**SW-846 Update V 6010D - 1 Revision 4 July 2014**  **METHOD 6010D**

**INDUCTIVELY COUPLED PLASMA—OPTICAL EMISSION SPECTR OMETRY** 

**SW-846 is not intended to be an analytical training manual. Therefore, method**  **procedures are written based on the assumption that they will be performed by analysts who are**  **formally trained in at least the basic principles o f chemical analysis and in the use of the subject**  **technology.**

**In addition, SW-846 methods, with the exception of required method use for the analysis**  **of method-defined parameters, are intended to be gu idance methods which contain general**  **information on how to perform an analytical procedu re or technique which a laboratory can use**  **as a basic starting point for generating its own de tailed standard operating procedure (SOP),**  **either for its own general use or for a specific pr oject application. The performance data**  **included in this method are for guidance purposes o nly, and are not intended to be and must not**  **be used as absolute quality control (QC) acceptance criteria for purposes of laboratory** 

**accreditation.**

**1.0 SCOPE AND APPLICATION**

**1.1 Inductively coupled plasma—optical emission spe ctrometry (ICP-OES) is a**  **spectrometric technique used to determine trace ele ments in aqueous solutions. In ICP-OES, a**  **sample solution is aspirated (i.e., nebulized) cont inuously into an inductively coupled, argon**  **plasma discharge, where analytes of interest are co nverted to excited-state, gas-phase atoms** 

**or ions. As the excited-state atoms or ions return to their ground state, they emit energy in the**  **form of light at wavelengths that are characteristi c of each specific element. The intensity of the**  **energy emitted at the chosen wavelength is proporti onal to the amount (concentration) of that**  **element in the analyzed sample. Thus, by determini ng which wavelengths are emitted by a**  **sample and their respective intensities, the elemen tal composition of the given sample relative**  **to a reference standard may be quantified. For acc urate results, direct ICP-OES analysis**  **should be conducted on only relatively clean, aqueo us matrices (e.g., pre-filtered groundwater**  **samples). Other, more complex aqueous and/or solid samples need acid digestion prior to**  **analysis; the analyst should insure that a sample d igestion method is chosen that is appropriate**  **for each analyte and the intended use of the data. Refer to Chapter Three for the appropriate**  **digestion procedures. SW-846 Update V 6010D - 2 Revision 4**  **July 2014 The following RCRA analytes have been determined by**  **this method:**

**Element Symbol**  **CASRN a**  **Element Symbol**  **CASRN a** 

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

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

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

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

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

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

**Cadmium Cd**  **7440-43-9 Silica**  **SiO 2**  **7631-86-9**

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

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

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

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

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

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

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

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

**Manganese Mn**  **7439-96-5**

**a Chemical Abstract Service Registry Number** 

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

**level quantitative analysis; however, this method c an be used as a screening tool**  **(e.g., prior to analysis by a low-level method when high concentrations of mercury are**  **expected).**

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

**that contain high level Hg concentration. See Meth od 6020B Sections 7.20.11,**  **7.22.3, and 11.1 for guidance when analyzing for me rcury.** 

**1.2 The table in Section 1.1 lists the elements for which this method has been**  **validated. The sensitivity and the optimum and lin ear ranges for each element will vary with the**  **wavelength, spectrometer, matrix, and operating con ditions. Refer to the manufacturer’s**  **instructions for recommended analytical wavelengths and estimated instrument detection limits**  **(IDLs) for the elements in a clean aqueous matrix w ith insignificant background interferences.**  **Other elements and matrices may be analyzed by this method if acceptable performance at the**  **concentrations of interest is demonstrated (see Sec . 9.0).** 

**1.3 IDLs are necessarily instrument-specific. Ther efore, if needed, an IDL must be**  **determined through a separate experimental study fo r each instrument in a laboratory. IDLs** **SW-846 Update V 6010D - 3 Revision 4 July 2014**  **should be established at minimum on an annual basis , for each matrix type analyzed and for**  **each preparatory/determinative method combination u sed (refer to Chapters One and Three for**  **guidance).**

**1.4 Analysts should clearly understand the data qua lity objectives (DQOs) prior to**  **analysis. Before using the method for routine envi ronmental analysis, analysts should**  **document and have on file the necessary initial dem onstration of performance (IDP) data, as** 

**described in Section 9.0.**

**1.5 Use of this method is restricted to spectroscop ists who are knowledgeable in the**  **correction of the spectral, chemical, and physical interferences described in this method.** 

**1.6 Prior to employing this method, analysts are a dvised to consult the preparatory**  **method for each type of procedure that may be emplo yed in the overall analysis (e.g., Methods** 
**3005, 3010, 3015, 3031, 3040, 3050, 3051, 3052, 700 0, and 6800) for additional information on**  **QC procedures, development of QC acceptance criteri a, calculations, and general guidance.**  **Analysts also should consult the disclaimer stateme nt at the front of the manual and the**  **information in Chapter Two for guidance on the inte nded flexibility in the choice of methods,**  **apparatus, materials, reagents, and supplies, and o n the responsibilities of the analyst for**  **demonstrating that the techniques employed are appr opriate for the analytes of interest, in the**  **matrix of interest, and at the levels of concern.**

**In addition, analysts and data users are advised th at, except where explicitly specified in a**  **regulation, the use of SW-846 methods is** not **mandatory in response to Federal testing requirements. The information contained in this me**  **thod is provided by EPA as guidance to be used by the analyst and the regulated community in**  **making judgments necessary to generate results that meet the DQOs for the intended applica**  **tion.**

**1.7 This method is restricted to use by, or under supervision of, properly experienced**  **and trained personnel. Each analyst must demonstra te the ability to generate acceptable** 

**results with this method.**

**2.0 SUMMARY OF METHOD**

**2.1 Prior to analysis, aqueous and solid samples ar e solubilized or digested using the**  **appropriate sample preparation methods (see Chapter Three). When analyzing groundwater**  **samples for dissolved constituents, acid digestion is not necessary, if the samples are filtered**  **and acid-preserved prior to analysis (e.g., Methods 3005, 3010, 3015, 3031, 3050, 3051 and**  **3052). Samples that are not digested necessitate t he use of either an internal standard or** 

**should be matrix-matched with the standards. If us ing the former option, the instrument**  **software should be programmed to correct for the in tensity differences of the internal standard**  **between samples and standards.**

**2.2 This method describes multi-element determinat ions by ICP-OES using sequential**  **or simultaneous optical systems, and axial or radia l viewing of the plasma. The ICP-OES**  **instrument measures characteristic emission spectra by optical spectroscopy. Samples are**  **nebulized and the resulting aerosol is transported to the plasma torch. Element-specific**  **emission spectra are produced by a radio-frequency, inductively coupled plasma. The spectra**  **are dispersed by a grating spectrometer, and the in tensities of the emission lines are monitored**  **by photosensitive devices. SW-846 Update V 6010D - 4 Revision 4**  **July 2014 2.3 Background correction is necessary for trace e**  **lement determination. Background emission must be measured adjacent to analyte lines**  **on samples during analysis. The position selected for the background-intensity measurement,**  **on either or both sides of the analytical line, will be determined by the complexity of the spectru**  **m adjacent to the analyte line. The position used should be as free as possible from spectral in**  **terference and should reflect the same change in background intensity as that which occurs**  **at the analyte wavelength being measured.**

**Background correction is** not **needed in cases of line broadening, where a backgr ound**  **correction measurement would actually degrade the a nalytical result. Analysts should**  **recognize the possibility of additional interferenc es, as identified in Sec. 4.0, and make**  **appropriate corrections. Tests for the presence of additional interferences are described in Sec.**  **9.9. Alternatively, analysts may choose multivaria te calibration methods, in which case, point**  **selections for background correction are superfluou s, since whole spectral regions are**  **processed.**

**3.0 DEFINITIONS**

**Refer to Chapter One, Chapter Three, and the manuf acturer's instructions for definitions**  **that may be relevant to this procedure.**

**4.0 INTERFERENCES**

**Interferences can arise from a variety of sources and serve to diminish the bias and**  **precision of analytical data, particularly when det ermining elements at trace levels.** 

**Interferences to ICP-OES have been studied in detai l and are well understood. A summary of**  **interferences to ICP-OES analysis as well as techni ques to mitigate their effects on data are**  **provided in the sections to follow.**

**4.1 Spectral interferences can arise from several s ources. Techniques to identify and**  **compensate for spectral interferences are discussed below.** 

**4.1.1 Background emission from continuous or recom bination phenomena**  **and/or stray light from the line emission of high c oncentration elements** 

**4.1.1.1 Compensation for background emission and s tray light can**  **usually be conducted by subtracting the background emission determined through**  **measurements obtained adjacent to the analyte wavel ength peak. Spectral scans**  **of samples or single-element solutions in the analy te regions may indicate when**  **the use of alternate wavelengths is desirable becau se of severe spectral** 

**interference. These scans will also show whether t he most appropriate estimate of**  **the background emission is provided by an interpola tion from measurements**  **obtained on both sides of the wavelength peak, or b y measured emission obtained**  **only on one side.**

**The locations selected for the measurement of back ground intensity will**  **be determined by the complexity of the spectrum adj acent to the wavelength peak.** 

**The locations used for routine measurement must be free of off-line spectral**  **interference (interelement or molecular), or otherw ise adequately corrected to** **SW-846 Update V 6010D - 5 Revision 4 July 2014**  **reflect the same change in background intensity as that which occurs at the**  **wavelength peak. For multivariate methods using wh ole spectral regions,**  **background scans should be included in the correcti on algorithm. Off-line spectral**  **interferences are handled by including spectra on i nterfering species in the**  **algorithm.**

**4.1.1.2 To determine the appropriate location for off-line background**  **correction, the area adjacent to the wavelength on either side must be scanned, so**  **that the apparent emission intensity from all other method analytes may be**  **recorded. This spectral information must be docume nted and kept on file. The**  **location selected for background correction must be either free of off-line inter**  **element spectral interference or a computer routine must be used for automatic**  **correction on all determinations. If a wavelength other than the recommended**  **wavelength is used, the analyst must determine and document both the**  **overlapping and nearby spectral interference effect s from all method analytes and**  **common elements and provide for their automatic cor rection on all analyses. Tests**  **to determine spectral interference must be performe d using analyte concentrations**  **that will adequately describe the interference. No rmally, 100-mg/L, single-element**  **solutions are sufficient. However, for analytes su ch as iron, that may be found in**  **the sample at high concentration, a more appropriat e test would be to use a**  **concentration near the upper limit of the analytica l range (refer to Chapter Three**  **for additional guidance).**

**4.1.2 Overlaps from the molecular spectra of the s ame target element may be**  **avoided through the use of an alternate wavelength for quantitation.** 

**4.1.3 Optical spectral-line overlaps between targe t elements** 

**4.1.3.1 Interelement spectral overlaps are typical ly compensated**  **through the use of equations that correct for inter element contributions.**  **Instruments that use equations for interelement cor rection necessitate that**  **interfering element(s) are analyzed at the same tim e as the target element(s) of**  **interest. When operative and uncorrected, interele ment interferences will produce**  **false positive or positively biased determinations. However, if the interference**  **affects the point selected for background correctio n, the resulting overcorrection**  **will cause a negative bias. More extensive informa tion on interferent effects at**  **various wavelengths and resolutions is available in reference wavelength tables**  **and books. Analysts may apply interelement-correct ion equations determined on**  **their instruments with tested concentration ranges to compensate (off-line or on**  **line) for the effects of interfering elements. Sel ected potential spectral**  **interferences observed for the recommended waveleng ths are given in Table 1.** 

**4.1.3.2 For multivariate calibration methods that employ whole**  **spectral regions, spectral interferences are handle d by including spectra of the**  **interfering elements in the calibration algorithm. The interferences listed in Table 1**  **are those that occur between method analytes. Only interferences of a direct**  **overlap nature are shown. These overlaps were obse rved with a single instrument**  **having a working resolution of 0.035 nm.**

**4.1.3.3 When using interelement-correction equatio ns, the**  **interference may be expressed as analyte concentrat ion equivalents (i.e., false** **SW-846 Update V 6010D - 6 Revision 4 July 2014**  **positive analyte concentrations) arising from 100 m g/L of the interference element.**  **For example, if As is to be determined at 193.696 n m in a sample containing**  **approximately 10 mg/L of Al, according to Table 1, 100 mg/L of Al will yield a false**  **positive signal equivalent to an As concentration o f approximately 1.3 mg/L.**  **Correspondingly, the presence of 10 mg/L of Al will result in a false positive signal**  **for As equivalent to approximately 0.13 mg/L. The analyst is cautioned that**  **alternate instruments may exhibit somewhat differen t levels of interference than** 

**those shown in Table 1. The interference effects m ust, therefore, be evaluated for** 
**each individual instrument, since the intensities w ill vary (see Sec. 4.1.3.5). It**  **should also be noted that instruments using an Eche lle grating are potentially**  **subject to interferences from different diffraction orders. These potential** 

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

**careful evaluation of interelement corrections as d escribed in Sec. 9.9.1 becomes** 

**even more vital.**

**4.1.3.4 Interelement corrections will vary for the same emission line**  **among instruments because of differences in resolut ion. Such differences are**  **determined by the grating, entrance and exit slit w idths, and by the order of**  **dispersion. Interelement corrections will also var y depending upon the choice of**  **background correction points. Selecting a backgrou nd correction point where an**  **interfering emission line may appear should be avoi ded when practical.**  **Interelement corrections that constitute a major po rtion of an emission signal may**  **not yield accurate data. Analysts should continuou sly note that some samples may**  **contain uncommon elements that could contribute spe ctral interferences.** 

**4.1.3.5 As already noted (Sec. 4.1.3.3), the inter element effects must**  **be evaluated for each individual instrument, whethe r configured as a sequential or** 
**simultaneous instrument. For each instrument, inte nsities will vary not only with**  **optical resolution, but also with operating conditi ons (such as power, viewing height**  **and argon-flow rate). When using the recommended w avelengths, the analyst**  **must determine and document for each wavelength the effect from referenced**  **interferences (Table 1) as well as any other suspec ted interferences that may be**  **specific to the instrument or matrix. The analyst should utilize a computer routine**  **for automatic correction on all analyses.**

**4.1.3.6 Analysts of sequential instruments must ve rify the absence of**  **spectral interference by scanning over a range of 0 .5 nm, centered on the**  **wavelength of interest, for several samples. The r ange for lead, for example,**  **would be from 220.6 - 220.1 nm. The procedure must be repeated whenever a**  **new matrix is to be analyzed and when a new calibra tion curve using different**  **instrumental conditions is to be prepared. Samples that show an elevated**  **background emission across the range may be backgro und-corrected by applying**  **a correction factor equal to the emission adjacent to the line or at two points on**  **either side of the line and interpolating between t hem. An alternate wavelength**  **that does not exhibit a background shift or spectra l overlap may also be used.** 

**4.1.3.7 The accuracy of interelement corrections s hould be verified**  **daily through the analysis of spectral-interference check (SIC) solutions. See**  **Secs. 7.12 and 9.9 for instructions on the preparat ion and use of SIC solutions.** **SW-846 Update V 6010D - 7 Revision 4 July 2014**  **4.1.3.8 When interelement corrections are** not **used, the absence of**

**interferences** must **be verified. Procedures for verifying the absence of**  **interferences are given in sections 7.12 and 9.9.**

**4.2 Physical interferences are effects associated with the sample nebulization and**  **transport processes. Changes in viscosity and surf ace tension can cause significant**  **inaccuracies, especially in samples containing high dissolved solids or acid concentrations. If**  **physical interferences are present, they must be re duced through (1) sample dilution, (2) the**  **use of a peristaltic pump; (3) the use of an intern al standard; or (4) the use of a high-solids** 

**nebulizer. Another problem that can occur, when high concentr**  **ations of dissolved solids are present, is salt buildup at the tip of the nebulizer, thus a**  **ffecting aerosol flow rate and resulting in instrumental drift. Salt buildup can be controlled**  **through (1) wetting the argon prior to nebulization; (2) use of a tip washer; (3) use of a**  **high-solids nebulizer; or (4) sample dilution. Also, it has been reported that better control of t**  **he argon flow rate, especially to the nebulizer, improves instrument performance. This may be accom**  **plished with the use of mass flow**

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

**4.3 Chemical interferences include molecular compo und formation, ionization effects,**  **and solute vaporization effects. Normally, these e ffects are not significant with the ICP**  **technique. However, if observed, they can be minim ized by (1) careful selection of operating**  **conditions (i.e., incident power, observation posit ion, etc.); (2) buffering of the sample through**  **matrix-matching; and (3) standard-addition procedur es. Chemical interferences are highly**  **dependent on matrix type and analyte.**

**4.3.1 The majority of interferences likely to be e ncountered when using this**  **method can be managed successfully using the techni ques discussed throughout Sec.**  **4.1. However, based on professional judgment, the m ethod of standard additions may be**  **useful when certain specific interferences are enco untered. Refer to Method 7000 for a**  **more detailed discussion on the use and application of the method of standard additions.** 

**4.3.2 An alternative to the method of standard add itions is the use of an internal**  **standard(s). In the internal standard technique, o ne or more elements not found in the**  **samples, and verified to not cause an interelement spectral interference, are added to the**  **samples, calibration standards, and blanks. Yttriu m or scandium is often used for this**  **purpose. The concentration should be sufficient fo r optimum precision, but not so high as** 

**to alter the salt concentration of the matrix. The internal standard element intensity is**  **used to ratio the analyte intensity signals for bot h calibration and quantitation. This**  **technique is very useful in overcoming matrix inter ferences, particularly in high solids** 

**matrices.**

**4.4 Memory interferences result when analytes in a previous sample contribute to the**  **intensity signals measured in a subsequent sample. Memory effects can result from sample**  **deposition on the uptake tubing to the nebulizer an d from the buildup of sample material in the**  **plasma torch and spray chamber. The site where the se effects occur is dependent on the**  **element and can be minimized by flushing the system with a rinse blank between samples. The**  **possibility of memory interferences should be consi dered within an analytical run. When**  **recognized, suitable rinse times should be establis hed to reduce them. The rinse times**  **necessary for a particular element must be estimate d prior to analysis. The estimation may be**  **made by aspirating a standard containing the elemen t(s) of interest at a concentration level that** **SW-846 Update V 6010D - 8 Revision 4 July 2014**  **is ten times the typical or expected amount, or at the upper limit of the linear range. The**  **aspiration time for the rinse time-estimation stand ard should be the same as a normal sample**  **analysis period, followed by analysis of the rinse blank at a series of designated intervals. The**  **length of the rinse time necessary for reducing the analyte signal(s) to less than or equal to the**  **IDL should be noted. A rinse period of at least 60 -sec should be used between samples and** 

**standards until a more suitable rinse time can be e stablished. If a memory interference is**  **determined to be present, the sample must be reanal yzed following use of the newly**  **established rinse period. Alternate rinse times ma y be established by the analyst based upon**  **the project-specific DQOs.**

**4.5 Analysts are advised that high salt concentrat ions can cause analyte signal**  **suppressions and confuse interference tests. If th e instrument does not display negative**  **values, fortify the SIC check solution with the ele ments of interest at 0.5 - 1 mg/L and measure**  **the added standard concentration accordingly. Conc entrations should be within 20% of the true**  **spiked concentration or dilution of the samples wil l be necessary. In the absence of measurable**  **analyte, overcorrection could go undetected if a ne gative value is reported as zero.** 

**4.6 The calibration blank (Sec. 7.11.2.1) may rest rict the quantitation sensitivity, or**  **otherwise degrade the precision and bias of the ana lysis. Chapter Three should be consulted**  **for clean chemistry methods and procedures for redu cing the magnitude and variability of the** 

**calibration blank.**

**4.7 Reagents and sample processing hardware may yi eld artifacts and/or interferences**  **to sample analysis. All of these materials must be demonstrated to be free from interferences**  **under the conditions of the analysis by analyzing m ethod blanks. Specific selection of reagents**  **may be necessary. Refer to each method to be used for specific guidance on QC procedures.** 

**5.0 SAFETY**

**5.1 This method does not address all safety issues associated with its use. The**  **laboratory is responsible for maintaining a safe wo rk environment and a current awareness file**  **of OSHA regulations regarding the safe handling of the chemicals specified in this method. A**  **reference file of material safety data sheets (MSDS s) should be available to all personnel**  **involved in these analyses.**

**5.2 Concentrated nitric and hydrochloric acids are moderately toxic and extremely**  **irritating to skin and mucus membranes. Use these reagents in a hood and if eye or skin**  **contact occurs, flush with large volumes of water. Always wear safety glasses or a shield for**  **eye protection when working with these reagents.**

**5.3** Hydrofluoric acid is a very toxic acid and penetrat es the skin and tissues deeply if not treated immediately. **Injury occurs in two stages: firstly, by hydrati on that**  **induces tissue necrosis; and secondly, by penetrati on of fluoride ions deep into the tissue and**  **thereby reacting with calcium. Boric acid and/or o ther complexing reagents and appropriate**  **treatment agents should be administered immediately**

**.**

**WARNING : Consult appropriate safety literature for determ**  **ining the proper protective eyewear,**

**clothing and gloves to use when handling hydrofluor ic acid.**  Always have appropriate treatment materials readily available p rior to working with this**SW-846 Update V 6010D - 9 Revision 4 July 2014**  acid. **See Method 3052 for additional recommendations fo r handling hydrofluoric**  **acid from a safety and an instrument standpoint.**

**5.4 Many metal salts, such as those of osmium, are extremely toxic if inhaled or** 

**swallowed.**

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

**and properly and that all exhaust gases are properl y vented. Wash hands**  **thoroughly after handling.**

**6.0 EQUIPMENT AND SUPPLIES**

**6.1 Inductively coupled, argon-plasma, optical emi ssion spectrometer** 

**6.1.1 Computer-controlled, emission spectrometer w ith background correction**  **capability**

**6.1.2 Radio-frequency generator - compliant with F CC regulations** 

**6.1.3 Optional mass-flow controller for argon nebu lizer-gas supply** 

**6.1.4 Optional peristaltic pump**

**6.1.5 Optional autosampler**

**6.1.6 Argon gas supply - high purity**

**6.2 Volumetric flasks of suitable material composi tion, precision and accuracy** 

**6.3 Volumetric pipets of suitable material composi tion, precision and accuracy** 

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

**7.0 REAGENTS AND STANDARDS**

**7.1 Reagent-grade, and whenever necessary, ultra-hi gh purity-grade chemicals, must**  **be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the**  **specifications of the Committee on Analytical Reage nts of the American Chemical Society,**  **where such specifications are available. Other gra des may be used, provided it is first**  **ascertained that the reagent is of sufficiently hig h purity to permit its use without lessening the**  **accuracy of the determination.**

**7.2 Reagent water - Reagent water must be interfer ence free. All references to water**  **in this method refer to reagent water unless otherw ise specified.** 

**7.3 Hydrochloric acid (concentrated), HCl**

**7.4 Hydrochloric acid (50% [v/v]), HCl - Prepare b y adding 500 mL concentrated HCl to**  **400 mL water and diluting to 1 L. SW-846 Update V 6010D - 10 Revision 4**  **July 2014 7.5 Hydrochloric acid (5% [v/v]), HCl - Prepare by**  **adding 50 mL concentrated HCl to 400 mL water and diluting to 1 L.** 

**7.6 Nitric acid (concentrated), HNO 3** 

**7.7 Nitric acid (50% [v/v]), HNO 3**  **- Prepare by adding 500 mL concentrated HNO 3**  **to 400 mL water and diluting to 1 L.** 

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

**matrices of the calibrations standards relative to those of the samples** 

**7.9 Standard stock solutions — Purchase standard s tock solutions from an appropriate**  **commercial source. Otherwise, prepare them manuall y in the laboratory using only ultra, high**  **purity grade chemicals or metals (** ≥ **99.99% purity). When preparing them manually,** except where specifically noted in the following sections **, dry all metal salts for one hour at 105 °C prior to use. Replace stock standards when succeed**  **ing dilutions for the preparation of**

**calibration standards cannot be verified**

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

**thoroughly after handling.**

**NOTE : This section does not apply when analyzing sampl**  **es prepared by Method 3040.**

**NOTE : The mass of each analyte is expressed to four de**  **cimal places, since rounding to two decimal places can contribute up to 4% error for so**  **me compounds.**

**7.9.1 Aluminum standard stock solution (1000 μg/mL Al) - Prepare by**  **dissolving exactly 1.000 g of aluminum metal in a b eaker containing an acid mixture of 4.0** 

**mL of 50% HCl and 1.0 mL of concentrated HNO 3**  **. Warm the beaker slowly to aid in dissolution of the metal. Afterwards, equilibrate**  **the solution to ambient temperature. Add**

**an additional 10.0 mL of 50% HCl and dilute to volu me in a 1-L volumetric flask with**  **reagent water.**

**7.9.2 Antimony standard stock solution (1000 μg/mL Sb) - Prepare by**  **dissolving exactly 2.6673 g of dried K(SbO)C 4**  **H 4**  **O 6**  **in reagent water. Add 10 mL 50% HCl**

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

**7.9.3 Arsenic standard stock solution (1000 μg/mL As) - Prepare by dissolving**  **exactly 1.3203 g of dried As 2**  **O 3**  **in 100 mL reagent water containing 0.4 g NaOH. Ac idify** 

**the solution with 2 mL concentrated HNO 3**  **and dilute to volume in a 1-L volumetric flask with reagent water.** 

**7.9.4 Barium standard stock solution (1000 μg/mL B a) - Prepare by dissolving**  **exactly 1.5163 g BaCl 2**  **(previously dried for two hours at 250** Ε **C) in a mixture of 10 mL of reagent water and 1 mL 50% HCl. Add 10.0 mL 50% HC**  **l and dilute to volume in a 1-L volumetric flask with reagent water.** **SW-846 Update V 6010D - 11 Revision 4 July 2014**  **7.9.5 Beryllium standard stock solution , (1000 μg /mL Be) - Prepare by**  **dissolving exactly 19.6463 g of** undried **BeSO 4**  **•4H 2**  **O in reagent water Add 10.0 mL**

**concentrated HNO 3**  **and dilute to volume in a 1-L volumetric flask wit h reagent water.** 

**CAUTION : Drying of beryllium salts can lead to a toxic in**  **halation hazard.**

**7.9.6 Boron standard stock solution (1000 μg/mL) - Prepare by dissolving**  **exactly 5.716 g of undried, anhydrous H 3**  **BO 3**  **in reagent water. Dilute to volume in a 1-L volumetric flask with reagent water. The use of a**  **non-glass volumetric flask is**

**recommended in order to avoid boron contamination f rom glassware. Transfer**  **immediately to an appropriate container for storage**

**.**

**7.9.7 Cadmium standard stock solution (1000 μg/mL Cd) - Prepare by**  **dissolving exactly 1.1423 g CdO in a minimum amount of 50% HNO**  **3 . Apply heat to aid in**  **dissolution. Following equilibration to ambient te mperature, add 10.0 mL of concentrated** 

**HNO 3**  **and dilute to volume in a 1-L volumetric flask wit h reagent water.** 

**7.9.8 Calcium standard stock solution (1000 μg/mL Ca) - Prepare by**  **suspending exactly 2.4969 g CaCO 3**  **(previously dried for one hour at 180** Ε **C) in reagent water. Dissolve cautiously with a minimum amount o**  **f 50% HNO 3**  **. Add 10.0 mL**

**concentrated HNO 3**  **and dilute to volume in a 1-L volumetric flask wit h reagent water.** 

**7.9.9 Chromium standard stock solution (1000 μg/mL Cr) - Prepare by**  **dissolving exactly 1.9231 g CrO 3**  **in reagent water. Following dissolution, acidify the** 

**solution with 10 mL concentrated HNO 3**  **and dilute to volume in a 1-L volumetric flask wit h**  **reagent water.**

**7.9.10 Cobalt standard stock solution (1000 μg/mL Co) - Prepare by dissolving**  **exactly 1.000 g of cobalt metal in a minimum amount of 50% HNO**  **3 . Add 10.0 mL 50%** 

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

**7.9.11 Copper standard stock solution (1000 μg/mL Cu) - Prepare by dissolving**  **exactly 1.2564 g CuO in a minimum amount of 50% HNO 3**  **. Add 10.0 mL concentrated**

**HNO 3**  **and dilute to volume in a 1-L volumetric flask wit h reagent water.** 

**7.9.12 Iron standard stock solution (1000 μg/mL Fe ) - Prepare by dissolving**  **exactly 1.4298 g Fe 2**  **O 3**  **in a warm mixture of 20 mL 50% HCl and 2 mL of con centrated** 

**HNO 3**  **. Following equilibration to ambient temperature, add an additional 5.0 mL of** 

**concentrated HNO 3**  **. Dilute the solution to volume in a 1-L volumetri c flask with reagent** 

**water.**

**7.9.13 Lead standard stock solution (1000 μg/mL Pb ) - Prepare by dissolving**  **exactly 1.5985 g Pb(NO 3**  **) 2**  **in a minimum amount of 50% HNO 3**  **. Add 10 mL 50% HNO 3**  **and dilute to volume in a 1-L volumetric flask with reagent water.** 

**7.9.14 Lithium standard stock solution (1000 μg/mL Li) - Prepare by dissolving**  **exactly 5.3248 g lithium carbonate in a minimum amo unt of 50% HCl. Dilute to volume in**  **a 1-L volumetric flask with reagent water. SW-846 Update V 6010D - 12 Revision 4**  **July 2014 7.9.15 Magnesium standard stock solution (1000 μg/**  **mL Mg) - Prepare by dissolving exactly 1.6584 g MgO in a minimum amount**  **of 50% HNO 3**  **. Add 10.0 mL 50%**

**HNO 3**  **and dilute to volume in a 1-L volumetric flask wit h reagent water.** 

**7.9.16 Manganese standard stock solution (1000 μg/ mL Mn) - Prepare by**  **dissolving exactly 1.000 g of manganese metal in an acid mixture of 10 mL concentrated** 

**HCl and 1 mL concentrated HNO 3**  **. Dilute to volume in a 1-L volumetric flask with reagent** 

**water.**

**7.9.17 Mercury standard stock solution (1000 μg/mL Hg) - Prepare by dissolving**  **exactly 1.354 g of** undried **HgCl 2**  **in reagent water. Add 50.0 mL concentrated HNO 3**  **and dilute to volume in 1-L volumetric flask with reage**  **nt water.**

**CAUTION : Drying of mercury salts can lead to a toxic inha**  **lation hazard.**

**7.9.18 Molybdenum standard stock solution (1000 μg /mL Mo) - Prepare by**  **dissolving exactly 1.7325 g (NH 4**  **) 6**  **Mo 7**  **O 24**  **•4H 2**  **O in reagent water and dilute to volume in a 1-L volumetric flask with reagent water.** 

**7.9.19 Nickel standard stock solution (1000 μg/mL Ni) - Prepare by dissolving**  **exactly 1.000 g of nickel metal in 10.0 mL of hot, concentrated HNO**  **3 . Following**  **equilibration to ambient temperature, dilute the so lution to volume in a 1-L volumetric flask**  **with reagent water.**

**7.9.20 Phosphate standard stock solution (1000 μg/ mL P) - Prepare by**  **dissolving exactly 4.3937 g of anhydrous KH 2**  **PO 4**  **in reagent water. Dilute to volume in a 1-L volumetric flask with reagent water.** 

**7.9.21 Potassium standard stock solution (1000 μg/ mL K) - Prepare by**  **dissolving exactly 1.9069 g KCl (dried to a constan t weight at 110**  Ε **C) in reagent water.**

**Dilute to volume in a 1-L volumetric flask with rea gent water.** 

**7.9.22 Selenium standard stock solution (1000 μg/m L Se) - Prepare by**  **dissolving exactly 1.6332 g of** undried **H 2**  **SeO 3**  **in reagent water and dilute to volume in a 1-L volumetric flask with reagent water.** 

**7.9.23 Silica standard stock solution (1000 μg/mL SiO**  **2 ) - Prepare by dissolving**  **exactly 2.964 g of** undried **(NH4) 2**  **SiF6 in 200 mL of 1:20 HCl. Heat solution to 85** Ε **C to aid in dissolution. After allowing the solution to**  **equilibrate to ambient temperature, dilute to volume in a 1-L volumetric flask with reagent wa**  **ter. Transfer immediately to an appropriate container for storage. Protect standar**  **d from light during storage.**

**7.9.24 Silver standard stock solution (1000 μg/mL Ag) - Prepare by dissolving**  **exactly 1.5748 g of AgNO 3**  **in a reagent water mixture of 10 mL concentrated H NO**  **3 . Dilute**  **to volume in a 1-L volumetric flask with reagent wa ter. Protect standard from light during**  **storage.**

**7.9.25 Sodium standard stock solution (1000 μg/mL Na) - Prepare by dissolving**  **exactly 2.5419 g of NaCl in reagent water. Add 10. 0 mL of concentrated HNO**  **3 and dilute**  **to volume in a 1-L volumetric flask with reagent wa ter.** **SW-846 Update V 6010D - 13 Revision 4 July 2014**  **7.9.26 Strontium standard stock solution (1000 μg/ mL Sr) - Prepare by**  **dissolving exactly 2.4154 g of Sr(NO 3**  **) 2**  **in a 1-L volumetric flask containing 10 mL of concentrated HCl and 700 mL of reagent water. Dilu**  **te to volume with reagent water.**

**7.9.27 Thallium standard stock solution (1000 μg/m L Tl) - Prepare by dissolving**  **exactly 1.3034 g TlNO 3**  **in reagent water. Add 10.0 mL of concentrated HNO 3**  **and dilute to volume in a 1-L volumetric flask with reagent water** 

**.**

**7.9.28 Tin standard stock solution (1000 μg/mL Sn) - Prepare by dissolving**  **exactly 1.000 g Sn shot in 200 mL of 50% HCl. Appl y heat to aid in dissolution. After**  **allowing the solution to equilibrate to ambient tem perature, dilute to volume in a 1-L** 

**volumetric flask with 50% HCl.**

**7.9.29 Vanadium standard stock solution (1000 μg/ mL V) - Prepare by dissolving**  **exactly 2.2957 g NH 4**  **VO 3**  **in a minimum amount of concentrated HNO 3**  **. Apply heat to aid in dissolution. After allowing the solution to equ**  **ilibrate to ambient temperature, add 10.0**

**mL of concentrated HNO 3**  **and dilute to volume in a 1-L volumetric flask wit h reagent** 

**water.**

**7.9.30 Zinc standard stock solution (1000 μg/mL Z n) - Prepare by dissolving**  **exactly 1.2447 g ZnO in a minimum amount of dilute HNO**  **3 . Add 10.0 mL of concentrated** 

**HNO 3**  **and dilute to volume in a 1-L volumetric flask wit h reagent water.** 

**7.9.31 Yttrium internal standard stock solution (1 000 μg/mL Y) - Prepare by**  **dissolving exactly 4.3081 g Y(NO 3**  **) 3**  **•6H 2**  **O in a minimum amount of concentrated HNO 3** 

**. Add 10.0 mL concentrated HNO**  **3 and dilute to volume in a 1-L volumetric flask wit**  **h reagent water.** 

**7.10 If the determination of one or more metals us ing a non-aqueous solvent is**  **required, then all standards and quality control sa mples must be prepared on a weight/weight**  **basis in the non-aqueous solvent since the density of non-aqueous solvents is not uniform.**  **Standards and quality control materials containing organometallic materials that are soluble in**  **non-aqueous solvents are available from a variety o f vendors.** 

**7.11 Working-level standard solutions and blanks**

**NOTE : Following the preparation of all intermediate- a**  **nd working-level standard solutions, blanks, and QC standards (Sec. 9.0) immediately tra**  **nsfer to an appropriate container for storage. For all intermediate and working stan**  **dards, especially low-level standards (i.e., < 1 μg/mL metal), the stability must be demo**  **nstrated prior to use. Working-level standards should be prepared as needed, recognizing**  **the fact that low-level metal standards can degrade rapidly over time (Refer to S**  **ec. 10.6 for guidance on determining the integrity of standards.)** 

**7.11.1 Mixed-calibration standard solutions — Prep are by combining proper** 

**volumes of the standard stock solutions in 100-mL v olumetric flasks. Add the appropriate**  **types and volumes of acids so that the matrices of the standards are matched, relative to**  **those of the sample digestates. Store all mixed-ca libration standards in an appropriate**  **container and protect from light. Prior to prepari ng the mixed standards, each standard**  **stock solution should be analyzed, separately, in o rder to determine possible spectral** **SW-846 Update V 6010D - 14 Revision 4 July 2014**  **interferences and/or the presence of impurities. S tandards which interfere with another**  **analyte, or which are contaminated with another ana lyte, may not be included in the same**  **calibration standard as that analyte. Refer to Tabl e 2 for recommendations in selecting the**  **most appropriate stock standards (Sec. 7.9) to comb ine for the preparation of working** 
**level, mixed–calibration standards.**

**NOTE : Care should be taken when preparing the calibrat**  **ion standards to ensure that the elements are compatible and stable when mixed t**  **ogether.**

**NOTE : Depending on the acid combination of the resulti**  **ng mixed-standard solution, the formation of a precipitate may occur upon addition**  **of the silver standard stock solution. If this happens, add 15 mL of reagent wa**  **ter and apply heat to the volumetric flask until the solution clears. Equili**  **brate the flask to ambient temperature following dissolution and dilute to vol**  **ume with reagent water. For such an acid combination, the silver concentration**  **should be limited to 2 mg/L.**

**Silver is stable under these conditions in a water matrix for 30 days if protected**  **from the light. Higher concentrations of silver ne cessitate the use of additional** 

**HCl.**

**7.11.2 Blanks - Two types of blanks are necessary for the analysis of samples**  **prepared by any method, other than Method 3040: (1 ) the calibration blank is used in**  **establishing the analytical curve; and (2) the meth od blank contains all of the exact same**  **reagents, and in the same proportions, as those use d for the processing of samples, and**  **is thus used to identify possible contamination res ulting from either the reagents (namely,**  **acids) or equipment (including even filters) used d uring sample processing.** 

**7.11.2.1 Calibration blank - Prepare by acidifying reagent water using** 

**the same combination and concentrations of acids us ed in the preparation of the**  **matrix-matched calibration standards (Sec. 7.11.1). Prepare a sufficient quantity,**  **such that it may be used to flush the system in bet ween standards and samples.** 

**The calibration blank will also be used for all ini tial calibration blank (ICB) and**  **continuing calibration blank (CCB) determinations.**

**7.11.2.2 Method blank - Prepare by processing eith er a volume of**  **reagent water equal to that used for actual aqueous samples, or, otherwise, a**  **clean, empty container, equivalent to that used for actual solid samples through all**  **of the preparatory and instrument determination ste ps used for making ICP-OES**  **determinations in samples. These steps may include , but are not limited to, pre**  **filtering, digestion, dilution, filtering, and anal ysis (refer to Sec. 9.7.1).** 

**7.11.3 Initial calibration verification (ICV) sta ndard - Prepare by combining**  **compatible metals from standard stock solution sour ces that differ from those used for the**  **preparation of the calibration standards (Sec. 7.11 .1); or otherwise, purchase an already**  **prepared, second-source reference material from a d ifferent commercial lot or vendor.**  **The ICV should be prepared so as to contain metal c oncentrations equal or nearly**  **equivalent to the midpoint concentration level of t he calibration curve (see Sec. 10.8 for**  **use).**

**7.11.4 Continuing calibration verification (CCV) s tandard - Prepare using the**  **same acid matrix and stock standards employed when preparing the calibration standards.** **SW-846 Update V 6010D - 15 Revision 4 July 2014**  **The CCV should be prepared so as to contain metal c oncentrations equal or nearly**  **equivalent to the midpoint concentration of the cal ibration curve (see Sec. 10.8 for use).** 

**7.12 Spectral interference check (SIC) solutions - The SIC solutions must be used**  **regardless of whether or not interelement correctio ns are applied. They evaluate both potential**  **spectral interferences and the accuracy of any corr ection equations.** 

**7.12.1 Individual element SIC solutions - Individua l element SIC solutions are used**  **to evaluate possible spectral interferences and to set interelement corrections if**  **necessary. A solution of each element is prepared a t the highest concentration in the**  **linear range likely to be observed in samples. The acid strength should be equivalent to** 

**that of the calibration standards. See section 9.9. 1 for use of the individual element SIC** 

**solutions. SIC solutions should be tested to veri fy that they are not contaminated with**  **elements of interest. The verification of purity c an be done by analysis using an alternate**  **technology, such as ICP-MS. For ICP-OES instrument s with solid-state detectors, the**  **verification might also be done by examining altern ate wavelengths. If the SIC solutions**  **are purchased ready-made, the vendor should provide details of any contaminants. In**  **some cases it may not be possible to obtain solutio ns completely free of contaminants, in**  **which case the known, verified concentration can be subtracted from the instrument result**  **before assessing any interferences.**

**7.12.2 Mixed element SIC solution - The mixed eleme nt SIC solution is used as an** 
**ongoing daily check of freedom from spectral interf erences. The mixed element SIC** 
**solution contains the following elements and is mad e up in an acid solution equivalent to** 

**the calibration standards. See section 9.9.2 for us e of the mixed element SIC solution. As** 
**for the single element solutions described in 7.12. 1 known and documented contaminants** 

**are subtracted from the observed values in the mixe d element SIC check.** 

**Mixed element SIC solution: Aluminum, 500mg/L; Cal cium, 500mg/L; Iron, 200mg/L;** 
**Magnesium, 500mg/L**

**8.0 SAMPLE COLLECTION, PRESERVATION, AND HANDLING**

**Sample collection, preservation and storage require ments may vary by EPA program and**  **may be specified in a regulation or project plannin g document that requires compliance**  **monitoring for a given contaminant. Where such req uirements are specified in the regulation,**  **follow those requirements. In the absence of speci fic regulatory requirements, use the following**  **information as guidance in determining the sample c ollection, preservation and storage**  **requirements.**

**See Chapter Three, Inorganic Analytes, for sample c ollection and preservation** 

**instructions. SW-846 Update V 6010D - 16 Revision 4**  **July 2014 9.0 QUALITY CONTROL** 

**9.1 Refer to Chapter One for guidance on quality as surance (QA) and QC protocols.**  **When inconsistencies exist between QC guidelines, m ethod-specific QC criteria take**  **precedence over those criteria given in Chapter One . Any effort involving the collection of**  **analytical data should include development of a str uctured and systematic planning document,**  **such as a Quality Assurance Project Plan (QAPP) or a Sampling and Analysis Plan (SAP),**  **which translates project objectives and specificati ons into directions for those that will implement**  **the project and assess the results. Each laborator y should maintain a formal quality assurance**  **program. The laboratory should also maintain recor ds to document the quality of the data**  **generated. All data sheets and QC data should be m aintained for reference or inspection.** 

**9.2 Refer to Methods 3005, 3010, 3015, 3031, 3040, 3050, 3051, 3052, 7000, and**  **6800 for QC procedures to ensure the proper operati on of the various sample preparation**  **techniques. Any more specific QC procedures provid ed in this method will supersede those**  **noted in Methods 3005, 3010, 3015, 3031, 3040, 3050 , 3051, 3052, 7000, and 6800.** 

**9.3 Instrument Detection Limits**

**Instrument detection limits (IDLs) are useful means to evaluate the instrument noise level**  **and response changes over time for each analyte fro m a series of reagent blank analyses to**  **obtain a calculated concentration. They are not to be confused with the lower limit of**  **quantitation, nor should they be used in establishi ng this limit. It may be helpful to compare the**  **calculated IDLs to the established lower limit of q uantitation, however, it should be understood**  **that the lower limit of quantitation needs to be ve rified according to the guidance in Sec. 9.8.**  **IDLs in μg/L can be estimated as the mean of the bl ank results plus three times the standard**  **deviation of 10 replicate analyses of the reagent b lank solution. (Use zero for the mean if the**  **mean is negative). Each measurement should be perfo rmed as though it were a separate**  **analytical sample (i.e., each measurement must be f ollowed by a rinse and/or any other**  **procedure normally performed between the analysis o f separate samples). IDLs should be**  **determined at least once using new equipment, after major instrument maintenance such as**  **changing the detector, and/or at a frequency design ated by the project. An instrument log book**  **should be kept with the dates and information perta ining to each IDL performed.** 

**9.4 Initial demonstration of proficiency**

**Each laboratory must demonstrate initial proficienc y with each sample preparation and**  **determinative method combination by generating data of acceptable precision and bias for**  **target analytes in a clean matrix. If an autosampl er is used to perform sample dilutions, before**  **using the autosampler to dilute samples, the labora tory should satisfy itself that those dilutions**  **are of equivalent or better accuracy than is achiev ed by an experienced analyst performing** 

**manual dilutions. It is recommended that the labor atory should repeat the demonstration of**  **proficiency whenever new staff members are trained or significant changes in instrumentation** 

**are made.**

**9.5 Initially, before processing any samples, the a nalyst should demonstrate that all**  **parts of the equipment that come into direct contac t with the sample and reagents are**  **interference-free. This is accomplished through th e analysis of a method blank. As a**  **continuing check, each time samples are digested an d analyzed, and when there is a change in**  **reagents, a method blank should be prepared and ana lyzed for the compounds of interest as a**  **safeguard against chronic laboratory contamination. If an interference is observed that would** **SW-846 Update V 6010D - 17 Revision 4 July 2014**  **prevent the determination of the target analyte, de termine the source and eliminate it, if**  **possible, before processing the samples. The metho d blank should be carried through all**  **stages of sample preparation and instrument determi nation procedures. When new reagents or**  **chemicals are received, the laboratory should monit or the preparation and/or analysis blanks**  **associated with samples for any signs of contaminat ion. It is not necessary to test every new**  **batch of reagents or chemicals prior to sample prep aration if the source shows no prior**  **problems. However, if reagents are changed during a preparation batch, separate blanks need**  **to be prepared for each set of reagents.**

**9.6 Linear range**

**The linear range establishes the highest concentrat ion that may be reported without**  **diluting the sample. Following calibration, the lab oratory may choose to analyze a standard at a**  **higher concentration than the high standard in the calibration. The standard must recover within**  **10% of the true value, and if successful, establish es the linear range. The linear range**  **standards must be analyzed in the same instrument r un as the calibration they are associated**  **with (i.e., on a daily basis) but may be analyzed a nywhere within that run. If a linear range**  **standard is not analyzed for any specific element, the highest standard in the calibration**  **becomes the linear range.**

**NOTE : Many of the alkali- and alkaline-earth metals ha**  **ve second-order response curves due to ionization and self-absorption effects. These effe**  **cts can be minimized by using an easily ionized element in excess in the internal st**  **andard or standards themselves. Lithium or cesium are good candidates. Second-orde**  **r calibration curves may be used**

**for alkali or alkaline earth metals if the instrume ntation and software can accommodate**  **them. However the effective range must be checked and the second-order curve fit** 

**should have a correlation coefficient of 0.995 or b etter. Third-order calibration fits are**  **not acceptable. Second-order response curves shoul d be revalidated and recalculated**  **at least every six months. These curves are much m ore sensitive to changes in**  **operating conditions than the first-order curves an d should be checked whenever there**  **have been moderate equipment changes.**

**9.7 Sample QC for preparation and analysis**

**The laboratory must also have procedures for docum enting the effect of the matrix on**  **method performance (precision, bias, and sensitivit y). At a minimum, this should include the**  **analysis of QC samples including a method blank, a matrix spike (MS), a laboratory control**  **sample (LCS), and a duplicate sample in each analyt ical batch. Any method blanks, LCS,**  **samples MS samples, and duplicate samples should be subjected to the same preparatory and**  **instrumentation procedures (Sec. 11.0) as those use d on actual samples.** 

**9.7.1 For each batch of samples analyzed, at least one method blank must be**  **carried throughout the entire sample preparation an d instrument determination process, as**  **described in Chapter One. The importance of the me thod blank is to aid in identifying**  **when and/or if sample contamination is occurring. The method blank is considered to be**  **acceptable if it does not contain the target analyt es at concentration levels that exceed the**  **acceptance limits defined in Chapter One or in the project-specific DQOs. The laboratory** 

**should not subtract the results of the method blank from those of any associated samples.** 

**Such "blank subtraction" is not reliable because it is based on a single method blank value**  **rather than a statistically determined blank concen tration.** **SW-846 Update V 6010D - 18 Revision 4 July 2014**  **Blanks are generally considered to be acceptable if target analyte concentrations**  **are less than 1⁄2 the LLOQ or are less than project-s pecific requirements. Blanks may**  **contain analyte concentrations greater than accepta nce limits if the associated samples in**  **the batch are unaffected (i.e. targets are not pres ent in samples or sample concentrations** 

are ≥10X

**the blank). Other criteria may be used depending o n the needs of the project.** 

**If the method blank fails to meet the necessary acc eptance criteria, it should be re**  **analyzed once. If still unacceptable, then all sam ples associated with the method blank**  **must be re-prepared and re-analyzed, along with all other appropriate analysis batch QC**  **samples. If the method blank results do not meet t he acceptance criteria and reanalysis is**  **not practical, then the laboratory should report th e sample results along with the method**  **blank results, and provide a discussion of the pote ntial impact of the contamination on the**  **sample results. However, if an analyte of interest is found in a sample in the batch near its**  **concentration confirmed in the blank, the presence and/or concentration of that analyte**  **should be considered suspect and may require qualif ication. Refer to Chapter One for**  **additional guidance regarding the proper protocol w hen analyzing method blanks.** 

**9.7.2 Documenting the effect of the matrix should include the analysis of at**  **least one MS and one duplicate unspiked sample or o ne matrix spike/matrix spike**  **duplicate (MS/MSD) pair for each batch of samples p rocessed, as described in Chapter**  **One. An MS/MSD pair is used to document the bias a nd precision of a method in a given**  **sample matrix. The decision on whether to prepare and analyze duplicate samples or an**  **MS/MSD pair must be based on knowledge of the sampl es in the analysis batch. If**  **samples are expected to contain target analytes, la boratories may choose to use an MS**  **and a duplicate analysis of an unspiked field sampl e. If samples are not expected to**  **contain target analytes, the laboratories should us e an MS/MSD pair.** 

**MS/MSD samples should be spiked with each target e lement at the project-specific**  **action levels, or, when lacking project-specific ac tion levels, between the low- and mid**  **level standards, as appropriate. Acceptance criter ia should be set at laboratory-derived**  **limits, developed through the use of historical ana lyses, for each matrix type being**  **analyzed. However, historically derived acceptance limits must not exceed ± 25%**  **recovery of the target element spike values for acc uracy, and ≤ 20 relative percent**  **difference (RPD) for precision. In the absence of historical data, MS/MSD acceptance**  **limits should be set at ± 25% recovery and ≤ 20 RPD . Refer to Sec. 4.0 of Chapter One**  **for further guidance. If the bias and precision in dicators in an analytical batch fail to meet**  **the acceptance criteria, then the interference test discussed in Sec. 9.11 should be**  **performed. Refer to the definitions of bias and pr ecision, in Chapter One, for the proper**  **data reduction protocols.**

**NOTE :**  **If the background sample concentration is very low or non-detect, a spike**  **of greater than 5 times the background concentratio n is still acceptable.**  **To assess data precision with duplicate analyses, i t is preferable to use a**  **high concentration field sample to prepare unspiked laboratory duplicates**  **for metals analyses.**

**Calculate the RPD between duplicate or MS determin ations as follows:** **SW-846 Update V 6010D - 19 Revision 4 July 2014**  **100**

**2 D**  **D D**  **D RPD** 

**2**

**1 2**  **1** ×

        + −

=

**where:**

**RPD = relative percent difference**

**D 1**  **= MS or first sample analysis value**

**D 2**  **= MSD or duplicate sample analysis value**

**9.7.3 At least one LCS should be prepared and anal yzed with each batch of**  **analytical samples processed, as described in Chapt er One. The LCS consists of an**  **aliquot of a clean (control) matrix similar to the sample matrix and of the same weight or**  **volume. The LCS should be spiked at the same level s and using the same spiking**  **materials as the corresponding MS/MSD (see above Se c. 9.7.2). When the results of the**  **MS analysis indicate a potential problem due to the sample matrix itself, the LCS results**  **are used to verify that the laboratory can acceptab ly perform the analysis in a clean matrix.** 

**LCS acceptance criteria should be set at laborator y-derived limits, developed**  **through the use of historical analyses. However, h istorically derived acceptance limits**  **must not exceed ± 20% of the target element spike v alues. In the absence of historical**  **data, LCS acceptance limits should be set at ± 20%. If the result of an LCS does not meet**  **the established acceptance criteria, it should be r e-analyzed once. If still unacceptable,**  **then all samples after the last acceptable method b lank must be re-prepared and re**  **analyzed, along with all other appropriate analysis batch QC samples.** 

**9.7.4 Reference materials containing known amounts of target elements are**  **recommended when an appropriately similar medium of interest are available as one type**  **of QC after appropriate sample preparation. The re ference material may be used as the**  **LCS. For soil reference materials, the manufacture rs’ established acceptance criterion**  **should be used. For solid reference materials, ± 2 0% recovery (see Sec. 9.7.3) of the**  **reported manufacturers’ target element values may n ot be achievable. Refer to Chapters** 

**One and Three for additional information.**

**9.8 Lower Limit of Quantitation (LLOQ) check stand ard** 

**9.8.1 The laboratory should establish the LLOQ as t he lowest point of**  **quantitation which, in most cases, is the lowest co ncentration in the calibration curve. The**  **LLOQ is initially verified by the analysis of at le ast 7 replicate samples, spiked at the LLOQ**  **and processed through all preparation and analysis steps of the method. The mean**  **recovery and relative standard deviation of these s amples provide an initial statement of**  **precision and accuracy at the LLOQ. In most cases t he mean recovery should be +/- 35%** 

**of the true value and RSD should be < 20%. In-house limits may be calculated when**  **sufficient data points exist. Monitoring recovery o f LLOQ over time is useful for assessing**  **precision and bias. Refer to a scientifically valid and published method such as Chapter 9**  **of Quality Assurance of Chemical Measurements (Tayl or 1987) or the Report of the**  **Federal Advisory Committee on Detection and Quantit ation Approaches and Uses in**  **Clean Water Act Programs (http://water.epa.gov/scit ech/methods/cwa/det/index.cfm**  **) for calculating precision and bias for LLOQ.** **SW-846 Update V 6010D - 20 Revision 4 July 2014**  **9.8.2 Ongoing LLOQ verification, at a minimum, is o n a quarterly basis to**  **validate quantitation capability at low analyte con centration levels. This verification may**  **be accomplished either with clean control material (e.g., reagent water, method blanks,**  **Ottawa sand, diatomaceous earth, etc.) or a represe ntative sample matrix (free of target**  **compounds). Optimally, the LLOQ should be less tha n the desired regulatory action levels**  **based on the stated project-specific requirements.**

**9.9 Spectral interference checks (SIC)**

**Two types of SIC checks are used. Individual eleme nt SIC checks are performed when the**  **instrument is initially setup, and periodically (at least once every 6 months) thereafter. The**  **mixed element SIC solution is used daily to check t hat the instrument is free from interference**  **from elements typically observed in high concentrat ion and to check that and interference**  **corrections applied are still valid.**

**9.9.1 Single element interference checks - At a min imum, single element SIC**  **checks must be performed for the following elements :** 

**Aluminum 500mg/L; Boron 50mg/L, Barium, 50mg/L, Cal cium 500mg/L; Copper**  **50mg/L; Iron 200mg/L; Magnesium 500mg/L; Manganese 50mg/L; Molybdenum 20mg/L;**  **Sodium 1000mg/L; Nickel 20mg/L; Selenium 20mg/L; Si licon 200mg/L; Tin 20mg/L;**  **Vanadium 20mg/L; Zinc 20mg/L**

**The absolute value of the concentration observed fo r any unspiked analyte in the**  **single element SIC checks must be less than two tim es the analytes’ LLOQ. The**  **concentration of the SIC checks are suggested, but become the highest concentration**  **allowed in a sample analysis, and cannot be higher than the highest established linear**  **range. Samples with concentrations of elements high er than the SIC check must be** 

**diluted until the concentration is less than the SI C check solution. Note that reanalysis of a**  **diluted sample is required even if the high concent ration element is not required to be**  **reported for the specific sample, since the functio n of the SIC check is to evaluate spectral** 

**interferences on other elements.**

**The single element SIC checks are performed when th e instrument is setup and**  **periodically (at least once every 6 months) thereaf ter.** 

**9.9.2 Mixed element interference check - The mixed element SIC solution (see**  **section 7.12.2) is analyzed at least once per day, immediately after the initial calibration.**  **The concentration measured for any target analytes must be less than +/- the LLOQ. If this**  **criterion is not met then sample analysis may not p roceed until the problem is corrected, or**  **alternatively the LLOQ may be raised to twice the c oncentration observed in the SIC**  **solution. The only exceptions are those elements t hat have been demonstrated to be**  **contaminants in the SIC solutions (see Section 7.12 .1). These may be present up to the**  **concentration documented plus the LLOQ.**

**9.10 It is recommended that the laboratory adopt a dditional QA practices for use with**  **this method. The specific practices that are most productive depend upon the needs of the**  **laboratory and the nature of the samples. Whenever possible, the laboratory should analyze**  **reference materials and participate in relevant per formance evaluation (PE) studies.** **SW-846 Update V 6010D - 21 Revision 4 July 2014**  **9.11 If less than acceptable bias and precision da ta are generated for the matrix**  **spike(s), the additional QC protocols in sections 9 .11.1 and/or 9.11.2 should be performed prior**  **to reporting concentration data for the elements in this method. At a minimum these tests should**  **be performed with each batch of samples prepared/an alyzed with corresponding unacceptable**  **data quality results. If matrix interference effect s are confirmed, then an alternative test method** 

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

**the same interference. The use of a standard-addition analysis procedure m**  **ay also be used to compensate for this effect (refer to Method 7000).** 

**9.11.1 Dilution test**

**If the analyte concentration is within the linear r ange of the instrument and**  **sufficiently high (minimally, a factor of 25 times greater than the LLOQ), an analysis of a**  **1:5 dilution should agree to within ± 20% of the or iginal determination. If not, then a**  **chemical or physical interference effect should be suspected.**  **The matrix spike is often a good choice of sample for the dilution test, since**  **reasonable concentrations of most analytes are present. Elements that fail the diluti**  **on test are reported as estimated values.**

**CAUTION : If spectral overlap is suspected, then the use o**  **f computerized compensation, an alternate wavelength, or comparison with an alte**  **rnate method is recommended.**

**9.11.2 Post-digestion MS**

**If a high concentration sample is not available for performing the dilution test, then**  **a post-digestion MS should be performed. The test o nly needs to be performed for the**  **specific elements that failed original matrix spike limits, and only if the spike concentration**  **added was greater than the concentration determined in the unspiked sample. Following**  **preparation, which may include, but is not limited to, pre-filtration, digestion, dilution and**  **filtration, an aliquot, or dilution thereof, should be obtained from the final aqueous,**  **unspiked-analytical sample, and spiked with a known quantity of target elements. The**  **spike addition should be based on the indigenous co ncentration of each element of**  **interest in the sample. The recovery of the post-d igestion MS should fall within a ± 25 %**  **acceptance range, relative to the known true value, or otherwise within the laboratory**  **derived acceptance limits. If the post-digestion MS recovery fails to meet the acceptance**  **criteria, the sample results must be reported as es timated values.** 

**10.0 CALIBRATION AND STANDARDIZATION**

**10.1 Before using this procedure for quantitation, ensure that initial demonstration of**  **performance data is available for viewing. Such da ta must document:** 

• **The selection criteria for background correction p oints;** 

• **analytical dynamic ranges, including the applicabl e equations, and upper limits of** 

**ranges;**

• **IDLs and method LLOQs; and**

• **The determination and verification of interelement correction equations, or other**  **routines for correcting spectral interferences. Th ese data must be generated using the**  **same instrument, operating conditions, and calibrat ion routine to be used for sample** **SW-846 Update V 6010D - 22 Revision 4 July 2014**  **analysis. The data must be kept on file and availa ble for review by the data user or** 

**auditor.**

**10.2 Set up the instrument using the appropriate o perating conditions. Follow the**  **instructions provided by the instrument manufacture r unless other conditions provide similar or**  **better results. Specific wavelengths for use in qu antitation should be selected from the**  **manufacturer’s instructions. Other wavelengths may be substituted if they can provide the**  **needed sensitivity and are corrected for spectral i nterferences. Because of differences among**  **various makes and models of spectrometers, specific instrument operating conditions cannot be**  **provided. The instrument and operating conditions utilized for determination must be capable of**  **providing data of acceptable quality based on the s pecific program and end user. Operating**  **conditions for aqueous solutions usually vary from:**

• **1100-1500-watts forward power;**

• **14-18-mm viewing height;**

• **15-19-L/min argon-coolant flow;**

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

• **1.0-1.8-mL/min sample-pumping rate; with a 1-min p re-flush time and measurement**  **time near 1 sec/wavelength peak for sequential inst ruments and 10 sec/sample for** 

**simultaneous instruments.**

**One recommended way in which to achieve repeatable interference correction factors is to**  **adjust the argon-aerosol flow to reproduce the Cu/M n intensity ratio at the wavelengths 324.754** 

**nm and 257.610 nm.**

**10.3 Plasma optimization**

**Optimize the plasma operating conditions prior to use of the instrument. The purpose of**  **plasma optimization is to provide a maximum signal- to-background ratio for some of the least**  **sensitive elements in the analytical array. The us e of a mass-flow controller to regulate the**  **nebulizer gas flow or source optimization software greatly facilitates the procedure. This routine**  **is not needed on a daily basis, but only is necessa ry when first setting up a new instrument, or**  **following a change in operating conditions. The fo llowing procedure is recommended;**  **otherwise follow the manufacturer’s guidelines.**

**10.3.1 Ignite the radial plasma and select an appr opriate incident RF power.**  **Allow the instrument to become thermally stable bef ore beginning; approximately 30 - 60**  **min of operation. Optimize the ICP per manufacture r’s instructions or alternatively by the**  **following procedure: While aspirating a 1000-μg/L solution of yttrium, follow the**  **instrument manufacturer's instructions and adjust t he aerosol carrier gas-flow rate through**  **the nebulizer, so that a definitive blue emission r egion of the plasma extends**  **approximately 5 - 20 mm above the top of the load c oil. Record the nebulizer gas-flow**  **rate or pressure setting for future reference. The yttrium solution can also be used for**  **coarse optical alignment of the torch, by observing the overlay of the blue light over the**  **entrance slit to the optical system. If yttrium is an analyte of interest in samples, be aware**  **it may take some time to rinse out 1000 μg/L yttriu m solution.** 

**10.3.2 After establishing the nebulizer gas-flow r ate, determine the solution**  **uptake rate of the nebulizer in mL/min, by aspirati ng a known volume of a calibration blank** **SW-846 Update V 6010D - 23 Revision 4 July 2014**  **for a period of at least one minute. Divide the vo lume (mL) aspirated by the time (min) and**  **record the uptake rate. Set the peristaltic pump t o deliver this rate.** 

**10.3.3 Profile the instrument per manufacturer’s d irections to align it optically, as**  **it will be used during analysis.**

**10.3.4 Complete the following procedure for vertic al optimization or follow** 

**manufacturer’s directions:**

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

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

**and Pb are the least sensitive of the elements and most in need of optimization.**  **However, other elements may be used, based on the p rofessional judgment of the**  **analyst. (V, Cr, Cu, Li and Mn have also been used with success). Collect intensity data**  **at the wavelength peak for each analyte at 1mm inte rvals from 14 – 18 mm above the**  **load coil. (This region of the plasma is referred to as the "analytical zone".) Repeat this**  **process using the calibration blank. Determine the net signal-to-blank-intensity ratio for**  **each analyte for each viewing height setting. Choo se the height for viewing the plasma**  **that provides the best net intensity ratios for the elements analyzed or the highest**  **intensity ratio for the least sensitive element.**

**For optimization in the axial mode, follow the ins trument manufacturer’s** 

**instructions.**

**10.3.5 The instrument operating conditions finally selected as being optimum**  **should provide the lowest reliable IDLs.**

**10.3.6 If the instrument operating conditions, such as incident power or nebulizer**  **gas-flow rate, are changed, or if a new torch injec tor with a different orifice internal**  **diameter is installed, then the plasma and viewing height should be re-optimized.** 

**10.3.7 After completing the initial optimization of operating conditions, and**  **before analyzing samples, establish and initially v erify an interelement spectral**  **interference correction routine to be used during s ample analysis. A general description of**  **spectral interferences and the analytical specifica tions for background correction, in**  **particular, are discussed in Sec. 4.0. Directions for verification of freedom from**  **interference are given in Sections 7.12 and 9.9. Th e criterion for determining that an**  **interelement spectral interference is present is an apparent positive or negative**  **concentration for the analyte that falls beyond ± t he LLOQ from zero. The upper control**  **limit is the analyte LLOQ. Once established, verif y the entire routine at least once every**  **six months. Only a portion of the correction routi ne must be verified more frequently or on**  **a daily basis. Initial and periodic verifications of the routine should be kept on file.** 

**10.3.8 Before daily calibration, and after the inst rument warm-up period, the**  **nebulizer gas-flow rate must be reset to the determ ined optimized flow. If a mass-flow**  **controller is being used, it should be set to the r ecorded optimized flow rate. In order to**  **maintain valid spectral interelement correction rou tines, the nebulizer gas-flow rate should**  **be the same (< 2% change) from day to day. SW-846 Update V 6010D - 24 Revision 4**  **July 2014 10.4 For operation with organic solvents, the use**  **of the auxiliary argon inlet is recommended, as is the use of solvent-resistant tub**  **ing, increased plasma (coolant) argon flow, decreased nebulizer flow, and increased RF power, i**  **n order to obtain a robust plasma, stable operating conditions, and precise measurements.** 

**10.5 At a minimum, the elements required for the pr oject plus any required for** 

**interference correction must be calibrated. Recomme nded wavelengths for the analytes in Sec.** 

**1.1 should be obtained from the instrument manufact urer. Flush the system in between each**  **standard and sample using the rinse blank. The rins e time needs to be sufficient to ensure that**  **analytes present at the linear range are effectivel y cleaned out prior to analysis of the**  **subsequent sample. Use the average of at least thre e integrations for both calibration standard**  **and sample analyses.**

**10.6 Calibration standards should be prepared on an as-needed basis unless stability**  **warrants preparing fresh daily, (or each time a bat ch of samples is analyzed). If the ICV**  **standard is prepared daily and the results of the I CV analyses meet the acceptance criteria,**  **then the calibration standards do not need to be pr epared daily and may be prepared and**  **stored for as long as the calibration standard viab ility can be verified through the use of the ICV.**  **If the ICV fails to meet the acceptance criteria, t rouble shoot the situation, and then prepare a** 

**new set of calibration standards if needed and reca librate the instrument** 

**10.7 A calibration curve must be analyzed daily. Th e instrument may be calibrated**  **using a single point standard and a calibration bla nk (ICB) or a multipoint calibration curve. If a**  **multipoint curve is used a minimum of three standar ds are required and the correlation**  **coefficient (r) should be > 0.995 or the coefficient of determination (r**  **2 ) should be >**  **0.990. Relative Standard Error may be used as an alternati**  **ve to r or r 2**  **, and should be < 20%. If a**  **multipoint calibration is used the low standard mus t be at or below the LLOQ.** 

**NOTE : Inversely weighted linear regressions are recomm**  **ended in order to minimize curve**

**fitting errors at the low end of the calibration cu rve.** 

**10.8 After the calibration is completed it is verif ied using several checks.** 

**10.8.1 Initial Calibration Verification (ICV) - The ICV is a standard prepared from**  **a separate source than the initial calibration stan dards. It is analyzed at approximately the** 

**mid-level of the calibration and serves as a check that the initial calibration standards are**  **at the correct concentrations. The acceptance range is 90-110% of the true value.** 

**10.8.2 Low-level readback or verification - For a m ulti-point calibration, the low**  **level standard should quantitate to within 80-120% of the true value. For a single point**  **calibration, a standard from the same source as the calibration standard and at the LLOQ**  **is analyzed and should recover within 80-120% of th e true value.** 

**10.8.3 Mid-level readback or verification - For a m ulti-point calibration, the mid**  **level standard should quantitate to within 90-110% of the true value. For a single point**  **calibration, a standard from the same source as the calibration standard and at the mid**  **point of the linear range is analyzed and should re cover within 90-110% of the true value.** 

**10.8.4 Initial Calibration blank (ICB) - If a multi -level calibration is used, an ICB is**  **analyzed immediately after the calibration (or afte r the ICV) and must not contain target**  **analytes above half the LLOQ. If a single point cal ibration is used, the calibration is forced** **SW-846 Update V 6010D - 25 Revision 4 July 2014**  **through the ICB, but a second ICB is analyzed as a check and must not contain target**  **analytes above half the LLOQ. If the ICB consistent ly has target analyte concentrations**  **greater than half the LLOQ, the LLOQ should be re-e valuated.** 

**10.8 5 Verify the ongoing validity of the calibrati on curve after every 10 samples,**  **and at the end of each analysis batch run, through the analysis of a CCV standard (Sec.**  **7.11.4 and a CCB (Sec. 7.11.2.1). For the curve to be considered valid the analysis result** 

**of the CCV standard must be within ± 10% of its tru e value and the CCB must not contain**  **target analytes above the LLOQ. If the calibration cannot be verified, sample analysis**  **must be discontinued, the cause of the problem dete rmined and the instrument**  **recalibrated. All samples following the last accep table CCV standard must be reanalyzed**  **Flow-injection systems may be used as long as they can meet the performance criteria of** 

**the method.**

**NOTE : During the course of an analytical run, the inst**  **rument may be recalibrated to**

**correct for instrument drift. A recalibration must then be followed immediately by a**  **new analysis of a CCV and CCB before any further sa mples may be analyzed.** 

**11.0 PROCEDURE**

**11.1 Preliminary treatment of most samples is nece ssary because of the complexity and**  **variability of sample matrices. Groundwater sample s which have been pre-filtered and acidified**  **will not need acid digestion. Samples which are no t digested must either use an internal**  **standard or be matrix-matched with the standards (i .e., acid concentrations should match).**  **Solubilization and digestion procedures are present ed in Chapter Three, Inorganic Analytes.** 

**11.2 Profile and calibrate the instrument accordin g to the instrument manufacturer's**  **recommended procedures, using the typical mixed-cal ibration standard solutions described in**  **Sec. 7.11.1. Prepare the calibration curve as deta iled in Sec. 10.7. Flush the system between**  **each standard using the calibration blank (Sec. 7.1 1.2.1), or as the manufacturer recommends.**  **In order to reduce random error, use the average in tensity of multiple exposures for both**  **standardization and sample analysis.**

**11.3 For all analytes and determinations, the labo ratory must analyze an ICV (Secs**  **7.11.3 and 10.8.1) and a CCV (Secs. 7.11.4 and 10.8 .5) and CCB (Secs. 7.11.2.1 and 10.8.5)**  **after every ten samples and at the end of the analy sis batch run.** 

**11.4 Analyze the samples and record the results. In between each sample or standard,**  **rinse the system using the calibration blank soluti on (Sec. 7.11.2.1). Use a minimum rinse time**  **of one minute. Each laboratory may establish a red uction in the rinse time following a suitable** 

**demonstration.**

**11.5 Determination of percent dry weight**

**When sample results are to be calculated on a dry-w eight basis, a separate portion of**  **sample for this determination should be weighed out at the same time as the portion used for**  **analytical determination.**

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

**contamination may result from a heavily contaminate d hazardous waste sample.** **SW-846 Update V 6010D - 26 Revision 4 July 2014**  **11.5.1 Immediately after weighing the sample aliquo t to be digested, weigh an**  **additional 5- to 10-g aliquot of the sample into a tared crucible. Dry this aliquot overnight** 

**at 105** Ε **C. Allow the sample to cool in a desiccator before weighing.** 

**11.5.2 Calculate the % dry weight as follows:**

**This oven-dried aliquot is not used for the extract ion and should be appropriately disposed**  **of once the dry weight is determined.**

**12.0 DATA ANALYSIS AND CALCULATIONS**

**12.1 If dilutions were performed, apply the approp riate dilution factors to the respective**  **sample values. Report results up to three signific ant figures.** 

**12.2 If appropriate, or required by the project or regulation for data reporting, calculate**  **results for solids on a dry-weight basis as follows :** 

**S W**  **V C**  **ion Concentrat**  **DW** × ×

=

**where:**

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

**C = Digest concentration (mg/L) V = Final volume after sample preparation (L)**  **W =Wet sample mass (kg) S = % Solids/100 = % dry weight/100** 

**13.0 METHOD PERFORMANCE**

**Performance data and related information are provi ded in SW-846 methods only as**  **examples and guidance. The data do not represent r equired performance criteria for users of**  **the methods. Instead, performance criteria should be developed on a project-specific basis,**  **and the laboratory should establish in-house QC per formance criteria for the application of this**  **method. These performance data are not intended to be and must not be used as absolute QC**  **acceptance criteria for purposes of laboratory accr editation** 

**.**

**13.1 In an EPA round-robin study, seven laboratori es applied the ICP-OES technique to**  **water matrices spiked with various metal concentrat es and acid-digested. Table 3 lists the true**  **values, the mean reported results, and the mean per cent relative standard deviations. These**  **data are provided for guidance purposes only.**

**13.2 Performance data for aqueous solutions and so lid samples from a multi-laboratory**  **study are provided in Tables 5 and 6. These data a re provided for guidance purposes only.**  **100 x**  **sample of**  **g sample**  **dry of**  **g =**  **weight dry**  **% SW-846 Update V 6010D - 27 Revision 4**  **July 2014 14.0 POLLUTION PREVENTION** 

**14.1 Pollution prevention encompasses any techniqu e that reduces or eliminates the**  **quantity and/or toxicity of waste at the point of g eneration. Numerous opportunities for pollution**  **prevention exist in laboratory operations. The EPA has established a preferred hierarchy of**  **environmental management techniques that places pol lution prevention as the management**  **option of first choice. Whenever feasible, laborat ory 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 th at may be applicable to laboratories** 

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

Reduction **, a free publication available from the American Ch emical Society (ACS), Committee**  **on Chemical Safety, http://portal.acs.org/portal/fileFetch/C/WPCP_01229**  **0/pdf/WPCP_012290.pdf.**

**15.0 WASTE MANAGEMENT**

**The Environmental Protection Agency requires that laboratory waste management**  **practices be conducted consistent with all applicab le rules and regulations. The Agency urges**  **laboratories to protect the air, water, and land by minimizing and controlling all releases from**  **hoods and bench operations, complying with the lett er and spirit of any sewer discharge permits**  **and regulations, and by complying with all solid an d hazardous waste regulations, particularly** 

**the hazardous waste identification rules and land d isposal restrictions. For further information**  **on waste management, consult the ACS publication listed in Sec. 14.2.** 

**16.0 REFERENCES**

**1. C.L. Jones,** et al **., "An Interlaboratory Study of Inductively Coupled Plasma Atomic**  **Emission Spectroscopy Method 6010 and Digestion Met hod 3050," EPA-600/4-87-032,**  **U.S. Environmental Protection Agency, Las Vegas, NV , 1987.** 

**2. Taylor, J. K., “Quality Assurance of Chemical Me asurements”, Lewis Publishers (1987).** 

**3. Federal Advisory Committee on Detection and Quan titation Approaches and Uses in**  **Clean Water Act Programs, Final Report, http://water.epa.gov/scitech/methods/cwa/det/index.**  **cfm (December 28, 2007).**

**17.0 TABLES, DIAGRAMS, FLOW CHARTS, AND VALIDATION DATA** 

**The pages to follow contain the tables, and figure s referenced by this method.** **SW-846 Update V 6010D - 28 Revision 4 July 2014**  **TABLE 1**

**POTENTIAL INTERFERENCES AND ANALYTE CONCENTRATION E QUIVALENTS (mg/L)** 

**ARISING FROM INTERFERENCE AT THE 100-mg/L LEVEL**

**Analyte Wavelength**  **c**

**(nm) Interferent**  **a,b**

**Al Ca**  **Cr Cu**  **Fe Mg**  **Mn Ni**  **Ti V** 

**Aluminum 308.215** 
**-- --**  **-- --**  **-- --**  **0.21**
**-- --**  **1.4**

**Antimony 206.833**  **0.47**
**-- 2.9** 
**-- 0.08** 
**-- --**  **-- 0.25**  **0.45**

**Arsenic 193.696**  **1.3**
**-- 0.44** 
**-- --**  **-- --**  **-- --**  **1.1**

**Barium 455.403** 
**-- --**  **-- --**  **-- --**  **-- --**  **-- --** 

**Beryllium 313.042** 
**-- --**  **-- --**  **-- --**  **-- --**  **0.04 0.05** 

**Cadmium 226.502** 
**-- --**  **-- --**  **0.03**
**-- --**  **0.02**
**-- --** 

**Calcium 317.933** 
**-- --**  **0.08**
**-- 0.01**  **0.01 0.04** 
**-- 0.03**  **0.03**

**Chromium 267.716** 
**-- --**  **-- --**  **0.003**
**-- 0.04** 
**-- --**  **0.04**

**Cobalt 228.616** 
**-- --**  **0.03**
**-- 0.005** 
**-- --**  **0.03 0.15** 
**--**

**Copper 324.754** 
**-- --**  **-- --**  **0.003**
**-- --**  **-- 0.05**  **0.02**

**Iron 259.940** 
**-- --**  **-- --**  **-- --**  **0.12**
**-- --**  **--**

**Lead 220.353**  **0.17**
**-- --**  **-- --**  **-- --**  **-- --**  **--**

**Magnesium 279.079** 
**-- 0.02**  **0.11**
**-- 0.13** 
**-- 0.25** 
**-- 0.07**  **0.12**

**Manganese 257.610**  **0.005**
**-- 0.01** 
**-- 0.002**  **0.002**
**-- --**  **-- --** 

**Molybdenum 202.030**  **0.05**
**-- --**  **-- 0.03** 
**-- --**  **-- --**  **--**

**Nickel 231.604** 
**-- --**  **-- --**  **-- --**  **-- --**  **-- --** 

**Selenium 196.026**  **0.23**
**-- --**  **-- 0.09** 
**-- --**  **-- --**  **--**

**Sodium 588.995** 
**-- --**  **-- --**  **-- --**  **-- --**  **0.08**
**--**

**Thallium 190.864**  **0.30**
**-- --**  **-- --**  **-- --**  **-- --**  **--**

**Vanadium 292.402** 
**-- --**  **0.05**
**-- 0.005** 
**-- --**  **-- 0.02** 
**--**

**Zinc 213.856** 
**-- --**  **-- 0.14** 
**-- --**  **-- 0.29** 
**-- --** 

**NOTE :**  **a Dashes indicate that no interference was observed e**  **ven when interferents were introduced at**

**the following levels:**

**Al at 1000 mg/L Cu at 200 mg/L Mn at 200 mg/L**

**Ca at 1000 mg/L Fe at 1000 mg/L Ti at 200 mg/L**

**Cr at 200 mg/L Mg at 1000 mg/L V at 200 mg/L**

**b The figures shown above as analyte concentration eq**  **uivalents are not the actual observed concentrations. To obtain those figures, add the l**  **isted concentration to the interferent figure.**

**c Interferences will be affected by background and wa**  **velength choice and other interferences may be present.** **SW-846 Update V 6010D - 29 Revision 4 July 2014**  **TABLE 2**

**MIXED STANDARD SOLUTIONS**

**Solution Elements** 

**I Be, Cd, Mn, Pb, Se and Zn** 

**II Ba, Co, Cu, Fe, and V** 

**III As and Mo** 

**IV Al, Ca, Cr, K, Na, Ni, Li, and Sr** 

**V Ag**  **a , Mg, Sb, and Tl** 

**VI P** 

**a See second note in Sec. 7.10.1.** **SW-846 Update V 6010D - 30** **Revision 4 July 2014** **TABLE 3 ICP PRECISION AND BIAS DATA** **a Sample No. 1** **Sample No. 2 Sample No. 3** **Element True** **Conc. (** μ**g/L) Mean** **Conc. (** μ**g/L) RSD** **b (%)** **Accuracy d** **(%) True** **Conc. (** μ**g/L) Mean** **Conc. (** μ**g/L) RSD** **b (%)** **Accuracy d** **(%) True** **Conc. (** μ**g/L) Mean** **Conc. (** μ**g/L) RSD** **b (%)** **Accuracy d** **(%) Be** **750 733** **6.2 98** **20 20** **9.8 100** **180 176** **5.2 98** **Mn 350** **345 2.7** **99 15** **15 6.7** **100 100** **99 3.3** **99 V** **750 749** **1.8 100** **70 69** **2.9 99** **170 169** **1.1 99** **As 200** **208 7.5** **104 22** **19 23** **86 60** **63 17** **105 Cr** **150 149** **3.8 99** **10 10** **18 100** **50 50** **3.3 100** **Cu 250** **235 5.1** **94 11** **11 40** **100 70** **67 7.9** **96 Fe** **600 594** **3.0 99** **20 19** **15 95** **180 178** **6.0 99** **Al 700** **696 5.6** **99 60** **62 33** **103 160** **161 13** **101 Cd** **50 48** **12 96** **2.5 2.9** **16 116** **14 13** **16 93** **Co 700** **512 10** **73 20** **20 4.1** **100 120** **108 21** **90 Ni** **250 245** **5.8 98** **30 28** **11 93** **60 55** **14 92** **Pb 250** **236 16** **94 24** **30 32** **125 80** **80 14** **100 Zn** **200 201** **5.6 100** **16 19** **45 119** **80 82** **9.4 102** **Se c** **40 32** **21.9 80** **6 8.5** **42 142** **10 8.5** **8.3 85** **NOTE :** **a Not all elements were analyzed by all laboratories.** **b RSD = relative standard deviation.** **c Results for Se are from two laboratories.** **d Accuracy is expressed as the mean concentration div** **ided by the true concentration times 100. SW-846 Update V 6010D - 31 Revision 4**  **July 2014 TABLE 4** 

**EXAMPLE ICP-OES PRECISION AND BIAS FOR AQUEOUS SOLU TIONS** 

**Element Mean Concentration** 

**(mg/L) n**  **RSD (%) Accuracy (%)** 

**Al 14.8**  **8 6.3**  **100**

**Sb 15.1**  **8 7.7**  **102**

**As 14.7**  **7 6.4**  **99**

**Ba 3.66**  **7 3.1**  **99**

**Be 3.78**  **8 5.8**  **102**

**Cd 3.61**  **8 7.0**  **97**

**Ca 15.0**  **8 7.4**  **101**

**Cr 3.75**  **8 8.2**  **101**

**Co 3.52**  **8 5.9**  **95**

**Cu 3.58**  **8 5.6**  **97**

**Fe 14.8**  **8 5.9**  **100**

**Pb 14.4**  **7 5.9**  **97**

**Mg 14.1**  **8 6.5**  **96**

**Mn 3.70**  **8 4.3**  **100**

**Mo 3.70**  **8 6.9**  **100**

**Ni 3.70**  **7 5.7**  **100**

**K 14.1**  **8 6.6**  **95**

**Se 15.3**  **8 7.5**  **104**

**Ag 3.69**  **6 9.1**  **100**

**Na 14.0**  **8 4.2**  **95**

**Tl 15.1**  **7 8.5**  **102**

**V 3.51**  **8 6.6**  **95**

**Zn 3.57**  **8 8.3**  **96**

**NOTE : 1. These performance values are independent of s**  **ample preparation because**

**the labs analyzed portions of the same solutions an d are provided for**  **illustrative purposes only. 2. n = Number of measurements.3. Accuracy is expres**  **sed as a percentage of the nominal value for each analyte in acidified, mu**  **lti-element solutions. SW-846 Update V 6010D - 32 Revision 4**  **July 2014 TABLE 5** 

**EXAMPLE ICP-OES PRECISION AND BIAS FOR SOLID WASTE DIGESTS** 

**Spiked Coal Fly Ash (NIST-SRM 1633a)**  **Spiked Electroplating Sludge**

**Element Mean** 

**Conc. (mg/L)**  **n RSD**  **(%) Bias** 

**(% AA) Mean** 

**Conc. (mg/L)**  **n RSD**  **(%) Bias** 

**(% AA)**

**Al 330**  **8 16**  **104 127**  **8 13**  **110**

**Sb 3.4**  **6 73**  **96 5.3**  **7 24**  **120**

**As 21**  **8 83**  **270 5.2**  **7 8.6**  **87**

**Ba 133**  **8 8.7**  **101 1.6**  **8 20**  **58**

**Be 4.0**  **8 57**  **460 0.9**  **7 9.9**  **110**

**Cd 0.97**  **6 5.7**  **101 2.9**  **7 9.9**  **90**

**Ca 87**  **6 5.6**  **208 954**  **7 7.0**  **97**

**Cr 2.1**  **7 36**  **106 154**  **7 7.8**  **93**

**Co 1.2**  **6 21**  **94 1.0**  **7 11**  **85**

**Cu 1.9**  **6 9.7**  **118 156**  **8 7.8**  **97**

**Fe 602**  **8 8.8**  **102 603**  **7 5.6**  **98**

**Pb 4.6**  **7 22**  **94 25**  **7 5.6**  **98**

**Mg 15**  **8 15**  **110 35**  **8 20**  **84**

**Mn 1.8**  **7 14**  **104 5.9**  **7 9.6**  **95**

**Mo 891**  **8 19**  **105 1.4**  **7 36**  **110**

**Ni 1.6**  **6 8.1**  **91 9.5**  **7 9.6**  **90**

**K 46**  **8 4.2**  **98 51**  **8 5.8**  **82**

**Se 6.4**  **5 16**  **73 8.7**  **7 13**  **101**

**Ag 1.4**  **3 17**  **140 0.75**  **7 19**  **270**

**Na 20**  **8 49**  **130 1380**  **8 9.8**  **95**

**Tl 6.7**  **4 22**  **260 5.0**  **7 20**  **180**

**V 1010**  **5 7.5**  **100 1.2**  **6 11**  **80**

**Zn 2.2**  **6 7.6**  **93 266**  **7 2.5**  **101**

**NOTE : 1. These performance values are independent of s**  **ample preparation because the labs**

**analyzed portions of the same digests and are provi ded for illustrative purposes only.** 

**2. n = Number of measurements.**

**3. Bias for the ICP-OES data is expressed as a perc entage of atomic absorption**  **spectroscopy (AA) data for the same digests. SW-846 Update V 6010D - 33 Revision 4**  **July 2014 METHOD 6010C** 

**INDUCTIVELY COUPLED PLASMA-OPTICAL EMISSION SPECTRO METRY** **SW-846 Update V 6010D - 34 Revision 4 July 2014**  

### Appendix A

**Summary of Revisions to Method 6010 (From Revision 3, February 2007):** 

**1. Improved overall method formatting for consisten cy with new SW-846 method style**  **guidance. 2. Changed title of method from “Inductively couple**  **d plasma—atomic emission spectrometry” to “Inductively coupled plasma—optica**  **l emission spectrometry”. All references to atomic emission spectrometry were cha**  **nged to optical emission spectrometry throughout the method.**  **3. Section 1.1 - added a note and caution regarding analysis of mercury by method 6010.** 

**4. Section 1.6 - inserted references to additional 3000 series preparatory methods to ICP**  **analysis. Also added method 6800 to sections 1.6 an d 9.2 as a preparatory method.**  **5. Inserted new section (7.10) regarding analysis o f non-aqueous solvents.**  **6. Made significant technical and editorial changes to Sec. 4.0 to improve method clarity and**  **technological accuracy. 7. Inserted additional safety guidance regarding th**  **e use of HF. 8. Reformatted certain paragraphs with the heading**  **"NOTE" or "WARNING" to better denote the importance of the recommendations provided ther**  **ein. 9. Extensively reformatted “REAGENTS AND STANDARDS”**  **section to meet current SW 846 method guidelines.**  **10. Significantly updated and expanded “QUALITY CON TROL” section for better adherence**  **to current SW-846 method guidelines and for improve d alignment with current universal**  **practices for published analytical methods. 11. Inserted new sections (Sections 7.12 and 9.9) t**  **o describe the preparation and use of the spectral interference check (SIC) solution; also ad**  **ded instructions to match the matrix of**

**this solution to that of the calibration standards. 12. Removed all references to "MDLs" and replaced t**  **hem with either "IDLs" or "LLOQs" as appropriate.**  **13. Removed all references to method 7000 except fo r guidance regarding the method of** 

**standard addition. 14. The term “accuracy” was replaced by “bias” wher**  **e appropriate. 15. In Section 7.9, 105EC was corrected to 105°C.**  **16. Added “Protect standard from light during stora ge.” to Section 7.9.24.**  **17. In Section 7.9.6, a correction was made to the concentration of boron in the standard**  **described by the text. 18. Replaced the term “unity” with “uniform” in Sec**  **tion 7.10. 19. In Section 9.4, the requirement to repeat the d**  **emonstration of proficiency for new staff and instrumentation changes was changed to a recommenda**  **tion. 20. Section 9.7.2 – Added a note regarding MS/MSD s**  **pike concentrations and unspiked laboratory duplicates.**  **21. The section regarding analysis of reference mat erials (Sec. 9.7.4) was revised for clarity**  **and the term “Standard Reference Material” was repl aced with “reference material”**  **throughout the method. 22. Inserted new section (Sec. 9.8) describing the**  **preparation and use of an LLOQ standard. This section includes two new references for guidan**  **ce on assessing precision and bias. 23. The section describing matrix interference chec**  **k samples (Sec. 9.11) has been revised for clarity. The post-digestion MS is only recommended**  **if a high concentration sample is not available for performing the dilution test.** **SW-846 Update V 6010D - 35 Revision 4 July 2014**  **24. Reformatted and/or renumbered “CALIBRATION AND STANDARDIZATION” (Sec. 10) for**  **better adherence to Style Guide recommendations and /or clarity.**  **25. Substituted certain terms with new terms (i.e. “must” in place of “shall”) to conform with the**  **Performance-based Methods Approach goal of flexibil ity.**  **26. Removed reference to “isotope abundances” as no ted by the Inorganic Methods Work**  **Group. 27. Removed reference to “linear dynamic range” as**  **noted by the Inorganic Methods Work Group. Section 9.6 regarding the linear range was a**  **dded.**

**28. Mid-level readback or verification standard add ed to Section 10.8.3.**  **29. Moved the sentence “If the ICB consistently has target analyte concentrations greater than**  **half the LLOQ, the LLOQ should be re-evaluated.” Fr om Section 10.8.5 to Section 10.8.4.** 

**30. Table 1 was determined to be outdated and remov ed. The method recommends**  **consulting the instrument manufacturer for appropri ate wavelengths and estimated** 

**instrument detection limits. 31. Language dealing with method blanks was updated**  **in Section 9.7.1.**