EPA-821-R-01-011
January 2001
METHOD 200.9
TRACE ELEMENTS IN WATER, SOLIDS, AND BIOSOLIDS BY
STABILIZED TEMPERATURE GRAPHITE FURNACE ATOMIC
ABSORPTION SPECTROMETRY
Revision 3.0
January 2001
U.S. Environmental Protection Agency
Office of Science and Technology
Ariel Rios Building
1200 Pennsylvania Avenue, N.W.
Washington, D.C. 20460
-------
Method 200.9
Acknowledgments
Revision 3.0 of Method 200.9 was prepared under the direction of William A. Telliard of the U.S.
Environmental Protection Agencies (EPA's) Office of Water (OW), Engineering and Analysis Division
(EAD) in collaboration with Ted Martin, of EPA's Office of Research and Development's National
Exposure Research Laboratory in Cincinnati, Ohio. The method was prepared under EPA Contract 68-
C3-0337 by DynCorp Consulting Services Division with assistance from Quality Works, Inc. and
Westover Scientific, Inc.
The following personnel at the EPA Office of Research and Development's National Exposure Research
Laboratory in Cincinnati, Ohio, are gratefully acknowledged for the development of the analytical
procedures described in this method:
J.T. Creed, T.D. Martin, L.B. Lobring, and J.W. O'Dell - Method 200.9, Revision 1.2 (1991)
J.T. Creed, T.D. Martin, and J.W. O'Dell - Method 200.9, Revision 2.2 (1994)
Disclaimer
This draft method has been reviewed and approved for publication by the Analytical Methods Staff within
the Engineering and Analysis Division of the U.S. Environmental Protection Agency. Mention of trade
names or commercial products does not constitute endorsement or recommendation for use. EPA plans
further validation of this draft method. The method may be revised following validation to reflect results of
the study. This method version contains minor editorial changes to the October 2000 version.
EPA welcomes suggestions for improvement of this method. Suggestions and questions concerning this
method or its application should be addressed to:
W.A. Telliard
Analytical Methods Staff (4303)
Office of Science and Technology
U.S. Environmental Protection Agency
Ariel Rios Building
1200 Pennsylvania Avenue, N.W.
Washington, D.C. 20460
Phone: 202/260-7134
Fax: 202/260-7185
Draft, January 2001
-------
Method 200.9
Note: This method is performance based. The laboratory is permitted to omit any step or modify
any procedure provided that all performance requirements in this method are met. The laboratory
may not omit any quality control analyses. The terms "must," "shall," and "may not" define
procedures required for producing reliable data for producing reliable results. The terms "may"
and "should" indicate optional steps that may be modified or omitted if the laboratory can
demonstrate that the modified method produces results equivalent or superior to results produced
by this method.
Draft, January 2001
-------
Method 200.9
Trace Elements in Water, Solids, and Biosolids by Stabilized
Temperature
Graphite Furnace Atomic Absorption Spectrometry
1.0 Scope and Application
1.1 This method provides procedures for the determination of dissolved and total recoverable elements
by graphite furnace atomic absorption spectrometry (GFAA) in ground water, surface water,
drinking water, storm runoff, and industrial and domestic wastewater (Reference 1). This method
is also applicable to the determination of total recoverable elements in sediment, biosolids
(municipal sewage sludge), and soil. This method is applicable to the following analytes:
Analyte
Aluminum
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Cobalt
Copper
Iron
Lead
Manganese
Nickel
Selenium
Silver
Thallium
Tin
(Al)
(Sb)
(As)
(Be)
(Cd)
(Cr)
(Co)
(Cu)
(Fe)
(Pb)
(Mn)
(Ni)
(Se)
(Ag)
(Tl)
(Sn)
Chemical Abstract Services
Registry Number (CASRN)
7429-90-5
7440-36-0
7440-38-2
7440-41-7
7440-43-9
7440-47-3
7440-48-4
7440-50-8
7439-89-6
7439-92-1
7439-96-5
7440-02-0
7782-49-2
7440-22-4
7440-28-0
7440-31-5
1.2 To confirm approval of this method 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 CFRPart 136 Table IB for NPDES, and Part 141 § 141.23 for
drinking water), and the latest Federal Register announcements.
1.3 Dissolved analytes can be determined in aqueous samples after suitable filtration and acid
preservation.
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 by direct injection into the
Draft, January 2001 1
-------
Method 200.9
furnace without acid digestion if the sample has been properly preserved with acid, has turbidity of
<1 NTU at the time of analysis, and is analyzed using the appropriate method matrix modifiers.
This total recoverable determination procedure is referred to as "direct analysis". However, in the
determination of some primary drinking water metal contaminants, such as arsenic and thallium,
preconcentration of the sample may be required prior to analysis in order to meet drinking water
acceptance performance criteria (Section 11.5.8).
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., soil,
biosolids, sediment and aqueous samples that may contain particulate and suspended solids).
Aqueous samples containing total suspended solids > 1% (w/v) should be extracted as a solid
sample.
1.6 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
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 extract of solid samples containing concentrations of silver >50 mg/kg should be
treated in a similar manner.
1.7 Method detection limits (MDLs; 40 CFR 136, Appendix B) and minimum levels (MLs) when no
interferences are present will be determined for this method through a validation study (Table 1).
The ML for each analyte can be calculated by multiplying the MDL by 3.18 and rounding to the
nearest (2, 5, or 10 X 10") where n is an integer.
1.8 The sensitivity and limited linear dynamic range (LDR) of GFAA often requires dilution of a
sample prior to analysis. The magnitude of the dilution as well as the cleanliness of the labware
used to perform the dilution can dramatically influence the quality of the analytical results.
Therefore, samples requiring large dilutions (>50:1) should be analyzed by another approved test
procedure having a larger LDR or having less sensitivity than GFAA.
1.9 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.
1.10 This method is accompanied by Appendix A: Total Solids in Solid and Semi-Solid Matrices. The
procedure in Appendix A should be followed for sludge and solid samples analyzed under Sections
11.3 and 11.4.
1.11 This method will be validated in biosolids for those analytes regulated under 40 CFR Part 503
only. It is believed to be applicable for the analysis of biosolids for all analytes listed in Section
1.1.
Draft, January 2001
-------
Method 200.9
2.0 Summary of Method
2.1 An aliquot of a well-mixed, homogeneous sample is accurately weighed or measured for sample
processing. For total recoverable analysis of a solid or aqueous sample containing undissolved
material, analytes are first solubilized by gentle refluxing with nitric and hydrochloric acids. For
total recoverable analysis of a sludge sample, analytes are first solubilized by gentle refluxing with
nitric and hydrochloric acids and hydrogen peroxide. After cooling, the sample is made up to
volume, 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 where sample turbidity is <1 NTU, the sample is made
ready for analysis by addition of nitric acid, and then diluted to a predetermined volume and mixed
before analysis.
2.2 The analytes listed in this method are determined by stabilized temperature platform graphite
furnace atomic absorption (STPGFAA). In STPGFAA, an aliquot of the sample and the matrix
modifier are first pipetted onto the instrument platform, a device which permits delayed
atomization. The furnace chamber is then purged with a continuous flow of a premixed gas (95%
argon - 5% hydrogen). The sample is allowed to dry at a relatively low temperature (about 120°C)
to avoid spattering. Once dried, the sample is pretreated in a char or ashing step which is designed
to minimize matrix interference effects. After the char step, the furnace is allowed to cool prior to
atomization. The atomization cycle is characterized by rapid heating of the furnace to a
temperature where the metal (analyte) is atomized from the pyrolytic graphite surface into a
stopped gas flow atmosphere of argon containing 5% hydrogen. (Selenium is determined in an
atmosphere of high purity argon). The resulting atomic cloud absorbs the element-specific atomic
emission produced by a hollow cathode lamp or an electrodeless discharge lamp (EDL). Following
analysis, the furnace is subjected to a clean out period of high temperature and continuous argon
flow. Because the resulting absorbance usually has a nonspecific component associated with the
actual analyte absorbance, a correction is required to subtract background absorbance from the
total signal. In the absence of interferences, background corrected absorbance is directly related to
the concentration of the analyte. Interferences relating to STPGFAA (Section 4.0) must be
recognized and corrected. Suppressions or enhancements of instrument response caused by the
sample matrix must be corrected by the method of standard addition (Section 11.6).
3.0 Definitions
3.1 Biosolids-A solid, semisolid, or liquid residue (sludge) generated during treatment of domestic
sewage in a treatment works.
3.2 Calibration blank-A volume of reagent water acidified with the same acid matrix as the calibration
standards. The calibration blank is a zero standard and is used to auto-zero the AA instrument
(Section 7.13.1).
3.3 Calibration standard-A solution prepared from the dilution of stock standard solutions (Section
7.11). The calibration solutions are used to calibrate instrument response with respect to analyte
concentration.
Draft, January 2001
-------
Method 200.9
3.4 Calibration verification (CV) solution-A solution of method analytes, used to evaluate
performance of the instrument system with respect to a defined set of method criteria (Sections
7.14 and 9.3).
3.5 Dissolved analvte-The concentration of analyte in an aqueous sample that will pass through a 0.45
(jm membrane filter assembly prior to sample acidification (Section 8.2).
3.6 Field blank-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 field blank is to determine if method analytes or other interferences are present in
the field environment (Section 9.5.2).
3.7 Linear dynamic range (LDR)-The concentration range over which the instrument response to an
analyte is linear (Section 9.2.3).
3.8 Matrix modifier-A substance added to the graphite furnace along with the sample in order to
minimize the interference effects by selective volatilization of either analyte or matrix components.
3.9 Matrix spike (MS) and matrix spike duplicate (MSD)-Two aliquots of the same environmental
sample to which known quantities of the method analytes are added in the laboratory. The MS and
MSB are analyzed exactly like a sample, and their purpose is to determine whether the sample
matrix contributes bias to the analytical results and to indicate precision associated with laboratory
procedures. The background concentrations of the analytes in the sample matrix must be
determined in a separate aliquot and the measured values in the MS and MSB corrected for
background concentrations (Section 9.4).
3.10 Mav-This action, activity, or procedural step is neither required nor prohibited.
3.11 May not-This action, activity, or procedural step is prohibited.
3.12 Method blank-An aliquot of reagent water or other blank matrices that is treated exactly as a
sample including exposure to all glassware, equipment, solvents, reagents, and internal standards
that are used with other samples. The method blank is used to determine if method analytes or
other interferences are present in the laboratory environment, reagents, or apparatus (Sections
7.13.2 and 9.5.1).
3.13 Method detection limit (MBL)-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 9.2.1 and Table 1). The MBL is determined according to procedures in 40 CFR Part 136
Appendix B.
3.14 Minimum level (ML)-The lowest level at which the entire analytical system gives a recognizable
signal and acceptable calibration point for the analyte. It is equivalent to the concentration of the
lowest calibration standard, assuming that all method-specific sample weights, volumes and
cleanup procedures have been employed.
Draft, January 2001
-------
Method 200.9
3.15 Must-This action, activity, or procedural step is required.
3.16 Ongoing precision and recovery (OPR) standard-The OPR test is used to ensure that the
laboratory meets performance criteria during the period that samples are analyzed. It also
separates laboratory performance from method performance on the sample matrix. For aqueous
samples, the OPR solution is an aliquot of method blank to which known quantities of the method
analytes are added in the laboratory. For solid samples, the use of clean sand, soil or peat moss to
which known quantities of the method analytes are added in the laboratory is recommended. The
OPR is analyzed in the same manner as samples (Section 9.6).
3.17 Shall-This action, activity or procedural step is required.
3.18 Should-This action, activity, or procedural step is suggested but not required.
3.19 Solid sample-For the purpose of this method, a sample taken from material classified as either soil,
sediment or industrial sludge.
3.20 Standard addition-The addition of a known amount of analyte to the sample in order to determine
the relative response of the detector to that analyte within the sample matrix. The relative response
is then used to assess either an operative matrix effect or the sample analyte concentration
(Sections 9.7 and 11.6).
3.21 Standard stock 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 7.11).
3.22 Total recoverable analvte-The concentration of analyte determined to be in either a solid sample or
an unfiltered aqueous sample following treatment by refluxing with hot dilute mineral acid(s) as
specified in the method (Sections 11.2, 11.3, and 11.4).
3.23 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 Several interference sources may cause inaccuracies in the determination of trace elements by
GFAA. These interferences can be classified into three major subdivisions: spectral, matrix, and
memory.
4.2 Spectral interferences are caused by the resulting absorbance of light from the spectrometer lamp
by a molecule or atom which is not the analyte of interest. Spectral interferences also can arise
from black body radiation coming from the carbon platform.
4.2.1 Spectral interferences caused by an element only occur if there is a spectral overlap
between the wavelength of the interfering element and the analyte of interest. Fortunately,
this type of interference is relatively uncommon in STPGFAA because of the narrow
atomic line widths associated with this technology. In addition, the use of appropriate
Draft, January 2001 5
-------
Method 200.9
furnace temperature programs and high spectral-purity lamps as light sources can
minimize this type of interference. However, molecular absorbances can span several
hundred nanometers producing broadband spectral interferences. This latter interference is
far more common in STPGFAA. Matrix modifiers, selective volatilization, and
background correctors can all be used to minimize unwanted nonspecific absorbance. The
nonspecific component of total absorbance can vary considerably among sample types.
Therefore, the effectiveness of a particular background correction device may vary
depending on the actual analyte wavelength used as well as the nature and magnitude of
the interference. The background correction device to be used with this method is not
specified. However, whichever one is chosen must provide an analytical condition that is
not subject to the occurring inter-element spectral interferences of palladium on copper,
iron on selenium, and aluminum on arsenic.
4.2.2 Spectral interferences are also caused by the emissions from black body radiation
produced during the atomization furnace cycle from the carbon surface of the sample
platform. The magnitude of this interference can be minimized by proper furnace tube
alignment and monochromator design. In addition, atomization temperatures which are
adjusted to adequately volatilize the analyte of interest while minimizing black body
radiation can reduce unwanted background emission.
4.3 Matrix interferences are caused by sample components which inhibit the formation of free atomic
analyte during the atomization cycle.
4.3.1 Matrix interferences can be of a chemical or physical nature. In this method, the use of a
delayed atomization device which provides stabilized temperatures is required. These
devices provide an environment which is more conducive to the formation of free analyte
atoms and thereby minimize matrix interferences. This type of interference can be detected
by analyzing the sample plus a sample aliquot fortified with a known concentration of the
analyte. If the determined concentration of the analyte addition is outside a designated
range, a possible matrix effect should be suspected (Section 9.4).
4.3.2 The use of nitric acid is preferred for most GFAA analyses in order to minimize vapor
state anionic chemical interferences. However, in this method hydrochloric acid is required
to maintain stability in solutions containing antimony and silver. When hydrochloric acid
is used, the chloride ion vapor state interferences must be reduced using an appropriate
matrix modifier. In this method, a combination modifier of palladium, magnesium nitrate
and a hydrogen(5%)-argon(95%) gas mixture is used. The effects and benefits of using
this modifier are discussed in detail in Reference 2. Listed in Section 4.4 are some
typically observed effects when using this modifier.
4.4 Specific element interferences.
4.4.1 Antimony-Antimony suffers from an interference produced by K2SO4 (Reference 3). In
the absence of hydrogen in the char cycle (1300°C), K2SO4 produces a relatively high (1.2
abs) background absorbance which can produce a false signal, even with Zeeman
background correction. However, this background level can be reduced dramatically (0.1
Draft, January 2001
-------
Method 200.9
abs) by the use of a hydrogen/argon gas mixture in the char step. This reduction in
background is strongly influenced by the temperature of the char step.
NOTE: The actual furnace temperature may vary from instrument to instrument. Therefore,
the optimal furnace temperature should be determined on each instrument.
4.4.2 Aluminum-The palladium matrix modifier may have elevated levels of Al which will cause
elevated blank absorbances.
4.4.3 Arsenic-HCl present from digestion can influence As sensitivity. Twenty micro liters of a
1% HC1 solution with Pd used as a modifier results in a 20% loss in sensitivity relative to
the analyte in a 1% HNO3 solution. Unfortunately, the use of Pd/Mg/H2 as a modifier
does not significantly reduce this suppression, and therefore, it is imperative that each
sample and calibration standard alike contain the same HC1 concentration (Reference 2).
4.4.4 Cadmium-HCl present from digestion can influence Cd sensitivity. Twenty micro liters of
a 1% HC1 solution with Pd used as a modifier results in an 80% loss in sensitivity relative
to the analyte in a 1% HNO3 solution. The use of Pd/Mg/H2 as a matrix modifier reduces
this suppression to less than 10% (Reference 2).
4.4.5 Lead-HCl present from digestion can influence Pb sensitivity. Twenty micro liters of a
1% HC1 solution with Pd used as a modifier results in a 75% loss in sensitivity relative to
the analyte response in a 1% HNO3 solution. The use of Pd/Mg/H2 as a matrix modifier
reduces this suppression to less than 10% (Reference 2).
4.4.6 Selenium-Iron has been shown to suppress Se response with continuum background
correction (Reference 3). In addition, the use of hydrogen as a purge gas during the dry
and char steps can cause a suppression in Se response if not purged from the furnace prior
to atomization.
4.4.7 Silver-Palladium used in a modifier preparation may have elevated levels of Ag which will
cause elevated blank absorbances.
4.4.8 Thallium-HCl present from digestion can influence Tl sensitivity. Twenty micro liters of
a 1% HC1 solution with Pd used as a modifier results in a 90% loss in sensitivity relative
to the analyte in a 1% HNO3 solution. The use of Pd/Mg/H2 as a matrix modifier reduces
this suppression to less than 10% (Reference 2).
4.5 Memory interferences result from analyzing a sample containing a high concentration of an element
(typically a high atomization temperature element) which cannot be removed quantitatively in one
complete set of furnace steps. Analyte which remains in a furnace can produce false positive
signals on subsequent sample(s). Therefore, an analyst should establish the analyte concentration
which can be injected into the furnace and adequately removed in one complete set of furnace
cycles. If this concentration is exceeded, the sample should be diluted and a blank analyzed to
assure the memory effect has been eliminated before analyzing the diluted sample.
Draft, January 2001
-------
Method 200.9
5.0 Safety
5.1 The toxicity and 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 (References 4-7). A reference file of material data handling
sheets should also be made available to all personnel involved in the chemical analysis.
Specifically, concentrated nitric and hydrochloric acids present various hazards to laboratory
personnel as both are moderately toxic and extremely irritating to skin and mucus membranes. Use
these reagents in a fume hood whenever possible and if eye or skin contact occurs, flush with large
volumes of water. Always wear safety glasses or a shield for eye protection as well as 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 agents.
5.4 During atomization, the graphite tube emits intense UV radiation. Suitable eye-safe precautions
should be taken to protect laboratory personnel.
5.5 The use of the argon/hydrogen gas mixture during the dry and char steps may evolve a
considerable amount of HC1 gas. Therefore, adequate ventilation is required.
5.6 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
NOTE: The mention of trade names or commercial products in this method is for illustrative
purposes only and does not constitute endorsement or recommendation for use by the
Environmental Protection Agency. Equivalent performance may be achievable using apparatus
and materials other than those suggested here. The laboratory is responsible for demonstrating
equivalent performance.
6.1 Graphite furnace atomic absorbance spectrophotometer.
6.1.1 The GFAA spectrometer must be capable of programmed heating of the graphite tube and
the associated delayed atomization device. The instrument must be equipped with an
adequate background correction device capable of removing undesirable nonspecific
absorbance over the spectral region of interest and provide an analytical condition not
subject to the occurrence of inter-element spectral overlap interferences. The furnace
device must be capable of using an alternate gas supply during specified cycles of the
analysis. The capability to record relatively fast (<1 s) transient signals and evaluate data
Draft, January 2001
-------
Method 200.9
on a peak area basis is preferred. In addition, a recirculating refrigeration bath is
recommended for improved reproducibility of furnace temperatures.
6.1.2 Single-element hollow cathode lamps or single-element electrodeless discharge lamps along
with the associated power supplies. Multi-element lamps may be used if they can be
shown to meet the detection limit and quality control requirements in Section 9.2.
6.1.3 Argon gas supply (high-purity grade, 99.99%) for use during the atomization of selenium,
for sheathing the furnace tube when in operation, and during furnace clean out.
6.1.4 Alternate gas mixture (hydrogen 5%-argon 95%) for use as a continuous gas flow
environment during the dry and char furnace cycles. This gas mixture must be used for all
metals. Care must be taken when the gas mixture is used for selenium (Section 4.4.6).
6.1.5 Autosampler capable of adding matrix modifier solutions to the furnace, a single addition
of analyte, and completing methods of standard additions when required.
6.2 Analytical balance, with capability to measure to 0.1 mg, for use in weighing solids, preparing
standards, and determining dissolved solids in digests or extracts.
6.3 A temperature adjustable hot plate capable of maintaining a temperature of 95 °C.
6.4 (Optional) A steel cabinet centrifuge with guard bowl, electric timer and brake.
6.5 A gravity convection drying oven with thermostatic control capable of maintaining 180°C±5°C.
6.6 (Optional) An air displacement pipetter capable of delivering volumes ranging from 100 - 2500
yL with an assortment of high quality, disposable pipet tips.
6.7 Mortar and pestle, ceramic or nonmetallic material.
6.8 Polypropylene sieve, 5-mesh (4 mm opening).
6.9 Labware-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) HNO3 or a mixture of dilute HNO3 and HC1 (1:2:9), rinsing with reagent water and
storing clean (Reference 1). Ideally, ground glass surfaces should be avoided to eliminate a
potential source of random contamination. When this is impractical, particular attention should be
given to all ground glass surfaces during cleaning. Chromic acid cleaning solutions must be
avoided because chromium is an analyte.
6.9.1 Glassware-Volumetric flasks, graduated cylinders, funnels and centrifuge tubes (glass
and/or metal-free plastic).
6.9.2 Assorted calibrated pipettes.
Draft, January 2001
-------
Method 200.9
6.9.3 Conical Phillips beakers, 250 mL with 50 mm watch glasses.
6.9.4 Griffin beakers, 250 mL with 75 mm watch glasses and (optional) 75 mm ribbed watch
glasses.
6.9.5 (Optional) PTFE and/or quartz Griffin beakers, 250 mL with PTFE covers.
6.9.6 Evaporating dishes or high-form crucibles, porcelain, 100 mL capacity.
6.9.7 Narrow-mouth storage bottles, FEP (fluorinated ethylene propylene) with screw closure,
125 mL to 1 L capacities.
6.9.8 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. Whenever possible,
high-purity reagents that conform to the American Chemical Society specifications should be used
(Reference 8). If the purity of a reagent is 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)-HC1.
7.2.1 Hydrochloric acid (1:1)- Add 500 mL concentrated HC1 to 400 mL reagent water and
dilute to 1 L.
7.2.2 Hydrochloric acid (1:4) - Add 200 mL concentrated HC1 to 400 mL reagent water and
dilute to 1 L.
7.3 Nitric acid, concentrated (sp.gr. 1.41)-HNO3.
7.3.1 Nitric acid (1: l)-Add 500 mL concentrated HNO3 to 400 mL reagent water and dilute to 1
L.
7.3.2 Nitric acid (l:5)-Add 50 mL concentrated HNO3 to 250 mL reagent water.
7.3.3 Nitric acid (l:9)-Add 10 mL concentrated HNO3 to 90 mL reagent water.
7.4 Reagent water-All references to water in this method refer to ASTM Type I grade water
(Reference 9).
7.5 Ammonium hydroxide, concentrated (sp. gr. 0.902).
7.6 Tartaric acid, ACS reagent grade.
10 Draft, January 2001
-------
Method 200.9
7.7 Matrix modifier-Dissolve 300 mg palladium (Pd) powder in cone. HNO3 (1 mL of HNO3, adding
0.1 mL of concentrated HC1 if necessary). Dissolve 200 mg of Mg(NO3)2 in reagent water. Pour
the two solutions together and dilute to 100 mL with reagent water.
NOTE: It is recommended that the matrix modifier be analyzed separately in order to assess
the contribution of the modifier to the absorbance of calibration and reagent blank solutions.
7.8 Hydrogen peroxide, 30%, stabilized certified reagent grade.
7.9 Clean sand or soil-All references to clean sand or soil in this method refer to sand or soil certified
to be free of the analytes of interest at or above their MDLs or to contain those analytes at certified
levels.
7.10 Peat moss-All references to peat moss in this method refer to sphagnum peat moss certified to be
free of arsenic, cadmium, copper, lead, nickel, and selenium at or above their MDLs or to contain
those analytes at certified levels.
7.11 Standard stock solutions 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. 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.
Draft, January 2001 11
-------
Method 200.9
Equation 1
From a pure element:
Where:
C = concentration (mg/L)
m = mass (mg)
V = volume (L)
From pure compound:
V
Where:
C = concentration (mg/L)
m = mass (mg)
gf= gravimetric factor (mass fraction of the analyte in the compound)
V = volume (L)
7.11.1 Aluminum solution, stock, 1 mL = 1000 (jg Al: Dissolve 1.000 g of aluminum metal,
weighed to at least four significant figures, in 4.0 mL (1:1) HC1 and 1.0 mL concentrated
HNO3 in a beaker. Warm the beaker slowly to effect solution. When dissolution is
complete, transfer solution quantitatively to a 1 L flask, add an additional 10.0 mL (1:1)
HC1 and dilute to volume with reagent water.
7.11.2 Antimony solution, stock, 1 mL = 1000 (jg Sb: Dissolve 1.000 g of antimony powder,
weighed accurately to at least four significant figures, in 20.0 mL (1:1) HNO3 and 10.0
mL concentrated HC1. Add 100 mL reagent water and 1.50 g tartaric acid. Warm
solution slightly to effect complete dissolution. Cool solution and add reagent water to
volume in a 1 L volumetric flask.
7.11.3 Arsenic solution, stock, 1 mL = 1000 (jg As: Dissolve 1.320 g of As2O3 (As fraction =
0.7574), weighed accurately to at least four significant figures, in 100 mL of reagent water
containing 10.0 mL concentrated NH4OH. Warm the solution gently to effect dissolution.
Acidify the solution with 20.0 mL concentrated HNO3 and dilute to volume in a 1 L
volumetric flask with reagent water.
7.11.4 Beryllium solution, stock, 1 mL = 1000 (jg Be: DO NOT DRY. Dissolve 19.66 g
BeSO4»4H2O (Be fraction = 0.0509), weighed accurately to at least four significant
figures, in reagent water, add 10.0 mL concentrated HNO3, and dilute to volume in a 1 L
volumetric flask with reagent water.
7.11.5 Cadmium solution, stock, 1 mL = 1000 (jg Cd: Dissolve 1.000 g Cd metal, acid cleaned
with (1:9) HNO3, weighed accurately to at least four significant figures, in 50 mL (1:1)
12 Draft, January 2001
-------
Method 200.9
HNO3 with heating to effect dissolution. Let solution cool and dilute with reagent water in
a 1 L volumetric flask.
7.11.6 Chromium solution, stock, 1 mL = 1000 (jg Cr: Dissolve 1.923 g CrO3 (Cr fraction =
0.5200), weighed accurately to at least four significant figures, in 120 mL (1:5) HNO3.
When solution is complete, dilute to volume in a 1 L volumetric flask with reagent water.
7.11.7 Cobalt solution, stock, 1 mL = 1000 (jg Co: Dissolve 1.000 g Co metal, acid cleaned with
(1:9) HNO3, weighed accurately to at least four significant figures, in 50.0 mL (1:1)
HNO3. Let solution cool and dilute to volume in a 1 L volumetric flask with reagent
water.
7.11.8 Copper solution, stock, 1 mL = 1000 (jg Cu: Dissolve 1.000 g Cu metal, acid cleaned
with (1:9) HNO3, weighed accurately to at least four significant figures, in 50.0 mL (1:1)
HNO3 with heating to effect dissolution. Let solution cool and dilute in a 1 L volumetric
flask with reagent water.
7.11.9 Iron solution, stock, 1 mL = 1000 (jg Fe: Dissolve 1.000 g Fe metal, acid cleaned with
(1:1) HC1, weighed accurately to four significant figures, in 100 mL (1:1) HC1 with
heating to effect dissolution. Let solution cool and dilute with reagent water in a 1 L
volumetric flask.
7.11.10 Lead solution, stock, 1 mL = 1000 (jg Pb: Dissolve 1.599 g Pb(NO3)2
(Pb fraction = 0.6256), weighed accurately to at least four significant figures, in a
minimum amount of (1:1) FINO3. Add 20.0 mL (1:1) FINO3 and dilute to volume
in a 1 L volumetric flask with reagent water.
7.11.11 Manganese solution, stock, 1 mL = 1000 (jg Mn: Dissolve 1.000 g of manganese
metal, weighed accurately to at least four significant figures, in 50 mL (1:1) HNO3
and dilute to volume in a 1 L volumetric flask with reagent water.
7.11.12 Nickel solution, stock, 1 mL = 1000 (jg Ni: Dissolve 1.000 g of nickel metal,
weighed accurately to at least four significant figures, in 20.0 mL hot concentrated
FINO3, cool, and dilute to volume in a 1 L volumetric flask with reagent water.
7.11.13 Selenium solution, stock, 1 mL = 1000 (jg 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.
7.11.14 Silver solution, stock, 1 mL = 1000 (jg Ag: Dissolve 1.000 g Ag metal, weighed
accurately to at least four significant figures, in 80 mL (1:1) FINO3 with heating to
effect dissolution. Let solution cool and dilute with reagent water in a 1 L
volumetric flask. Store solution in amber bottle or wrap a clear bottle completely
with aluminum foil to protect solution from light.
7.11.15 Thallium solution, stock, 1 mL = 1000 (jg Tl: Dissolve 1.303 g T1NO3
(Tl fraction = 0.7672), weighed accurately to at least four significant figures, in
Draft, January 2001 13
-------
Method 200.9
reagent water. Add 10.0 mL concentrated HNO3 and dilute to volume in a 1 L
volumetric flask with reagent water.
7.11.16 Tin solution, stock, 1 mL = 1000 (jg Sn: Dissolve 1.000 g Sn shot, weighed
accurately to at least four significant figures, in an acid mixture of 10.0 mL
concentrated HC1 and 2.0 mL (1:1) HNO3 with heating to effect dissolution. Let
solution cool, add 200 mL concentrated HC1, and dilute to volume in a 1 L
volumetric flask with reagent water.
7.12 Preparation of calibration standards-Fresh calibration standards should be prepared every two
weeks, or as needed. Dilute each of the stock standard solutions to levels appropriate to the
operating range of the instrument using the appropriate acid diluent (see note). The element
concentrations in each calibration solution should be sufficiently high to produce good
measurement precision and to accurately define the slope of the response curve. The instrument
calibration should be initially verified using a quality control sample (Sections 7.15 and 9.2.4).
NOTE: The appropriate acid diluent for the determination of dissolved elements in water and
for the "direct analysis " of drinking water with turbidity <1 NTU is 1 % HNO3. For total
recoverable elements in waters, the appropriate acid diluent is 2% HNO3 and 1 % HCl, and the
appropriate acid diluent for total recoverable elements in sludge and solid samples is 2% HNO3
and 2% HCl. The reason for these different diluents is to match the types of acids and the acid
concentrations of the samples with the acid present in the standards and blanks.
7.13 Blanks-Three types of blanks are required for this method. A calibration blank is used to establish
the analytical calibration curve, a method blank is used to assess possible contamination from the
sample preparation procedure and to assess spectral background, and a rinse blank is used to flush
the instrument autosampler uptake system. All diluent acids should be made from concentrated
acids (Sections 7.2 and 7.3) and reagent water.
7.13.1 The calibration blank consists of the appropriate acid diluent (Section 7.12 note)
(HC1/HNO3) in ASTM Type I water. The calibration blank should be stored in a FEP
bottle.
7.13.2 The method blank must contain all reagents in the same volumes as used in processing the
samples. The method blank must be carried through the same entire preparation scheme as
the samples including sample digestion, when applicable.
7.13.3 The rinse blank is prepared as needed by adding 1.0 mL of cone. HNO3 and 1.0 mL cone.
HCl to 1 L of ASTM Type I water. The blank may be stored in a convenient manner.
7.14 Calibration verification (CV) solution-The CV solution is used to periodically verify instrument
calibration during analysis. It should be prepared in the same acid mixture as the calibration
standards (Section 7.12 note) by combining method analytes at appropriate concentrations to
approximate the midpoint of the calibration curve. The CV solution should be prepared from the
same standard stock solutions used to prepare the calibration standards and stored in a FEP bottle.
Agency programs may specify or request that additional calibration verification solutions be
prepared at specified concentrations in order to meet specific program needs.
14 Draft, January 2001
-------
Method 200.9
7.15 Quality control sample (Reference sample)-The QCS must be obtained from an outside source
separate from standard stock solutions, and is prepared in the same acid mixture as the calibration
standards (Section 7.12 note). For initial and periodic verification of calibration standards and
instrument performance, analysis of a method blank that has been fortified with the QCS is
required. Analyte concentrations in the QCS solution should be such that the resulting solution
will provide an absorbance reading of approximately 0.1. 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 if instability is noted.
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 aliquots
are removed 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 dissolved metals, the sample must be filtered through a 0.45 (jm capsule
membrane filter at the time of collection or as soon thereafter as is practical. (A glass or metal-free
plastic filtering apparatus is recommended to avoid possible contamination). 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 to pH <2 with (1:1) HNO3 immediately following filtration.
8.3 For the determination of total recoverable elements in aqueous samples, samples are not filtered,
but acidified with (1:1) HNO3 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 immediately prior to
withdrawing an aliquot for processing or "direct analysis." If for some reason such as high
alkalinity, sample pH is >2, more acid must be added and the sample held for an additional 16
hours until verified to be pH <2.
NOTE: When the nature of the sample is either unknown or known to be hazardous,
acidification should be done in a fume hood (Section 5.2).
8.4 Solid samples usually 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 if required by the data user.
Use the same container and acid as used in sample collection.
9.0 Quality Control
9.1 Each laboratory applying this method is required to maintain a formal quality assurance program.
The minimum requirements of this program consist of an initial demonstration of laboratory
Draft, January 2001 15
-------
Method 200.9
capability, analysis of samples spiked with metals of interest to evaluate and document data
quality, and analysis of standards and blanks as tests of continued performance. Laboratory
performance is compared to established performance criteria to demonstrate that results of the
analysis meet the performance criteria of the method.
9.1.1 The analyst must make an initial demonstration of the ability to generate acceptable
accuracy and precision with this method. This ability is established as described in
Section 9.2.
9.1.2 In recognition of advances that are occurring in analytical technology, the analyst is
permitted to exercise certain options to eliminate interferences or lower the costs of
measurements. These options include alternate digestion, preconcentration, cleanup
procedures, and changes in instrumentation. Alternate determinative techniques, such as
the substitution of a colorimetric technique or changes that degrade method performance,
are not allowed. If an analytical technique other than the techniques specified in this
method is used, then that technique must have a specificity equal to or better than the
specificity of the techniques in the method for the analytes of interest.
9.1.2.1 Each time the method is modified, the analyst is required to repeat the
procedure in Section 9.2. If the change will affect the detection limit of
the method, the laboratory is required to demonstrate that the MDLs (40
CFR Part 136, Appendix B) are lower than the MDLs for the analytes in
this method, or one-third the regulatory compliance level, whichever is
higher. If the change will affect calibration, the analyst must recalibrate
the instrument according to Section 10.0.
9.1.2.2 The laboratory is required to maintain records of modifications made to
this method. These records include the following, at a minimum:
9.1.2.2.1 The names, titles, addresses, and telephone numbers of the
analyst(s) who performed the analyses and modification, and of
the quality control officer who witnessed and will verify the
analyses and modification.
9.1.2.2.2 A listing of metals measured, by name and CAS Registry number.
9.1.2.2.3 A narrative stating reason(s) for the modification(s).
9.1.2.2.4 Results from all quality control (QC) tests comparing the
modified method to this method, including:
(a) Calibration
(b) Calibration verification
(c) Initial precision and recovery
(d) Analysis of blanks
(e) Accuracy assessment
16 Draft, January 2001
-------
Method 200.9
9.1.2.2.5 Data that will allow an independent reviewer to validate each
determination by tracing the instrument output (peak height, area,
or other signal) to the final result. These data are to include,
where possible:
(a) Sample numbers and other identifiers
(b) Digestion/preparation or extraction dates
(c) Analysis dates and times
(d) Analysis sequence/run chronology
(e) Sample weight or volume
(f) Volume before the extraction/concentration step
(g) Volume after each extraction/concentration step
(h) Final volume before analysis
(i) Injection volume
(j) Dilution data, differentiating between dilution of a sample
or extract
(k) Instrument and operating conditions (make, model,
revision, modifications)
(1) Sample introduction system (ultrasonic nebulizer, flow
injection system, etc.)
(m) Preconcentration system
(n) Operating conditions (background corrections,
temperature program, flow rates, etc.)
(o) Detector (type, operating conditions, etc.)
(p) Spectra, printer tapes, and other recordings of raw data
(q) Quantitation reports, data system outputs, and other data
to link raw data to results reported
9.1.3 Analyses of blanks are required to demonstrate freedom from contamination. Section 9.5
describes the required types, procedures, and criteria for analysis of blanks.
9.1.4 Analyses of MS and MSD samples are required to demonstrate the accuracy and precision
of the method and to monitor for matrix interferences (Section 9.4). When results of these
spikes indicate atypical method performance, alternative extraction or cleanup techniques
must be used to bring method performance within acceptable limits. If method
performance cannot be brought within the limits given in this method, the results may not
be reported for regulatory compliance purposes.
9.1.5 The laboratory must, on an ongoing basis, demonstrate through calibration verification
(Section 9.3) and through analysis of the ongoing precision and recovery standard (Section
9.6) that the analytical system is meeting the performance criteria.
9.1.6 The laboratory must maintain records to define the quality of data that are generated.
Development of accuracy statements is described in Section 9.4.4.1 and 9.6.7.
9.1.7 All samples must be associated with an acceptable OPR, MS/MSD, IPR, and
uncontaminated blanks.
Draft, January 2001 17
-------
Method 200.9
9.2 Initial demonstration of laboratory capability.
9.2.1 Method detection limit—To establish the ability to detect the trace metals of interest, the
analyst must determine the MDL for each analyte according to the procedure in 40 CFR
136, Appendix B using the apparatus, reagents, and standards that will be used in the
practice of this method. The laboratory must produce an MDL that is less than or equal to
the MDL listed in Table 1 (to be confirmed during validation study), or one-third the
regulatory compliance limit, whichever is greater. MDLs should be determined when a
new operator begins work or whenever a change in instrument hardware or operating
conditions is made that may affect the MDL. MDLs must be determined for solids with
clean sand or soil if solid samples are to be analyzed, peat moss for biosolids and/or for
reagent water if aqueous samples are to be analyzed. MDLs also must be determined for
biosolids with peat moss if sludge samples are to be analyzed for arsenic, cadmium,
copper, lead, nickel, and selenium.
9.2.2 Initial precision and recovery (IPR)-To establish the ability to generate acceptable
precision and recovery, the analyst must perform the following operations.
9.2.2.1 Spike four aliquots of reagent water for aqueous samples, clean sand or
soil for solid samples, or peat moss for biosolid samples, with the metal(s)
of interest at one to five times the ML. Analyze the four aliquots
according to the procedures in Section 11.0. All digestion, extraction, and
concentration steps, and the containers, labware, and reagents that will be
used with samples must be used in this test.
9.2.2.2 Using results of the set of four analyses, compute the average percent
recovery (X) for the metal(s) in each aliquot and the standard deviation of
the recovery (s) for each metal.
9.2.2.3 For each metal, compare s and X with the corresponding limits for IPR in
(Table 2- to be determined in validation study). If s and X for all metal(s)
meet the acceptance criteria, system performance is acceptable and
analysis of blanks and samples may begin. If, however, any individual s
exceeds the precision limit or any individual X falls outside the range for
accuracy, system performance is unacceptable for that metal. Correct the
problem and repeat the test.
9.2.3 Linear dynamic range (LDR)-The upper limit of the LDR must be established for the
wavelength used for each analyte by determining the signal responses from a minimum of
six different concentration standards across the range, two of which should be close to the
upper limit of the LDR. Determined LDRs must be documented and kept on file. The
linear calibration range which may be used for the analysis of samples should be judged by
the analyst from the resulting data. The upper LDR limit should be an observed signal no
more than 10% below the level extrapolated from the four lower standards. Sample
analyte concentrations that exceed the upper limit of the linear calibration range must
either be diluted and analyzed again with concern for memory effects (Section 4.5) or be
18 Draft, January 2001
-------
Method 200.9
analyzed by another approved method. The LDRs should be verified annually or
whenever, in the judgement of the analyst, there is a change in analytical performance.
NOTE: Multiple clean out furnace cycles may be necessary in order to fully define or utilize
the LDRfor certain elements such as chromium. For this reason the upper limit of the linear
calibration range may not correspond to the upper LDR limit.
9.2.4 Quality Control Sample (QCS)-When beginning the use of this method, quarterly, and as
required to meet data quality needs, the analyst must verify the calibration standards and
acceptable instrument performance by preparing and analyzing three aliquots of a
reference sample (Section 7.15). To verify the calibration standards, the determined mean
concentration from three analyses of the reference sample must be within ± 5% of the
stated reference sample values. If the reference sample results are not within the required
limits, an immediate second analysis of the reference sample is recommended to confirm
unacceptable performance. If the calibration standards and acceptable instrument
performance cannot be verified, the source of the problem must be identified and corrected
before either proceeding with further sample analyses.
9.3 Calibration verification (CV) solution-A laboratory must analyze a CV solution (Section 7.12) and
a calibration blank immediately following each calibration, after every 10th sample (or more
frequently, if required) and at the end of the sample run.
9.3.1 The calibration blank results must always be less than the analyte ML, or one-third the
regulatory compliance level, whichever is greater. The results must also by greater than a
negative signal in concentration units equal to the ML.
9.3.2 Analysis of the CV solution immediately following calibration must verify that the
instrument is within performance criteria to be determined by the validation study (Table 2
- to be determined by the validation study).
9.3.3 If calibration cannot be verified within the specified limits, reanalyze either or both the CV
solution and the calibration blank. If the second analysis of the CV solution or the
calibration blank confirms that the calibration is outside acceptable limits, sample analysis
must be discontinued, the cause determined, and/or, in the case of drift, the instrument
recalibrated. All samples following the last acceptable CV solution and calibration blank
must be analyzed again. Analysis data of the calibration blank and CV solution must be
kept on file with sample analyses data.
9.4 Matrix spike (MS) and matrix spike duplicates (MSD)-To assess the performance of the method
on a given sample matrix, the laboratory must spike, in duplicate, a minimum of 10% (one sample
in ten) of the samples from a given sampling site or, if for compliance monitoring, from a given
discharge. Blanks may not be used for MS/MSD analysis.
9.4.1 The concentration of the MS and MSB spike shall be determined as follows:
9.4.1.1 If, as in compliance monitoring, the concentration of analytes in the
sample is being checked against a regulatory concentration limit, the
Draft, January 2001 19
-------
Method 200.9
spiking level shall be at that limit or at 1-5 times the background
concentration of the sample, whichever is greater.
9.4.1.2 If the concentration of analytes in a sample is not being checked against a
regulatory concentration limit, the spike shall be at 1-5 times the
background concentration of the sample.
9.4.1.3 For solid and sludge samples, 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 O.lL/O.OOlkg = 100, Section 12.4). (For notes on Ag, see
Sections 1.6).
9.4.2 Assessing spike recovery.
9.4.2.1 To determine the background concentration (B), analyze one sample
aliquot from each set of 10 samples from each site or discharge according
to the procedure in Section 11. If the expected background concentration
is known from previous experience or other knowledge, the spiking level
may be established a priori.
9.4.2.2 Prepare a standard solution to produce an appropriate concentration in the
sample (Section 9.4.1).
NOTE: The concentration of iron and aluminum in solids can vary greatly and is not
necessarily predictable. Fortifying these analytes in routine samples at the same concentration
used for the OPR may prove to be of little use in assessing data quality for these analytes. For
these analytes sample dilution and reanalysis is recommended. After subtraction of the OPR
spike, the calculated sample concentration after dilution should agree within 10% of the original
determination of sample concentration. 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 possibly affect the analysis.
9.4.2.2 Spike two additional sample aliquots with the spiking solution and analyze
these aliquots to determine the concentration after spiking (A). Calculate
the percent recovery (P) in each aliquot (Equation 2).
20 Draft, January 2001
-------
Method 200.9
Equation 2
(A- B}
p= 100*- -
T
where:
P = Percent recovery
A = Measured concentration ofanalyte after spiking
B = Measured concentration ofanalyte before spiking
T = True concentration of the spike
9.4.3 Compare the percent recovery with the QC acceptance criteria in Table 2 (to be
determined in validation study).
9.4.3.1 If P falls outside the designated range for recovery in Table 2, the results
have failed to meet the established performance criteria. If P is
unacceptable, analyze the OPR standard (Section 9.6). If the OPR is
within established performance criteria (Table 2), the analytical system is
within specification and the problem can be attributed to interference by
the sample matrix. 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.
9.4.3.2 If the analyte MS/MSD recovery is <70% and the background absorbance
is <1.0, the analyte addition test (Section 9.7) should be performed on an
undiluted portion of an unfortified sample aliquot. Test results should be
evaluated as follows:
9.4.3.2.1 If recovery of the analyte addition test (<85%) confirms a low
recovery for the MS/MSD, a suppressive matrix interference is
indicated and an unfortified sample aliquot must be analyzed by
the method of standard additions (Section 11.6).
9.4.3.2.2 If recovery of the analyte addition test is between 85 - 115%, a
low recovery of the analyte in the MS/MSD (<70%) may be
related to the heterogeneous nature of the sample, the result of
precipitation loss during sample preparation, or an incorrect
addition prior to preparation. Report analyte data determined
from the analysis of an unfortified sample aliquot.
9.4.3.3 If laboratory performance is shown to be acceptable (Section 9.5.1 and
Section 9.6), but analyte recovery in the MS/MSD is either >130% or
above the upper calibration limit, and the background absorbance is <1.0,
the analyte addition test should be performed (Section 9.7) on an
unfortified sample aliquot. (If the MS/MSD concentration is above the
upper calibration limit, dilute a portion of an unfortified aliquot with
Draft, January 2001 21
-------
Method 200.9
acidified reagent water before completing the analyte addition test).
Evaluate the test results as follows:
9.4.3.3.1 If the percent recovery of an analyte addition test is >115%, an
enhancing matrix interference (albeit rare) is indicated and the
unfortified sample aliquot or its appropriate dilution must be
analyzed by the method of standard additions (Section 11.6).
9.4.3.3.2 If the percent recovery of an analyte addition test is between 85 -
115%, high recovery in the MS/MSD may have been caused by
random sample contamination, sample heterogeneity, or incorrect
addition of the analyte prior to sample processing. Report
analytical data from an unfortified sample aliquot or its
appropriate dilution.
9.4.3.3.3 If the percent recovery of an analyte addition test is <85%, a
heterogenous sample with a suppressive matrix may be indicated.
Other possible causes may be a combination of random
contamination and a positive matrix interference. Reported data
should be flagged accordingly.
9.4.3.4 If laboratory performance is shown to be acceptable (Section 9.5.1 and
Section 9.6), but the background absorbance is >1.0, a nonspecific
spectral interference should be suspected. A portion of the unfortified
aliquot should be diluted (1:3) with acidified reagent water and analyzed
again. (Dilution may dramatically reduce molecular background to an
acceptable level. Ideally, background absorbance in the unfortified
aliquot diluted (1:3) should be < 1.0. However, additional dilution may be
necessary). If dilution reduces background absorbance to an acceptable
level (<1.0), complete the analyte addition test (Section 9.7) on a dilute
unfortified aliquot. Evaluate test results as follows:
9.4.3.4.1 If recovery of the analyte addition test is between 85 - 115%,
report the analytical data acquired from the dilute, unfortified
aliquot.
9.4.3.4.2 If recovery of the analyte addition test is outside the range of 85 -
115%, complete sample analysis by analyzing a dilute, unfortified
aliquot following the method of standard additions (Section 11.6).
9.4.3.5 If either analysis of MS/MSD samples or application of the analyte
addition test indicate a positive interference, all other samples in the batch
which are typical and have a matrix similar to the MS/MSD or the tested
samples must be analyzed in the same manner. Also, the data user must
be informed when a matrix interference is so severe that it prevents the
22 Draft, January 2001
-------
Method 200.9
successful analysis of the analyte or when the heterogeneous nature of the
sample precludes the use of duplicate analyses.
9.4.3.6 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 an analyst's and a laboratory's ability to
perform a method acceptably.
9.4.4 Recovery for samples should be assessed and records maintained.
9.4.4.1 After the analysis of five samples of a given matrix type (river water,
biosolids, etc.) for which the metal(s) pass the tests in Section 9.4.3,
compute the average percent recovery (P) and the standard deviation of
the percent recovery (SP) for the metal(s). Express the accuracy
assessment as a percent recovery interval from P - 2SP to P + 2SP for
each matrix. For example, if P = 90% and SP = 10% for five analyses,
the accuracy interval is expressed as 70 - 110%.
9.4.4.2 Update the accuracy assessment for each metal in each matrix on a
regular basis (e.g., after each 5-10 new measurements).
9.4.5 Precision of matrix spike and matrix spike duplicate.
9.4.5.1 Calculate the relative percent difference (RPB) between the MS and MSB
(Equation 3). Use the concentrations found in the MS and MSB. Bo not
use the recoveries calculated in Section 9.4.3 for this calculation because
the RPB is inflated when the background concentration is near the spike
concentration.
Equation 3
(A + A)
where:
RPD = Relative percent difference
D, = Concentration of the analyte in the MS sample.
D2 = Concentration of the analyte in the MSP sample.
9.4.5.2 The relative percent difference between the matrix spike and the matrix
spike duplicate must be less than 20% (RPB acceptance value will be
verified in the validation study). If this criterion is not met, the analytical
system is out of control. In this case, correct the problem and reanalyze
all samples in the sample batch associated with the MS/MSB that failed
the RPB test.
Draft, January 2001 23
-------
Method 200.9
9.5 Blanks.
9.5.1 Method blank.
9.5.1.1
9.5.1.2
Prepare a method blank with each sample batch (samples of the same
matrix -reagent water for aqueous samples, clean sand or soil for solid
samples, peat moss for biosolid samples) started through the sample
preparation process (Section 11.0) on the same 12-hour shift, for a
maximum of 20 samples. Analyze the blank immediately after the OPR is
analyzed (Section 9.6) to demonstrate freedom from contamination.
If the analyte(s) of interest or any potentially interfering substance is
found in the method blank at a concentration equal to or greater than the
ML (Table 1 to be determined during the validation study) or 1/3 the
regulatory compliance level, whichever is greater, sample analysis must be
halted, the source of contamination determined, the samples and a new
method blank prepared, and the new sample batch and method blank
analyzed.
9.5.1.3
9.5.1.4
9.5.2 Field blank.
Alternatively, if a sufficient number (three minimum) of blanks are
analyzed, the average concentration plus two standard deviations must be
less than the regulatory compliance level.
If the result for a single method blank remains above the ML or if the
result for the average concentration plus two standard deviations of three
or more blanks exceeds the regulatory compliance level, results for
samples associated with those blanks may not be reported for regulatory
compliance purposes. Stated another way, results for IPR tests (Section
9.2) and all samples must be associated with an uncontaminated method
blank before these results may be reported for regulatory compliance
purposes.
9.5.2.1 Analyze the field blank(s) shipped with each set of samples (samples
collected from the same site at the same time, to a maximum of 10
samples). Analyze the blank immediately before analyzing the samples in
the batch.
9.5.2.2 If the metal of interest or any potentially interfering substance is found in
the field blank at a concentration equal to or greater than the ML, or
greater than one-fifth the level in the associated sample(s), whichever is
greater, results for the associated samples may be the result of
contamination and may not be reported for regulatory compliance
purposes.
24
Draft, January 2001
-------
Method 200.9
9.5.2.3 Alternatively, if a sufficient number (three minimum) of field blanks are
analyzed to characterize the nature of the field blank, the average
concentration plus two standard deviations must be less than the
regulatory compliance level or less than one-half the level in the associated
sample for that analyte, whichever is greater.
9.5.2.4 If contamination of the field blanks and associated samples is known or
suspected, the laboratory should communicate this to the sampling team
so that the source of contamination can be identified and corrective
measures taken prior to sampling.
9.5.3 Equipment blanks—Before any sampling equipment is used at a given site, it is
recommended that the laboratory or cleaning facility generate equipment blanks to
demonstrate that the sampling equipment is free from contamination. Two types of
equipment blanks are recommended: bottle blanks and sampler check blanks.
9.5.3.1 Bottle blanks—After undergoing appropriate cleaning procedures (Section
6.9), bottles should be subjected to conditions of use to verify the
effectiveness of the cleaning procedures. A representative set of sample
bottles should be filled with reagent water acidified to pH < 2 and allowed
to stand for a minimum of 24 hours. Ideally, the time that the bottles are
allowed to stand should be as close as possible to the actual time that
sample will be in contact with the bottle. After standing, the water should
be analyzed for any signs of contamination. If any bottle shows signs of
contamination, the problem must be identified, the cleaning procedures
corrected or cleaning solutions changed, and all affected bottles cleaned
again.
9.5.3.2 Sampler check blanks—Sampler check blanks are generated in the
laboratory or at the equipment cleaning contractor's facility by processing
reagent water through the sampling devices using the same procedures
that are used in the field.
9.5.3.2.1 Sampler check blanks are generated by filling a large carboy or
other container with reagent water (Section 7.1) and processing
the reagent water through the equipment using the same
procedures that are used in the field. For example, manual grab
sampler check blanks are collected by directly submerging a
sample bottle into the water, filling the bottle, and capping.
Subsurface sampler check blanks are collected by immersing the
sampler into the water and pumping water into a sample
container. Whatever precautions and equipment are used in the
field should also be used to generate these blanks.
9.5.3.2.2 The sampler check blank should be analyzed using the procedures
in this method. If the target analyte(s) or any potentially
interfering substance is detected in the blank, the source of
Draft, January 2001 25
-------
Method 200.9
contamination or interference must be identified and the problem
corrected. The equipment should be demonstrated to be free from
contamination before the equipment is used in the field.
9.5.3.2.3 Sampler check blanks should be run on all equipment that will be
used in the field. If, for example, samples are to be collected
using both a grab sampling device and a subsurface sampling
device, a sampler check blank must be run on both pieces of
equipment.
9.6 Ongoing precision and recovery.
9.6.1 For aqueous samples, prepare an OPR solution identical to the IPR aliquots (Section
9.2.2). The solution must be analyzed with each preparation batch (samples of the same
matrix started through the sample preparation process (Section 11.0) on the same 12-hour
shift, to a maximum of 20 samples).
9.6.2 For solid samples, the use of clean sand or soil fortified as in Section 9.6.1 is
recommended.
9.6.3 For biosolid samples, the use of peat moss fortified as in Section 9.6.1 is recommended.
9.6.4 Analyze the OPR solution before the method blank and samples are analyzed.
9.6.5 Compute the percent recovery of each metal in the OPR sample.
9.6.6 For each metal, compare the OPR concentration to the limits for ongoing recovery in
(Table 2- to be determined in validation study). If all metal(s) meet the acceptance criteria,
system performance is acceptable and analysis of blanks and samples may proceed. If,
however, any individual recovery falls outside of the range given, the analytical processes
are not being performed properly for that metal. Correct the problem, prepare the sample
batch again, and repeat the OPR test.
9.6.7 Add results that pass the specifications in Section 9.6.6 to IPR and previous OPR data for
each metal in each matrix. Update QC charts to form a graphic representation of
continued laboratory performance. Develop a statement of laboratory accuracy for each
metal in each matrix type by calculating average percent recovery (P) and standard
deviation of percent recovery (SP). Express accuracy as a recovery interval from P - 2SP
to P + 2SP. For example, if P = 95% and SP = 5%, accuracy is 85 - 105%.
9.7 An analyte addition test can be used to assess possible matrix interference effects and the need to
complete a sample analysis using the method of standard additions (MSA, Section 11.6). Results
of this test should not be considered conclusive unless the determined sample background
absorbance is <1.0. An analyte standard, when added to a portion of a prepared sample or its
dilution, should be recovered to within 85-115% of the known value. The analyte addition may
be added directly to sample in the furnace and should produce a minimum level absorbance of 0.1.
The concentration of the analyte addition plus that in the sample should not exceed the linear
26 Draft, January 2001
-------
Method 200.9
calibration range of the analyte. If the analyte is not recovered within the specified limits, a matrix
effect should be suspected and the sample must be analyzed by MSA (Section 11.6).
10.0 Calibration and Standardization
10.1 Prior to an initial calibration, the linear dynamic range of the analyte must be determined (Section
9.2.3) using optimized instrument operating conditions (Section 11.5). For all determinations,
allow an instrument and hollow cathode lamp warm up period of not less than 15 minutes. If an
EDL is to be used, allow 30 minutes for warm up.
10.2 For initial and daily operation, calibrate the instrument according to the instrument manufacturer's
recommended procedures using the calibration blank (Section 7.13.1) and calibration standards
(Section 7.12) prepared at three or more concentrations within the usable linear dynamic range of
the analyte (Section 9.2.3). The lowest calibration point (excluding the calibration blank) must be
equal to the ML (Table 1, to be determined during the validation study).
10.2 The calibration line should include at least three non-zero points with the high standard near the
upper limit of the linear dynamic range (Section 9.2.3) and the low standard that contains the
analyte(s) of interest at the ML (to be determined during the validation study). Replicates of a
calibration blank (Section 7.13.1) and the 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 (Reference 12).
10.3 Calculate the slope and intercept of a line using weighted linear regression. Use the inverse of the
standard's concentration squared (1/x2) as the weighting factor. The calibration is acceptable if the
R2 is greater than 0.995 and the absolute value of the intercept is less than the MDL for the target
analyte. If these conditions are not met, then the laboratory may not report data analyzed under
that calibration and must recalibrate the instrument.
10.4 The concentration of samples is determined using Equation 4.
Equation 4
y = mx + b
where y = sample concentration
m = slope (calculated in Section 10.3)
x = instrument response
b = intercept (calculated in Section 10.3)
10.5 Response factor may be calculated as an alternative to weighted linear regression for instrument
calibration. Calculate the response factor (RF) of the analytes for each of the standards (Equation
5.)
Draft, January 2001 27
-------
Method 200.9
Equation 5
x
where:
Rx = Peak height or area
_ Cx = Concentration of standard x
10.5.1 Calculate the mean response factor (RFm), the standard deviation of the RFm, and the
relative standard deviation (RSD) of the mean (Equation 6).
Equation 6
SD
RSD= 100*-
where:
RSD = Relative standard deviation of the mean
SD = Standard deviation of the RFm
RFm = the mean response factor
10.5.2 Performance criteria for the calibration will be calculated after the validation of the
method.
11.0 Procedure
11.1 Aqueous sample preparation (Dissolved analytes)-For the determination of dissolved analytes in
ground and surface waters, pipet an aliquot (>20 mL) of filtered, acid preserved sample into a 50
mL polypropylene centrifuge tube. Add an appropriate volume of (1:1) HNO3 to adjust the acid
concentration of the aliquot to approximate a 1% (v/v) HNO3 solution (e.g., add 0.2 mL (1:1)
HNO3 to a 20 mL aliquot of sample). Cap the tube and mix. The sample is now ready for
analysis. Allowance for sample dilution should be made in the calculations (Section 12).
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 "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. Make allowance for sample dilution in
the data calculation (Sections 12). For determination of total recoverable analytes in all
other aqueous samples, follow the procedure given in Sections 11.2.2 through 11.2.7.
11.2.2 For 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,
28 Draft, January 2001
-------
Method 200.9
acid-preserved sample to a 250 mL Griffin beaker. (When necessary, smaller sample
aliquot volumes may be used).
NOTE: If the sample is not a biosolids sample and contains undissolved solids >1%, a well
mixed, acid preserved aliquot containing no more than 1 g paniculate 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) HNO3 and 1.0 mL of (1:1) HC1 to a 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 to prevent sample contamination
from the fume hood environment. Other contamination avoidance steps should be taken as
needed.
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).
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 HC1-H2O azeotrope).
11.2.6 Allow the beaker to cool. Quantitatively transfer the sample solution to a 50 mL
volumetric flask. Add reagent water to bring the final volume of the sample solution to 50
mL. Stopper the volumetric flask 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 a sample contains
suspended solids that would clog or adversely affect an instrument sample introduction
system, a portion of the sample may be filtered 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 sample
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 a tared weighing dish. For samples with
Draft, January 2001 29
-------
Method 200.9
<35% moisture, a 20 g portion is sufficient. For samples with moisture >35%, a larger
aliquot of 50 - 100 g is required. Dry the sample to a constant weight at 60°C (The
sample is dried at 60 °C to prevent the loss of volatile metallic compounds).
11.3.2 To achieve homogeneity, sieve the dried sample using a 5-mesh polypropylene sieve, and
grind it with a mortar and pestle. (The sieve, mortar, and pestle should be cleaned between
samples). From the dried, ground material, weigh a representative 1.0 ± 0.01 g aliquot
(W) of the sample and transfer it to a 250 mL Phillips beaker for acid extraction.
11.3.3 To the beaker, add 4 mL of (1:1) HNO3 and 10 mL of (1:4) HC1. Cover the beaker with a
watch glass. Place the beaker on a hot plate for reflux extraction of analytes. The hot
plate should be located in a fume hood and previously adjusted to provide a reflux
temperature of approximately 95 °C.
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).
11.3.4 Heat the sample and gently reflux for 30 minutes. Very slight boiling may occur, but
vigorous boiling must be avoided to prevent loss of the HC1-H2O azeotrope. Some
solution evanoration will occur (anDroximatelv 3-4 mL).
vigorous ooiiing musi oe avoiueu 10 preveni loss 01 me nv
solution evaporation will occur (approximately 3-4 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 or affect the
sample introduction system, a portion of the extract solution may be filtered prior to
analysis. However, care should be exercised to avoid 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 completed sample preparation.
11.3.7 Determine the total solids content of the sample using the procedure in Appendix A.
11.4 Sludge sample preparation-Total recoverable analytes.
11.4.1 Determination of total recoverable analytes in sludge samples containing estimated total
suspended solids > 1% (w/v).
11.4.1.1 Mix the sample thoroughly. Transfer a portion (>20 g) of the sample to a
tared weighing dish, weigh the sample, and record the wet weight. For
samples with <35% moisture, a 20 g portion is sufficient. For samples
with moisture >35%, a larger aliquot of 50 - 100 g is required. Dry the
30 Draft, January 2001
-------
Method 200.9
sample to a constant weight at 60 °C (The sample is dried at 60 °C to
prevent the loss of volatile metallic compounds).
11.4.1.2 To achieve homogeneity, sieve the dried sample using a 5-mesh
polypropylene sieve and grind it in a mortar and pestle. (The sieve,
mortar, and pestle should be cleaned between samples). From the dried,
ground material weigh a representative 1.0 ± 0.01 g aliquot (W) of the
sample and transfer to a 250 mL Phillips beaker for acid extraction.
11.4.1.3 Add 1 OmL of (1:1) HNO3 to the beaker and cover the beaker with a
watch glass. Place the beaker on a hot plate and reflux the sample for 10
minutes. Remove the sample from the hot plate and allow to cool. Add 5
mL of concentrated HNO3 to the beaker, replace the watch glass, return to
the hot plate, and reflux for 30 minutes. Repeat this last step once.
Remove the beaker from the hot plate and allow to cool. Add 2 mL of
reagent water and 3 mL of 30% H2O2. Place the beaker on the hot plate
and heat the sample until a gentle effervescence is observed. Once the
reaction has subsided, additional 1 mL aliquots of 30% H2O2 should be
added until no effervescence is observed. The total amount of 30% H2O2
added should not exceed 10 mL. Add 2 mL concentrated HC1 and 10 mL
of reagent water to the sample, cover with a watch glass, and reflux for 15
minutes.
11.4.1.4 Cool the sample and dilute to 100 mL with reagent water. Any remaining
solid material should be allowed to settle, or an aliquot of the final sample
may be centrifuged.
11.4.1.5 Determine the total solids content of the sample using the procedure in
Appendix A.
11.4.2 Determination of total recoverable analytes in sludge samples containing estimated total
suspended solids < 1% (w/v).
11.4.2.1 Transfer 100 mL of well-mixed sample to a 250 mL Griffin beaker.
11.4.2.2 Add 3 mL of concentrated HNO3 and place the beaker on a hot plate.
Heat the sample and cautiously evaporate to a volume of 5 mL. If the
sample contains a large amount of dissolved solids, adjust this volume
upwards to prevent the sample from going to dryness. Remove the beaker
from the hot plate and allow the sample to cool. Add 3 mL of
concentrated HNO3, cover with a watch glass and gently reflux the sample
until the sample is completely digested or no further changes in
appearance occur, adding additional aliquots of acid, if necessary, to
prevent the sample from going to dryness. Remove the watch glass and
reduce the sample volume to 3 mL, again adjusting upwards if necessary.
Draft, January 2001 31
-------
Method 200.9
11.4.2.2 Cool the beaker, then add 10 mL of reagent water and 4 mL of (1:1) HC1
to the sample and reflux for 15 minutes. Cool the sample and dilute to
100 mL with reagent water. Any remaining solid material should be
allowed to settle, or an aliquot of the final sample volume may be
centrifuged.
11.4.2.3 Determine the total solids content of the sample using the procedure in
Appendix A.
11.5 Sample analysis.
11.5.1 Inspect the graphite furnace, the sample uptake system, and autosampler injector for any
problems that would affect instrument performance. If necessary, clean the system and
replace the graphite tube and/or platform.
11.5.2 Configure the instrument.
11.5.2.1 Specific wavelengths and instrument operating conditions are listed in
Table 3. However, because of differences among makes and models of
spectrophotometers and electrothermal furnace devices, the actual
instrument conditions selected may vary from those listed.
11.5.2.2 Prior to the use of this method, instrument operating conditions must be
optimized. An analyst should follow the instructions provided by the
manufacturer while using the conditions listed in Table 3 as a guide. Of
particular importance is the determination of the charring temperature
limit for each analyte. This limit is the furnace temperature setting when
a loss in analyte will occur prior to atomization. This limit should be
determined by conducting char temperature profiles for each analyte and
when necessary, in the matrix of question. The charring temperature
selected should minimize background absorbance while providing some
furnace temperature variation without loss of analyte. For routine
analyses, the charring temperature is set typically to at least 100°C below
this limit. Optimum conditions should provide the lowest reliable MDLs
and be similar to those listed in Table 1 (to be confirmed during
collaborative validation study). Once optimum operating conditions have
been determined, they should be recorded and available for daily
reference.
11.5.2.3 Configure the instrument system to optimize operating conditions for the
"direct analysis" of drinking water with turbidity <1 NTU. Initiate the
data system and allow a period of not less than 15 minutes for instrument
and hollow cathode lamp warm up. If an EDL is to be used, allow 30
minutes for warm up.
11.5.2.4 After the warm up period, but before calibration, instrument stability must
be demonstrated by analyzing a standard solution with a concentration
32 Draft, January 2001
-------
Method 200.9
20 times the ML, a minimum of five times. The resulting relative
standard deviation (RSD) of absorbance signals must be <5%. If the
RSD is >5%, determine and correct the cause before calibrating the
instrument.
11.5.3 Before using the method to analyze samples, there must be data available documenting
initial demonstration of laboratory capability. Required and acceptable data and
procedures are described in Section 9.2. This data must be generated using the same
instrument operating conditions and calibration routine (Sections 10.0 and 11.5.2)
subsequently used for sample analysis. These documented data must be kept on file and be
available for review by the data user.
11.5.4 An autosampler must be used to introduce all solutions to the graphite furnace. Once the
standard, sample or QC solution plus the matrix modifier is injected, the furnace controller
completes furnace cycles and clean out periods as programmed. Analyte signals must be
integrated and collected as peak area measurements. Background absorbances,
background corrected analyte signals, and determined analyte concentrations on all
solutions must be displayed on a CRT for immediate review by the analyst and be
available as hard copy for documentation to be kept on file. The autosampler solution
uptake system must be flushed with the rinse blank (Section 7.13.3) between injections.
11.5.5 During the analysis of samples, a laboratory must comply with the required quality control
described in Sections 9.0. Only during determination of dissolved analytes or "direct
analysis" of drinking water with turbidity of <1 NTU is the sample digestion step of the
method blank, OPR, MS, and MSD not required.
11.5.6 Matrix interferences.
11.5.6.1 For every new or unusual matrix, it is highly recommended that an
inductively coupled plasma atomic emission spectrometer be used to
screen for high element concentrations whenever practical. Information
gained may reduce potential damage to the atomic absorption instrument
and estimate which elements require graphite furnace analysis.
11.5.6.2 When it is necessary to assess an operative matrix interference (e.g.,
signal reduction due to high dissolved solids), the test described in Section
9.7 is recommended.
11.5.7 Sample analyte concentrations measured at 90% or more of the upper limit of calibration
must either be diluted with acidified reagent water and analyzed with concern for memory
effects (Section 4.5), or be determined by another approved test procedure that is less
sensitive. Samples with a background absorbance >1.0 must be appropriately diluted with
acidified reagent water and analyzed again (Section 9.4.3.4). If the method of standard
additions is required, follow the instructions described in Section 11.6.
11.5.8 In order to meet or achieve lower MDLs than those listed in Table 1 for "direct analysis"
of drinking water with turbidity <1 NTU, analyte preconcentration is required. This may
Draft, January 2001 33
-------
Method 200.9
be accomplished prior to sample introduction into the GFAA or with the use of multiple
aliquot depositions on the GFAA platform or associated delayed atomization device.
When using multiple depositions, the same number of equal volume aliquots of either the
calibration standards or acid preserved samples must be deposited prior to atomization.
Following each deposition, the drying cycle must be completed before beginning the next
deposition. Matrix modifier must be added along with each deposition and the total
volume of each deposition must not exceed the instrument recommended capacity of the
delayed atomization device. To reduce analysis time, the minimum number of depositions
required to achieve the desired analytical result should be used. Use of this multiple
deposition technique for the "direct analysis" of drinking water must be completed using
optimized instrument operating conditions (Section 11.5.2) and must comply with the
method requirements described in Section 9.2. (See Table 3 for information and data on
the determination of arsenic by this procedure).
11.5.9 Report data as directed in Section 12.0.
11.6 Standard additions-If the method of standard addition (MSA) is required, the following procedure
is recommended:
11.6.1 The standard addition technique involves preparing new standards in the sample matrix by
adding known amounts of standard to one or more aliquots of the processed sample
solution (Reference 11). This technique compensates for a sample constituent that
enhances or depresses the analyte signal, thus producing a different slope from that of the
calibration standards. It will not correct for additive interference, which causes a baseline
shift. The simplest version of this technique is the single-addition method. The procedure
is as follows: Two identical aliquots of the sample solution, each of volume V2, are taken.
To the first (aliquot 1) is added a small volume (V\) of a standard analyte solution of
concentration C. To the second (aliquot 2) is added the same volume (V\) of reagent
matrix water. It is best if V2 is much less than Vl to avoid excess dilution of the sample
matrix. The analytical signals of aliquots 1 and 2 are measured and corrected for non-
analyte signals. The unknown sample concentration (Cs) is calculated:
34 Draft, January 2001
-------
Method 200.9
Equation 7
S2*Vl*C
c =
where:
Cs = Sample concentration (mg/L)
C = Concentration of the standard solution (mg/L)
S1 = Signal for fortified aliquot
S2 = Signal for unfortified aliquot
V1 = Volume of the standard addition (L)
V2 = Volume of the sample aliquot used for MSA (L)
If a separation or concentration step is required, the additions are made before separation
or concentration and carried through the entire procedure. For the results from this
technique to be valid, the following limitations apply:
1. The calibration curve must be linear.
2. The chemical form of the analyte added must respond in the same manner
as the analyte in the sample.
3. The interference effect must be constant over the working range.
4. The signal must be corrected for any additive interference.
12.0 Data Analysis and Calculations
12.1 Data should be reported in mg/L for aqueous samples and mg/kg dry weight for sludge and solid
samples.
12.2 For dissolved analytes in aqueous samples (Section 11.1) report the data generated directly from
the instrument with allowance for sample dilution. Do not report analyte concentrations below the
MDL.
12.3 For total recoverable analytes in aqueous samples (Section 11.2), multiply solution analyte
concentrations by the dilution factor (when a 100 mL aliquot is used to produce the 50 mL final
solution, the dilution factor will equal 0.5). Round the data to the tenths place and report the data
in mg/L up to three significant figures. If a different aliquot volume other than 100 mL is used for
sample preparation, adjust the dilution factor accordingly. Also, account for any additional
dilution of the prepared sample solution needed to complete the determination of analytes exceeding
the upper limit of the calibration curve. 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.
Draft, January 2001 35
-------
Method 200.9
12.4 For total recoverable analytes in solid and sludge samples (Sections 11.3 and 11.4), round the
solution analyte concentrations (mg/L) to the tenths place. 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 Equation 8. Do not report analyte data below the solids MDL.
Equation 8
C*V*D
GS= w
where:
Cs = Sample concentration (mg/kg, dry-weight basis)
C = Concentration in the extract (mg/L)
V = Volume of ex.tract (L, 100mL = 0.1 L)
D = Dilution factor (undiluted = 1)
W = Weight of sample aliquot extracted (kg, 1 g = 0.001 kg)
12.5 To report percent solids in solid and sludge samples, use the procedure given in Appendix A.
12.6 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 Instrument operating conditions used for single laboratory application of the method and resulting
MDLs are listed in Table 1.
13.2 Method performance criteria is given in Table 2 (to be determined in validation study).
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. EPA has established a preferred hierarchy of environmental management
techniques that places pollution prevention as the management option of first choice. Whenever
feasible, laboratory personnel should use pollution prevention techniques to address their waste
generation. When wastes cannot be feasibly reduced at the source, the Agency recommends
recycling as the next best option.
14.2 For information about pollution prevention that may be applicable to laboratories and research
institutions, consult "Less is Better: Laboratory Chemical Management for Waste Reduction,
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.
36 Draft, January 2001
-------
Method 200.9
15.0 Waste Management
15.1 The Environmental Protection Agency requires that laboratory waste management practices be
conducted consistent with all applicable rule and regulations. The Agency urges laboratories to
protect the air, water, and land by minimizing and controlling all releases from hoods and bench
operations, by complying discharge permit requirements 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. Method 200.9, Determination of Trace Elements
by Stabilized Temperature Graphite Furnace Atomic Absorption Spectrometry, Revision
1.2, 1991.
2. Creed, J.T., T.D. Martin, L.B. Lobring and J.W. O'Dell. Environ. Sci. Techno!.,
26:102-106, 1992.
3. Waltz, B., G. Schlemmar and J.R. Mudakavi. JAAS. 3, 695, 1988.
4. 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.
5. OSHA Safety and Health Standards, General Industry, (29 CFR 1910), Occupational
Safety and Health Administration, OSHA 2206, (Revised, January 1976).
6. Safety in Academic Chemistry Laboratories, American Chemical Society Publication,
Committee on Chemical Safety, 3rd Edition, 1979.
7. Proposed OSHA Safety and Health Standards, Laboratories, Occupational Safety and
Health Administration, Federal Register, July 24, 1986.
8. Rohrbough, W.G. et al. Reagent Chemicals, American Chemical Society Specifications,
7th edition. American Chemical Society, Washington, D.C., 1986.
9. American Society for Testing and Materials. Standard Specification for Reagent Water,
D1193-77. Annual Book of ASTM Standards, Vol. 11.01. Philadelphia, PA, 1991.
10. Code of Federal Regulation 40. Pt. 136, Appendix B.
11. Winefordner, J.D., Trace Analysis: Spectroscopic Methods for Elements, Chemical
Analysis, Vol. 46, pp. 41.
Draft, January 2001 37
-------
Method 200.9
12. 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, 994 Rowlett, Suite 6, Houston TX 77075, 1989.
38 Draft, January 2001
-------
Method 200.9
17.0 Tables, Diagrams, Flow Charts, and Validation Data
Table 1: MDLs and MLs of the method (to be determined during collaborative validation study).
Table 2: Performance criteria of the method (to be determined during collaborative validation study).
Draft, January 2001 39
-------
Method 200.9
TABLE 3.
RECOMMENDED
GRAPHITE FURNACE
OPERATING
CONDITIONS
AND RECOMMENDED MATRIX MODIFIER1 3
Element
Ag
Al
As7
Be
Cd
Co
Cr
Cu
Fe
Mn
Ni
Pb
Sb7
Se7
Sn7
Tl
Wavelength
328.1
309.3
193.7
234.9
228.8
242.5
357.9
324.8
248.3
279.5
232.0
283.3
217.6
196.0
286.3
276.8
Slit
0.7
0.7
0.7
0.7
0.7
0.2
0.7
0.7
0.2
0.2
0.2
0.7
0.7
2.0
0.7
0.7
Temperature
Char
1000
1700
1300
1200
800
1400
1650
1300
1400
1400
1400
1250
1100
1000
1400s
1000
(C)5 Atom
1800
2600
2200
2500
1600
2500
26006
26006
2400
2200
2500
2000
2000
2000
2300
1600
MDL4
(^g/L)
0.59
7.89
0.5
0.02
0.05
0.7
0.1
0.7
-
0.3
0.6
0.7
0.8
0.6
1.7
0.7
Matrix Modifier = 0.015 mg Pd + 0.01 mg Mg(NO3)2.
A 5% H2 in Ar gas mix is used during the dry and char steps at 300 mL/min. for all
elements.
A cool down step between the char and atomization is recommended.
Obtained using a 20 i\L sample size and stop flow atomization.
Actual char and atomization temperatures may vary from instrument to instrument and are
best determined on an individual basis. The actual drying temperature may vary depending
on the temperature of the water used to cool the furnace.
A 7-s atomization is necessary to quantitatively remove the analyte from the graphite
furnace.
An electrodeless discharge lamp was used for this element.
An additional low temperature (approximately 200 °C) per char is recommended.
Pd modifier was determined to have trace level contamination of this element.
40 Draft, January 2001
-------
Method 200.9
Appendix A: Total Solids in Solid and Semisolid Matrices
1.0 Scope and Application
1.1 This procedure is applicable to the determination of total solids in such solid and semisolid samples
as soils, sediments, biosolids (municipal sewage sludge) separated from water and wastewater
treatment processes, and sludge cakes from vacuum filtration, centrifugation, or other biosolids
dewatering processes.
1.2 This procedure is taken from EPA Method 1684: Total, Fixed, and Volatile Solids in Solid and
Semi-Solid Matrices.
1.3 Method detection limits (MDLs) and minimum levels (MLs) have not been formally established for
this draft procedure. These values will be determined during the validation of Method 1684.
1.4 This procedure is performance based. The laboratory is permitted to omit any step or modify any
procedure (e.g. to overcome interferences, to lower the cost of measurement), provided that all
performance requirements in this procedure are met. Requirements for establishing equivalency
are given in Section 9.1.2 of Method 200.9.
1.5 Each laboratory that uses this procedure must demonstrate the ability to generate acceptable results
using the procedure in Section 9.2.
2.0 Summary of Method
2.1 Sample aliquots of 25-50 g are dried at 103 °C to 105 °C to drive off water in the sample.
2.3 The mass of total solids in the sample is determined by comparing the mass of the sample before
and after each drying step.
3.0 Definitions
3.1 Total Solids-The residue left in the vessel after evaporation of liquid from a sample and
subsequent drying in an oven at 103 °C to 105 °C.
3.2 Additional definitions are given in Sections 3.0 of Method 200.9.
4.0 Interferences
4.1 Sampling, subsampling, and pipeting multi-phase samples may introduce serious errors (Reference
13.1). Make and keep such samples homogeneous during transfer. Use special handling to ensure
sample integrity when subsampling. Mix small samples with a magnetic stirrer. If visible
suspended solids are present, pipet with wide-bore pipets. If part of a sample adheres to the
sample container, intensive homogenization is required to ensure accurate results. When dried,
Draft, January 2001 41
-------
Method 200.9
some samples form a crust that prevents evaporation; special handling such as extended drying
times are required to deal with this. Avoid using a magnetic stirrer with samples containing
magnetic particles.
4.2 The temperature and time of residue drying has an important bearing on results (Reference 1).
Problems such as weight losses due to volatilization of organic matter, and evolution of gases from
heat-induced chemical decomposition, weight gains due to oxidation, and confounding factors like
mechanical occlusion of water and water of crystallization depend on temperature and time of
heating. It is therefore essential that samples be dried at a uniform temperature, and for no longer
than specified. Each sample requires close attention to desiccation after drying. Minimize the time
the desiccator is open because moist air may enter and be absorbed by the samples. Some samples
may be stronger desiccants than those used in the desiccator and may take on water.
4.3 Residues dried at 103 °C to 105 °C may retain some bound water as water of crystallization or as
water occluded in the interstices of crystals. They lose CO2 in the conversion of bicarbonate to
carbonate. The residues usually lose only slight amounts of organic matter by volatilization at this
temperature. Because removal of occluded water is marginal at this temperature, attainment of
constant weight may be very slow.
4.4 Results for residues high in oil or grease may be questionable because of the difficulty of drying to
constant weight in a reasonable time.
4.5 The determination of total solids is subject to negative error due to loss of ammonium carbonate
and volatile organic matter during the drying step at 103 °C to 105 °C. Carefully observe specified
ignition time and temperature to control losses of volatile inorganic salts if these are a problem.
5.0 Safety
5.1 Refer to Section 5.0 of Method 200.9 for safety precautions.
6.0 Equipment and Supplies
NOTE: Brand names, suppliers, and part numbers are cited for illustrative purposes only. No
endorsement is implied. Equivalent performance may be achieved using equipment and
materials other than those specified here, but demonstration of equivalent performance that
meets the requirements of this method is the responsibility of the laboratory.
6.1 Evaporating Dishes-Dishes of 100-mL capacity. The dishes may be made of porcelain (90-mm
diameter), platinum, or high-silica glass.
6.2 Watch glass-Capable of covering the evaporating dishes (Section 6.1).
6.3 Steam bath.
42 Draft, January 2001
-------
Method 200.9
6.4 Desiccator-Moisture concentration in the desiccator should be monitored by an instrumental
indicator or with a color-indicator desiccant.
6.5 Drying oven-Thermostatically-controlled, capable of maintaining a uniform temperature of 103 °C
to 105 °C throughout the drying chamber.
6.6 Analytical balance-Capable of weighing to 0.1 mg for samples having a mass up to 200 g.
6.7 Container handling apparatus-Gloves, tongs, or a suitable holder for moving and handling hot
containers after drying.
6.8 Bottles-Glass or plastic bottles of a suitable size for sample collection.
6.9 Rubber gloves (Optional).
6.10 No. 7 Cork borer (Optional).
7.0 Reagents and Standards
7.1 Reagent water-Deionized, distilled, or otherwise purified water.
7.2 Sodium chloride-potassium hydrogen phthalate standard (NaCl-KHP).
7.2.1 Dissolve 0.10 g sodium chloride (NaCl) in 500 mL reagent water. Mix to dissolve.
7.2.2 Add 0.10 g potassium hydrogen phthalate (KHP) to the NaCl solution (Section 7.2.1) and
mix. If the KHP does not dissolve readily, warm the solution while mixing. Dilute to 1 L
with reagent water. Store at 4°C. Assuming 100% volatility of the acid phthalate ion, this
solution contains 200 mg/L total solids, 81.0 mg/L volatile solids, and 119 mg/L fixed
solids.
8.0 Sample Collection, Preservation, and Storage
8.1 Use resistant-glass or plastic bottles to collect sample for solids analysis, provided that the material
in suspension does not adhere to container walls. Sampling should be done in accordance with
Reference 13.2. Begin analysis as soon as possible after collection because of the impracticality of
preserving the sample. Refrigerate the sample at 4 °C up to the time of analysis to minimize
microbiological decomposition of solids. Preferably do not hold samples more than 24 hours.
Under no circumstances should the sample be held more than seven days. Bring samples to room
temperature before analysis.
9.0 Quality Control
9.1 Quality control requirements and requirements for performance-based methods are given in Section
9.1 of Method 200.9.
Draft, January 2001 43
-------
Method 200.9
9.2 Initial demonstration of laboratory capability - The initial demonstration of laboratory capability is
used to characterize laboratory performance and method detection limits.
9.2.1 Method detection limit (MDL) - The method detection limit should be established for the
analyte, using diluted NaCl-KHP standard (Section 7.2). To determine MDL values, take
seven replicate aliquots of the diluted NaCl-KHP solution and process each aliquot
through each step of the analytical method. Perform all calculations and report the
concentration values in the appropriate units. MDLs should be determined every year or
whenever a modification to the method or analytical system is made that will affect the
method detection limit.
9.2.2 Initial Precision and Recovery (IPR) - To establish the ability to generate acceptable preci-
sion and accuracy, the analyst shall perform the following operations:
9.2.2.1 Prepare four samples by diluting NaCl-KHP standard (Section 7.2) to 1-5
times the MDL. Using the procedures in Section 11, analyze these
samples for total solids.
9.2.2.2 Using the results of the four analyses, compute the average percent recov-
ery (x) and the standard deviation (s, Equation 1) of the percent recovery
for total solids.
Equation 1
Is-2-
„ 1
(I-2)
n
\ n-\
Where:
n = number of samples
x = % recovery in each sample
s = standard deviation
9.2.2.3 Compare s and x with the corresponding limits for initial precision and
recovery in Table 2 (to be determined in validation study). If s and x meet
the acceptance criteria, system performance is acceptable and analysis of
samples may begin. If, however, s exceeds the precision limit or x falls
outside the range for recovery, system performance is unacceptable. In
this event, correct the problem, and repeat the test.
9.3 Laboratory blanks
9.3.1 Prepare and analyze a laboratory blank initially (i.e. with the tests in Section 9.2) and with
each analytical batch. The blank must be subjected to the same procedural steps as a
sample, and will consist of approximately 25 g of reagent water.
44 Draft, January 2001
-------
Method 200.9
9.3.2 If material is detected in the blank at a concentration greater than the MDL (Section 1.3),
analysis of samples must be halted until the source of contamination is eliminated and a
new blank shows no evidence of contamination. All samples must be associated with an
uncontaminated laboratory blank before the results may be reported for regulatory compli-
ance purposes.
9.4 Ongoing Precision and Recovery
9.4.1 Prepare an ongoing precision and recovery (OPR) solution identical to the IPR solution
described in Section 9.2.2.1.
9.4.2 An aliquot of the OPR solution must be analyzed with each sample batch (samples started
through the sample preparation process (Section 11) on the same 12-hour shift, to a
maximum of 20 samples).
9.4.3 Compute the percent recovery of total solids in the OPR sample.
9.4.4 Compare the results to the limits for ongoing recovery in Table 2 (to be determined in
validation study). If the results meet the acceptance criteria, system performance is
acceptable and analysis of blanks and samples may proceed. If, however, the recovery of
total solids falls outside of the range given, the analytical processes are not being
performed properly. Correct the problem, reprepare the sample batch, and repeat the OPR
test. All samples must be associated with an OPR analysis that passes acceptance criteria
before the sample results can be reported for regulatory compliance purposes.
9.4.5 results that pass the specifications in Section 9.4.4 to IPR and previous OPR data. Update
QC charts to form a graphic representation of continued laboratory performance. Develop
a statement of laboratory accuracy for each analyte by calculating the average percent
recovery (R) and the standard deviation of percent recovery (SR). Express the accuracy as
a recovery interval from R-2SRto R+2SR. For example, if R=05% and SR=5%, the
accuracy is 85-115%.
9.5 Duplicate analyses
9.5.1 Ten percent of samples must be analyzed in duplicate. The duplicate analyses must be
performed within the same sample batch (samples whose analysis is started within the
same 12-hour period, to a maximum of 20 samples).
9.5.2 The total solids of the duplicate samples must be within 10%.
10.0 Calibration and Standardization
10.1 Calibrate the analytical balance at 2 mg and 1000 mg using class "S" weights.
10.2 Calibration shall be within ± 10% (i.e. ±0.2 mg) at 2 mg and ± 0.5% (i.e. ±5 mg) at 1000 mg. If
values are not within these limits, recalibrate the balance.
Draft, January 2001 45
-------
Method 200.9
11.0 Procedure
11.1 Preparation of evaporating dishes-Heat dishes and watch glasses at 103 °C to 105 °C for 1 hour in
an oven. Cool and store the dried equipment in a desiccator. Weigh each dish and watch glass
prior to use (record combined weight as "Wdlsh").
11.2 Preparation of samples
11.2.1 Fluid samples-If the sample contains enough moisture to flow readily, stir to homogenize,
place a 25 to 50 g sample aliquot on the prepared evaporating dish. If the sample is to be
analyzed in duplicate, the mass of the two aliquots may not differ by more than 10%.
Spread each sample so that it is evenly distributed over the evaporating dish. Evaporate the
samples to dryness on a steam bath. Cover each sample with a watch glass, and weigh
(record weight as "Wsample").
NOTE: Weigh wet samples quickly because wet samples tend to lose weight by evaporation.
Samples should be weighed immediately after aliquots are prepared.
11.2.2 Solid samples-If the sample consists of discrete pieces of solid material (dewatered
sludge, for example), take cores from each piece with a No. 7 cork borer or pulverize the
entire sample coarsely on a clean surface by hand, using rubber gloves. Place a 25 to 50 g
sample aliquot of the pulverized sample on the prepared evaporating dish. If the sample is
to be analyzed in duplicate, the mass of the two aliquots may not differ by more than 10%.
Spread each sample so that it is evenly distributed over the evaporating dish. Cover each
sample with a watch glass, and weigh (record weight as "Wsample").
11.3 Dry the samples at 103 °C to 105 °C for a minimum of 12 hours, cool to balance temperature in an
individual desiccator containing fresh desiccant, and weigh. Heat the residue again for 1 hour, cool
it to balance temperature in a desiccator, and weigh. Repeat this heating, cooling, desiccating, and
weighing procedure until the weight change is less than 5% or 50 mg, whichever is less. Record
the final weight as "Wtotal."
NOTE: It is imperative that dried samples weighed quickly since residues often are very
hygroscopic and rapidly absorb moisture from the air. Samples must remain in the dessicator
until the analyst is ready to weigh them.
12.0 Data Analysis and Calculations
12.1 Calculate the % solids or the mg solids/kg sludge for total solids (Equation 2).
46 Draft, January 2001
-------
Method 200.9
Equation 2
% total solids = —^ — * 100
IJ/ I/i/
"sample "dish
or
mg total solids W. ., - W,.,
,—71, = u u * 1,000,000
kg sludge Wsample - Wdish
Where:
Wdlsh=Weightofdish (mg)
Wsample=Weight of wet sample and dish (mg)
Wtotai=Weight of dried residue and dish (mg)
12.2 Sample results should be reported as % solids or mg/kg to three significant figures. Report results
below the ML as < the ML, or as required by the permitting authority or in the permit.
13.0 Method Performance
13.1 Method performance (MDL and quality control acceptance criteria) will be determined during the
multi-lab validation of this method.
13.2 Total solids duplicate determinations must agree within 10% to be reported for permitting
purposes. If duplicate samples do not meet this criteria, the problem must be discovered and the
sample must be run over.
14.0 Pollution Prevention
14.2 Pollution prevention details are given in Section 14 of Method 200.9.
15.0 Waste Management
15.1 Waste management details are given in Section 15 of Method 200.9.
16.0 References
16.1 "Standard Methods for the Examination of Water and Wastewater," 18th ed. and later revisions,
American Public Health Association, 1015 15th Street NW, Washington, DC 20005. 1-35:
Section 1090 (Safety), 1992.
16.2 U.S. Environmental Protection Agency, 1992. Control of Pathogens and Vector Attraction in
Sewage Sludge. Publ 625/R-92/013. Office of Research and Development, Washington, DC.
Draft, January 2001 47
-------
Method 200.9
17.0 Tables, Diagrams, Flowcharts, and Validation Data
17.1 Tables containing method requirements for QA/QC will be added after the validation study has
been performed.
48 Draft, January 2001
------- |