interfere with another 

analyte, or which are contaminated with another analyte, may not be included in the same 

calibration standard as that analyte. Refer to Table 2 for recommendations in selecting the 

most appropriate stock standards (Sec. 7.9) to combine for the preparation of workinglevel, mixed–calibration standards. 

NOTE: Care should be taken when preparing the calibration standards to ensure that 

the elements are compatible and stable when mixed together. 
SW-846 Update V 6010D - 14 Revision 4 

October 2012 

NOTE: Depending on the acid combination of the resulting mixed-standard solution, the 

formation of a precipitate may occur upon addition of the silver standard stock 

solution. If this happens, add 15 mL of reagent water and apply heat to the 

volumetric flask until the solution clears. Equilibrate the flask to ambient 

temperature following dissolution and dilute to volume with reagent water. For 

such an acid combination, the silver concentration should be limited to 2 mg/L. 

Silver is stable under these conditions in a water matrix for 30 days if protected 

from the light. Higher concentrations of silver necessitate the use of additional 

HCl. 

 7.11.2 Blanks - Two types of blanks are necessary for the analysis of samples 

prepared by any method, other than Method 3040: (1) the calibration blank is used in 

establishing the analytical curve; and (2) the method blank contains all of the exact same 

reagents, and in the same proportions, as those used for the processing of samples, and is 

thus used to identify possible contamination resulting from either the reagents (namely, 

acids) or equipment (including even filters) used during sample processing. 

 7.11.2.1 Calibration blank - Prepare by acidifying reagent water using 

the same combination and concentrations of acids used in the preparation of the 

matrix-matched calibration standards (Sec. 7.11.1). Prepare a sufficient quantity, 

such that it may be used to flush the system in between standards and samples. 

The calibration blank will also be used for all initial calibration blank (ICB) and 

continuing calibration blank (CCB) determinations. 

 7.11.2.2 Method blank - Prepare by processing either a volume of 

reagent water equal to that used for actual aqueous samples, or, otherwise, a 

clean, empty container, equivalent to that used for actual solid samples through all 

of the preparatory and instrument determination steps used for making ICP-OES 

determinations in samples. These steps may include, but are not limited to, prefiltering, digestion, dilution, filtering, and analysis (refer to Sec. 9.7.1). 

 7.11.3 Initial calibration verification (ICV) standard - Prepare by combining 

compatible metals from standard stock solution sources that differ from those used for the 

preparation of the calibration standards (Sec. 7.11.1); or otherwise, purchase an alreadyprepared, second-source reference material from a different commercial lot or vendor. The 

ICV should be prepared so as to contain metal concentrations equal or nearly equivalent to 

the midpoint concentration level of the calibration curve (see Sec. 10.8 for use). 

 7.11.4 Continuing calibration verification (CCV) standard - Prepare using the 

same acid matrix and stock standards employed when preparing the calibration standards. 

The CCV should be prepared so as to contain metal concentrations equal or nearly 

equivalent to the midpoint concentration of the calibration curve (see Sec. 10.8 for use). 

7.12 Spectral interference check (SIC) solutions - The SIC solutions must be used 

regardless of whether or not interelement corrections are applied. They evaluate both potential 

spectral interferences and the accuracy of any correction equations. 

7.12.1 Individual element SIC solutions - Individual element SIC solutions are used 

to evaluate possible spectral interferences and to set interelement corrections if necessary. 

A solution of each element is prepared at the highest concentration in the linear range 

likely to be observed in samples. The acid strength should be equivalent to that of the 
SW-846 Update V 6010D - 15 Revision 4 

October 2012 

calibration standards. See section 9.9.1 for use of the individual element SIC solutions. 

SIC solutions should be tested to verify that they are not contaminated with elements of 

interest. The verification of purity can be done by analysis using an alternate technology, 

such as ICP-MS. For ICP-OES instruments with solid-state detectors, the verification 

might also be done by examining alternate wavelengths. If the SIC solutions are purchased 

ready-made, the vendor should provide details of any contaminants. In some cases it may 

not be possible to obtain solutions completely free of contaminants, in which case the 

known, verified concentration can be subtracted from the instrument result before 

assessing any interferences. 

7.12.2 Mixed element SIC solution - The mixed element SIC solution is used as an 

ongoing daily check of freedom from spectral interferences. The mixed element SIC 

solution contains the following elements and is made up in an acid solution equivalent to 

the calibration standards. See section 9.9.2 for use of the mixed element SIC solution. As 

for the single element solutions described in 7.12.1 known and documented contaminants 

are subtracted from the observed values in the mixed element SIC check. 

Mixed element SIC solution: Aluminum, 500mg/L; Calcium, 500mg/L; Iron, 200mg/L; 

Magnesium, 500mg/L 

8.0 SAMPLE COLLECTION, PRESERVATION, AND HANDLING 

Sample collection, preservation and storage requirements may vary by EPA program and 

may be specified in a regulation or project planning document that requires compliance 

monitoring for a given contaminant. Where such requirements are specified in the regulation, 

follow those requirements. In the absence of specific regulatory requirements, use the following 

information as guidance in determining the sample collection, preservation and storage 

requirements. 

See Chapter Three, Inorganic Analytes, for sample collection and preservation 

instructions. 

9.0 QUALITY CONTROL 

 

9.1 Refer to Chapter One for guidance on quality assurance (QA) and QC protocols. 

When inconsistencies exist between QC guidelines, method-specific QC criteria take 

precedence over those criteria given in Chapter One. Any effort involving the collection of 

analytical data should include development of a structured and systematic planning document, 

such as a Quality Assurance Project Plan (QAPP) or a Sampling and Analysis Plan (SAP), which 

translates project objectives and specifications into directions for those that will implement the 

project and assess the results. Each laboratory should maintain a formal quality assurance 

program. The laboratory should also maintain records to document the quality of the data 

generated. All data sheets and QC data should be maintained for reference or inspection. 

9.2 Refer to Methods 3005, 3010, 3015, 3031, 3040, 3050, 3051, 3052, 7000, and 

6800 for QC procedures to ensure the proper operation of the various sample preparation 

techniques. Any more specific QC procedures provided in this method will supersede those 

noted in Methods 3005, 3010, 3015, 3031, 3040, 3050, 3051, 3052, 7000, and 6800. 
SW-846 Update V 6010D - 16 Revision 4 

October 2012 

9.3 Instrument Detection Limits 

Instrument detection limits (IDLs) are useful means to evaluate the instrument noise level 

and response changes over time for each analyte from a series of reagent blank analyses to 

obtain a calculated concentration. They are not to be confused with the lower limit of 

quantitation, nor should they be used in establishing this limit. It may be helpful to compare the 

calculated IDLs to the established lower limit of quantitation, however, it should be understood 

that the lower limit of quantitation needs to be verified according to the guidance in Sec. 9.8. 

IDLs in μg/L can be estimated as the mean of the blank results plus three times the standard 

deviation of 10 replicate analyses of the reagent blank solution. (Use zero for the mean if the 

mean is negative). Each measurement should be performed as though it were a separate 

analytical sample (i.e., each measurement must be followed by a rinse and/or any other 

procedure normally performed between the analysis of separate samples). IDLs should be 

determined at least once using new equipment, after major instrument maintenance such as 

changing the detector, and/or at a frequency designated by the project. An instrument log book 

should be kept with the dates and information pertaining to each IDL performed. 

9.4 Initial demonstration of proficiency 

Each laboratory must demonstrate initial proficiency with each sample preparation and 

determinative method combination by generating data of acceptable precision and bias for target 

analytes in a clean matrix. If an autosampler is used to perform sample dilutions, before using 

the autosampler to dilute samples, the laboratory should satisfy itself that those dilutions are of 

equivalent or better accuracy than is achieved by an experienced analyst performing manual 

dilutions. It is recommended that the laboratory should repeat the demonstration of proficiency 

whenever new staff members are trained or significant changes in instrumentation are made. 

9.5 Initially, before processing any samples, the analyst should demonstrate that all 

parts of the equipment that come into direct contact with the sample and reagents are 

interference-free. This is accomplished through the analysis of a method blank. As a continuing 

check, each time samples are digested and analyzed, and when there is a change in reagents, a 

method blank should be prepared and analyzed for the compounds of interest as a safeguard 

against chronic laboratory contamination. If an interference is observed that would prevent the 

determination of the target analyte, determine the source and eliminate it, if possible, before 

processing the samples. The method blank should be carried through all stages of sample 

preparation and instrument determination procedures. When new reagents or chemicals are 

received, the laboratory should monitor the preparation and/or analysis blanks associated with 

samples for any signs of contamination. It is not necessary to test every new batch of reagents 

or chemicals prior to sample preparation if the source shows no prior problems. However, if 

reagents are changed during a preparation batch, separate blanks need to be prepared for each 

set of reagents. 

9.6 Linear range 

The linear range establishes the highest concentration that may be reported without 

diluting the sample. Following calibration, the laboratory may choose to analyze a standard at a 

higher concentration than the high standard in the calibration. The standard must recover within 

10% of the true value, and if successful, establishes the linear range. The linear range standards 

must be analyzed in the same instrument run as the calibration they are associated with (i.e., on 

a daily basis) but may be analyzed anywhere within that run. If a linear range standard is not 
SW-846 Update V 6010D - 17 Revision 4 

October 2012 

analyzed for any specific element, the highest standard in the calibration becomes the linear 

range. 

NOTE: Many of the alkali- and alkaline-earth metals have second-order response curves due to 

ionization and self-absorption effects. These effects can be minimized by using an easily 

ionized element in excess in the internal standard or standards themselves. Lithium or 

cesium are good candidates. Second-order calibration curves may be used for alkali or 

alkaline earth metals if the instrumentation and software can accommodate them. 

However the effective range must be checked and the second-order curve fit should 

have a correlation coefficient of 0.995 or better. Third-order calibration fits are not 

acceptable. Second-order response curves should be revalidated and recalculated at 

least every six months. These curves are much more sensitive to changes in operating 

conditions than the first-order curves and should be checked whenever there have been 

moderate equipment changes. 

9.7 Sample QC for preparation and analysis 

 The laboratory must also have procedures for documenting the effect of the matrix on 

method performance (precision, bias, and sensitivity). At a minimum, this should include the 

analysis of QC samples including a method blank, a matrix spike (MS), a laboratory control 

sample (LCS), and a duplicate sample in each analytical batch. Any method blanks, LCS, 

samples MS samples, and duplicate samples should be subjected to the same preparatory and 

instrumentation procedures (Sec. 11.0) as those used on actual samples. 

 9.7.1 For each batch of samples analyzed, at least one method blank must be 

carried throughout the entire sample preparation and instrumentation determination 

process, as described in Chapter One. The importance of the method blank is to aid in 

identifying when and/or if sample contamination is occurring. The method blank is 

considered to be acceptable if it does not contain the target analytes at concentration 

levels that exceed the acceptance limits defined in the project-specific DQOs. The 

laboratory should not subtract the results of the method blank from those of any associated 

samples. Such "blank subtraction" may lead to negative sample results. 

 In the absence of project-specific DQOs, the method blank may be considered to 

be acceptable with respect to each target element, if it is less than the LLOQ, 50% of the 

regulatory limit, or 10% of the lowest sample concentration, whichever is greater. If the 

method blank fails to meet the necessary acceptance criteria, it should be re-analyzed 

once. If still unacceptable, then all samples associated with the method blank must be reprepared and re-analyzed, along with all other appropriate analysis batch QC samples. If 

the method blank results do not meet the acceptance criteria and reanalysis is not 

practical, then the laboratory should report the sample results along with the method blank 

results, and provide a discussion of the potential impact of the contamination on the 

sample results. If the method blank exceeds the acceptance criteria, but the sample 

results are all either below the reporting level, regulatory limit or other applicable DQOs, 

then the sample data may be considered to be valid, despite the contamination indicated in 

the method blank. Refer to Chapter One for additional guidance regarding the proper 

protocol when analyzing method blanks. 

 9.7.2 Documenting the effect of the matrix should include the analysis of at 

least one MS and one duplicate unspiked sample or one matrix spike/matrix spike 
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October 2012 

duplicate (MS/MSD) pair for each batch of samples processed, as described in Chapter 

One. An MS/MSD pair is used to document the bias and precision of a method in a given 

sample matrix. The decision on whether to prepare and analyze duplicate samples or an 

MS/MSD pair must be based on knowledge of the samples in the analysis batch. If 

samples are expected to contain target analytes, laboratories may choose to use an MS 

and a duplicate analysis of an unspiked field sample. If samples are not expected to 

contain target analytes, the laboratories should use an MS/MSD pair. 

 MS/MSD samples should be spiked with each target element at the project-specific 

action levels, or, when lacking project-specific action levels, between the low- and midlevel standards, as appropriate. Acceptance criteria should be set at laboratory-derived 

limits, developed through the use of historical analyses, for each matrix type being 

analyzed. However, historically derived acceptance limits must not exceed ± 25% recovery 

of the target element spike values for accuracy, and ≤ 20 relative percent difference (RPD) 

for precision. In the absence of historical data, MS/MSD acceptance limits should be set at 

± 25% recovery and ≤ 20 RPD. Refer to Sec. 4.0 of Chapter One for further guidance. If 

the bias and precision indicators in an analytical batch fail to meet the acceptance criteria, 

then the interference test discussed in Sec. 9.11 should be performed. Refer to the 

definitions of bias and precision, in Chapter One, for the proper data reduction protocols. 

 Calculate the RPD between duplicate or MS determinations as follows: 

100

2

D D

D D

RPD

1 2

1 2

×















 +

−

=

where: 

RPD = relative percent difference 

D1 = MS or first sample analysis value 

D2 = MSD or duplicate sample analysis value 

 9.7.3 At least one LCS should be prepared and analyzed with each batch of 

analytical samples processed, as described in Chapter One. The LCS consists of an 

aliquot of a clean (control) matrix similar to the sample matrix and of the same weight or 

volume. The LCS should be spiked at the same levels and using the same spiking 

materials as the corresponding MS/MSD (see above Sec. 9.7.2). When the results of the 

MS analysis indicate a potential problem due to the sample matrix itself, the LCS results 

are used to verify that the laboratory can acceptably perform the analysis in a clean matrix. 

 LCS acceptance criteria should be set at laboratory-derived limits, developed 

through the use of historical analyses. However, historically derived acceptance limits 

must not exceed ± 20% of the target element spike values. In the absence of historical 

data, LCS acceptance limits should be set at ± 20%. If the result of an LCS does not meet 

the established acceptance criteria, it should be re-analyzed once. If still unacceptable, 

then all samples after the last acceptable method blank must be re-prepared and reanalyzed, along with all other appropriate analysis batch QC samples. 
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October 2012 

 9.7.4 Reference materials containing known amounts of target elements are 

recommended when an appropriately similar medium of interest are available as one type 

of QC after appropriate sample preparation. The reference material may be used as the 

LCS. For soil reference materials, the manufacturers’ established acceptance criterion 

should be used. For solid reference materials, ± 20% recovery (see Sec. 9.7.3) of the 

reported manufacturers’ target element values may not be achievable. Refer to Chapters 

One and Three for additional information. 

 9.8 Lower Limit of Quantitation (LLOQ) check standard 

9.8.1 The laboratory should establish the LLOQ as the lowest point of 

quantitation which, in most cases, is the lowest concentration in the calibration curve. The 

LLOQ is initially verified by the analysis of at least 7 replicate samples, spiked at the LLOQ 

and processed through all preparation and analysis steps of the method. The mean 

recovery and relative standard deviation of these samples provide an initial statement of 

precision and accuracy at the LLOQ. In most cases the mean recovery should be +/- 35% 

of the true value and RSD should be < 20%. In-house limits may be calculated when 

sufficient data points exist. Monitoring recovery of LLOQ over time is useful for assessing 

precision and bias. Refer to a scientifically valid and published method such as Chapter 9 

of Quality Assurance of Chemical Measurements (Taylor 1987) or the Report of the 

Federal Advisory Committee on Detection and Quantitation Approaches and Uses in Clean 

Water Act Programs (http://water.epa.gov/scitech/methods/cwa/det/index.cfm) for 

calculating precision and bias for LLOQ. 

9.8.2 Ongoing LLOQ verification, at a minimum, is on a quarterly basis to 

validate quantitation capability at low analyte concentration levels. This verification may be 

accomplished either with clean control material (e.g., reagent water, method blanks, 

Ottawa sand, diatomaceous earth, etc.) or a representative sample matrix (free of target 

compounds). Optimally, the LLOQ should be less than the desired regulatory action levels 

based on the stated project-specific requirements. 

 9.9 Spectral interference checks (SIC) 

 Two types of SIC checks are used. Individual element SIC checks are performed when the 

instrument is initially setup, and periodically (at least once every 6 months) thereafter. The mixed 

element SIC solution is used daily to check that the instrument is free from interference from 

elements typically observed in high concentration and to check that and interference corrections 

applied are still valid. 

9.9.1 Single element interference checks - At a minimum, single element SIC 

checks must be performed for the following elements: 

Aluminum 500mg/L; Boron 50mg/L, Barium, 50mg/L, Calcium 500mg/L; Copper 

50mg/L; Iron 200mg/L; Magnesium 500mg/L; Manganese 50mg/L; Molybdenum 20mg/L; 

Sodium 1000mg/L; Nickel 20mg/L; Selenium 20mg/L; Silicon 200mg/L; Tin 20mg/L; 

Vanadium 20mg/L; Zinc 20mg/L 

The absolute value of the concentration observed for any unspiked analyte in the 

single element SIC checks must be less than two times the analytes’ LLOQ. The 

concentration of the SIC checks are suggested, but become the highest concentration 
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October 2012 

allowed in a sample analysis, and cannot be higher than the highest established linear 

range. Samples with concentrations of elements higher than the SIC check must be diluted 

until the concentration is less than the SIC check solution. Note that reanalysis of a diluted 

sample is required even if the high concentration element is not required to be reported for 

the specific sample, since the function of the SIC check is to evaluate spectral 

interferences on other elements. 

The single element SIC checks are performed when the instrument is setup and 

periodically (at least once every 6 months) thereafter. 

9.9.2 Mixed element interference check - The mixed element SIC solution (see 

section 7.12.2) is analyzed at least once per day, immediately after the initial calibration. 

The concentration measured for any target analytes must be less than +/- the LLOQ. If this 

criterion is not met then sample analysis may not proceed until the problem is corrected, or 

alternatively the LLOQ may be raised to twice the concentration observed in the SIC 

solution. The only exceptions are those elements that have been demonstrated to be 

contaminants in the SIC solutions (see Section 7.12.1). These may be present up to the 

concentration documented plus the LLOQ. 

 9.10 It is recommended that the laboratory adopt additional QA practices for use with 

this method. The specific practices that are most productive depend upon the needs of the 

laboratory and the nature of the samples. Whenever possible, the laboratory should analyze 

reference materials and participate in relevant performance evaluation (PE) studies. 

 9.11 If less than acceptable bias and precision data are generated for the matrix 

spike(s), the additional QC protocols in sections 9.11.1 and/or 9.11.2 should be performed prior 

to reporting concentration data for the elements in this method. At a minimum these tests should 

be performed with each batch of samples prepared/analyzed with corresponding unacceptable 

data quality results. If matrix interference effects are confirmed, then an alternative test method 

should be considered or the current test method modified, so that the analysis is not affected by 

the same interference. The use of a standard-addition analysis procedure may also be used to 

compensate for this effect (refer to Method 7000). 

9.11.1 Dilution test 

If the analyte concentration is within the linear range of the instrument and 

sufficiently high (minimally, a factor of 25 times greater than the LLOQ), an analysis of a 

1:5 dilution should agree to within ± 20% of the original determination. If not, then a 

chemical or physical interference effect should be suspected. The matrix spike is often a 

good choice of sample for the dilution test, since reasonable concentrations of most 

analytes are present. Elements that fail the dilution test are reported as estimated values. 

CAUTION: If spectral overlap is suspected, then the use of computerized compensation, 

an alternate wavelength, or comparison with an alternate method is recommended. 

9.11.2 Post-digestion MS 

If a high concentration sample is not available for performing the dilution test, then 

a post-digestion MS should be performed. The test only needs to be performed for the 

specific elements that failed original matrix spike limits, and only if the spike concentration 

added was greater than the concentration determined in the unspiked sample. Following 
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October 2012 

preparation, which may include, but is not limited to, pre-filtration, digestion, dilution and 

filtration, an aliquot, or dilution thereof, should be obtained from the final aqueous, 

unspiked-analytical sample, and spiked with a known quantity of target elements. The 

spike addition should be based on the indigenous concentration of each element of 

interest in the sample. The recovery of the post-digestion MS should fall within a ± 25 % 

acceptance range, relative to the known true value, or otherwise within the laboratoryderived acceptance limits. If the post-digestion MS recovery fails to meet the acceptance 

criteria, the sample results must be reported as estimated values. 

 

10.0 CALIBRATION AND STANDARDIZATION 

 10.1 Before using this procedure for quantitation, ensure that initial demonstration of 

performance data is available for viewing. Such data must document: 

• The selection criteria for background correction points; 

• analytical dynamic ranges, including the applicable equations, and upper limits of 

ranges; 

• IDLs and method LLOQs; and 

• The determination and verification of interelement correction equations, or other 

routines for correcting spectral interferences. These data must be generated using the 

same instrument, operating conditions, and calibration routine to be used for sample 

analysis. The data must be kept on file and available for review by the data user or 

auditor. 

 10.2 Set up the instrument using the appropriate operating conditions. Follow the 

instructions provided by the instrument manufacturer unless other conditions provide similar or 

better results. Specific wavelengths for use in quantitation should be selected from the 

manufacturer’s instructions. Other wavelengths may be substituted if they can provide the 

needed sensitivity and are corrected for spectral interferences. Because of differences among 

various makes and models of spectrometers, specific instrument operating conditions cannot be 

provided. The instrument and operating conditions utilized for determination must be capable of 

providing data of acceptable quality based on the specific program and end user. Operating 

conditions for aqueous solutions usually vary from:

• 1100-1500-watts forward power; 

• 14-18-mm viewing height; 

• 15-19-L/min argon-coolant flow; 

• 0.6-1.5-L/min argon-nebulizer flow; and 

• 1.0-1.8-mL/min sample-pumping rate; with a 1-min pre-flush time and measurement 

time near 1 sec/wavelength peak for sequential instruments and 10 sec/sample for 

simultaneous instruments. 

 One recommended way in which to achieve repeatable interference correction factors is to 

adjust the argon-aerosol flow to reproduce the Cu/Mn intensity ratio at the wavelengths 324.754 

nm and 257.610 nm. 

 10.3 Plasma optimization 

 Optimize the plasma operating conditions prior to use of the instrument. The purpose of 

plasma optimization is to provide a maximum signal-to-background ratio for some of the least 
SW-846 Update V 6010D - 22 Revision 4 

October 2012 

sensitive elements in the analytical array. The use of a mass-flow controller to regulate the 

nebulizer gas flow or source optimization software greatly facilitates the procedure. This routine 

is not needed on a daily basis, but only is necessary when first setting up a new instrument, or 

following a change in operating conditions. The following procedure is recommended; otherwise 

follow the manufacturer’s guidelines. 

 10.3.1 Ignite the radial plasma and select an appropriate incident RF power. 

Allow the instrument to become thermally stable before beginning; approximately 30 - 60 

min of operation. Optimize the ICP per manufacturer’s instructions or alternatively by the 

following procedure: While aspirating a 1000-μg/L solution of yttrium, follow the 

instrument manufacturer's instructions and adjust the aerosol carrier gas-flow rate through 

the nebulizer, so that a definitive blue emission region of the plasma extends 

approximately 5 - 20 mm above the top of the load coil. Record the nebulizer gas-flow rate 

or pressure setting for future reference. The yttrium solution can also be used for coarse 

optical alignment of the torch, by observing the overlay of the blue light over the entrance 

slit to the optical system. If yttrium is an analyte of interest in samples, be aware it may take 

some time to rinse out 1000 μg/L yttrium solution. 

 10.3.2 After establishing the nebulizer gas-flow rate, determine the solutionuptake rate of the nebulizer in mL/min, by aspirating a known volume of a calibration blank 

for a period of at least one minute. Divide the volume (mL) aspirated by the time (min) and 

record the uptake rate. Set the peristaltic pump to deliver this rate. 

 10.3.3 Profile the instrument per manufacturer’s directions to align it optically, as 

it will be used during analysis. 

 10.3.4 Complete the following procedure for vertical optimization or follow 

manufacturer’s directions: 

NOTE: This procedure can be used for both vertical and horizontal optimization. 

 Aspirate a solution containing 10 μg/L of several selected elements. As, Se, Tl, 

and Pb are the least sensitive of the elements and most in need of optimization. 

However, other elements may be used, based on the professional judgment of the 

analyst. (V, Cr, Cu, Li and Mn have also been used with success). Collect intensity data 

at the wavelength peak for each analyte at 1mm intervals from 14 – 18 mm above the 

load coil. (This region of the plasma is referred to as the "analytical zone".) Repeat this 

process using the calibration blank. Determine the net signal-to-blank-intensity ratio for 

each analyte for each viewing height setting. Choose the height for viewing the plasma 

that provides the best net intensity ratios for the elements analyzed or the highest 

intensity ratio for the least sensitive element. 

 For optimization in the axial mode, follow the instrument manufacturer’s 

instructions. 

10.3.5 The instrument operating conditions finally selected as being optimum 

should provide the lowest reliable IDLs. 

10.3.6 If the instrument operating conditions, such as incident power or nebulizer 

gas-flow rate, are changed, or if a new torch injector with a different orifice internal 

diameter is installed, then the plasma and viewing height should be re-optimized. 
SW-846 Update V 6010D - 23 Revision 4 

October 2012 

10.3.7 After completing the initial optimization of operating conditions, and before 

analyzing samples, establish and initially verify an interelement spectral interference 

correction routine to be used during sample analysis. A general description of spectral 

interferences and the analytical specifications for background correction, in particular, are 

discussed in Sec. 4.0. Directions for verification of freedom from interference are given in 

Sections 7.12 and 9.9. The criterion for determining that an interelement spectral 

interference is present is an apparent positive or negative concentration for the analyte that 

falls beyond ± the LLOQ from zero. The upper control limit is the analyte LLOQ. Once 

established, verify the entire routine at least once every six months. Only a portion of the 

correction routine must be verified more frequently or on a daily basis. Initial and periodic 

verifications of the routine should be kept on file. 

10.3.8 Before daily calibration, and after the instrument warm-up period, the 

nebulizer gas-flow rate must be reset to the determined optimized flow. If a mass-flow 

controller is being used, it should be set to the recorded optimized flow rate. In order to 

maintain valid spectral interelement correction routines, the nebulizer gas-flow rate should 

be the same (< 2% change) from day to day. 

 10.4 For operation with organic solvents, the use of the auxiliary argon inlet is 

recommended, as is the use of solvent-resistant tubing, increased plasma (coolant) argon flow, 

decreased nebulizer flow, and increased RF power, in order to obtain a robust plasma, stable 

operating conditions, and precise measurements. 

10.5 At a minimum, the elements required for the project plus any required for 

interference correction must be calibrated. Recommended wavelengths for the analytes in Sec. 

1.1 should be obtained from the instrument manufacturer. Flush the system in between each 

standard and sample using the rinse blank. The rinse time needs to be sufficient to ensure that 

analytes present at the linear range are effectively cleaned out prior to analysis of the 

subsequent sample. Use the average of at least three integrations for both calibration standard 

and sample analyses. 

10.6 Calibration standards should be prepared on an as-needed basis unless stability 

warrants preparing fresh daily, (or each time a batch of samples is analyzed). If the ICV 

standard is prepared daily and the results of the ICV analyses meet the acceptance criteria, then 

the calibration standards do not need to be prepared daily and may be prepared and stored for 

as long as the calibration standard viability can be verified through the use of the ICV. If the ICV 

fails to meet the acceptance criteria, trouble shoot the situation, and then prepare a new set of 

calibration standards if needed and recalibrate the instrument 

10.7 A calibration curve must be analyzed daily. The instrument may be calibrated 

using a single point standard and a calibration blank (ICB) or a multipoint calibration curve. If a 

multipoint curve is used a minimum of three standards are required and the correlation 

coefficient (r) should be > 0.995 or the coefficient of determination (r2

) should be > 0.990. 

Relative Standard Error may be used as an alternative to r or r2, and should be < 20%. If a 

multipoint calibration is used the low standard must be at or below the LLOQ. 

NOTE: Inversely weighted linear regressions are recommended in order to minimize curve 

fitting errors at the low end of the calibration curve. 

10.8 After the calibration is completed it is verified using several checks. 
SW-846 Update V 6010D - 24 Revision 4 

October 2012 

10.8.1 Initial Calibration Verification (ICV) - The ICV is a standard prepared from 

a separate source than the initial calibration standards. It is analyzed at approximately the 

mid-level of the calibration and serves as a check that the initial calibration standards are 

at the correct concentrations. The acceptance range is 90-110% of the true value. 

10.8.2 Low-level readback or verification - For a multi-point calibration, the low 

level standard should quantitate to within 80-120% of the true value. For a single point 

calibration, a standard from the same source as the calibration standard and at the LLOQ 

is analyzed and should recover within 80-120% of the true value. 

10.8.3 Mid-level readback or verification - For a multi-point calibration, the midlevel standard should quantitate to within 90-110% of the true value. For a single point 

calibration, a standard from the same source as the calibration standard and at the midpoint of the linear range is analyzed and should recover within 90-110% of the true value. 

10.8.4 Initial Calibration blank (ICB) - If a multi-level calibration is used, an ICB is 

analyzed immediately after the calibration (or after the ICV) and must not contain target 

analytes above half the LLOQ. If a single point calibration is used, the calibration is forced 

through the ICB, but a second ICB is analyzed as a check and must not contain target 

analytes above half the LLOQ. 

10.8 5 Verify the ongoing validity of the calibration curve after every 10 samples, 

and at the end of each analysis batch run, through the analysis of a CCV standard (Sec. 

7.11.4 and a CCB (Sec. 7.11.2.1). For the curve to be considered valid the analysis result 

of the CCV standard must be within ± 10% of its true value and the CCB must not contain 

target analytes above the LLOQ. If the calibration cannot be verified, sample analysis 

must be discontinued, the cause of the problem determined and the instrument 

recalibrated. All samples following the last acceptable CCV standard must be reanalyzed 

If the ICB consistently has target analyte concentrations greater than half the LLOQ, the 

LLOQ should be re-evaluated. Flow-injection systems may be used as long as they can 

meet the performance criteria of the method. 

NOTE: During the course of an analytical run, the instrument may be recalibrated to 

correct for instrument drift. A recalibration must then be followed immediately by a 

new analysis of a CCV and CCB before any further samples may be analyzed. 

11.0 PROCEDURE 

 11.1 Preliminary treatment of most samples is necessary because of the complexity and 

variability of sample matrices. Groundwater samples which have been pre-filtered and acidified 

will not need acid digestion. Samples which are not digested must either use an internal 

standard or be matrix-matched with the standards (i.e., acid concentrations should match). 

Solubilization and digestion procedures are presented in Chapter Three, Inorganic Analytes. 

 11.2 Profile and calibrate the instrument according to the instrument manufacturer's 

recommended procedures, using the typical mixed-calibration standard solutions described in 

Sec. 7.11.1. Prepare the calibration curve as detailed in Sec. 10.7. Flush the system between 

each standard using the calibration blank (Sec. 7.11.2.1), or as the manufacturer recommends. 
SW-846 Update V 6010D - 25 Revision 4 

October 2012 

In order to reduce random error, use the average intensity of multiple exposures for both 

standardization and sample analysis. 

 11.3 For all analytes and determinations, the laboratory must analyze an ICV (Secs 

7.11.3 and 10.8.1) and a CCV (Secs. 7.11.4 and 10.8.5) and CCB (Secs. 7.11.2.1 and 10.8.5) 

after every ten samples and at the end of the analysis batch run. 

 11.4 Analyze the samples and record the results. In between each sample or standard, 

rinse the system using the calibration blank solution (Sec. 7.11.2.1). Use a minimum rinse time 

of one minute. Each laboratory may establish a reduction in the rinse time following a suitable 

demonstration. 

11.5 Determination of percent dry weight 

When sample results are to be calculated on a dry-weight basis, a separate portion of 

sample for this determination should be weighed out at the same time as the portion used for 

analytical determination. 

CAUTION: The drying oven should be contained in a hood or vented. Significant laboratory 

contamination may result from a heavily contaminated hazardous waste sample. 

11.5.1 Immediately after weighing the sample aliquot to be digested, weigh an 

additional 5- to 10-g aliquot of the sample into a tared crucible. Dry this aliquot overnight at 

105 ΕC. Allow the sample to cool in a desiccator before weighing. 

11.5.2 Calculate the % dry weight as follows: 

This oven-dried aliquot is not used for the extraction and should be appropriately disposed 

of once the dry weight is determined. 

12.0 DATA ANALYSIS AND CALCULATIONS 

 12.1 If dilutions were performed, apply the appropriate dilution factors to the respective 

sample values. Report results up to three significant figures. 

 12.2 If appropriate, or required by the project or regulation for data reporting, calculate 

results for solids on a dry-weight basis as follows: 

W S

C V

ConcentrationDW

×

×

=

 where: 

ConcentrationDW = Concentration on a dry weight basis (mg/kg) 

C = Digest concentration (mg/L) 

 x 100

 g of sample

 g of dry sample % dry weight = 
SW-846 Update V 6010D - 26 Revision 4 

October 2012 

V = Final volume after sample preparation (L) 

W =Wet sample mass (kg) 

S = % Solids/100 = % dry weight/100 

13.0 METHOD PERFORMANCE 

 Performance data and related information are provided in SW-846 methods only as 

examples and guidance. The data do not represent required performance criteria for users of 

the methods. Instead, performance criteria should be developed on a project-specific basis, and 

the laboratory should establish in-house QC performance criteria for the application of this 

method. These performance data are not intended to be and must not be used as absolute QC 

acceptance criteria for purposes of laboratory accreditation. 

 13.1 In an EPA round-robin study, seven laboratories applied the ICP-OES technique to 

water matrices spiked with various metal concentrates and acid-digested. Table 3 lists the true 

values, the mean reported results, and the mean percent relative standard deviations. These 

data are provided for guidance purposes only. 

 13.2 Performance data for aqueous solutions and solid samples from a multi-laboratory 

study are provided in Tables 5 and 6. These data are provided for guidance purposes only. 

14.0 POLLUTION PREVENTION 

 14.1 Pollution prevention encompasses any technique that reduces or eliminates the 

quantity and/or toxicity of waste at the point of generation. Numerous opportunities for pollution 

prevention exist in laboratory operations. The EPA has established a preferred hierarchy of 

environmental management techniques that places pollution prevention as the management 

option of first choice. Whenever feasible, laboratory personnel should use pollution prevention 

techniques to address their waste generation. When wastes cannot be feasibly reduced at the 

source, the Agency recommends recycling as the next best option. 

 14.2 For information about pollution prevention that may be applicable to laboratories 

and research institutions consult Less is Better: Laboratory Chemical Management for Waste 

Reduction, a free publication available from the American Chemical Society (ACS), Committee 

on Chemical Safety, 

http://portal.acs.org/portal/fileFetch/C/WPCP_012290/pdf/WPCP_012290.pdf. 

15.0 WASTE MANAGEMENT 

 The Environmental Protection Agency requires that laboratory waste management 

practices be conducted consistent with all applicable rules and regulations. The Agency urges 

laboratories to protect the air, water, and land by minimizing and controlling all releases from 

hoods and bench operations, complying with the letter and spirit of any sewer discharge permits 

and regulations, and by complying with all solid and hazardous waste regulations, particularly the 

hazardous waste identification rules and land disposal restrictions. For further information on 

waste management, consult the ACS publication listed in Sec. 14.2. 
SW-846 Update V 6010D - 27 Revision 4 

October 2012 

16.0 REFERENCES 

1. C.L. Jones, et al., "An Interlaboratory Study of Inductively Coupled Plasma Atomic 

Emission Spectroscopy Method 6010 and Digestion Method 3050," EPA-600/4-87-032, 

U.S. Environmental Protection Agency, Las Vegas, NV, 1987. 

2. Taylor, J. K., “Quality Assurance of Chemical Measurements”, Lewis Publishers (1987). 

3. Federal Advisory Committee on Detection and Quantitation Approaches and Uses in Clean 

Water Act Programs, Final Report, http://water.epa.gov/scitech/methods/cwa/det/index.cfm 

 (December 28, 2007). 

17.0 TABLES, DIAGRAMS, FLOW CHARTS, AND VALIDATION DATA 

 The pages to follow contain the tables, and figures referenced by this method. 
SW-846 Update V 6010D - 28 Revision 4 

October 2012 

TABLE 1 

POTENTIAL INTERFERENCES AND ANALYTE CONCENTRATION EQUIVALENTS (mg/L) 

ARISING FROM INTERFERENCE AT THE 100-mg/L LEVEL 

Analyte Wavelengthc

(nm) 

Interferenta,b

Al Ca Cr Cu Fe Mg Mn Ni Ti V 

Aluminum 308.215 -- -- -- -- -- -- 0.21 -- -- 1.4 

Antimony 206.833 0.47 -- 2.9 -- 0.08 -- -- -- 0.25 0.45 

Arsenic 193.696 1.3 -- 0.44 -- -- -- -- -- -- 1.1 

Barium 455.403 -- -- -- -- -- -- -- -- -- -- 

Beryllium 313.042 -- -- -- -- -- -- -- -- 0.04 0.05 

Cadmium 226.502 -- -- -- -- 0.03 -- -- 0.02 -- -- 

Calcium 317.933 -- -- 0.08 -- 0.01 0.01 0.04 -- 0.03 0.03 

Chromium 267.716 -- -- -- -- 0.003 -- 0.04 -- -- 0.04 

Cobalt 228.616 -- -- 0.03 -- 0.005 -- -- 0.03 0.15 -- 

Copper 324.754 -- -- -- -- 0.003 -- -- -- 0.05 0.02 

Iron 259.940 -- -- -- -- -- -- 0.12 -- -- -- 

Lead 220.353 0.17 -- -- -- -- -- -- -- -- -- 

Magnesium 279.079 -- 0.02 0.11 -- 0.13 -- 0.25 -- 0.07 0.12 

Manganese 257.610 0.005 -- 0.01 -- 0.002 0.002 -- -- -- -- 

Molybdenum 202.030 0.05 -- -- -- 0.03 -- -- -- -- -- 

Nickel 231.604 -- -- -- -- -- -- -- -- -- -- 

Selenium 196.026 0.23 -- -- -- 0.09 -- -- -- -- -- 

Sodium 588.995 -- -- -- -- -- -- -- -- 0.08 -- 

Thallium 190.864 0.30 -- -- -- -- -- -- -- -- -- 

Vanadium 292.402 -- -- 0.05 -- 0.005 -- -- -- 0.02 -- 

Zinc 213.856 -- -- -- 0.14 -- -- -- 0.29 -- -- 

NOTE: 

a

Dashes indicate that no interference was observed even when interferents were introduced at 

the following levels: 

Al at 1000 mg/L Cu at 200 mg/L Mn at 200 mg/L 

Ca at 1000 mg/L Fe at 1000 mg/L Ti at 200 mg/L 

Cr at 200 mg/L Mg at 1000 mg/L V at 200 mg/L 

b

The figures shown above as analyte concentration equivalents are not the actual observed 

concentrations. To obtain those figures, add the listed concentration to the interferent figure. 

c

Interferences will be affected by background and wavelength choice and other interferences may 

be present. 
SW-846 Update V 6010D - 29 Revision 4 

October 2012 

TABLE 2 

MIXED STANDARD SOLUTIONS 

Solution Elements 

I Be, Cd, Mn, Pb, Se and Zn 

II Ba, Co, Cu, Fe, and V 

III As and Mo 

IV Al, Ca, Cr, K, Na, Ni, Li, and Sr 

V Aga, Mg, Sb, and Tl 

VI P 

a

See second note in Sec. 7.10.1.
SW-846 Update V 6010D - 30 

TABLE 3 

ICP PRECISION AND BIAS DATAa

Sample No. 1 Sample No. 2 Sam

Element 

True 

Conc. 

(μg/L) 

Mean 

Conc. (μg/L) 

RSDb

 (%) 

Accuracyd

(%) 

True 

Conc. 

(μg/L) 

Mean 

Conc. (μg/L) 

RSDb

(%) 

Accuracyd

(%) 

True 

Conc. (μg/L) 

Mean 

Conc. (μg/L) 

Be 750 733 6.2 98 20 20 9.8 100 180 176 Mn 350 345 2.7 99 15 15 6.7 100 100 99 V 750 749 1.8 100 70 69 2.9 99 170 169 

As 200 208 7.5 104 22 19 23 86 60 63 

Cr 150 149 3.8 99 10 10 18 100 50 50 Cu 250 235 5.1 94 11 11 40 100 70 67 Fe 600 594 3.0 99 20 19 15 95 180 178 

Al 700 696 5.6 99 60 62 33 103 160 161 

Cd 50 48 12 96 2.5 2.9 16 116 14 13 Co 700 512 10 73 20 20 4.1 100 120 108 Ni 250 245 5.8 98 30 28 11 93 60 55 Pb 250 236 16 94 24 30 32 125 80 80 Zn 200 201 5.6 100 16 19 45 119 80 82 Sec 40 32 21.9 80 6 8.5 42 142 10 8.5 

NOTE: a Not all elements were analyzed by all laboratories.

b RSD = relative standard deviation. c Results for Se are from two laboratories. d Accuracy is expressed as the mean concentration divided by the true concentration times 100. 
SW-846 Update V 6010D - 31 Revision 4 

May 2012 

TABLE 4 

EXAMPLE ICP-OES PRECISION AND BIAS FOR AQUEOUS SOLUTIONS 

Element Mean Concentration 

(mg/L) 

n RSD (%) Accuracy (%)

Al 14.8 8 6.3 100

Sb 15.1 8 7.7 102

As 14.7 7 6.4 99

Ba 3.66 7 3.1 99

Be 3.78 8 5.8 102

Cd 3.61 8 7.0 97

Ca 15.0 8 7.4 101

Cr 3.75 8 8.2 101

Co 3.52 8 5.9 95

Cu 3.58 8 5.6 97

Fe 14.8 8 5.9 100

Pb 14.4 7 5.9 97

Mg 14.1 8 6.5 96

Mn 3.70 8 4.3 100

Mo 3.70 8 6.9 100

Ni 3.70 7 5.7 100

K 14.1 8 6.6 95

Se 15.3 8 7.5 104

Ag 3.69 6 9.1 100

Na 14.0 8 4.2 95

Tl 15.1 7 8.5 102 

V 3.51 8 6.6 95

Zn 3.57 8 8.3 96

NOTE: 1. These performance values are independent of sample preparation because 

the labs analyzed portions of the same solutions and are provided for 

illustrative purposes only. 

2. n = Number of measurements.3. Accuracy is expressed as a percentage of 

the nominal value for each analyte in acidified, multi-element solutions. 
SW-846 Update V 6010D - 32 Revision 4 

May 2012 

TABLE 5 

 EXAMPLE ICP-OES PRECISION AND BIAS FOR SOLID WASTE DIGESTS 

Spiked Coal Fly Ash 

(NIST-SRM 1633a) Spiked Electroplating Sludge 

Element 

Mean 

Conc. 

(mg/L) 

n 

RSD 

(%) 

Bias 

(% AA) 

Mean 

Conc. 

(mg/L) 

n 

RSD 

(%) 

Bias 

(% AA) 

Al 330 8 16 104 127 8 13 110 

Sb 3.4 6 73 96 5.3 7 24 120 

As 21 8 83 270 5.2 7 8.6 87 

Ba 133 8 8.7 101 1.6 8 20 58 

Be 4.0 8 57 460 0.9 7 9.9 110 

Cd 0.97 6 5.7 101 2.9 7 9.9 90 

Ca 87 6 5.6 208 954 7 7.0 97 

Cr 2.1 7 36 106 154 7 7.8 93 

Co 1.2 6 21 94 1.0 7 11 85 

Cu 1.9 6 9.7 118 156 8 7.8 97 

Fe 602 8 8.8 102 603 7 5.6 98 

Pb 4.6 7 22 94 25 7 5.6 98 

Mg 15 8 15 110 35 8 20 84 

Mn 1.8 7 14 104 5.9 7 9.6 95 

Mo 891 8 19 105 1.4 7 36 110 

Ni 1.6 6 8.1 91 9.5 7 9.6 90 

K 46 8 4.2 98 51 8 5.8 82 

Se 6.4 5 16 73 8.7 7 13 101 

Ag 1.4 3 17 140 0.75 7 19 270 

Na 20 8 49 130 1380 8 9.8 95 

Tl 6.7 4 22 260 5.0 7 20 180 

V 1010 5 7.5 100 1.2 6 11 80 

Zn 2.2 6 7.6 93 266 7 2.5 101 

NOTE: 1. These performance values are independent of sample preparation because the labs 

analyzed portions of the same digests and are provided for illustrative purposes only. 

2. n = Number of measurements. 

3. Bias for the ICP-OES data is expressed as a percentage of atomic absorption 

spectroscopy (AA) data for the same digests. 
SW-846 Update V 6010D - 33 Revision 4 

May 2012 

METHOD 6010C 

INDUCTIVELY COUPLED PLASMA-OPTICAL EMISSION SPECTROMETRY
SW-846 Update V 6010D - 34 Revision 4 

May 2012 

Appendix A 

Summary of Revisions to Method 6010 (From Revision 3, February 2007):

1. Improved overall method formatting for consistency with new SW-846 method style guidance. 

2. Changed title of method from “Inductively coupled plasma—atomic emission spectrometry” to 

“Inductively coupled plasma—optical emission spectrometry”. All references to atomic 

emission spectrometry were changed to optical emission spectrometry throughout the method. 

3. Section 1.1 - added a note and caution regarding analysis of mercury by method 6010. 

4. Section 1.6 - inserted references to additional 3000 series preparatory methods to ICP 

analysis. Also added method 6800 to sections 1.6 and 9.2 as a preparatory method. 

5. Inserted new section (7.10) regarding analysis of non-aqueous solvents. 

6. Made significant technical and editorial changes to Sec. 4.0 to improve method clarity and 

technological accuracy. 

7. Inserted additional safety guidance regarding the use of HF. 

8. Reformatted certain paragraphs with the heading "NOTE" or "WARNING" to better denote the 

importance of the recommendations provided therein.

9. Extensively reformatted “REAGENTS AND STANDARDS” section to meet current SW-846 

method guidelines. 

10. Significantly updated and expanded “QUALITY CONTROL” section for better adherence to 

current SW-846 method guidelines and for improved alignment with current universal 

practices for published analytical methods. 

11. Inserted new sections (Sections 7.12 and 9.9) to describe the preparation and use of the 

spectral interference check (SIC) solution; also added instructions to match the matrix of this 

solution to that of the calibration standards. 

12. Removed all references to "MDLs" and replaced them with either "IDLs" or "LLOQs" as 

appropriate. 

13. Removed all references to method 7000 except for guidance regarding the method of 

standard addition. 

14. The term “accuracy” was replaced by “bias” where appropriate. 

15. In Section 7.9.6, a correction was made to the concentration of boron in the standard 

described by the text. 

16. In Section 9.4, the requirement to repeat the demonstration of proficiency for new staff and 

instrumentation changes was changed to a recommendation. 

17. The section regarding analysis of reference materials (Sec. 9.7.4) was revised for clarity and 

the term “Standard Reference Material” was replaced with “reference material” throughout the 

method. 

18. Inserted new section (Sec. 9.8) describing the preparation and use of an LLOQ standard. 

This section includes two new references for guidance on assessing precision and bias. 

19. The section describing matrix interference check samples (Sec. 9.11) has been revised for 

clarity. The post-digestion MS is only recommended if a high concentration sample is not 

available for performing the dilution test. 

20. Reformatted and/or renumbered “CALIBRATION AND STANDARDIZATION” (Sec. 10) for 

better adherence to Style Guide recommendations and/or clarity. 

21. Substituted certain terms with new terms (i.e. “must” in place of “shall”) to conform with the 

Performance-based Methods Approach goal of flexibility. 

22. Removed reference to “isotope abundances” as noted by the Inorganic Methods Work Group. 

23. Removed reference to “linear dynamic range” as noted by the Inorganic Methods Work Group. 

Section 9.6 regarding the linear range was added. 

24. Mid-level readback or verification standard added to Section 10.8.3. 
SW-846 Update V 6010D - 35 Revision 4 

May 2012 

25. Table 1 was determined to be outdated and removed. The method recommends consulting 

the instrument manufacturer for appropriate wavelengths and estimated instrument detection 

limits.