200.7-1

METHOD 200.7

DETERMINATION OF METALS AND TRACE ELEMENTS IN WATER AND WASTES

BY INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROMETRY

Revision 4.4

EMMC Version

USEPA-ICP Users Group (Edited by T.D. Martin and J.F. Kopp) - Method 200.7, Revision 1.0,

(Printed 1979, Published 1982)

T.D. Martin and E.R. Martin - Method 200.7, Revision 3.0 (1990)

T.D. Martin, C.A. Brockhoff, J.T. Creed, and S.E. Long (Technology Applications Inc.) -

Method 200.7, Revision 3.3 (1991)

T.D. Martin, C.A. Brockhoff, J.T. Creed, and EMMC Methods Work Group - Method 200.7,

Revision 4.4 (1994)

ENVIRONMENTAL MONITORING SYSTEMS LABORATORY

OFFICE OF RESEARCH AND DEVELOPMENT

U. S. ENVIRONMENTAL PROTECTION AGENCY

CINCINNATI, OHIO 45268
200.7-2

METHOD 200.7

DETERMINATION OF METALS AND TRACE ELEMENTS IN WATER AND WASTES

BY INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROMETRY

1.0 SCOPE AND APPLICATION

1.1 Inductively coupled plasma-atomic emission spectrometry (ICP-AES) is used to

determine metals and some nonmetals in solution. This method is a

consolidation of existing methods for water, wastewater, and solid wastes. 1-4

(For analysis of petroleum products see References 5 and 6, Section 16.0) This

method is applicable to the following analytes:

Analyte Registry Number (CASRN)

Chemical Abstract Services

Aluminum (Al) 7429-90-5

Antimony (Sb) 7440-36-0

Arsenic (As) 7440-38-2

Barium (Ba) 7440-39-3

Beryllium (Be) 7440-41-7

Boron (B) 7440-42-8

Cadmium (Cd) 7440-43-9

Calcium (Ca) 7440-70-2

Cerium (Cr) 7440-45-1 a

Chromium (Cr) 7440-47-3

Cobalt (Co) 7440-48-4

Copper (Cu) 7440-50-8

Iron (Fe) 7439-89-6

Lead (Pb) 7439-92-1

Lithium (Li) 7439-93-2

Magnesium (Mg) 7439-95-4

Manganese (Mn) 7439-96-5

Mercury (Hg) 7439-97-6

Molybdenum (Mo) 7439-98-7

Nickel (Ni) 7440-02-0

Phosphorus (P) 7723-14-0

Potassium (K) 7440-09-7

Selenium (Se) 7782-49-2

Silica (SiO ) 7631-86-9 b

Silver (Ag) 7440-22-4

2

Cerium has been included as method analyte for correction of potential a

interelement spectral interference. 

This method is not suitable for the determination of silica in solids. b
Analyte Registry Number (CASRN)

Chemical Abstract Services

200.7-3

Sodium (Na) 7440-23-5

Strontium (Sr) 7440-24-6

Thallium (Tl) 7440-28-0

Tin (Sn) 7440-31-5

Titanium (Ti) 7440-32-6

Vanadium (V) 7440-62-2

Zinc (Zn) 7440-66-6

1.2 For reference where this method is approved for use in compliance monitoring

programs [e.g., Clean Water Act (NPDES) or Safe Drinking Water Act

(SDWA)] consult both the appropriate sections of the Code of Federal

Regulation (40 CFR Part 136 Table 1B for NPDES, and Part 141 § 141.23 for

drinking water), and the latest Federal Register announcements. 

1.3 ICP-AES can be used to determine dissolved analytes in aqueous samples after

suitable filtration and acid preservation. To reduce potential interferences,

dissolved solids should be <0.2% (w/v) (Section 4.2).

1.4 With the exception of silver, where this method is approved for the

determination of certain metal and metalloid contaminants in drinking water,

samples may be analyzed directly by pneumatic nebulization without acid

digestion if the sample has been properly preserved with acid and has

turbidity of <1 NTU at the time of analysis. This total recoverable

determination procedure is referred to as "direct analysis". However, in the

determination of some primary drinking water metal contaminants,

preconcentration of the sample may be required prior to analysis in order to

meet drinking water acceptance performance criteria (Sections 11.2.2 through

11.2.7).

1.5 For the determination of total recoverable analytes in aqueous and solid

samples a digestion/extraction is required prior to analysis when the elements

are not in solution (e.g., soils, sludges, sediments and aqueous samples that

may contain particulate and suspended solids). Aqueous samples containing

suspended or particulate material ≥1% (w/v) should be extracted as a solid

type sample.

1.6 When determining boron and silica in aqueous samples, only plastic, PTFE or

quartz labware should be used from time of sample collection to completion of

analysis. For accurate determination of boron in solid samples only quartz or

PTFE beakers should be used during acid extraction with immediate transfer

of an extract aliquot to a plastic centrifuge tube following dilution of the

extract to volume. When possible, borosilicate glass should be avoided to

prevent contamination of these analytes. 
200.7-4

1.7 Silver is only slightly soluble in the presence of chloride unless there is a

sufficient chloride concentration to form the soluble chloride complex. 

Therefore, low recoveries of silver may occur in samples, fortified sample

matrices and even fortified blanks if determined as a dissolved analyte or by

"direct analysis" where the sample has not been processed using the total

recoverable mixed acid digestion. For this reason it is recommended that

samples be digested prior to the determination of silver. The total recoverable

sample digestion procedure given in this method is suitable for the

determination of silver in aqueous samples containing concentrations up to 0.1

mg/L. For the analysis of wastewater samples containing higher

concentrations of silver, succeeding smaller volume, well mixed aliquots

should be prepared until the analysis solution contains <0.1 mg/L silver. The

extraction of solid samples containing concentrations of silver >50 mg/kg

should be treated in a similar manner. Also, the extraction of tin from solid

samples should be prepared again using aliquots <1 g when determined

sample concentrations exceed 1%.

1.8 The total recoverable sample digestion procedure given in this method will

solubilize and hold in solution only minimal concentrations of barium in the

presence of free sulfate. For the analysis of barium in samples having varying

and unknown concentrations of sulfate, analysis should be completed as soon

as possible after sample preparation.

1.9 The total recoverable sample digestion procedure given in this method is not

suitable for the determination of volatile organo-mercury compounds. 

However, if digestion is not required (turbidity <1 NTU), the combined

concentrations of inorganic and organo-mercury in solution can be determined

by "direct analysis" pneumatic nebulization provided the sample solution is

adjusted to contain the same mixed acid (HNO + HCl) matrix as the total 3

recoverable calibration standards and blank solutions.

1.10 Detection limits and linear ranges for the elements will vary with the

wavelength selected, the spectrometer, and the matrices. Table 1 provides

estimated instrument detection limits for the listed wavelengths. However, 7

actual method detection limits and linear working ranges will be dependent on

the sample matrix, instrumentation, and selected operating conditions.

1.11 Users of the method data should state the data-quality objectives prior to

analysis. Users of the method must document and have on file the required

initial demonstration performance data described in Section 9.2 prior to using

the method for analysis. 

2.0 SUMMARY OF METHOD

2.1 An aliquot of a well mixed, homogeneous aqueous or solid sample is

accurately weighed or measured for sample processing. For total recoverable

analysis of a solid or an aqueous sample containing undissolved material,

analytes are first solubilized by gentle refluxing with nitric and hydrochloric
200.7-5

acids. After cooling, the sample is made up to volume, is mixed and

centrifuged or allowed to settle overnight prior to analysis. For the

determination of dissolved analytes in a filtered aqueous sample aliquot, or for

the "direct analysis" total recoverable determination of analytes in drinking

water where sample turbidity is <1 NTU, the sample is made ready for

analysis by the appropriate addition of nitric acid, and then diluted to a

predetermined volume and mixed before analysis. 

2.2 The analysis described in this method involves multielemental determinations

by ICP-AES using sequential or simultaneous instruments. The instruments

measure characteristic atomic-line emission spectra by optical spectrometry. 

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 line spectra are monitored at specific

wavelengths by a photosensitive device. Photocurrents from the

photosensitive device are processed and controlled by a computer system. A

background correction technique is required to compensate for variable

background contribution to the determination of the analytes. Background

must be measured adjacent to the analyte wavelength during analysis. 

Various interferences must be considered and addressed appropriately as

discussed in Sections 4.0, 7.0, 9.0, 10.0, and 11.0.

3.0 DEFINITIONS

3.1 Calibration Blank - A volume of reagent water acidified with the same acid

matrix as in the calibration standards. The calibration blank is a zero standard

and is used to calibrate the ICP instrument (Section 7.10.1).

3.2 Calibration Standard (CAL) - A solution prepared from the dilution of stock

standard solutions. The CAL solutions are used to calibrate the instrument

response with respect to analyte concentration (Section 7.9).

3.3 Dissolved Analyte - The concentration of analyte in an aqueous sample that

will pass through a 0.45 μm membrane filter assembly prior to sample

acidification (Section 11.1).

3.4 Field Reagent Blank (FRB) - An aliquot of reagent water or other blank matrix

that is placed in a sample container in the laboratory and treated as a sample

in all respects, including shipment to the sampling site, exposure to the

sampling site conditions, storage, preservation, and all analytical procedures. 

The purpose of the FRB is to determine if method analytes or other

interferences are present in the field environment (Section 8.5). 

3.5 Instrument Detection Limit (IDL) - The concentration equivalent to the

analyte signal which is equal to three times the standard deviation of a series

of 10 replicate measurements of the calibration blank signal at the same

wavelength (Table 1.).
200.7-6

3.6 Instrument Performance Check (IPC) Solution - A solution of method

analytes, used to evaluate the performance of the instrument system with

respect to a defined set of method criteria (Sections 7.11 and 9.3.4).

3.7 Internal Standard - Pure analyte(s) added to a sample, extract, or standard

solution in known amount(s) and used to measure the relative responses of

other method analytes that are components of the same sample or solution. 

The internal standard must be an analyte that is not a sample component

(Section 11.5).

3.8 Laboratory Duplicates (LD1 and LD2) - Two aliquots of the same sample

taken in the laboratory and analyzed separately with identical procedures. 

Analyses of LD1 and LD2 indicates precision associated with laboratory

procedures, but not with sample collection, preservation, or storage

procedures.

3.9 Laboratory Fortified Blank (LFB) - An aliquot of LRB to which known

quantities of the method analytes are added in the laboratory. The LFB is

analyzed exactly like a sample, and its purpose is to determine whether the

methodology is in control and whether the laboratory is capable of making

accurate and precise measurements (Sections 7.10.3 and 9.3.2).

3.10 Laboratory Fortified Sample Matrix (LFM) - An aliquot of an environmental

sample to which known quantities of the method analytes are added in the

laboratory. The LFM is analyzed exactly like a sample, and its purpose is to

determine whether the sample matrix contributes bias to the analytical results. 

The background concentrations of the analytes in the sample matrix must be

determined in a separate aliquot and the measured values in the LFM

corrected for background concentrations (Section 9.4).

3.11 Laboratory Reagent Blank (LRB) - An aliquot of reagent water or other blank

matrices that are treated exactly as a sample including exposure to all

glassware, equipment, solvents, reagents, and internal standards that are used

with other samples. The LRB is used to determine if method analytes or other

interferences are present in the laboratory environment, reagents, or apparatus

(Sections 7.10.2 and 9.3.1).

3.12 Linear Dynamic Range (LDR) - The concentration range over which the

instrument response to an analyte is linear (Section 9.2.2).

3.13 Method Detection Limit (MDL) - The minimum concentration of an analyte

that can be identified, measured, and reported with 99% confidence that the

analyte concentration is greater than zero (Section 9.2.4 and Table 4.).

3.14 Plasma Solution - A solution that is used to determine the optimum height

above the work coil for viewing the plasma (Sections 7.15 and 10.2.3).
200.7-7

3.15 Quality Control Sample (QCS) - A solution of method analytes of known

concentrations which is used to fortify an aliquot of LRB or sample matrix. 

The QCS is obtained from a source external to the laboratory and different

from the source of calibration standards. It is used to check either laboratory

or instrument performance (Sections 7.12 and 9.2.3). 

3.16 Solid Sample - For the purpose of this method, a sample taken from material

classified as either soil, sediment or sludge.

3.17 Spectral Interference Check (SIC) Solution - A solution of selected method

analytes of higher concentrations which is used to evaluate the procedural

routine for correcting known interelement spectral interferences with respect to

a defined set of method criteria (Sections 7.13, 7.14 and 9.3.5).

3.18 Standard Addition - The addition of a known amount of analyte to the sample

in order to determine the relative response of the detector to an analyte within

the sample matrix. The relative response is then used to assess either an

operative matrix effect or the sample analyte concentration (Sections 9.5.1 and

11.5).

3.19 Stock Standard Solution - A concentrated solution containing one or more

method analytes prepared in the laboratory using assayed reference materials

or purchased from a reputable commercial source (Section 7.8).

3.20 Total Recoverable Analyte - The concentration of analyte determined either by

"direct analysis" of an unfiltered acid preserved drinking water sample with

turbidity of <1 NTU (Section 11.2.1), or by analysis of the solution extract of a

solid sample or an unfiltered aqueous sample following digestion by refluxing

with hot dilute mineral acid(s) as specified in the method (Sections 11.2 and

11.3).

3.21 Water Sample - For the purpose of this method, a sample taken from one of

the following sources: drinking, surface, ground, storm runoff, industrial or

domestic wastewater. 

4.0 INTERFERENCES

4.1 Spectral interferences are caused by background emission from continuous or

recombination phenomena, stray light from the line emission of high

concentration elements, overlap of a spectral line from another element, or

unresolved overlap of molecular band spectra. 

4.1.1 Background emission and stray light can usually be compensated for by

subtracting the background emission determined by measurement(s)

adjacent to the analyte wavelength peak. Spectral scans of samples or

single element solutions in the analyte regions may indicate not only

when alternate wavelengths are desirable because of severe spectral

interference, but also will show whether the most appropriate estimate
200.7-8

of the background emission is provided by an interpolation from

measurements on both sides of the wavelength peak or by the

measured emission on one side or the other. The location(s) selected

for the measurement of background intensity will be determined by the

complexity of the spectrum adjacent to the wavelength peak. The

location(s) used for routine measurement must be free of off-line

spectral interference (interelement or molecular) or adequately corrected

to reflect the same change in background intensity as occurs at the

wavelength peak. 

4.1.2 Spectral overlaps may be avoided by using an alternate wavelength or

can be compensated for by equations that correct for interelement

contributions, which involves measuring the interfering elements. 

Some potential on-line spectral interferences observed for the

recommended wavelengths are given in Table 2. When operative and

uncorrected, these interferences will produce false-positive

determinations and be reported as analyte concentrations. The

interferences listed are only those that occur between method analytes. 

Only interferences of a direct overlap nature that were observed with a

single instrument having a working resolution of 0.035 nm are listed. 

More extensive information on interferant effects at various

wavelengths and resolutions is available in Boumans' Tables. Users 8

may apply interelement correction factors determined on their

instruments within tested concentration ranges to compensate (off-line

or on-line) for the effects of interfering elements. 

4.1.3 When interelement corrections are applied, there is a need to verify

their accuracy by analyzing spectral interference check solutions as

described in Section 7.13. Interelement corrections will vary for the

same emission line among instruments because of differences in

resolution, as determined by the grating plus the 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. Users should not forget that some samples

may contain uncommon elements that could contribute spectral

interferences. 7,8

4.1.4 The interference 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 given in Table 1, the analyst is required to determine and

document for each wavelength the effect from the known interferences

given in Table 2, and to utilize a computer routine for their automatic
200.7-9

correction on all analyses. To determine the appropriate location for

off-line background correction, the user must scan the area on either

side adjacent to the wavelength and record the apparent emission

intensity from all other method analytes. 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 their

automatic correction on all determinations. If a wavelength other than

the recommended wavelength is used, the user must determine and

document both the on-line and off-line spectral interference effect from

all method analytes and provide for their automatic correction on all

analyses. Tests to determine the spectral interference must be done

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 at high

concentration a more appropriate test would be to use a concentration

near the upper LDR limit. See Section 10.4 for required spectral

interference test criteria. 

4.1.5 When interelement corrections are not used, either on-going SIC

solutions (Section 7.14) must be analyzed to verify the absence of

interelement spectral interference or a computer software routine must

be employed for comparing the determinative data to limits files for

notifying the analyst when an interfering element is detected in the

sample at a concentration that will produce either an apparent false

positive concentration, greater than the analyte IDL, or false negative

analyte concentration, less than the 99% lower control limit of the

calibration blank. When the interference accounts for 10% or more of

the analyte concentration, either an alternate wavelength free of

interference or another approved test procedure must be used to

complete the analysis. For example, the copper peak at 213.853 nm

could be mistaken for the zinc peak at 213.856 nm in solutions with

high copper and low zinc concentrations. For this example, a spectral

scan in the 213.8 nm region would not reveal the misidentification

because a single peak near the zinc location would be observed. The

possibility of this misidentification of copper for the zinc peak at

213.856 nm can be identified by measuring the copper at another

emission line, e.g., 324.754 nm. Users should be aware that, depending

upon the instrumental resolution, alternate wavelengths with adequate

sensitivity and freedom from interference may not be available for all

matrices. In these circumstances the analyte must be determined using

another approved test procedure.

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 high acid concentrations. If physical interferences are present, they must

be reduced by such means as a high-solids nebulizer, diluting the sample,
200.7-10

using a peristaltic pump, or using an appropriate internal standard element. 

Another problem that can occur with high dissolved solids is salt buildup at

the tip of the nebulizer, which affects aerosol flow rate and causes

instrumental drift. This problem can be controlled by a high-solids nebulizer,

wetting the argon prior to nebulization, using a tip washer, or diluting the

sample. Also, it has been reported that better control of the argon flow rates,

especially for the nebulizer, improves instrument stability and precision; this is

accomplished with the use of mass flow controllers. 

4.3 Chemical interferences include molecular-compound formation, ionization

effects, and solute-vaporization effects. Normally, these effects are not

significant with the ICP-AES technique. If observed, they can be minimized by

careful selection of operating conditions (such as incident power and

observation height), by buffering of the sample, by matrix matching, and by

standard-addition procedures. Chemical interferences are highly dependent on

matrix type and the specific analyte element.

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

the signals measured in a new 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 (Section 7.10.4). The possibility

of memory interferences should be recognized within an analytical run and

suitable rinse times should be used to reduce them. The rinse times necessary

for a particular element must be estimated prior to analysis. This may be

achieved by aspirating a standard containing elements corresponding to either

their LDR or a concentration ten times those usually encountered. The

aspiration time should be the same as a normal sample analysis period,

followed by analysis of the rinse blank at designated intervals. The length of

time required to reduce analyte signals to within a factor of two of the method

detection limit, should be noted. Until the required rinse time is established,

this method requires a rinse period of at least 60 seconds between samples and

standards. If a memory interference is suspected, the sample must be reanalyzed after a long rinse period.

5.0 SAFETY

5.1 The toxicity or carcinogenicity of each reagent used in this method have not

been fully established. Each chemical should be regarded as a potential health

hazard and exposure to these compounds should be as low as reasonably

achievable. Each laboratory is responsible for maintaining a current awareness

file of OSHA regulations regarding the safe handling of the chemicals specified

in this method. A reference file of material data handling sheets should also 9-12

be made available to all personnel involved in the chemical analysis. 

Specifically, concentrated nitric and hydrochloric acids present various hazards

and are moderately toxic and extremely irritating to skin and mucus

membranes. Use these reagents in a fume hood whenever possible and if eye
200.7-11

or skin contact occurs, flush with large volumes of water. Always wear safety

glasses or a shield for eye protection, protective clothing and observe proper

mixing when working with these reagents.

5.2 The acidification of samples containing reactive materials may result in the

release of toxic gases, such as cyanides or sulfides. Acidification of samples

should be done in a fume hood.

5.3 All personnel handling environmental samples known to contain or to have

been in contact with human waste should be immunized against known

disease causative agents.

5.4 The inductively coupled plasma should only be viewed with proper eye

protection from the ultraviolet emissions.

5.5 It is the responsibility of the user of this method to comply with relevant

disposal and waste regulations. For guidance see Sections 14.0 and 15.0. 

6.0 EQUIPMENT AND SUPPLIES

6.1 Inductively coupled plasma emission spectrometer:

6.1.1 Computer-controlled emission spectrometer with background-correction

capability. The spectrometer must be capable of meeting and

complying with the requirements described and referenced in Section

2.2.

6.1.2 Radio-frequency generator compliant with FCC regulations.

6.1.3 Argon gas supply - High purity grade (99.99%). When analyses are

conducted frequently, liquid argon is more economical and requires less

frequent replacement of tanks than compressed argon in conventional

cylinders.

6.1.4 A variable speed peristaltic pump is required to deliver both standard

and sample solutions to the nebulizer.

6.1.5 (Optional) Mass flow controllers to regulate the argon flow rates,

especially the aerosol transport gas, are highly recommended. Their

use will provide more exacting control of reproducible plasma

conditions.

6.2 Analytical balance, with capability to measure to 0.1 mg, for use in weighing

solids, for preparing standards, and for determining dissolved solids in digests

or extracts.

6.3 A temperature adjustable hot plate capable of maintaining a temperature of

95°C.
200.7-12

6.4 (Optional) A temperature adjustable block digester capable of maintaining a

temperature of 95°C and equipped with 250 mL constricted digestion tubes.

6.5 (Optional) A steel cabinet centrifuge with guard bowl, electric timer and

brake.

6.6 A gravity convection drying oven with thermostatic control capable of

maintaining 180°C ± 5°C.

6.7 (Optional) An air displacement pipetter capable of delivering volumes ranging

from 0.1-2500 μL with an assortment of high quality disposable pipet tips. 

6.8 Mortar and pestle, ceramic or nonmetallic material.

6.9 Polypropylene sieve, 5-mesh (4 mm opening).

6.10 Labware - For determination of trace levels of elements, contamination and

loss are of prime consideration. Potential contamination sources include

improperly cleaned laboratory apparatus and general contamination within the

laboratory environment from dust, etc. A clean laboratory work area

designated for trace element sample handling must be used. Sample

containers can introduce positive and negative errors in the determination of

trace elements by (1) contributing contaminants through surface desorption or

leaching, (2) depleting element concentrations through adsorption processes. 

All reusable labware (glass, quartz, polyethylene, PTFE, FEP, etc.) should be

sufficiently clean for the task objectives. Several procedures found to provide

clean labware include washing with a detergent solution, rinsing with tap

water, soaking for four hours or more in 20% (v/v) nitric acid or a mixture of

HNO and HCl (1+2+9), rinsing with reagent water and storing clean. 3

2,3

Chromic acid cleaning solutions must be avoided because chromium is an

analyte. 

6.10.1 Glassware - Volumetric flasks, graduated cylinders, funnels and

centrifuge tubes (glass and/or metal-free plastic).

6.10.2 Assorted calibrated pipettes.

6.10.3 Conical Phillips beakers (Corning 1080-250 or equivalent), 250 mL with

50 mm watch glasses.

6.10.4 Griffin beakers, 250 mL with 75 mm watch glasses and (optional) 75

mm ribbed watch glasses.

6.10.5 (Optional) PTFE and/or quartz Griffin beakers, 250 mL with PTFE

covers.

6.10.6 Evaporating dishes or high-form crucibles, porcelain, 100 mL capacity. 
200.7-13

6.10.7 Narrow-mouth storage bottles, FEP (fluorinated ethylene propylene)

with screw closure, 125 mL to 1 L capacities.

6.10.8 One-piece stem FEP wash bottle with screw closure, 125 mL capacity.

7.0 REAGENTS AND STANDARDS

7.1 Reagents may contain elemental impurities which might affect analytical data. 

Only high-purity reagents that conform to the American Chemical Society

specifications should be used whenever possible. If the purity of a reagent is 13

in question, analyze for contamination. All acids used for this method must be

of ultra high-purity grade or equivalent. Suitable acids are available from a

number of manufacturers. Redistilled acids prepared by sub-boiling

distillation are acceptable.

7.2 Hydrochloric acid, concentrated (sp.gr. 1.19) - HCl. 

7.2.1 Hydrochloric acid (1+1) - Add 500 mL concentrated HCl to 400 mL

reagent water and dilute to 1 L.

7.2.2 Hydrochloric acid (1+4) - Add 200 mL concentrated HCl to 400 mL

reagent water and dilute to 1 L.

7.2.3 Hydrochloric acid (1+20) - Add 10 mL concentrated HCl to 200 mL

reagent water. 

7.3 Nitric acid, concentrated (sp.gr. 1.41) - HNO . 3

7.3.1 Nitric acid (1+1) - Add 500 mL concentrated HNO to 400 mL reagent 3

water and dilute to 1 L. 

7.3.2 Nitric acid (1+2) - Add 100 mL concentrated HNO to 200 mL reagent 3

water.

7.3.3 Nitric acid (1+5) - Add 50 mL concentrated HNO to 250 mL reagent 3

water.

7.3.4 Nitric acid (1+9) - Add 10 mL concentrated HNO to 90 mL reagent 3

water.

7.4 Reagent water. All references to water in this method refer to ASTM Type I

grade water. 14

7.5 Ammonium hydroxide, concentrated (sp. gr. 0.902). 

7.6 Tartaric acid, ACS reagent grade. 
200.7-14

7.7 Hydrogen peroxide, 50%, stabilized certified reagent grade.

7.8 Standard Stock Solutions - Stock standards may be purchased or prepared

from ultra-high purity grade chemicals (99.99-99.999% pure). All compounds

must be dried for one hour at 105°C, unless otherwise specified. It is

recommended that stock solutions be stored in FEP bottles. Replace stock

standards when succeeding dilutions for preparation of calibration standards

cannot be verified.

CAUTION: Many of these chemicals are extremely toxic if inhaled or

swallowed (Section 5.1). Wash hands thoroughly after handling.

Typical stock solution preparation procedures follow for 1 L quantities, but for

the purpose of pollution prevention, the analyst is encouraged to prepare

smaller quantities when possible. Concentrations are calculated based upon

the weight of the pure element or upon the weight of the compound

multiplied by the fraction of the analyte in the compound.

From pure element, 

From pure compound,

where: gravimetric factor = the weight fraction of the analyte in the

compound

7.8.1 Aluminum solution, stock, 1 mL = 1000 μg Al: Dissolve 1.000 g of

aluminum metal, weighed accurately to at least four significant figures,

in an acid mixture of 4.0 mL of (1+1) HCl and 1 mL of concentrated

HN0 in a beaker. Warm beaker slowly to effect solution. When 3

dissolution is complete, transfer solution quantitatively to a 1 L flask,

add an additional 10.0 mL of (1+1) HCl and dilute to volume with

reagent water.

7.8.2 Antimony solution, stock, 1 mL = 1000 μg Sb: Dissolve 1.000 g of

antimony powder, weighed accurately to at least four significant

figures, in 20.0 mL (1+1) HNO and 10.0 mL concentrated HCl. Add 3

100 mL reagent water and 1.50 g tartaric acid. Warm solution slightly
200.7-15

to effect complete dissolution. Cool solution and add reagent water to

volume in a 1 L volumetric flask. 

7.8.3 Arsenic solution, stock, 1 mL = 1000 μg As: Dissolve 1.320 g of As O2 3

(As fraction = 0.7574), weighed accurately to at least four significant

figures, in 100 mL of reagent water containing 10.0 mL concentrated

NH OH. Warm the solution gently to effect dissolution. Acidify the 4

solution with 20.0 mL concentrated HNO and dilute to volume in a 1 L 3

volumetric flask with reagent water.

7.8.4 Barium solution, stock, 1 mL = 1000 μg Ba: Dissolve 1.437 g BaCO (Ba 3

fraction = 0.6960), weighed accurately to at least four significant figures,

in 150 mL (1+2) HNO with heating and stirring to degas and dissolve 3

compound. Let solution cool and dilute with reagent water in 1 L

volumetric flask.

7.8.5 Beryllium solution, stock, 1 mL = 1000 μg Be: DO NOT DRY. Dissolve

19.66 g BeSO C4H O (Be fraction = 0.0509), weighed accurately to at 4 2

least four significant figures, in reagent water, add 10.0 mL

concentrated HNO , and dilute to volume in a 1 L volumetric flask with 3

reagent water.

7.8.6 Boron solution, stock, 1 mL = 1000 μg B: DO NOT DRY. Dissolve

5.716 g anhydrous H BO (B fraction = 0.1749), weighed accurately to at 3 3

least four significant figures, in reagent water and dilute in a 1 L

volumetric flask with reagent water. Transfer immediately after mixing

to a clean FEP bottle to minimize any leaching of boron from the glass

volumetric container. Use of a nonglass volumetric flask is

recommended to avoid boron contamination from glassware.

7.8.7 Cadmium solution, stock, 1 mL = 1000 μg Cd: Dissolve 1.000 g Cd

metal, acid cleaned with (1+9) HNO , weighed accurately to at least 3

four significant figures, in 50 mL (1+1) HNO with heating to effect 3

dissolution. Let solution cool and dilute with reagent water in a 1 L

volumetric flask.

7.8.8 Calcium solution, stock, 1 mL = 1000 μg Ca: Suspend 2.498 g CaCO3

(Ca fraction = 0.4005), dried at 180°C for one hour before weighing,

weighed accurately to at least four significant figures, in reagent water

and dissolve cautiously with a minimum amount of (1+1) HNO . Add 3

10.0 mL concentrated HNO and dilute to volume in a 1 L volumetric 3

flask with reagent water.

7.8.9 Cerium solution, stock, 1 mL = 1000 μg Ce: Slurry 1.228 g CeO2

(Ce fraction = 0.8141), weighed accurately to at least four significant

figures, in 100 mL concentrated HNO and evaporate to dryness. 3

Slurry the residue in 20 mL H O, add 50 mL concentrated HNO , with 2 3

heat and stirring add 60 mL 50% H O dropwise in 1 mL increments 2 2
200.7-16

allowing periods of stirring between the 1 mL additions. Boil off excess

H O before diluting to volume in a 1 L volumetric flask with reagent 2 2

water. 

7.8.10 Chromium solution, stock, 1 mL = 1000 μg Cr: Dissolve 1.923 g CrO3

(Cr fraction = 0.5200), weighed accurately to at least four significant

figures, in 120 mL (1+5) HNO . When solution is complete, dilute to 3

volume in a 1 L volumetric flask with reagent water.

7.8.11 Cobalt solution, stock, 1 mL = 1000 μg Co: Dissolve 1.000 g Co metal,

acid cleaned with (1+9) HNO , weighed accurately to at least four 3

significant figures, in 50.0 mL (1+1) HNO . Let solution cool and dilute 3

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

7.8.12 Copper solution, stock, 1 mL = 1000 μg Cu: Dissolve 1.000 g Cu metal,

acid cleaned with (1+9) HNO , weighed accurately to at least four 3

significant figures, in 50.0 mL (1+1) HNO with heating to effect 3

dissolution. Let solution cool and dilute in a 1 L volumetric flask with

reagent water.

7.8.13 Iron solution, stock, 1 mL = 1000 μg Fe: Dissolve 1.000 g Fe metal, acid

cleaned with (1+1) HCl, weighed accurately to four significant figures,

in 100 mL (1+1) HCl with heating to effect dissolution. Let solution

cool and dilute with reagent water in a 1 L volumetric flask.

7.8.14 Lead solution, stock, 1 mL = 1000 μg Pb: Dissolve 1.599 g Pb(NO )3 2

(Pb fraction = 0.6256), weighed accurately to at least four significant

figures, in a minimum amount of (1+1) HNO . Add 20.0 mL (1+1) 3

HNO and dilute to volume in a 1 L volumetric flask with reagent 3

water.

7.8.15 Lithium solution, stock, 1 mL = 1000 μg Li: Dissolve 5.324 g Li CO 2 3

(Li fraction = 0.1878), weighed accurately to at least four significant

figures, in a minimum amount of (1+1) HCl and dilute to volume in a 1

L volumetric flask with reagent water.

7.8.16 Magnesium solution, stock, 1 mL = 1000 μg Mg: Dissolve 1.000 g

cleanly polished Mg ribbon, accurately weighed to at least four

significant figures, in slowly added 5.0 mL (1+1) HCl (CAUTION:

reaction is vigorous). Add 20.0 mL (1+1) HNO and dilute to volume 3

in a 1 L volumetric flask with reagent water.

7.8.17 Manganese solution, stock, 1 mL = 1000 μg Mn: Dissolve 1.000 g of

manganese metal, weighed accurately to at least four significant figures,

in 50 mL (1+1) HNO and dilute to volume in a 1 L volumetric flask 3

with reagent water.
200.7-17

7.8.18 Mercury solution, stock, 1 mL = 1000 μg Hg: DO NOT DRY. 

CAUTION: highly toxic element. Dissolve 1.354 g HgCl (Hg fraction 2

= 0.7388) in reagent water. Add 50.0 mL concentrated HNO and dilute 3

to volume in 1 L volumetric flask with reagent water.

7.8.19 Molybdenum solution, stock, 1 mL = 1000 μg Mo: Dissolve 1.500 g

MoO (Mo fraction = 0.6666), weighed accurately to at least four 3

significant figures, in a mixture of 100 mL reagent water and 10.0 mL

concentrated NH OH, heating to effect dissolution. Let solution cool 4

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

7.8.20 Nickel solution, stock, 1 mL = 1000 μg Ni: Dissolve 1.000 g of nickel

metal, weighed accurately to at least four significant figures, in 20.0 mL

hot concentrated HNO , cool, and dilute to volume in a 1 L volumetric 3

flask with reagent water.

7.8.21 Phosphorus solution, stock, 1 mL = 1000 μg P: Dissolve 3.745 g

NH H PO (P fraction = 0.2696), weighed accurately to at least four 42 4

significant figures, in 200 mL reagent water and dilute to volume in a 1

L volumetric flask with reagent water. 

7.8.22 Potassium solution, stock, 1 mL = 1000 μg K: Dissolve 1.907 g KCl

(K fraction = 0.5244) dried at 110°C, weighed accurately to at least four

significant figures, in reagent water, add 20 mL (1+1) HCl and dilute to

volume in a 1 L volumetric flask with reagent water.

7.8.23 Selenium solution, stock, 1 mL = 1000 μg Se: Dissolve 1.405 g SeO2

(Se fraction = 0.7116), weighed accurately to at least four significant

figures, in 200 mL reagent water and dilute to volume in a 1 L

volumetric flask with reagent water. 

7.8.24 Silica solution, stock, 1 mL = 1000 μg SiO : DO NOT DRY 2 . Dissolve

2.964 g (NH ) SiF , weighed accurately to at least four significant 42 6

figures, in 200 mL (1+20) HCl with heating at 85°C to effect dissolution. 

Let solution cool and dilute to volume in a 1 L volumetric flask with

reagent water.

7.8.25 Silver solution, stock, 1 mL = 1000 μg Ag: Dissolve 1.000 g Ag metal,

weighed accurately to at least four significant figures, in 80 mL (1+1)

HNO with heating to effect dissolution. Let solution cool and dilute 3

with reagent water in a 1 L volumetric flask. Store solution in amber

bottle or wrap bottle completely with aluminum foil to protect solution

from light. 

7.8.26 Sodium solution, stock, 1 mL = 1000 μg Na: Dissolve 2.542 g NaCl

(Na fraction = 0.3934), weighed accurately to at least four significant

figures, in reagent water. Add 10.0 mL concentrated HNO and dilute 3

to volume in a 1 L volumetric flask with reagent water.
200.7-18

7.8.27 Strontium solution, stock, 1 mL = 1000 μg Sr: Dissolve 1.685 g SrCO3

(Sr fraction = 0.5935), weighed accurately to at least four significant

figures, in 200 mL reagent water with dropwise addition of 100 mL

(1+1) HCl. Dilute to volume in a 1 L volumetric flask with reagent

water. 

7.8.28 Thallium solution, stock, 1 mL = 1000 μg Tl: Dissolve 1.303 g TlNO3

(Tl fraction = 0.7672), weighed accurately to at least four significant

figures, in reagent water. Add 10.0 mL concentrated HNO and dilute 3

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

7.8.29 Tin solution, stock, 1 mL = 1000 μg Sn: Dissolve 1.000 g Sn shot,

weighed accurately to at least four significant figures, in an acid

mixture of 10.0 mL concentrated HCl and 2.0 mL (1+1) HNO with 3

heating to effect dissolution. Let solution cool, add 200 mL

concentrated HCl, and dilute to volume in a 1 L volumetric flask with

reagent water. 

7.8.30 Titanium solution, stock, 1 mL = 1000 μg Ti: DO NOT DRY. Dissolve

6.138 g (NH ) TiO(C O ) 42 2 42 2 CH O (Ti fraction = 0.1629), weighed accurately

to at least four significant figures, in 100 mL reagent water. Dilute to

volume in a 1 L volumetric flask with reagent water.

7.8.31 Vanadium solution, stock, 1 mL = 1000 μg V: Dissolve 1.000 g V metal,

acid cleaned with (1+9) HNO , weighed accurately to at least four 3

significant figures, in 50 mL (1+1) HNO with heating to effect 3

dissolution. Let solution cool and dilute with reagent water to volume

in a 1 L volumetric flask.

7.8.32 Yttrium solution, stock 1 mL = 1000 μg Y: Dissolve 1.270 g Y O2 3

(Y fraction = 0.7875), weighed accurately to at least four significant

figures, in 50 mL (1+1) HNO , heating to effect dissolution. Cool and 3

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

7.8.33 Zinc solution, stock, 1 mL = 1000 μg Zn: Dissolve 1.000 g Zn metal,

acid cleaned with (1+9) HNO , weighed accurately to at least four 3

significant figures, in 50 mL (1+1) HNO with heating to effect 3

dissolution. Let solution cool and dilute with reagent water to volume

in a 1 L volumetric flask.

7.9 Mixed Calibration Standard Solutions - For the analysis of total recoverable

digested samples prepare mixed calibration standard solutions (see Table 3) by

combining appropriate volumes of the stock solutions in 500 mL volumetric

flasks containing 20 mL (1+1) HNO and 20 mL (1+1) HCl and dilute to 3

volume with reagent water. Prior to preparing the mixed standards, each

stock solution should be analyzed separately to determine possible spectral

interferences or the presence of impurities. Care should be taken when

preparing the mixed standards to ensure that the elements are compatible and
200.7-19

stable together. To minimize the opportunity for contamination by the

containers, it is recommended to transfer the mixed-standard solutions to acidcleaned, never-used FEP fluorocarbon (FEP) bottles for storage. Fresh mixed

standards should be prepared, as needed, with the realization that

concentrations can change on aging. Calibration standards not prepared from

primary standards must be initially verified using a certified reference solution. 

For the recommended wavelengths listed in Table 1 some typical calibration

standard combinations are given in Table 3.

Note: If the addition of silver to the recommended mixed-acid calibration

standard results in an initial precipitation, add 15 mL of reagent water and

warm the flask until the solution clears. For this acid combination, the silver

concentration should be limited to 0.5 mg/L. 

7.10 Blanks - Four types of blanks are required for the analysis. The calibration

blank is used in establishing the analytical curve, the laboratory reagent blank

is used to assess possible contamination from the sample preparation

procedure, the laboratory fortified blank is used to assess routine laboratory

performance and a rinse blank is used to flush the instrument uptake system

and nebulizer between standards, check solutions, and samples to reduce

memory interferences. 

7.10.1 The calibration blank for aqueous samples and extracts is prepared by

acidifying reagent water to the same concentrations of the acids as used

for the standards. The calibration blank should be stored in a FEP

bottle. 

7.10.2 The laboratory reagent blank (LRB) must contain all the reagents in the

same volumes as used in the processing of the samples. The LRB must

be carried through the same entire preparation scheme as the samples

including sample digestion, when applicable.

7.10.3 The laboratory fortified blank (LFB) is prepared by fortifying an aliquot

of the laboratory reagent blank with all analytes to a suitable

concentration using the following recommended criteria: Ag ≤0.1

mg/L, ≥K 5.0 mg/L and all other analytes 0.2 mg/L or a concentration

approximately 100 times their respective MDL, whichever is greater. 

The LFB must be carried through the same entire preparation scheme

as the samples including sample digestion, when applicable.

7.10.4 The rinse blank is prepared by acidifying reagent water to the same

concentrations of acids as used in the calibration blank and stored in a

convenient manner.

7.11 Instrument Performance Check (IPC) Solution - The IPC solution is used to

periodically verify instrument performance during analysis. It should be

prepared in the same acid mixture as the calibration standards by combining

method analytes at appropriate concentrations. Silver must be limited to
200.7-20

<0.5 mg/L; while potassium and phosphorus because of higher MDLs and

silica because of potential contamination should be at concentrations of 10

mg/L. For other analytes a concentration of 2 mg/L is recommended. The

IPC solution should be prepared from the same standard stock solutions used

to prepare the calibration standards and stored in an FEP bottle. Agency

programs may specify or request that additional instrument performance check

solutions be prepared at specified concentrations in order to meet particular

program needs.

7.12 Quality Control Sample (QCS) - Analysis of a QCS is required for initial and

periodic verification of calibration standards or stock standard solutions in

order to verify instrument performance. The QCS must be obtained from an

outside source different from the standard stock solutions and prepared in the

same acid mixture as the calibration standards. The concentration of the

analytes in the QCS solution should be ≥1 mg/L, except silver, which must be

limited to a concentration of 0.5 mg/L for solution stability. The QCS solution

should be stored in a FEP bottle and analyzed as needed to meet data-quality

needs. A fresh solution should be prepared quarterly or more frequently as

needed. 

7.13 Spectral Interference Check (SIC) Solutions - When interelement corrections are

applied, SIC solutions are needed containing concentrations of the interfering

elements at levels that will provide an adequate test of the correction factors. 

7.13.1 SIC solutions containing (a) 300 mg/L Fe; (b) 200 mg/L AL; (c) 50

mg/L Ba; (d) 50 mg/L Be; (e) 50 mg/L Cd; (f) 50 mg/L Ce; (g) 50

mg/L Co; (h) 50 mg/L Cr; (i) 50 mg/L Cu; (j) 50 mg/L Mn; (k) 50

mg/L Mo; (l) 50 mg/L Ni; (m) 50 mg/L Sn; (n) 50 mg/L SiO ; (o) 50 2

mg/L Ti; (p) 50 mg/L Tl and (q) 50 mg/L V should be prepared in the

same acid mixture as the calibration standards and stored in FEP

bottles. These solutions can be used to periodically verify a partial list

of the on-line (and possible off-line) interelement spectral correction

factors for the recommended wavelengths given in Table 1. Other

solutions could achieve the same objective as well. (Multielement SIC

solutions may be prepared and substituted for the single element 3

solutions provided an analyte is not subject to interference from more

than one interferant in the solution.)

Note: If wavelengths other than those recommended in Table 1 are

used, other solutions different from those above (a through q) may be

required. 

7.13.2 For interferences from iron and aluminum, only those correction factors

(positive or negative) when multiplied by 100 to calculate apparent

analyte concentrations that exceed the determined analyte IDL or fall

below the lower 3-sigma control limit of the calibration blank need be

tested on a daily basis.
200.7-21

7.13.3 For the other interfering elements, only those correction factors (positive

or negative) when multiplied by 10 to calculate apparent analyte

concentrations that exceed the determined analyte IDL or fall below the

lower 3-sigma control limit of the calibration blank need be tested on a

daily basis.

7.13.4 If the correction routine is operating properly, the determined apparent

analyte(s) concentration from analysis of each interference solution (a

through q) should fall within a specific concentration range bracketing

the calibration blank. This concentration range is calculated by

multiplying the concentration of the interfering element by the value of

the correction factor being tested and dividing by 10. If after

subtraction of the calibration blank the apparent analyte concentration

is outside (above or below) this range, a change in the correction factor

of more than 10% should be suspected. The cause of the change should

be determined and corrected and the correction factor should be

updated.

Note: The SIC solution should be analyzed more than once to confirm

a change has occurred with adequate rinse time between solutions and

before subsequent analysis of the calibration blank.

7.13.5 If the correction factors tested on a daily basis are found to be within

the 10% criteria for five consecutive days, the required verification

frequency of those factors in compliance may be extended to a weekly

basis. Also, if the nature of the samples analyzed is such (e.g., finished

drinking water) that they do not contain concentrations of the

interfering elements at the 10 mg/L level, daily verification is not

required; however, all interelement spectral correction factors must be

verified annually and updated, if necessary.

7.13.6 If the instrument does not display negative concentration values, fortify

the SIC solutions with the elements of interest at 1 mg/L and test for

analyte recoveries that are below 95%. In the absence of measurable

analyte, over-correction could go undetected because a negative value

could be reported as zero. 

7.14 For instruments without interelement correction capability or when

interelement corrections are not used, SIC solutions (containing similar

concentrations of the major components in the samples, e.g., ≥10 mg/L) can

serve to verify the absence of effects at the wavelengths selected. These data

must be kept on file with the sample analysis data. If the SIC solution

confirms an operative interference that is ≥10% of the analyte concentration,

the analyte must be determined using a wavelength and background

correction location free of the interference or by another approved test

procedure. Users are advised that high salt concentrations can cause analyte

signal suppressions and confuse interference tests. 
200.7-22

7.15 Plasma Solution - The plasma solution is used for determining the optimum

viewing height of the plasma above the work coil prior to using the method

(Section 10.2). The solution is prepared by adding a 5 mL aliquot from each of

the stock standard solutions of arsenic, lead, selenium, and thallium to a

mixture of 20 mL (1+1) nitric acid and 20 mL (1+1) hydrochloric acid and

diluting to 500 mL with reagent water. Store in a FEP bottle.

8.0 SAMPLE COLLECTION, PRESERVATION, AND STORAGE

8.1 Prior to the collection of an aqueous sample, consideration should be given to

the type of data required, (i.e., dissolved or total recoverable), so that

appropriate preservation and pretreatment steps can be taken. The pH of all

aqueous samples must be tested immediately prior to aliquoting for processing

or "direct analysis" to ensure the sample has been properly preserved. If

properly acid preserved, the sample can be held up to six months before

analysis. 

8.2 For the determination of the dissolved elements, the sample must be filtered

through a 0.45 μm pore diameter membrane filter at the time of collection or

as soon thereafter as practically possible. (Glass or plastic filtering apparatus

are recommended to avoid possible contamination. Only plastic apparatus

should be used when the determinations of boron and silica are critical.) Use

a portion of the filtered sample to rinse the filter flask, discard this portion and

collect the required volume of filtrate. Acidify the filtrate with (1+1) nitric acid

immediately following filtration to pH <2. 

8.3 For the determination of total recoverable elements in aqueous samples,

samples are not filtered, but acidified with (1+1) nitric acid to pH <2

(normally, 3 mL of (1+1) acid per liter of sample is sufficient for most ambient

and drinking water samples). Preservation may be done at the time of

collection, however, to avoid the hazards of strong acids in the field, transport

restrictions, and possible contamination it is recommended that the samples be

returned to the laboratory within two weeks of collection and acid preserved

upon receipt in the laboratory. Following acidification, the sample should be

mixed, held for 16 hours, and then verified to be pH <2 just prior withdrawing

an aliquot for processing or "direct analysis". If for some reason such as high

alkalinity the sample pH is verified to be >2, more acid must be added and the

sample held for 16 hours until verified to be pH <2. See Section 8.1. 

Note: When the nature of the sample is either unknown or is known to be

hazardous, acidification should be done in a fume hood. See Section 5.2. 

8.4 Solid samples require no preservation prior to analysis other than storage at

4°C. There is no established holding time limitation for solid samples.

8.5 For aqueous samples, a field blank should be prepared and analyzed as

required by the data user. Use the same container and acid as used in sample

collection. 
200.7-23

9.0 QUALITY CONTROL

9.1 Each laboratory using this method is required to operate a formal quality

control (QC) program. The minimum requirements of this program consist of

an initial demonstration of laboratory capability, and the periodic analysis of

laboratory reagent blanks, fortified blanks and other laboratory solutions as a

continuing check on performance. The laboratory is required to maintain

performance records that define the quality of the data thus generated.

9.2 Initial Demonstration of Performance (mandatory).

9.2.1 The initial demonstration of performance is used to characterize

instrument performance (determination of linear dynamic ranges and

analysis of quality control samples) and laboratory performance

(determination of method detection limits) prior to analyses conducted

by this method.

9.2.2 Linear dynamic range (LDR) - The upper limit of the LDR must be

established for each wavelength utilized. It must be determined from a

linear calibration prepared in the normal manner using the established

analytical operating procedure for the instrument. The LDR should be

determined by analyzing succeedingly higher standard concentrations

of the analyte until the observed analyte concentration is no more than

10% below the stated concentration of the standard. Determined LDRs

must be documented and kept on file. The LDR which may be used

for the analysis of samples should be judged by the analyst from the

resulting data. Determined sample analyte concentrations that are

greater than 90% of the determined upper LDR limit must be diluted

and reanalyzed. The LDRs should be verified annually or whenever, in

the judgement of the analyst, a change in analytical performance caused

by either a change in instrument hardware or operating conditions

would dictate they be redetermined. 

 9.2.3 Quality control sample (QCS) - When beginning the use of this method,

on a quarterly basis, after the preparation of stock or calibration

standard solutions or as required to meet data-quality needs, verify the

calibration standards and acceptable instrument performance with the

preparation and analyses of a QCS (Section 7.12). To verify the

calibration standards the determined mean concentrations from three

analyses of the QCS must be within ±5% of the stated values. If the

calibration standard cannot be verified, performance of the

determinative step of the method is unacceptable. The source of the

problem must be identified and corrected before either proceeding on

with the initial determination of method detection limits or continuing

with on-going analyses.
200.7-24

9.2.4 Method detection limit (MDL) - MDLs must be established for all

wavelengths utilized, using reagent water (blank) fortified at a

concentration of two to three times the estimated instrument detection

limit. To determine MDL values, take seven replicate aliquots of the 15

fortified reagent water and process through the entire analytical

method. Perform all calculations defined in the method and report the

concentration values in the appropriate units. Calculate the MDL as

follows:

Where:

t = students' t value for a 99% confidence level and a

standard deviation estimate with n-1 degrees of freedom

[t = 3.14 for seven replicates]

S = standard deviation of the replicate analyses

Note: If additional confirmation is desired, reanalyze the seven

replicate aliquots on two more nonconsecutive days and again calculate

the MDL values for each day. An average of the three MDL values for

each analyte may provide for a more appropriate MDL estimate. If the

relative standard deviation (RSD) from the analyses of the seven

aliquots is <10%, the concentration used to determine the analyte MDL

may have been inapprop-riately high for the determination. If so, this

could result in the calculation of an unrealistically low MDL. 

Concurrently, determination of MDL in reagent water represents a best

case situation and does not reflect possible matrix effects of real world

samples. However, successful analyses of LFMs (Section 9.4) and the

analyte addition test described in Section 9.5.1 can give confidence to

the MDL value determined in reagent water. Typical single laboratory

MDL values using this method are given in Table 4.

The MDLs must be sufficient to detect analytes at the required levels

according to compliance monitoring regulation (Section 1.2). MDLs

should be determined annually, when a new operator begins work or

whenever, in the judgement of the analyst, a change in analytical

performance caused by either a change in instrument hardware or

operating conditions would dictate they be redetermined.

9.3 Assessing Laboratory Performance (mandatory) 

9.3.1 Laboratory reagent blank (LRB) - The laboratory must analyze at least

one LRB (Section 7.10.2) with each batch of 20 or fewer samples of the

same matrix. LRB data are used to assess contamination from the

laboratory environment. LRB values that exceed the MDL indicate

laboratory or reagent contamination should be suspected. When LRB

values constitute 10% or more of the analyte level determined for a
200.7-25

sample or is 2.2 times the analyte MDL whichever is greater, fresh

aliquots of the samples must be prepared and analyzed again for the

affected analytes after the source of contamination has been corrected

and acceptable LRB values have been obtained.

9.3.2 Laboratory fortified blank (LFB) - The laboratory must analyze at least

one LFB (Section 7.10.3) with each batch of samples. Calculate accuracy

as percent recovery using the following equation: 

Where:

R = percent recovery

LFB = laboratory fortified blank

LRB = laboratory reagent blank

s = concentration equivalent of analyte added to fortify

the LBR solution

If the recovery of any analyte falls outside the required control limits of

85-115%, that analyte is judged out of control, and the source of the

problem should be identified and resolved before continuing analyses.

9.3.3 The laboratory must use LFB analyses data to assess laboratory

performance against the required control limits of 85-115% (Section

9.3.2). When sufficient internal performance data become available

(usually a minimum of 20-30 analyses), optional control limits can be

developed from the mean percent recovery (x) and the standard

deviation (S) of the mean percent recovery. These data can be used to

establish the upper and lower control limits as follows:

UPPER CONTROL LIMIT = x + 3S

LOWER CONTROL LIMIT = x - 3S

The optional control limits must be equal to or better than the required

control limits of 85-115%. After each five to 10 new recovery

measurements, new control limits can be calculated using only the most

recent 20-30 data points. Also, the standard deviation (S) data should

be used to establish an on-going precision statement for the level of

concentrations included in the LFB. These data must be kept on file

and be available for review.
200.7-26

9.3.4 Instrument performance check (IPC) solution - For all determinations

the laboratory must analyze the IPC solution (Section 7.11) and a

calibration blank immediately following daily calibration, after every

10th sample (or more frequently, if required) and at the end of the

sample run. Analysis of the calibration blank should always be < the

analyte IDL, but greater than the lower 3-sigma control limit of the

calibration blank. Analysis of the IPC solution immediately following

calibration must verify that the instrument is within ±5% of calibration

with a relative standard deviation <3% from replicate integrations ≥4. 

Subsequent analyses of the IPC solution must be within ±10% of

calibration. If the calibration cannot be verified within the specified

limits, reanalyze either or both the IPC solution and the calibration

blank. If the second analysis of the IPC solution or the calibration

blank confirm calibration to be outside the limits, sample analysis must

be discontinued, the cause determined, corrected and/or the instrument

recalibrated. All samples following the last acceptable IPC solution

must be reanalyzed. The analysis data of the calibration blank and IPC

solution must be kept on file with the sample analyses data.

9.3.5 Spectral interference check (SIC) solution - For all determinations the

laboratory must periodically verify the interelement spectral

interference correction routine by analyzing SIC solutions. The

preparation and required periodic analysis of SIC solutions and test

criteria for verifying the interelement interference correction routine are

given in Section 7.13. Special cases where on-going verification is

required are described in Section 7.14.

9.4 Assessing Analyte Recovery and Data Quality

9.4.1 Sample homogeneity and the chemical nature of the sample matrix can

affect analyte recovery and the quality of the data. Taking separate

aliquots from the sample for replicate and fortified analyses can in

some cases assess the effect. Unless otherwise specified by the data

user, laboratory or program, the following laboratory fortified matrix

(LFM) procedure (Section 9.4.2) is required. Also, other tests such as

the analyte addition test (Section 9.5.1) and sample dilution test (Section

9.5.2) can indicate if matrix effects are operative. 

9.4.2 The laboratory must add a known amount of each analyte to a

minimum of 10% of the routine samples. In each case the LFM aliquot

must be a duplicate of the aliquot used for sample analysis and for

total recoverable determinations added prior to sample preparation. 

For water samples, the added analyte concentration must be the same

as that used in the laboratory fortified blank (Section 7.10.3). For solid

samples, however, the concentration added should be expressed as

mg/kg and is calculated for a one gram aliquot by multiplying the

added analyte concentration (mg/L) in solution by the conversion

factor 100 (mg/L x 0.1L/0.001kg = 100, Section 12.5). (For notes on Ag,
200.7-27

Ba, and Sn see Sections 1.7 and 1.8.) Over time, samples from all

routine sample sources should be fortified. 

Note: The concentration of calcium, magnesium, sodium and strontium

in environmental waters, along with iron and aluminum in solids can

vary greatly and are not necessarily predictable. Fortifying these

analytes in routine samples at the same concentration used for the LFB

may prove to be of little use in assessing data quality for these analytes. 

For these analytes sample dilution and reanalysis using the criteria

given in Section 9.5.2 is recommended. Also, if specified by the data

user, laboratory or program, samples can be fortified at higher

concentrations, but even major constituents should be limited to <25

mg/L so as not to alter the sample matrix and affect the analysis. 

9.4.3 Calculate the percent recovery for each analyte, corrected for

background concentrations measured in the unfortified sample, and

compare these values to the designated LFM recovery range of 70-130%

or a 3-sigma recovery range calculated from the regression equations

given in Table 9. Recovery calculations are not required if the 16

concentration added is less than 30% of the sample background

concentration. Percent recovery may be calculated in units appropriate

to the matrix, using the following equation:

Where:

R = percent recovery

C = fortified sample concentration s

C = sample background concentration

s = concentration equivalent of analyte added to fortify

the sample

9.4.4 If the recovery of any analyte falls outside the designated LFM recovery

range, and the laboratory performance for that analyte is shown to be

in control (Section 9.3), the recovery problem encountered with the

fortified sample is judged to be matrix related, not system related. The

data user should be informed that the result for that analyte in the

unfortified sample is suspect due to either the heterogeneous nature of

the sample or matrix effects and analysis by method of standard

addition or the use of an internal standard(s) (Section 11.5) should be

considered.

9.4.5 Where reference materials are available, they should be analyzed to

provide additional performance data. The analysis of reference samples

is a valuable tool for demonstrating the ability to perform the method
200.7-28

acceptably. Reference materials containing high concentrations of

analytes can provide additional information on the performance of the

spectral interference correction routine.

9.5 Assess the possible need for the method of standard additions (MSA) or

internal standard elements by the following tests. Directions for using MSA or

internal standard(s) are given in Section 11.5. 

9.5.1 Analyte addition test: An analyte(s) standard added to a portion of a

prepared sample, or its dilution, should be recovered to within 85% to

115% of the known value. The analyte(s) addition should produce a

minimum level of 20 times and a maximum of 100 times the method

detection limit. If the analyte addition is <20% of the sample analyte

concentration, the following dilution test should be used. If recovery of

the analyte(s) is not within the specified limits, a matrix effect should

be suspected, and the associated data flagged accordingly. The method

of additions or the use of an appropriate internal standard element may

provide more accurate data.

9.5.2 Dilution test: If the analyte concentration is sufficiently high

(minimally, a factor of 50 above the instrument detection limit in the

original solution but <90% of the linear limit), an analysis of a 1+4

dilution should agree (after correction for the fivefold dilution) within

±10% of the original determination. If not, a chemical or physical

interference effect should be suspected and the associated data flagged 

accordingly. The method of standard additions or the use of an

internal-standard element may provide more accurate data for samples

failing this test.

10.0 CALIBRATION AND STANDARDIZATION

10.1 Specific wavelengths are listed in Table 1. Other wavelengths may be

substituted if they can provide the needed sensitivity and are corrected for

spectral interference. However, because of the difference among various

makes and models of spectrometers, specific instrument operating conditions

cannot be given. The instrument and operating conditions utilized for

determination must be capable of providing data of acceptable quality to the

program and data user. The analyst should follow the instructions provided

by the instrument manufacturer unless other conditions provide similar or

better performance for a task. Operating conditions for aqueous solutions

usually vary from 1100-1200 watts forward power, 15-16 mm viewing height,

15-19 L/min. argon coolant flow, 0.6-1 L/min. argon aerosol flow, 1-1.8

mL/min. sample pumping rate with a one minute preflush time and

measurement time near 1 s per wavelength peak (for sequential instruments)

and near 10 s per sample (for simultaneous instruments). Use of the Cu/Mn

intensity ratio at 324.754 nm and 257.610 nm (by adjusting the argon aerosol

flow) has been recommended as a way to achieve repeatable interference

correction factors.17
200.7-29

10.2 Prior to using this method optimize the plasma operating conditions. The

following procedure is recommended for vertically configured plasmas. The

purpose of plasma optimization is to provide a maximum signal-tobackground ratio for the least sensitive element in the analytical array. The

use of a mass flow controller to regulate the nebulizer gas flow rate greatly

facilitates the procedure.

10.2.1 Ignite the plasma and select an appropriate incident rf power with

minimum reflected power. Allow the instrument to become thermally

stable before beginning. This usually requires at least 30 to 60 minutes

of operation. While aspirating the 1000 μg/mL solution of yttrium

(Section 7.8.32), follow the instrument manufacturer's instructions and

adjust the aerosol carrier gas flow rate through the nebulizer so a

definitive blue emission region of the plasma extends approximately

from 5-20 mm above the top of the work coil. Record the nebulizer 18

gas flow rate or pressure setting for future reference.

10.2.2 After establishing the nebulizer gas flow rate, determine the solution

uptake rate of the nebulizer in mL/min. by aspirating a known volume

calibration blank for a period of at least three minutes. Divide the

spent volume by the aspiration time (in minutes) and record the uptake

rate. Set the peristaltic pump to deliver the uptake rate in a steady

even flow.

10.2.3 After horizontally aligning the plasma and/or optically profiling the

spectrometer, use the selected instrument conditions from Sections

10.2.1 and 10.2.2, and aspirate the plasma solution (Section 7.15),

containing 10 μg/mL each of As, Pb, Se and Tl. Collect intensity data

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

mm above the top of the work coil. (This region of the plasma is

commonly referred to as the analytical zone.) Repeat the process 19

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 largest intensity ratio

for the least sensitive element of the four analytes. If more than one

position provides the same ratio, select the position that provides the

highest net intensity counts for the least sensitive element or accept a

compromise position of the intensity ratios of all four analytes.

10.2.4 The instrument operating condition finally selected as being optimum

should provide the lowest reliable instrument detection limits and

method detection limits. Refer to Tables 1 and 4 for comparison of

IDLs and MDLs, respectively.

10.2.5 If either the instrument operating conditions, such as incident power

and/or nebulizer gas flow rate are changed, or a new torch injector

tube having a different orifice i.d. is installed, the plasma and plasma

viewing height should be reoptimized.
200.7-30

 

10.2.6 Before daily calibration and after the instrument warmup period, the

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

mass flow controller is being used, it should be reset to the recorded

optimized flow rate. In order to maintain valid spectral interelement

correction routines the nebulizer gas flow rate should be the same from

day-to-day (<2% change). The change in signal intensity with a change

in nebulizer gas flow rate for both "hard" (Pb 220.353 nm) and "soft"

(Cu 324.754) lines is illustrated in Figure 1.

10.3 Before using the procedure (Section 11.0) to analyze samples, there must be

data available documenting initial demonstration of performance. The

required data and procedure is described in Section 9.2. This data must be

generated using the same instrument operating conditions and calibration

routine (Section 11.4) to be used for sample analysis. These documented data

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

10.4 After completing the initial demonstration of performance, but before

analyzing samples, the laboratory must establish and initially verify an

interelement spectral interference correction routine to be used during sample

analysis. A general description concerning spectral interference and the

analytical requirements for background correction and for correction of

interelement spectral interference in particular are given in Section 4.1. To

determine the appropriate location for background correction and to establish

the interelement interference correction routine, repeated spectral scan about

the analyte wavelength and repeated analyses of the single element solutions

may be required. Criteria for determining an interelement spectral interference

is an apparent positive or negative concentration on the analyte that is outside

the 3-sigma control limits of the calibration blank for the analyte. (The uppercontrol limit is the analyte IDL.) Once established, the entire routine must be

initially and periodically verified annually, or whenever there is a change in

instrument operating conditions (Section 10.2.5). Only a portion of the

correction routine must be verified more frequently or on a daily basis. Test

criteria and required solutions are described in Section 7.13. Initial and

periodic verification data of the routine should be kept on file. Special cases

where on-going verification are required is described in Section 7.14. 

11.0 PROCEDURE

11.1 Aqueous Sample Preparation - Dissolved Analytes

11.1.1 For the determination of dissolved analytes in ground and surface

waters, pipet an aliquot (≥20 mL) of the filtered, acid preserved sample

into a 50 mL polypropylene centrifuge tube. Add an appropriate

volume of (1+1) nitric acid to adjust the acid concentration of the

aliquot to approximate a 1% (v/v) nitric acid solution (e.g., add 0.4 mL

(1+1) HNO to a 20 mL aliquot of sample). Cap the tube and mix. The 3

sample is now ready for analysis (Section 1.3). Allowance for sample
200.7-31

dilution should be made in the calculations. (If mercury is to be

determined, a separate aliquot must be additionally acidified to contain

1% (v/v) HCl to match the signal response of mercury in the

calibration standard and reduce memory interference effects. Section

1.9).

Note: If a precipitate is formed during acidification, transport, or

storage, the sample aliquot must be treated using the procedure

described in Sections 11.2.2 through 11.2.7 prior to analysis.

11.2 Aqueous Sample Preparation - Total Recoverable Analytes

11.2.1 For the "direct analysis" of total recoverable analytes in drinking water

samples containing turbidity <1 NTU, treat an unfiltered acid preserved

sample aliquot using the sample preparation procedure described in

Section 11.1.1 while making allowance for sample dilution in the data

calculation (Section 1.2). For the determination of total recoverable

analytes in all other aqueous samples or for preconcentrating drinking

water samples prior to analysis follow the procedure given in

Sections 11.2.2 through 11.2.7.

11.2.2 For the determination of total recoverable analytes in aqueous samples

(other than drinking water with <1 NTU turbidity), transfer a 100 mL

(±1 mL) aliquot from a well mixed, acid preserved sample to a 250 mL

Griffin beaker (Sections 1.2, 1.3, 1.6, 1.7, 1.8, and 1.9). (When necessary,

smaller sample aliquot volumes may be used.) 

Note: If the sample contains undissolved solids >1%, a well mixed,

acid preserved aliquot containing no more than 1 g particulate material

should be cautiously evaporated to near 10 mL and extracted using the

acid-mixture procedure described in Sections 11.3.3 through 11.3.6.

11.2.3 Add 2 mL (1+1) nitric acid and 1.0 mL of (1+1) hydrochloric acid to the

beaker containing the measured volume of sample. Place the beaker on

the hot plate for solution evaporation. The hot plate should be located

in a fume hood and previously adjusted to provide evaporation at a

temperature of approximately but no higher than 85°C. (See the

following note.) The beaker should be covered with an elevated watch

glass or other necessary steps should be taken to prevent sample

contamination from the fume hood environment.

Note: For proper heating adjust the temperature control of the hot

plate such that an uncovered Griffin beaker containing 50 mL of water

placed in the center of the hot plate can be maintained at a temperature

approximately but no higher than 85°C. (Once the beaker is covered

with a watch glass the temperature of the water will rise to

approximately 95°C.) 
200.7-32

11.2.4 Reduce the volume of the sample aliquot to about 20 mL by gentle

heating at 85°C. DO NOT BOIL. This step takes about two hours for a

100 mL aliquot with the rate of evaporation rapidly increasing as the

sample volume approaches 20 mL. (A spare beaker containing 20 mL

of water can be used as a gauge.)

11.2.5 Cover the lip of the beaker with a watch glass to reduce additional

evaporation and gently reflux the sample for 30 minutes. (Slight

boiling may occur, but vigorous boiling must be avoided to prevent

loss of the HCl-H O azeotrope.) 2

11.2.6 Allow the beaker to cool. Quantitatively transfer the sample solution to

a 50 mL volumetric flask, make to volume with reagent water, stopper

and mix.

11.2.7 Allow any undissolved material to settle overnight, or centrifuge a

portion of the prepared sample until clear. (If after centrifuging or

standing overnight the sample contains suspended solids that would

clog the nebulizer, a portion of the sample may be filtered for their

removal prior to analysis. However, care should be exercised to avoid

potential contamination from filtration.) The sample is now ready for

analysis. Because the effects of various matrices on the stability of

diluted samples cannot be characterized, all analyses should be

performed as soon as possible after the completed preparation.

11.3 Solid Sample Preparation - Total Recoverable Analytes

11.3.1 For the determination of total recoverable analytes in solid samples,

mix the sample thoroughly and transfer a portion (>20 g) to tared

weighing dish, weigh the sample and record the wet weight (WW). 

(For samples with <35% moisture a 20 g portion is sufficient. For

samples with moisture >35% a larger aliquot 50-100 g is required.) Dry

the sample to a constant weight at 60°C and record the dry weight

(DW) for calculation of percent solids (Section 12.6). (The sample is

dried at 60°C to prevent the loss of mercury and other possible volatile

metallic compounds, to facilitate sieving, and to ready the sample for

grinding.) 

11.3.2 To achieve homogeneity, sieve the dried sample using a 5-mesh

polypropylene sieve and grind in a mortar and pestle. (The sieve,

mortar and pestle should be cleaned between samples.) From the

dried, ground material weigh accurately a representative 1.0 ± 0.01 g

aliquot (W) of the sample and transfer to a 250 mL Phillips beaker for

acid extraction (Sections1.6, 1.7, 1.8, and 1.9).

11.3.3 To the beaker add 4 mL of (1+1) HNO and 10 mL of (1+4) HCl. Cover 3

the lip of the beaker with a watch glass. Place the beaker on a hot

plate for reflux extraction of the analytes. The hot plate should be
200.7-33

located in a fume hood and previously adjusted to provide a reflux

temperature of approximately 95°C. (See the following note.)

Note: For proper heating adjust the temperature control of the hot

plate such that an uncovered Griffin beaker containing 50 mL of water

placed in the center of the hot plate can be maintained at a temperature

approximately but no higher than 85°C. (Once the beaker is covered

with a watch glass the temperature of the water will rise to

approximately 95°C.) Also, a block digester capable of maintaining a

temperature of 95°C and equipped with 250 mL constricted volumetric

digestion tubes may be substituted for the hot plate and conical beakers

in the extraction step.

11.3.4 Heat the sample and gently reflux for 30 minutes. Very slight boiling

may occur, however vigorous boiling must be avoided to prevent loss

of the HCl-H O azeotrope. Some solution evaporation will occur (3-4 2

mL).

11.3.5 Allow the sample to cool and quantitatively transfer the extract to a

100 mL volumetric flask. Dilute to volume with reagent water, stopper

and mix. 

11.3.6 Allow the sample extract solution to stand overnight to separate

insoluble material or centrifuge a portion of the sample solution until

clear. (If after centrifuging or standing overnight the extract solution

contains suspended solids that would clog the nebulizer, a portion of

the extract solution may be filtered for their removal prior to analysis. 

However, care should be exercised to avoid potential contamination

from filtration.) The sample extract is now ready for analysis. Because

the effects of various matrices on the stability of diluted samples cannot

be characterized, all analyses should be performed as soon as possible

after the completed preparation.

11.4 Sample Analysis 

11.4.1 Prior to daily calibration of the instrument inspect the sample

introduction system including the nebulizer, torch, injector tube and

uptake tubing for salt deposits, dirt and debris that would restrict

solution flow and affect instrument performance. Clean the system

when needed or on a daily basis.

11.4.2 Configure the instrument system to the selected power and operating

conditions as determined in Sections 10.1 and 10.2.

11.4.3 The instrument must be allowed to become thermally stable before

calibration and analyses. This usually requires at least 30 to 60 minutes

of operation. After instrument warmup, complete any required optical

profiling or alignment particular to the instrument. 
200.7-34

11.4.4 For initial and daily operation calibrate the instrument according to the

instrument manufacturer's recommended procedures, using mixed

calibration standard solutions (Section 7.9) and the calibration blank

(Section 7.10.1). A peristaltic pump must be used to introduce all

solutions to the nebulizer. To allow equilibrium to be reached in the

plasma, aspirate all solutions for 30 seconds after reaching the plasma

before beginning integration of the background corrected signal to

accumulate data. When possible, use the average value of replicate

integration periods of the signal to be correlated to the analyte

concentration. Flush the system with the rinse blank (Section 7.10.4) for

a minimum of 60 seconds (Section 4.4) between each standard. The

calibration line should consist of a minimum of a calibration blank and

a high standard. Replicates of the blank and highest standard provide

an optimal distribution of calibration standards to minimize the

confidence band for a straight-line calibration in a response region with

uniform variance.20

11.4.5 After completion of the initial requirements of this method (Sections

10.3 and 10.4), samples should be analyzed in the same operational

manner used in the calibration routine with the rinse blank also being

used between all sample solutions, LFBs, LFMs, and check solutions

(Section 7.10.4).

11.4.6 During the analysis of samples, the laboratory must comply with the

required quality control described in Sections 9.3 and 9.4. Only for the

determination of dissolved analytes or the "direct analysis" of drinking

water with turbidity of <1 NTU is the sample digestion step of the LRB,

LFB, and LFM not required.

11.4.7 Determined sample analyte concentrations that are 90% or more of the

upper limit of the analyte LDR must be diluted with reagent water that

has been acidified in the same manner as calibration blank and

reanalyzed (see Section 11.4.8). Also, for the interelement spectral

interference correction routines to remain valid during sample analysis,

the interferant concentration must not exceed its LDR. If the interferant

LDR is exceeded, sample dilution with acidified reagent water and

reanalysis is required. In these circumstances analyte detection limits

are raised and determination by another approved test procedure that

is either more sensitive and/or interference free is recommended.

11.4.8 When it is necessary to assess an operative matrix interference (e.g.,

signal reduction due to high dissolved solids), the tests described in

Section 9.5 are recommended. 

11.4.9 Report data as directed in Section 12.0.

11.5 If the method of standard additions (MSA) is used, standards are added at one

or more levels to portions of a prepared sample. This technique compensates 21
200.7-35

for enhancement or depression of an analyte signal by a matrix. It will not

correct for additive interferences such as contamination, interelement

interferences, or baseline shifts. This technique is valid in the linear range

when the interference effect is constant over the range, the added analyte

responds the same as the endogenous analyte, and the signal is corrected for

additive interferences. The simplest version of this technique is the singleaddition method. This procedure calls for two identical aliquots of the sample

solution to be taken. To the first aliquot, a small volume of standard is added;

while to the second aliquot, a volume of acid blank is added equal to the

standard addition. The sample concentration is calculated by the following:

where:

C = Concentration of the standard solution (mg/L)

S = Signal for fortified aliquot 1

S = Signal for unfortified aliquot 2

V = Volume of the standard addition (L) 1

V = Volume of the sample aliquot (L) used for MSA 2

For more than one fortified portion of the prepared sample, linear regression

analysis can be applied using a computer or calculator program to obtain the

concentration of the sample solution. An alternative to using the method of

standard additions is use of the internal standard technique by adding one or

more elements (not in the samples and verified not to cause an uncorrected

interelement spectral interference) at the same concentration (which is

sufficient for optimum precision) to the prepared samples (blanks and

standards) that are affected the same as the analytes by the sample matrix. 

Use the ratio of analyte signal to the internal standard signal for calibration

and quantitation. 

12.0 DATA ANALYSIS AND CALCULATIONS

12.1 Sample data should be reported in units of mg/L for aqueous samples and

mg/kg dry weight for solid samples. 

12.2 For dissolved aqueous analytes (Section 11.1) report the data generated directly

from the instrument with allowance for sample dilution. Do not report analyte

concentrations below the IDL. 

12.3 For total recoverable aqueous analytes (Section 11.2), multiply solution analyte

concentrations by the dilution factor 0.5, when 100 mL aliquot is used to

produce the 50 mL final solution, and report data as instructed in Section 12.4. 

If a different aliquot volume other than 100 mL is used for sample preparation,
200.7-36

adjust the dilution factor accordingly. Also, account for any additional

dilution of the prepared sample solution needed to complete the determination

of analytes exceeding 90% or more of the LDR upper limit. Do not report data

below the determined analyte MDL concentration or below an adjusted

detection limit reflecting smaller sample aliquots used in processing or

additional dilutions required to complete the analysis.

12.4 For analytes with MDLs <0.01 mg/L, round the data values to the thousandth

place and report analyte concentrations up to three significant figures. For

analytes with MDLs ≥0.01 mg/L round the data values to the 100th place and

report analyte concentrations up to three significant figures. Extract

concentrations for solids data should be rounded in a similar manner before

calculations in Section 12.5 are performed.

12.5 For total recoverable analytes in solid samples (Section 11.3), round the

solution analyte concentrations (mg/L) as instructed in Section 12.4. Report

the data up to three significant figures as mg/kg dry-weight basis unless

specified otherwise by the program or data user. Calculate the concentration

using the equation below:

where:

C = Concentration in extract (mg/L)

V = Volume of extract (L, 100 mL = 0.1L)

D = Dilution factor (undiluted = 1)

W = Weight of sample aliquot extracted (g x 0.001 = kg)

Do not report analyte data below the estimated solids MDL or an adjusted

MDL because of additional dilutions required to complete the analysis.

12.6 To report percent solids in solid samples (Section 11.3) calculate as follows:

where:

DW = Sample weight (g) dried at 60°C

WW = Sample weight (g) before drying

Note: If the data user, program or laboratory requires that the reported

percent solids be determined by drying at 105°C, repeat the procedure given in
200.7-37

Section 11.3 using a separate portion (>20 g) of the sample and dry to constant

weight at 103-105°C. 

12.7 The QC data obtained during the analyses provide an indication of the quality

of the sample data and should be provided with the sample results.

13.0 METHOD PERFORMANCE

13.1 Listed in Table 4 are typical single laboratory total recoverable MDLs

determined for the recommended wavelengths using simultaneous ICP-AES

and the operating conditions given in Table 5. The MDLs were determined in

reagent blank matrix (best case situation). PTFE beakers were used to avoid

boron and silica contamination from glassware with the final dilution to 50 mL

completed in polypropylene centrifuged tubes. The listed MDLs for solids are

estimates and were calculated from the aqueous MDL determinations.

13.2 Data obtained from single laboratory method testing are summarized in Table

6 for five types of water samples consisting of drinking water, surface water,

ground water, and two wastewater effluents. The data presented cover all

analytes except cerium and titanium. Samples were prepared using the

procedure described in Section 11.2. For each matrix, five replicate aliquots

were prepared, analyzed and the average of the five determinations used to

define the sample background concentration of each analyte. In addition, two

pairs of duplicates were fortified at different concentration levels. For each

method analyte, the sample background concentration, mean percent recovery,

standard deviation of the percent recovery, and relative percent difference

between the duplicate fortified samples are listed in Table 6. The variance of

the five replicate sample background determinations is included in the

calculated standard deviation of the percent recovery when the analyte

concentration in the sample was greater than the MDL. The tap and well

waters were processed in Teflon and quartz beakers and diluted in

polypropylene centrifuged tubes. The nonuse of borosilicate glassware is

reflected in the precision and recovery data for boron and silica in those two

sample types. 

 13.3 Data obtained from single laboratory method testing are summarized in Table

7 for three solid samples consisting of EPA 884 Hazardous Soil, SRM 1645

River Sediment, and EPA 286 Electroplating Sludge. Samples were prepared

using the procedure described in Section 11.3. For each method analyte, the

sample background concentration, mean percent recovery of the fortified

additions, the standard deviation of the percent recovery, and relative percent

difference between duplicate additions were determined as described in

Section 13.2. Data presented are for all analytes except cerium, silica, and

titanium. Limited comparative data to other methods and SRM materials are

presented in Reference 23 of Section 16.0. 

13.4 Performance data for aqueous solutions independent of sample preparation

from a multilaboratory study are provided in Table 8.22
200.7-38

13.5 Listed in Table 9 are regression equations for precision and bias for 25 analytes

abstracted from EPA Method Study 27, a multilaboratory validation study of

Method 200.7. These equations were developed from data received from 1

12 laboratories using the total recoverable sample preparation procedure on

reagent water, drinking water, surface water and three industrial effluents. 

For a complete review and description of the study. See Reference 16 of

Section 16.0. 

14.0 POLLUTION PREVENTION

14.1 Pollution prevention encompasses any technique that reduces or eliminates the

quantity or toxicity of waste at the point of generation. Numerous

opportunities for pollution prevention exist in laboratory operation. 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 (e.g., Section 7.8). 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”, available from the American

Chemical Society's Department of Government Relations and Science Policy,

1155 16th Street N.W., Washington D.C. 20036, (202)872-4477.

15.0 WASTE MANAGEMENT

15.1 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 Waste

Management Manual for Laboratory Personnel”, available from the American

Chemical Society at the address listed in the Section 14.2.

16.0 REFERENCES

1. U.S. Environmental Protection Agency. Inductively Coupled Plasma- Atomic

Emission Spectrometric Method for Trace Element Analysis of Water and

Wastes-Method 200.7, Dec. 1982. EPA-600/4-79-020, revised March 1983.

2. U.S. Environmental Protection Agency. Inductively Coupled Plasma Atomic

Emission Spectroscopy Method 6010, SW-846 Test Methods for Evaluating

Solid Waste, 3rd Edition, 1986.
200.7-39

3. U.S. Environmental Protection Agency. Method 200.7: Determination of

Metals and Trace Elements in Water and Wastes by Inductively Coupled

Plasma-Atomic Emission Spectrometry, revision 3.3, EPA 600 4-91/010 June

1991.

4. U.S. Environmental Protection Agency. Inductively Coupled Plasma - Atomic

Emission Spectrometry Method for the Analysis of Waters and Solids, EMMC,

July 1992.

5. Fassel, V.A. et al. Simultaneous Determination of Wear Metals in Lubricating

Oils by Inductively-Coupled Plasma Atomic Emission Spectrometry. Anal.

Chem. 48:516-519, 1976.

6. Merryfield, R.N. and R.C. Loyd. Simultaneous Determination of Metals in Oil

by Inductively Coupled Plasma Emission Spectrometry. Anal. Chem. 51:1965-

1968, 1979.

7. Winge, R.K. et al. Inductively Coupled Plasma-Atomic Emission Spectroscopy: 

An Atlas of Spectral Information, Physical Science Data 20. Elsevier Science

Publishing, New York, New York, 1985.

8. Boumans, P.W.J.M. Line Coincidence Tables for Inductively Coupled Plasma

Atomic Emission Spectrometry, 2nd edition. Pergamon Press, Oxford, United

Kingdom, 1984.

9. Carcinogens - Working With Carcinogens, Department of Health, Education,

and Welfare, Public Health Service, Center for Disease Control, National

Institute for Occupational Safety and Health, Publication No. 77-206, Aug.

1977. Available from the National Technical Information Service (NTIS) as PB277256.

10. OSHA Safety and Health Standards, General Industry, (29 CFR 1910),

Occupational Safety and Health Administration, OSHA 2206, (Revised,

January 1976). 

11. Safety in Academic Chemistry Laboratories, American Chemical Society

Publication, Committee on Chemical Safety, 3rd Edition, 1979.

12. Proposed OSHA Safety and Health Standards, Laboratories, Occupational

Safety and Health Administration, Federal Register, July 24, 1986.

13. Rohrbough, W.G. et al. Reagent Chemicals, American Chemical Society

Specifications, 7th edition. American Chemical Society, Washington, DC, 1986.

14. American Society for Testing and Materials. Standard Specification for

Reagent Water, D1193-77. Annual Book of ASTM Standards, Vol. 11.01. 

Philadelphia, PA, 1991.
200.7-40

15. Code of Federal Regulations 40, Ch. 1, Pt. 136 Appendix B.

16. Maxfield, R. and b. Mindak. EPA Method Study 27, Method 200.7 Trace

Metals by ICP, Nov. 1983. Available from National Technical Information

Service (NTIS) as PB 85-248-656.

17. Botto, R.I. Quality Assurance in Operating a Multielement ICP Emission

Spectrometer. Spectrochim. Acta, 39B(1):95-113, 1984.

18. Wallace, G.F., Some Factors Affecting the Performance of an ICP Sample

Introduction System. Atomic Spectroscopy, Vol. 4, p. 188-192, 1983.

19. Koirtyohann, S.R. et al. Nomenclature System for the Low-Power Argon

Inductively Coupled Plasma, Anal. Chem. 52:1965, 1980

20. Deming, S.N. and S.L. Morgan. Experimental Design for Quality and

Productivity in Research, Development, and Manufacturing, Part III, pp 119-

123. Short course publication by Statistical Designs, 9941 Rowlett, Suite 6,

Houston, TX 77075, 1989.

21. Winefordner, J.D., Trace Analysis: Spectroscopic Methods for Elements, 

Chemical Analysis, Vol. 46, pp. 41-42.

22. Jones, C.L. 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, Nevada,

1987.

23. Martin, T.D., E.R. Martin and S.E. Long. Method 200.2: Sample Preparation

Procedure for Spectrochemical Analyses of Total Recoverable Elements, EMSL

ORD, USEPA, 1989.
200.7-41

17.0 TABLES, DIAGRAMS, FLOWCHARTS, AND VALIDATION DATA

TABLE 1: WAVELENGTHS, ESTIMATED INSTRUMENT DETECTION

LIMITS, AND RECOMMENDED CALIBRATION

Analyte (nm) (μg/L) (mg/L)

Wavelength Limit to a

Estimated

Detection Calibrate

b

c

Aluminum 308.215 45 10

Antimony 206.833 32 5

Arsenic 193.759 53 10

Barium 493.409 2.3 1

Beryllium 313.042 0.27 1

Boron 249.678 5.7 1

Cadmium 226.502 3.4 2

Calcium 315.887 30 10

Cerium 413.765 48 2

Chromium 205.552 6.1 5

Cobalt 228.616 7.0 2

Copper 324.754 5.4 2

Iron 259.940 6.2 10

Lead 220.353 42 10

Lithium 670.784 3.7 5

Magnesium 279.079 30 10

Manganese 257.610 1.4 2

Mercury 194.227 2.5 2

Molybdenum 203.844 12 10

Nickel 231.604 15 2

Phosphorus 214.914 76 10

Potassium 766.491 700 20

Selenium 196.090 75 5

Silica (SiO ) 251.611 26 (SiO ) 10 2

Silver 328.068 7.0 0.5

Sodium 588.995 29 10

Strontium 421.552 0.77 1

Thallium 190.864 40 5

Tin 189.980 25 4

Titanium 334.941 3.8 10

Vanadium 292.402 7.5 2

Zinc 213.856 1.8 5

d

e

d

2

The wavelengths listed are recommended because of their sensitivity and overall a

acceptability. Other wavelengths may be substituted if they can provide the needed

sensitivity and are treated with the same corrective techniques for spectral interference

(see Section 4.1).
200.7-42

These estimated 3-sigma instrumental detection limits are provided only as a guide b 16

to instrumental limits. The method detection limits are sample dependent and may

vary as the sample matrix varies. Detection limits for solids can be estimated by

dividing these values by the grams extracted per liter, which depends upon the

extraction procedure. Divide solution detection limits by 10 for 1 g extracted to 100

mL for solid detection limits.

Suggested concentration for instrument calibration. Other calibration limits in the c 2

linear ranges may be used.

Calculated from 2-sigma data. d 5

Highly dependent on operating conditions and plasma position. e
200.7-43

TABLE 2: ON-LINE METHOD INTERELEMENT SPECTRAL INTERFERANCES

ARISING FROM INTERFERANTS AT THE 100 mg/L LEVEL

Analyte (nm) Interferant*

Wavelength

Ag 328.068 Ce, Ti, Mn

Al 308.215 V, Mo, Ce, Mn

As 193.759 V, Al, Co, Fe, Ni

B 249.678 None

Ba 493.409 None

Be 313.042 V, Ce

Ca 315.887 Co, Mo, Ce

Cd 226.502 Ni, Ti, Fe, Ce

Ce 413.765 None

Co 228.616 Ti, Ba, Cd, Ni, Cr, Mo, Ce

Cr 205.552 Be, Mo, Ni

Cu 324.754 Mo, Ti

Fe 259.940 None

Hg 194.227 V, Mo

K 766.491 None

Li 670.784 None

Mg 279.079 Ce

Mn 257.610 Ce

Mo 203.844 Ce

Na 588.995 None

Ni 231.604 Co, Tl

P 214.914 Cu, Mo

Pb 220.353 Co, Al, Ce, Cu, Ni, Ti, Fe

Sb 206.833 Cr, Mo, Sn, Ti, Ce, Fe

Se 196.099 Fe

SiO 251.611 None 2

Sn 189.980 Mo, Ti, Fe, Mn, Si

Sr 421.552 None

Tl 190.864 Ti, Mo, Co, Ce, Al, V, Mn

Ti 334.941 None

V 292.402 Mo, Ti, Cr, Fe, Ce

Zn 213.856 Ni, Cu, Fe

*These on-line interferences from method analytes and titanium only were observed

using an instrument with 0.035 nm resolution (see Section 4.1.2). Interferant ranked

by magnitude of intensity with the most severe interferant listed first in the row. 
200.7-44

TABLE 3: MIXED STANDARD SOLUTIONS

Solution Analytes

I Ag, As, B, Ba, Ca, Cd, Cu, Mn, Sb, and Se

II K, Li, Mo, Na, Sr, and Ti

III Co, P, V, and Ce

IV Al, Cr, Hg, SiO , Sn, and Zn

V Be, Fe, Mg, Ni, Pb, and Tl

2
200.7-45

TABLE 4: TOTAL RECOVERABLE METHOD DETECTION LIMITS (MDL)

Analyte Aqueous, mg/L ) Solids, mg/kg (1

MDLs

(2)

Ag 0.002 0.3

Al 0.02 3

As 0.008 2

B 0.003 –

Ba 0.001 0.2

Be 0.0003 0.1

Ca 0.01 2

Cd 0.001 0.2

Ce 0.02 3

Co 0.002 0.4

Cr 0.004 0.8

Cu 0.003 0.5

Fe 0.03* 6

Hg 0.007 2

K 0.3 60

Li 0.001 0.2

Mg 0.02 3

Mn 0.001 0.2

Mo 0.004 1

Na 0.03 6

Ni 0.005 1

P 0.06 12

Pb 0.01 2

Sb 0.008 2

Se 0.02 5

SiO 0.02 – 2

Sn 0.007 2

Sr 0.0003 0.1

Tl 0.001 0.2

Ti 0.02 3

V 0.003 1

Zn 0.002 0.3

 MDL concentrations are computed for original matrix with allowance for 2x (1)

sample preconcentration during preparation. Samples were processed in PTFE and

diluted in 50-mL plastic centrifuge tubes.

 Estimated, calculated from aqueous MDL determinations. (2)

– Boron not reported because of glassware contamination. Silica not determined in

solid samples.

* Elevated value due to fume-hood contamination.
200.7-46

TABLE 5: INDUCTIVELY COUPLED PLASMA INSTRUMENT

OPERATING CONDITIONS

Incident rf power 1100 watts

Reflected rf power <5 watts

Viewing height above work coil 15 mm

Injector tube orifice i.d. 1 mm

Argon supply liquid argon

Argon pressure 40 psi

Coolant argon flow rate 19 L/min.

Aerosol carrier argon flow rate 620 mL/min.

Auxiliary (plasma) argon flow rate 300 mL/min.

Sample uptake rate controlled to 1.2 mL/min.
200.7-47

TABLE 6: PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES

TAP WATER

Analyte mg/L mg/L R (%) S (R) RPD mg/L R (%) S (R) RPD

Sample Low Average High Average

Conc. Spike Recovery Spike Recovery

Ag <0.002 0.05 95 0.7 2.1 0.2 96 0.0 0.0

Al 0.185 0.05 98 8.8 1.7 0.2 105 3.0 3.1

As <0.008 0.05 108 1.4 3.7 0.2 101 0.7 2.0

B 0.023 0.1 98 0.2 0.0 0.4 98 0.2 0.5

Ba 0.042 0.05 102 1.6 2.2 0.2 98 0.4 0.8

Be <0.0003 0.01 100 0.0 0.0 0.1 99 0.0 0.0

Ca 35.2 5.0 101 8.8 1.7 20.0 103 2.0 0.9

Cd <0.001 0.01 105 3.5 9.5 0.1 98 0.0 0.0

Co <0.002 0.02 100 0.0 0.0 0.2 99 0.5 1.5

Cr <0.004 0.01 110 0.0 0.0 0.1 102 0.0 0.0

Cu <0.003 0.02 103 1.8 4.9 0.2 101 1.2 3.5

Fe 0.008 0.1 106 1.0 1.8 0.4 105 0.3 0.5

Hg <0.007 0.05 103 0.7 1.9 0.2 100 0.4 1.0

K 1.98 5.0 109 1.4 2.3 20. 107 0.7 1.7

Li 0.006 0.02 103 6.9 3.8 0.2 110 1.9 4.4

Mg 8.08 5.0 104 2.2 1.5 20.0 100 0.7 1.1

Mn <0.001 0.01 100 0.0 0.0 0.1 99 0.0 0.0

Mo <0.004 0.02 95 3.5 10.5 0.2 108 0.5 1.4

Na 10.3 5.0 99 3.0 2.0 20.0 106 1.0 1.6

Ni <0.005 0.02 108 1.8 4.7 0.2 104 1.1 2.9

P 0.045 0.1 102 13.1 9.4 0.4 104 3.2 1.3

Pb <0.01 0.05 95 0.7 2.1 0.2 100 0.2 0.5

Sb <0.008 0.05 99 0.7 2.0 0.2 102 0.7 2.0

Se <0.02 0.1 87 1.1 3.5 0.4 99 0.8 2.3

SiO 6.5 5.0 104 3.3 3.4 20.0 96 1.1 2.3 2

Sn <0.007 0.05 103 2.1 5.8 0.2 101 1.8 5.0

Sr 0.181 0.1 102 3.3 2.1 0.4 105 0.8 1.0

Tl <0.02 0.1 101 3.9 10.9 0.4 101 0.1 0.3

V <0.003 0.05 101 0.7 2.0 0.2 99 0.2 0.5

Zn 0.005 0.05 101 3.7 9.0 0.2 98 0.9 2.5

S (R) Standard deviation of percent recovery.

RPD Relative percent difference between duplicate spike determinations.

< Sample concentration below established method detection limit.

* Spike concentration <10% of sample background concentration.
200.7-48

TABLE 6: PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES

(Cont’d)

POND WATER

Analyte mg/L mg/L R (%) S (R) RPD mg/L R (%) S (R) RPD

Sample Low Average High Average

Conc. Spike Recovery Spike Recovery

Ag <0.002 0.05 92 0.0 0.0 0.2 94 0.0 0.0

Al 0.819 0.2 88 10.0 5.0 0.8 100 2.9 3.7

As <0.008 0.05 102 0.0 0.0 0.2 98 1.4 4.1

B 0.034 0.1 111 8.9 6.9 0.4 103 2.0 0.0

Ba 0.029 0.05 96 0.9 0.0 0.2 97 0.3 0.5

Be <0.0003 0.01 95 0.4 1.1 0.2 95 0.0 0.0

Ca 53.9 5.0 * * 0.7 20.0 100 2.0 1.5

Cd <0.001 0.01 107 0.0 0.0 0.1 97 0.0 0.0

Co <0.002 0.02 100 2.7 7.5 0.2 97 0.7 2.1

Cr <0.004 0.01 105 3.5 9.5 0.1 103 1.1 2.9

Cu <0.003 0.02 98 2.1 4.4 0.2 100 0.5 1.5

Fe 0.875 0.2 95 8.9 2.8 0.8 97 3.2 3.6

Hg <0.007 0.05 97 3.5 10.3 0.2 98 0.0 0.0

K 2.48 5.0 106 0.3 0.1 20.0 103 0.2 0.4

Li <0.001 0.02 110 0.0 0.0 0.2 106 0.2 0.5

Mg 10.8 5.0 102 0.5 0.0 20.0 96 0.7 1.3

Mn 0.632 0.01 * * 0.2 0.1 97 2.3 0.3

Mo <0.004 0.02 105 3.5 9.5 0.2 103 0.4 1.0

Na 17.8 5.0 103 1.3 0.4 20.0 94 0.3 0.0

Ni <0.005 0.02 96 5.6 9.1 0.2 100 0.7 1.5

P 0.196 0.1 91 14.7 0.3 0.4 108 3.9 1.3

Pb <0.01 0.05 96 2.6 7.8 0.2 100 0.7 2.0

Sb <0.008 0.05 102 2.8 7.8 0.2 104 0.4 1.0

Se <0.02 0.1 104 2.1 5.8 0.4 103 1.6 4.4

SiO 7.83 5.0 151 1.6 1.3 20.0 117 0.4 0.6 2

Sn <0.007 0.05 98 0.0 0.0 0.2 99 1.1 3.0

Sr 0.129 0.1 105 0.4 0.0 0.4 99 0.1 0.2

Tl <0.02 0.1 103 1.1 2.9 0.4 97 1.3 3.9

V 0.003 0.05 94 0.4 0.0 0.2 98 0.1 0.0

Zn 0.006 0.05 97 1.6 1.8 0.2 94 0.4 0.0

 

S (R) Standard deviation of percent recovery.

RPD Relative percent difference between duplicate spike determinations.

< Sample concentration below established method detection limit.

* Spike concentration <10% of sample background concentration.
200.7-49

TABLE 6: PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES

(Cont’d)

WELL WATER

Analyte mg/L mg/L R (%) S (R) RPD mg/L R (%) S (R) RPD

Sample Low Average High Average

Conc. Spike Recovery Spike Recovery

Ag <0.002 0.05 97 0.7 2.1 0.2 96 0.2 0.5

Al 0.036 0.05 107 7.6 10.1 0.2 101 1.1 0.8

As <0.008 0.05 107 0.7 1.9 0.2 104 0.4 1.0

B 0.063 0.1 97 0.6 0.7 0.4 98 0.8 2.1

Ba 0.102 0.05 102 3.0 0.0 0.2 99 0.9 1.0

Be <0.0003 0.01 100 0.0 0.0 0.1 100 0.0 0.0

Ca 93.8 5.0 * * 2.1 20.0 100 4.1 0.1

Cd 0.002 0.01 90 0.0 0.0 0.1 96 0.0 0.0

Co <0.002 0.02 94 0.4 1.1 0.2 94 0.4 1.1

Cr <0.004 0.01 100 7.1 20.0 0.1 100 0.4 1.0

Cu <0.005 0.02 100 1.1 0.4 0.2 96 0.5 1.5

Fe 0.042 0.1 99 2.3 1.4 0.4 97 1.4 3.3

Hg <0.007 0.05 94 2.8 8.5 0.2 93 1.2 3.8

K 6.21 5.0 96 3.4 3.6 20.0 101 1.2 2.3

Li 0.001 0.02 100 7.6 9.5 0.2 104 1.0 1.9

Mg 24.5 5.0 95 5.6 0.3 20.0 93 1.6 1.2

Mn 2.76 0.01 * * 0.4 0.1 * * 0.7

Mo <0.004 0.02 108 1.8 4.7 0.2 101 0.2 0.5

Na 35.0 5.0 101 11.4 0.8 20.0 100 3.1 1.5

Ni <0.005 0.02 112 1.8 4.4 0.2 96 0.2 0.5

P 0.197 0.1 95 12.7 1.9 0.4 98 3.4 0.9

Pb <0.01 0.05 87 4.9 16.1 0.2 95 0.2 0.5

Sb <0.008 0.05 98 2.8 8.2 0.2 99 1.4 4.0

Se <0.02 0.1 102 0.4 1.0 0.4 94 1.1 3.4

SiO 13.1 5.0 93 4.8 2.8 20.0 99 0.8 0.0 2

Sn <0.007 0.05 98 2.8 8.2 0.2 94 0.2 0.5

Sr 0.274 0.1 94 5.7 2.7 0.4 95 1.7 2.2

Tl <0.02 0.1 92 0.4 1.1 0.4 95 1.1 3.2

V <0.003 0.05 98 0.0 0.0 0.2 99 0.4 1.0

Zn 0.538 0.05 * * 0.7 0.2 99 2.5 1.1

S (R) Standard deviation of percent recovery.

RPD Relative percent difference between duplicate spike determinations.

< Sample concentration below established method detection limit.

* Spike concentration <10% of sample background concentration.
200.7-50

TABLE 6: PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES

(Cont’d)

SEWAGE TREATMENT PRIMARY EFFLUENT

Analyte mg/L mg/L R (%) S (R) RPD mg/L R (%) S (R) RPD

Sample Low Average High Average

Conc. Spike Recovery Spike Recovery

Ag 0.009 0.05 92 1.5 3.6 0.2 95 0.1 0.0

Al 1.19 0.05 * * 0.9 0.2 113 12.4 2.1

As <0.008 0.05 99 2.1 6.1 0.2 93 2.1 6.5

B 0.226 0.1 217 16.3 9.5 0.4 119 13.1 20.9

Ba 0.189 0.05 90 6.8 1.7 0.2 99 1.6 0.5

Be <0.0003 0.01 94 0.4 1.1 0.1 100 0.4 1.0

Ca 87.9 5.0 * * 0.6 20.0 101 3.7 0.0

Cd 0.009 0.01 89 2.6 2.3 0.1 97 0.4 1.0

Co 0.016 0.02 95 3.1 0.0 0.2 93 0.4 0.5

Cr 0.128 0.01 * * 1.5 0.1 97 2.4 2.7

Cu 0.174 0.02 98 33.1 4.7 0.2 98 3.0 1.4

Fe 1.28 0.1 * * 2.8 0.4 111 7.0 0.6

Hg <0.007 0.05 102 1.4 3.9 0.2 98 0.5 1.5

K 10.6 5.0 104 2.8 1.3 20.0 101 0.6 0.0

Li 0.011 0.02 103 8.5 3.2 0.2 105 0.8 0.5

Mg 22.7 5.0 100 4.4 0.0 20.0 92 1.1 0.2

Mn 0.199 0.01 * * 2.0 0.1 104 1.9 0.3

Mo 0.125 0.02 110 21.2 6.8 0.2 102 1.3 0.9

Na 0.236 5.0 * * 0.0 20.0 * * 0.4

Ni 0.087 0.02 122 10.7 4.5 0.2 98 0.8 1.1

P 4.71 0.1 * * 2.6 0.4 * * 1.4

Pb 0.015 0.05 91 3.5 5.0 0.2 96 1.3 2.9

Sb <0.008 0.05 97 0.7 2.1 0.2 103 1.1 2.9

Se <0.02 0.1 108 3.9 10.0 0.4 101 2.6 7.2

SiO 16.7 5.0 124 4.0 0.9 20.0 108 1.1 0.8 2

Sn 0.016 0.05 90 3.8 0.0 0.2 95 1.0 0.0

Sr 0.515 0.1 103 6.4 0.5 0.4 96 1.6 0.2

Tl <0.02 0.1 105 0.4 1.0 0.4 95 0.0 0.0

V 0.003 0.05 93 0.9 2.0 0.2 97 0.2 0.5

Zn 0.160 0.05 98 3.3 1.9 0.2 101 1.0 1.4

 

 

 

 

S (R) Standard deviation of percent recovery.

RPD Relative percent difference between duplicate spike determinations.

< Sample concentration below established method detection limit.

* Spike concentration <10% of sample background concentration.
200.7-51

TABLE 6: PRECISION AND RECOVERY DATA IN AQUEOUS MATRICES

(Cont’d)

INDUSTRIAL EFFLUENT

Analyte mg/L mg/L R (%) S (R) RPD mg/L R (%) S (R) RPD

Sample Low Average High Average

Conc. Spike Recovery Spike Recovery

Ag <0.0003 0.05 88 0.0 0.0 0.2 84 0.9 3.0

Al 0.054 0.05 88 11.7 12.2 0.2 90 3.9 8.1

As <0.02 0.05 82 2.8 9.8 0.2 88 0.5 1.7

B 0.17 0.1 162 17.6 13.9 0.4 92 4.7 9.3

Ba 0.083 0.05 86 8.2 1.6 0.2 85 2.3 2.4

Be <0.0006 0.01 94 0.4 1.1 0.1 82 1.4 4.9

Ca 500 5.0 * * 2.8 20.0 * * 2.3

Cd 0.008 0.01 85 4.7 6.1 0.1 82 1.4 4.4

Co <0.004 0.02 93 1.8 5.4 0.2 83 0.4 1.2

Cr 0.165 0.01 * * 4.5 0.1 106 6.6 5.6

Cu 0.095 0.02 93 23.3 0.9 0.2 95 2.7 2.8

Fe 0.315 0.1 88 16.4 1.0 0.4 99 6.5 8.0

Hg <0.01 0.05 87 0.7 2.3 0.2 86 0.4 1.2

K 2.87 5.0 101 3.4 2.4 20.0 100 0.8 0.4

Li 0.069 0.02 103 24.7 5.6 0.2 104 2.5 2.2

Mg 6.84 5.0 87 3.1 0.0 20.0 87 0.9 1.2

Mn 0.141 0.01 * * 1.2 0.1 89 6.6 4.8

Mo 1.27 0.02 * * 0.0 0.2 100 15.0 2.7

Na 1500 5.0 * * 2.7 20.0 * * 2.0

Ni 0.014 0.02 98 4.4 3.0 0.2 87 0.5 1.1

P 0.326 0.1 105 16.0 4.7 0.4 97 3.9 1.4

Pb 0.251 0.05 80 19.9 1.4 0.2 88 5.0 0.9

Sb 2.81 0.05 * * 0.4 0.2 * * 2.0

Se 0.021 0.1 106 2.6 3.2 0.4 105 1.9 4.6

SiO 6.83 5.0 99 6.8 1.7 20.0 100 2.2 3.0 2

Sn <0.01 0.05 87 0.7 2.3 0.2 86 0.4 1.2

Sr 6.54 0.1 * * 2.0 0.4 * * 2.7

Tl <0.03 0.1 87 1.8 5.8 0.4 84 1.1 3.6

V <0.005 0.05 90 1.4 4.4 0.2 84 1.1 3.6

Zn 0.024 0.05 89 6.0 4.4 0.2 91 3.5 8.9

 

S (R) Standard deviation of percent recovery.

RPD Relative percent difference between duplicate spike determinations.

< Sample concentration below established method detection limit.

* Spike concentration <10% of sample background concentration.
200.7-52

TABLE 7: PRECISION AND RECOVERY DATA IN SOLID MATRICES

EPA HAZARDOUS SOIL #884

Analyte mg/kg mg/kg R (%) S (R) RPD mg/kg R (%) S (R) RPD

Sample Low Average High Average

Conc. Spike Recovery Spike Recovery

+ +

Ag 1.1 20 98 0.7 1.0 100 96 0.2 0.6 

Al 5080 20 * * 7.2 100 * * 5.4 

As 5.7 20 95 5.4 10.6 100 96 1.4 3.6 

B 20.4 100 93 2.7 5.3 400 100 2.1 5.5 

Ba 111 20 98 71.4 22.2 100 97 10.0 1.0 

Be 0.66 20 97 0.7 2.3 100 99 0.1 0.2 

Ca 85200 – – – – – – – – 

Cd 2 20 93 0.7 1.0 100 94 0.2 0.4 

Co 5.5 20 96 3.5 7.7 100 93 0.8 2.1 

Cr 79.7 20 87 28.8 16.5 100 104 1.3 1.1 

Cu 113 20 110 16.2 4.4 100 104 4.0 4.2 

Fe 16500 – – – – – – – – 

Hg <1.4 10 92 2.5 7.7 40 98 0.0 0.0 

K 621 500 121 1.3 0.0 2000 107 0.9 1.8 

Li 6.7 10 113 3.5 4.4 40 106 0.6 0.6 

Mg 24400 500 * * 8.4 2000 * * 10.1 

Mn 343 20 * * 8.5 100 95 11.0 1.6 

Mo 5.3 20 88 5.3 13.2 100 91 1.4 4.1 

Na 195 500 102 2.2 2.4 2000 100 1.5 3.7 

Ni 15.6 20 100 1.8 0.0 100 94 1.5 3.6 

P 595 500 106 13.4 8.0 2000 103 3.2 2.7 

Pb 145 20 88 51.8 17.9 100 108 15.6 17.4 

Sb 6.1 20 83 3.9 7.5 100 81 1.9 5.9 

Se <5 20 79 14.7 52.4 100 99 0.7 2.1 

Sn 16.6 20 91 34.6 5.8 80 112 8.7 2.8 

Sr 102 100 84 9.6 10.8 400 94 2.5 4.6 

Tl <4 20 92 4.8 14.6 100 91 1.5 4.6 

V 16.7 20 104 4.2 5.4 100 99 0.8 1.7 

Zn 131 20 103 31.2 7.3 100 104 7.2 6.4 

S (R) Standard deviation of percent recovery.

RPD Relative percent difference between duplicate spike determinations.

< Sample concentration below established method detection limit.

* Spike concentration <10% of sample background concentration.

– Not spiked.

 Equivalent. +
200.7-53

TABLE 7: PRECISION AND RECOVERY DATA IN SOLID MATRICES (Cont’d)

EPA ELECTROPLATING SLUDGE #286

Analyte mg/kg mg/kg R (%) S (R) RPD mg/kg R (%) S (R) RPD

Sample Low Average High Average

Conc. Spike Recovery Spike Recovery

+ +

Ag 6 20 96 0.2 0.4 100 93 0.1 0.4 

Al 4980 20 * * 4.4 100 * * 5.6 

As 32 20 94 1.3 0.8 100 97 0.7 1.6 

B 210 100 113 2.0 1.6 400 98 1.9 3.5 

Ba 39.8 20 0 6.8 0.3 100 0 1.6 5.7 

Be 0.32 20 96 0.2 0.5 100 101 0.7 2.0 

Ca 48500 – – – – – – – – 

Cd 108 20 98 2.5 0.8 100 96 0.5 0.5 

Co 5.9 20 93 2.9 5.7 100 93 0.6 1.5 

Cr 7580 20 * * 0.7 100 * * 1.3 

Cu 806 20 * * 1.5 100 94 8.3 0.7 

Fe 31100 – – – – – – – – 

Hg 6.1 10 90 2.5 4.0 40 97 1.7 4.3 

K 2390 500 75 8.3 4.0 2000 94 2.9 3.8 

Li 9.1 10 101 2.8 0.5 40 106 1.6 3.1 

Mg 1950 500 110 2.0 0.8 2000 108 2.3 3.2 

Mn 262 20 * * 1.8 100 91 1.2 0.9 

Mo 13.2 20 92 2.1 2.9 100 92 0.3 0.0 

Na 73400 500 * * 1.7 2000 * * 1.4 

Ni 456 20 * * 0.4 100 88 2.7 0.9 

P 9610 500 * * 2.9 2000 114 7.4 3.4 

Pb 1420 20 * * 2.1 100 * * 1.3 

Sb <2 20 76 0.9 3.3 100 75 2.8 10.7 

Se 6.3 20 86 9.0 16.6 100 103 1.6 2.7 

Sn 24.0 20 87 4.0 2.7 80 92 0.7 0.0 

Sr 145 100 90 8.1 8.1 400 93 2.4 4.6 

Tl 16 20 89 4.6 5.3 100 92 0.8 0.9 

V 21.7 20 95 1.2 1.0 100 96 0.4 0.9 

Zn 12500 20 * * 0.8 100 * * 0.8 

S (R) Standard deviation of percent recovery.

RPD Relative percent difference between duplicate spike determinations.

< Sample concentration below established method detection limit.

* Spike concentration <10% of sample background concentration.

– Not spiked.

 Equivalent. +
200.7-54

TABLE 7: PRECISION AND RECOVERY DATA IN SOLID MATRICES (Cont’d)

NBS 1645 RIVER SEDIMENT

Analyte mg/kg mg/kg R (%) S (R) RPD mg/kg R (%) S (R) RPD

Sample Low Average High Average

Conc. Spike Recovery Spike Recovery

+ +

Ag 1.6 20 92 0.4 1.0 100 96 0.3 0.9 

Al 5160 20 * * 8.4 100 * * 2.4 

As 62.8 20 89 14.4 9.7 100 97 2.9 5.0 

B 31.9 100 116 7.1 13.5 400 95 0.6 1.5 

Ba 54.8 20 95 6.1 2.8 100 98 1.2 1.3 

Be 0.72 20 101 0.4 1.0 100 103 1.4 3.9 

Ca 28000 – – – – – – – – 

Cd 9.7 20 100 1.1 0.0 100 101 0.7 1.8 

Co 9.4 20 98 3.8 4.8 100 98 0.9 1.8 

Cr 28500 20 * * 0.4 100 * * 0.7 

Cu 109 20 115 8.5 0.0 100 102 1.8 1.0 

Fe 84800 – – – – – – – – 

Hg 3.1 10 99 4.3 7.7 40 96 0.7 1.0 

K 452 500 98 4.1 2.0 2000 106 1.4 2.3 

Li 3.7 10 101 2.0 0.7 40 108 1.3 3.0 

Mg 6360 500 * * 1.8 2000 93 2.7 1.0 

Mn 728 20 * * 3.5 100 97 12.4 2.2 

Mo 17.9 20 97 12.5 18.5 100 98 0.6 0.0 

Na 1020 500 92 2.6 0.0 2000 97 1.1 1.7 

Ni 36.2 20 94 5.9 4.0 100 100 1.1 1.5 

P 553 500 102 1.4 0.9 2000 100 0.8 1.6 

Pb 707 20 * * 0.8 100 103 5.9 0.4 

Sb 22.8 20 86 2.3 0.0 100 88 0.6 0.9 

Se 6.7 20 103 14.3 27.1 100 98 3.1 7.6 

Sn 309 20 * * 1.0 80 101 7.9 2.7 

Sr 782 100 91 12.3 3.0 400 96 3.3 2.6 

Tl <4 20 90 0.0 0.0 100 95 1.3 4.0 

V 20.1 20 89 5.4 5.8 100 98 0.7 0.0 

Zn 1640 20 * * 1.8 100 * * 1.1 

S (R) Standard deviation of percent recovery.

RPD Relative percent difference between duplicate spike determinations.

< Sample concentration below established method detection limit.

* Spike concentration <10% of sample background concentration.

– Not spiked.

 Equivalent. +
200.7-55

TABLE 8: ICP-AES INSTRUMENTAL PRECISION AND ACCURACY FOR

AQUEOUS SOLUTIONSa

Element (mg/L) N (%) (% of Nominal)

Mean

Conc. RSD Accuracy b

c

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 

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 

These performance values are independent of sample preparation because the labs a

analyzed portions of the same solutions using sequential or simultaneous

instruments.22

N = Number of measurements for mean and relative standard deviation (RSD). b

Accuracy is expressed as a percentage of the nominal value for each analyte in the c

acidified, multi-element solutions.
200.7-56

TABLE 9: MULTILABORATORY ICP PRECISION AND

ACCURACY DATA*

Analyte μg/L μ/L

Concentration Total Recoverable Digestion

Aluminum 69-4792 X = 0.9380 (C) + 22.1

Antimony 77-1406 X = 0.8908 (C) + 0.9

Arsenic 69-1887 X = 1.0175 (C) + 3.9

Barium 9-377 X = 0.8380 (C) + 1.68

Beryllium 3-1906 X = 1.0177 (C) - 0.55

Boron 19-5189 X = 0.9676 (C) + 18.7

Cadmium 9-1943 X = 1.0137 (C) - 0.65

Calcium 17-47170 X = 0.9658 (C) + 0.8

Chromium 13-1406 X = 1.0049 (C) - 1.2

Cobalt 17-2340 X = 0.9278 (C) - 1.5

Copper 8-1887 X = 0.9647 (C) - 3.64

Iron 13-9359 X = 0.9830 (C) + 5.7

Lead 42-4717 X = 1.0056 (C) + 4.1

SR = 0.0481 (X) + 18.8

SR = 0.0682 (X) + 2.5

SR = 0.0643 (X) + 10.3

SR = 0.0826 (X) + 3.54

SR = 0.0445 (X) - 0.10

SR = 0.0743 (X) + 21.1

SR = 0.0332 (X) + 0.90

SR = 0.0327 (X) + 10.1

SR = 0.0571 (X) + 1.0

SR = 0.0407 (X) + 0.4

SR = 0.0406 (X) + 0.96

SR = 0.0790 (X) + 11.5

SR = 0.0448 (X) + 3.5

 - Regression equations abstracted from Reference 16. *

X = Mean Recovery, μg/L.

C = True Value for the Concentration, μg/L.

SR = Single-analyst Standard Deviation, μg/L.
TABLE 9: MULTILABORATORY ICP PRECISION AND

ACCURACY DATA*

Analyte μg/L μ/L

Concentration Total Recoverable Digestion

200.7-57

Magnesium 34-13868 X = 0.9879 (C) + 2.2

Manganese 4-1887 X = 0.9725 (C) + 0.07

Molybdenum 17-1830 X = 0.9707 (C) - 2.3

Nickel 17-47170 X = 0.9869 (C) + 1.5

Potassium 347-14151 X = 0.9355 (C) - 183.1

Selenium 69-1415 X = 0.9737 (C) - 1.0

Silicon 189-9434 X = 0.9737 (C) - 60.8

Silver 8-189 X = 0.3987 (C) + 8.25

Sodium 35-47170 X = 1.0526 (C) + 26.7

Thallium 79-1434 X = 0.9238 (C) + 5.5

Vanadium 13-4698 X = 0.9551 (C) + 0.4

Zinc 7-7076 X = 0.9500 (C) + 1.82

SR = 0.0268 (X) + 8.1

SR = 0.0400 (X) + 0.82

SR = 0.0529 (X) + 2.1

SR = 0.0393 (X) + 2.2

SR = 0.0329 (X) + 60.9

SR = 0.0443 (X) + 6.6

SR = 0.2133 (X) + 22.6

SR = 0.1836 (X) - 0.27

SR = 0.0884 (X) + 50.5

SR = -0.0106 (X) + 48.0

SR = 0.0472 (X) + 0.5

SR = 0.0153 (X) + 7.78

 - Regression equations abstracted from Reference 16. *

X = Mean Recovery, μg/L.

C = True Value for the Concentration, μg/L.

SR = Single-analyst Standard Deviation, μg/L.
200.7-58