**SW-846 Update V THREE - i Revision 5**

**October 2012 CHAPTER THREE** 

**TABLE OF CONTENTS**

**Section Page** 

**3.0 INTRODUCTION 1** 

**3.1 DEFINITIONS 1** 

**3.2 SAFETY 4** 

**3.3 SAMPLING CONSIDERATIONS 4** 

**3.4 SPECIAL CONSIDERATIONS FOR DETERMINING INORGANI C ANALYTES AT** 

**ULTRA-TRACE CONCENTRATION LEVELS 6** 

**3.5 REAGENT PURITY 11** 

**3.6 SAMPLE DIGESTION METHODS 11** 

**3.7 METHODS FOR DETERMINATION OF INORGANIC ANALYTES 13** 

**3.8 REFERENCES FOR PREVIOUS SECTIONS AND THE TABLES AND FIGURES 16** 

**TABLE**

**3-1 MATERIALS FOR USE IN SAMPLE COLLECTION FOR INOR GANIC ANALYTE** 

**DETERMINATIONS 19** 

**3-2 RECOMMENDED SAMPLE HOLDING TIMES, PRESERVATION, COLLECTION** 

**QUANTITIES, AND DIGESTION VOLUMES FOR SELECTED INOR GANIC ANALYTE** 
**DETERMINATIONS IN AQUEOUS AND SOLID SAMPLES 20** 

**3-3 EXAMPLES OF THE ANALYTICAL BLANK INFLUENCE ON U LTRA-TRACE** 

**ANALYSIS OF ELEMENTS IN GLASS 22** 

**3-4 EXAMPLES OF LEAD CONCENTRATIONS IN AIR 22** 

**3-5 CLEANLINESS LEVELS IN INTERNATIONAL STANDARD IS O 14644-1 23** 

**3-6 PARTICULATE CONCENTRATIONS IN LABORATORY AIR 24**

**3-7 NON-CONTAMINATING MATERIALS AND FOR USE AS DIGE STION VESSELS AND** 

**SAMPLE CONTAINERS IN ULTRA-TRACE ANALYSIS 24** 

**FIGURE**

**3-1 COMPARISON OF CLEAN VERSUS CONVENTIONAL SAMPLIN G AND ANALYSIS** 

**TECHNIQUES USED IN THE ANALYSIS OF SOUTH TEXAS ESTU ARY WATERS**  **25**

**3-2 COMPARISON OF PARTICLE COUNT ANALYSIS OF A CLEA N ROOM AND A** 

**STANDARD LABORATORY AT DUQUESNE UNIVERSITY IN PITTS BURGH, PA**  **26**

**3-3 PARTICLE SIZE COMPARISON CHART FOR COMMON PARTI CULATES 27** 

**Appendix A SUMMARY OF UPDATES/CHANGES IN CHAPTER 3 28** **SW-846 Update V THREE - 1 Revision 5**

**October 2012 CHAPTER THREE** 

**INORGANIC ANALYTES**

**Prior to employing the methods in this chapter, an alysts are advised to consult the** 

**disclaimer statement at the front of this manual an d the information in Chapter Two for guidance**  **on the allowed flexibility in the choice of apparat us, reagents, and supplies. In addition, unless**  **specified in a regulation, the use of SW-846 method s is not mandatory in response to Federal**  **testing requirements. The information contained in each procedure is provided by EPA as**  **guidance to be used by the analyst and the regulate d community in making judgments**  **necessary to meet the data quality objectives or ne eds for the intended use of the data.** 

**For a summary of changes in Chapter Three, please s ee Appendix A at the end of this** 

**document.**

**3.0 INTRODUCTION**

**This chapter provides guidance for the analysis of inorganic analytes in a variety of**  **matrices. The analytical methods are written as sp ecific steps in the overall analysis scheme --**  **sample handling and preservation, sample digestion or preparation, and sample analysis for**  **specific inorganic components. From these methods, the analyst should assemble a total**  **analytical protocol which is appropriate for the sa mple to be analyzed and for the information**  **required. This introduction discusses the options available in general terms, provides**  **background information on the analytical techniques , and highlights some of the considerations**  **to be made when selecting a total analysis protocol**

**.**

**3.1 DEFINITIONS**

**The following terms are relevant for the determin ation of inorganic analytes:** 

**Calibration blank: The calibration blank is a sam ple of analyte-free media**  **prepared with the same amounts of acids or other re agents as were the standards**  **and samples that can be used along with prepared st andards to calibrate the**  **instrument. A calibration blank may also be used t o verify absence of instrument**  **contamination (e.g., initial calibration blank and continuing calibration blank).** 

**Calibration curve: The functional relationship bet ween instrument response and**  **target analyte concentration determined for a serie s of calibration standards. The**  **calibration curve is obtained by plotting the instr ument response versus**  **concentration and performing a regression analysis of the data.** 

**Calibration standards: A series of solutions conta ining the target analyte at known** 

**and various concentrations used to calibrate the in strument response with respect**  **to analyte concentration (i.e., preparation of the calibration curve).** 

**Continuing calibration verification (CCV): A solut ion containing a known**  **concentration of analyte typically derived from the same source as the calibration** 

**standards. The CCV is used to assure calibration a ccuracy during each analysis**  **run. It should be run for each analyte as describe d in the particular analytical**  **method. At a minimum, it should be analyzed at the beginning of the run and after** **SW-846 Update V THREE - 2 Revision 5**

**October 2012 the last analytical sample. The CCV concentration**  **should be at or near the mid range levels of the calibration curve.** 

**Dissolved metals: The concentration of metals dete rmined in an aqueous sample**  **after the sample is filtered through a 0.45-μm filt er (see Method 3005).** 

**Initial calibration verification (ICV) standard: A certified or independently-prepared** 

**solution from a source other than used for the cali bration standards and used to**  **verify the accuracy of the initial calibration.**

**Instrument detection limit (IDL): Typically used i n metals analysis to evaluate the**  **instrument noise level and response changes over ti me for analytes of interest.**  **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 blank solution. (Use zero**  **for the mean if the mean is negative). Each measur ement should be performed as**  **though it were a separate calibration standard (i.e ., each measurement must be**  **followed by a rinse and/or any other procedure norm ally performed between the**  **analysis of separate samples). IDLs should be dete rmined at least once using new**  **equipment, after major instrument maintenance such as changing the detector,**  **and/or at a frequency designated by the project. A n instrument log book should be**  **kept with the dates and information pertaining to e ach IDL performed.** 

**Laboratory control sample (LCS): A volume of reage nt water spiked with known**  **concentrations of analytes and carried through the sample preparation and**  **determinative procedure. It is used to monitor lab oratory performance on analyte**  **loss/recovery in a clean matrix. The LCS should be prepared from the same**  **source as the calibration standards to remove poten tial error contribution from**  **standards of different sources. An independently p repared LCS may also be**  **obtained as or prepared from a certified reference solution or prepared from a**  **certified reagent solid or from an alternate lot re agent solid relative to the**  **calibration standards source if, for each analytica l batch, at least one LCS is**  **prepared from the same source as the calibration st andards. In this way, if the**  **recoveries of both the LCS and the matrix spike are outside the acceptance limits,**  **the analyst will be able to determine whether the p roblem is due to calibration error** 

**or matrix interference.**

**Linear range: In both inductively coupled plasma o ptical emission spectrometry**  **(ICP-OES) and inductively coupled plasma mass spect rometry (ICP-MS) analysis,**  **the concentration range over which instrument respo nse is linear. The linear range**  **establishes the highest concentration that may be r eported without diluting the**  **sample. Following calibration, the laboratory may c hoose to analyze a standard at**  **a higher concentration than the high standard in th e calibration. The standard must**  **recover within 10% of the true value, and if succes sful, establishes the linear**  **range. The linear range standards must be analyzed in the same instrument run as**  **the calibration they are associated with (i.e., on a daily basis) but may be analyzed**  **anywhere within that run. If a linear range standar d is not analyzed for any specific**  **element, the highest standard in the calibration be comes the linear range.** 

**NOTE : Other standards exist that have alternative meth**  **ods for determining the linear range (e.g., ISO 17025). Therefore, the met**  **hod used to define and verify the linear range should meet the requirements of the pr**  **oject.**

**Lower limit of quantitation (LLOQ): The lowest poi nt of quantitation, or in most**  **cases, the lowest point in the calibration curve, w hich is ideally less than or equal** **SW-846 Update V THREE - 3 Revision 5**

**October 2012 to the desired regulatory action levels based on th**  **e stated project requirements. Laboratory-specific recovery limits should be estab**  **lished when the laboratory has determined sufficient data points exist. Individua**  **l methods specify recovery limits for use until the laboratory has sufficient data to**  **determine acceptance limits statistically.** 

**Method blank: A volume of reagent water equal to t hat used for aqueous samples,**  **or, otherwise, a clean, empty container, equivalent to that used for actual solid**  **samples, processed through each sample preparation and determinative**  **procedure. Analysis of a method blank is used to a ssess contamination from the**  **laboratory environment, sample processing equipment , and/or reagents.** 

**Method of standard addition (MSA): An alternative calibration procedure employed**  **when the instrument response of the analyte of inte rest is different in a particular**  **matrix than when it is in reagent water. The proce dure is generally reserved for**  **analyzing complex matrices. The standard addition technique involves the addition**  **of known amounts of the target analyte to each of a series of replicate sample**  **aliquots. The final concentrations of the sample r eplicates should span the**  **calibration range of the method. The analytical re sponses versus the standard**  **addition concentration for each of the replicates i s plotted. After performing a**  **linear regression, the curve is extrapolated to the x-axis. The analyte**  **concentration in the original unspiked sample is eq ual to the inverse of the x**  **intercept. See Method 7000, for more information.**

**Sample holding time: The storage time allowed betw een sample collection and**  **sample analysis when the designated preservation an d storage techniques are**  **employed. Different times may be specified for hol ding field samples prior to**  **extraction, digestion, or other such preparation pr ocedures versus holding**  **prepared samples (e.g. an extract or a digestate) p rior to analysis.** 

**Sensitivity: The ability of an analytical techniqu e or instrument to discriminate**  **between small differences in analyte concentration (Reference 1). For metals**  **analysis, the following methods are commonly employ ed to determine sensitivity.** 

**(a) Atomic absorption (AA): The concentration of m etal, in mg/L, that**  **produces a transmission of 1%.**

**(b) Graphite furnace AA (GFAA): The mass of analyt e required to give a**  **response of 0.044 absorbance-seconds.**

**(c) Inductively coupled plasma (ICP-OES or ICP-MS): Sensitivity is** 

**measured in terms of the instrument detection limit s as defined elsewhere** 

**in the definitions.**

**Spectral Interference Check solution (SIC): A solu tion containing both interfering**  **and analyte elements of known concentration that ca n be used in ICP-OES and**  **ICP-MS analysis to verify background and inter-elem ent correction factors.** 

**Suspended metals: The concentration of metals dete rmined in the portion of an**  **aqueous sample that is retained by a 0.45-μm filter (Method 3005).** 

**Total acid soluble/recoverable metals: The concent ration of metals determined in**  **an unfiltered sample following digestion using hot mineral acid by Methods 3005,**  **3010, 3015, 3020, 3050, or 3051. SW-846 Update V THREE - 4 Revision 5** 

**October 2012 NOTE**  **: Methods 3010 and 3020 state they are used to dete rmine “total metals”.**  **However, because these methods do not use hydrofluo ric acid, they are unable to** 

**break down silicates and have been defined here for the “total acid** 

**soluble/recoverable metals” fraction.**

**Total metals: The concentration of metals determin ed in a sample following**  **digestion by Method 3052.**

**3.2 SAFETY**

**The methods in this chapter do not address all saf ety issues associated with their use.**  **The laboratory is responsible for maintaining a saf e work environment and a current awareness**  **file of OSHA regulations regarding the safe handlin g of the chemicals specified in this method.**  **A reference file of material safety data sheets (MS DSs) should be available to all personnel**  **involved in these analyses.**

**The toxicity or carcinogenicity of each reagent us ed in these methods has not been**  **precisely defined. However, each chemical compound should be treated as a potential health**  **hazard. From this viewpoint, exposure to these che micals should be reduced to the lowest**  **possible level by whatever means available. The fo llowing additional references to laboratory**  **safety are available:**

**1. "Carcinogens - Working with Carcinogens," Depart ment of Health, Education, and**  **Welfare, Public Health Service, Centers for Disease Control, National Institute for**  **Occupational Safety and Health, Publication No. 77 -206, August 1977.** 

**2. "Handbook of Chemical Health and Safety," Americ an Chemical Society, Oxford**  **University Press, New York, 2001.**

**3. "NIOSH Pocket Guide to Chemical Hazards," Depart ment of Health and Human**  **Services, Centers for Disease Control, National Ins titute for Occupational Safety and**  **Health, Publication No. 2005-149, September 2005.**

**4. "Occupational Safety and Health Standards," 29 C FR Part 1910, Occupational Safety**  **and Health Administration, Department of Labor.**

**5. "Safety in Academic Chemistry Laboratories," 7 th**  **Edition, Volumes 1 and 2, American Chemical Society, Committee on Chemical Safety, Was**  **hington, D.C., 2003.**

**3.3 SAMPLING CONSIDERATIONS**

**3.3.1 Sample Collection**

**The fundamental goal of all field sampling activit ies is to collect samples that are**  **representative of the water, soil or waste from whi ch they were collected. Thus,**  **representative sampling may be considered to be the sampling analog to analytical**  **accuracy. Of equal importance is sampling precisio n for ensuring consistency both within**  **a single sampling event and between sampling events conducted over time. Sampling**  **imprecision can be a significant source of measurem ent error. High quality field practices**  **are, therefore, necessary for generating representa tive samples on a consistent basis.**  **Sampling quality assurance includes the development of a quality assurance plan, data** **SW-846 Update V THREE - 5 Revision 5**

**October 2012 quality objectives and the generation of field qual**  **ity control samples including equipment rinsates, trip blanks and field duplicates. Regard**  **less of the specific program needs, the documentation of all relevant field and sample info**  **rmation is the final essential component of a sampling event for providing evidence that pro**  **per procedures and quality assurance were performed during sample collection. Use of in**  **adequate field procedures and documentation can jeopardize an entire sampling pro**  **gram despite adequate planning, analytical facilities, and personnel.** 

**While advances in analytical sensitivity are conti nuing to be made that allow for**  **quantification of environmental contaminants at ult ra-trace levels (i.e., < 0.1 ppb), clean**  **sampling techniques are consequently being devised and practiced in order to minimize or**  **eliminate sources of contamination during the colle ction of samples intended for ultra-trace**  **contaminant testing. Such clean sampling and analy sis techniques are not generally**  **needed or required under the RCRA program and are b eyond the scope of this chapter.**  **However, as an introduction to this topic, Sec. 3.4 provides a more detailed discussion on**  **the special category and requirements of clean anal ysis for determining constituents at** 

**ultra-trace levels.**

**3.3.2 Sample Containers**

**Sample container materials can introduce either po sitive or negative errors in**  **measurement, particularly at low or ultra-trace lev els, by contributing contaminants**  **through leaching or surface desorption, or by deple ting concentrations through adsorption.**  **Additionally, the sample containers should be compa tible with the reagents used for**  **sample preservation. Thus, the collection and cont ainment of the sample prior to analysis**  **requires particular attention. Sample contaminatio n introduced through field collection**  **activities including sample containment and shipmen t can be assessed from the analysis**  **of equipment rinsates and trip blanks. Guidelines on the selection of appropriate sample**  **container materials for the collection of inorganic analytical samples are provided in Table** 

**3-1.**

**3.3.3 Cleaning of Sample Containers**

**Sample containers should be scrupulously clean so as not to introduce**  **contaminants that could interfere with quantificati on of the target analyte(s). This is of**  **particular importance when determining trace or ult ra-trace analyte concentration levels.**  **The following cleaning sequence has been determined to be adequate to minimize**  **contamination in the sample bottle, whether borosil icate glass, linear polyethylene,**  **polypropylene, or PTFE:**

• **Phosphate-free detergent**

• **Tap water**

• **1:1 HNO 3** 

• **Tap water**

• **1:1 HCl**

• **Tap water**

• **Reagent water**

**NOTE :**  Chromic acid should not be used to clean glassware **, especially if chromium is to be included in the analytical scheme. Commercia**  **l, non-chromate products may be used in place of chromic acid, if adequate cleaning**  **is documented by an analytical quality control program. Chromic acid should not be used w**  **ith plastic bottles. SW-846 Update V THREE - 6 Revision 5** 

**October 2012 3.3.4 Sample Handling and Preservation** 

**Recommended materials to use for sample collection are listed in Table 3-1.**  **Sample holding times, recommended collection volume s or masses and recommended**  **digestion volumes, and preservatives are listed in Table 3-2. The sample collection and**  **digestion amounts depend on the combination of dige stion or extraction and determinative**  **procedures that will be employed for a given sample as well as the sensitivity and tolerable**  **sampling errors that are required for a specific pr oject (see References 20 through 22).**  **Likewise, the use of alternative preservatives to t hose indicated in Table 3-2 may be**  **necessary depending on the objectives of the projec t. In all cases, the sample quantity**  **that is collected should be representative of the b ulk material whenever feasible.** 

**3.3.5 Sample Preparation**

**For all non-speciated digestion methods, great red uction in analytical variability can**  **be achieved through the use of appropriate sample p reparation procedures. Generally, a**  **reduction in subsampling variance can be accomplish ed by increasing the subsample**  **aliquot size, reducing the sample particle size, an d/or thoroughly mixing the resulting fines**  **(see References 20 through 23 for additional inform ation on sampling and sub-sampling).**  **Under most circumstances, it is recommended that th e sample be analyzed without drying.**  **If it is necessary to report the analytical data on a dry-weight basis, then a separate aliquot**  **may be analyzed for moisture content and the wet-we ight data corrected accordingly.** 

**If the sample cannot be well-mixed and homogenized in the form in which it was**  **received by the laboratory, then air- or oven-dryin g at 30 °C or less, crushing, sieving,**  **grinding, and mixing should be performed as needed or feasible to homogenize the**  **sample until the subsampling variance is less than the data quality objectives of the**  **analysis. While proper sample preparation generall y produces great reduction in**  **analytical variability, it should be noted that in certain unusual circumstances there could**  **be loss of volatile metals (e.g., mercury, organome tallics) or irreversible chemical changes**  **( e.g., precipitation of insoluble species, change in valence state) caused by inappropriate**  **sample preparation procedures.**

**Variability due to sample heterogeneity is assesse d by analyzing individually**  **prepared sample replicates such as field duplicates (FD), laboratory matrix du**  **plicates (MD), and matrix spike (MS)/matrix spike duplicate**  **(MSD). Variability inherent in the analytical determinative procedure can be assessed**  **by matrix spiking of individually digested samples (i.e., post-digestion matrix spike**  **) or by analyzing laboratory splits of the digestate.** 

**3.4 SPECIAL CONSIDERATIONS FOR DETERMINING INORGANI C ANALYTES AT ULTRA** 

**TRACE CONCENTRATION LEVELS**

**3.4.1 Clean Sampling Techniques**

**For the determination of ultra-trace analyte conce ntrations in environmental**  **samples, it is essential that samples be collected and subsequently managed using**  **techniques specifically designed to minimize sample contamination from field collection**  **activities and to ensure target analyte stability. Such techniques represent a special**  **category of sampling procedures designed specifical ly for ultra-trace analyses and are**  **commonly referred to as clean or ultra-clean sampli ng procedures. Clean sampling**  **methods are generally not intended for the determin ation of discharges from industrial**  **facilities. Rather, they are primarily applicable for the determination of ambient element**  **concentrations at levels of 0.1 ppb or less. At th ese concentrations, the opportunity for** **SW-846 Update V THREE - 7 Revision 5**

**October 2012 sample contamination during sample collection or an**  **alysis in the laboratory is significant and should be managed accordingly. Figure 3-1 prov**  **ides a demonstration of the impact of clean sampling and analysis techniques on data obta**  **ined for estuarine waters. Clean sampling typically involves the following key steps**  **:**

• **Special container pre-cleaning and pre-packaging r equirements** 

• **Specific sampling equipment and container material s selection** 

• **Specific cleaning protocols for sampling equipment**

• **Equipment and container blank determinations prior to field use** 

• **"Clean hands/dirty hands" sample collection techni ques based on a 2-person**  **sampling crew**

- **Dirty hands sampler manages sampling equipment onl y** 

- **Clean hands sampler manages the sample container**

• **Special sample packaging prior to shipment**

• **Use of a laboratory trained and properly equipped to perform clean analysis of**  **the analytes of interest**

**Given the laboratory resources required to perform clean analysis techniques, it is**  **paramount that samples be collected using ultra-cle an techniques and conditions in the**  **field. Otherwise, subsequent analytical efforts be come futile. The information provided in**  **this section is intended only as an introduction to the topic of clean sampling. Specific**  **guidelines for clean sampling may be found in Refer ence 2 and other sources.** 

**3.4.2 Clean Analysis and the Analytical Blank**

**The significant role of the analytical blank in ch emical analysis of trace metals**  **cannot be overemphasized. Sensitive instrumentatio n such as ICP-MS, ICP-OES, and**  **GFAA requires that sample preparation be at least a s sophisticated as the instruments**  **used for analysis. The analytical blank is normall y a primary source of error in ultra-trace**  **element analysis. Ultra-trace analysis is as depen dent on control of the analytical blank as**  **it is on the bias and precision of the instrument m aking the measurement. Inability to**  **control contamination is frequently the limiting fa ctor in trace (parts per million (ppm) to**  **parts per billion (ppb)) and ultra-trace (ppb to pa rts per trillion (ppt)) analysis. Analytical**  **blank contributions occur from the following four m ajor sources (References 3 through 7):** 

• **The atmosphere in which the sample preparation and analysis are conducted** 

• **The purity and the quantities of the reagents used in sample preparation,**  **including all reagents added directly to the sample**

• **The materials and equipment used in digestion or e xtraction vessels that come**  **in contact with the sample during the sample prepar ation and analysis (i.e., the** 

**cleanliness and maintenance as well as their materi al properties).** 

• **The analyst’s technique and skill in preparing the samples and performing the**  **analyses**

**The four primary areas that affect the analytical blank can be demonstrated using**  **standard reference materials in analysis. Table 3- 3 illustrates and isolates the main**  **influencing parameters on the blank: environment, reagents, materials, and analyst skills.**  **The skill of the analyst was kept constant as the s ame analyst changed the environment,**  **reagents, and combinations of these parameters in t he analysis (see Reference 6). The**  **trace elements in glass (TEG) standard reference ma terial from the National Institute of**  **Standards and Technology (NIST) was used to keep sa mple homogeneity constant and to**  **permit removal of the sampling error by using sampl e sizes in which appropriate**  **homogeneity had previously been demonstrated. It i s important to note that the**  **relationship of the precision and measurement remai ned relatively constant. The** **SW-846 Update V THREE - 8 Revision 5**

**October 2012 significance of the first two major sources of cont**  **amination, environment and reagents, is evaluated. The contamination in the laboratory air**  **and in the acid used for the reagent blank altered the accuracy of the example above by**  **over two orders of magnitude for both lead and silver. The larger influence of the two s**  **ources in this example is the laboratory environment in which the samples were prepared.** 

**3.4.2.1 Sample Preparation and Analysis Atmosphere**

**The atmosphere in which the sample is prepared is a major source of**  **contamination for most target analytes when analyzi ng at ultra-trace levels. With**  **the exception of some rare constituents, contaminat ion from airborne sources**  **represents the most significant of the four main co ntamination sources. For**  **example, the mercury in a dental amalgam filling ma y cause blank**  **contamination. To illustrate this point, Table 3-4 presents concentrations of lead**  **found in samples of ambient air.**

**This contamination can also be seen in the compari son of 58,000**  **particles per liter of air measured in a normal lab oratory in Pittsburgh, PA, and**  **inside a clean chamber in an adjacent laboratory fi ve meters away. Figure 3-2** 

**demonstrates the dramatic difference between the tw o environments. Cost**  **effective methods of creating clean chambers for sa mple preparation are**  **documented along with this data in Reference 4.**

**Any laboratory air that comes into contact with th e sample may deposit**  **airborne contamination into the sample. The sample is especially vulnerable**  **when it is being digested with acid. When samples are being digested with**  **acid(s), contamination of the sample by particulate s in the laboratory air can**  **cause results that are biased high.**

**To prevent air from contaminating a sample for ult ra-trace analysis, the**  **sample should be processed in a clean environment. This is much easier to**  **accomplish than it may appear at first. These prec autions are becoming state-of**  **the-art in many analytical and environmental labora tories. The prevention of**  **airborne contamination is most frequently dealt wit h by employing a laminar flow**  **clean bench or a clean laboratory facility. Instru ctions are referenced for the**  **construction of both from component parts; both are relatively inexpensive and**  **uncomplicated, once the concepts are understood (Re ference 4).** 

**There are many sources of airborne contamination. Several of the**  **sources have been described and their particle size ranges are provided in**  **Figure 3-3. These sources primarily provide partic ulates in discrete size ranges.**  **Depending on whether the laboratory is located in a n industrial, urban, or rural**  **area, or near the sea, the distribution of these so urce particles will be different,**  **as will their composition. The vertical dashed lin e in Figure 3 indicates the**  **particle size cutoff, usually 0.5 μm, for the high efficiency particulate air (HEPA)**  **filter used to prevent particulate contamination. Particles above this size cannot**  **pass through a HEPA filter that is in good working order. These filters are in**  **common use today (References 4 and 8).**

**The definition of clean air is derived from Intern ational Standard ISO**  **14644-1, which defines cleanliness levels. Table 3 -5 lists these conditions.** 

**"Laminar flow" is directed coherent air movement th at does not contain any** 

**turbulence. SW-846 Update V THREE - 9 Revision 5** 

**October 2012 A dramatic reduction in airborne contaminants can**  **be achieved by using**

**HEPA-filtered air in laminar-flow clean hoods or en tire clean laboratories. Table** 

**3-6 demonstrates the dramatic differences in airbor ne contaminant**  **concentrations in an ordinary laboratory, a clean l aboratory, and a clean hood**  **inside a clean laboratory.**

**3.4.2.2 Reagent Purity for Ultra-trace Analysis**

**The purity of the reagents used for acid digestion , leaching, and**  **extraction is extremely important to the overall le vel of the blank. Reagents have**  **very different purities, depending on their process ing grade and purpose.**  **Frequently, the analyst should purchase special rea gents, or purify lesser-grade**  **reagents prior to use, in order to minimize the ana lytical blank.** 

**In addition to the purity of the reagents, the qua ntity of reagent that is**  **added to the sample may have a significant impact. When reagents are added,**  **they bring with them elemental and molecular compon ents that exist as**  **contaminants. Increasing the reagent used in exces s of the stoichiometric**  **reaction, leads to greater potential for blank cont amination. Reagents of high**  **purity should either be purchased or produced in th e laboratory.** 

**In the preparation of high purity reagents, there is only one significant and**  **practical choice for the method of purification, i. e., sub-boiling distillation**  **(References 9 through 11). Different from normal d istillation, sub-boiling** 

**distillation uses an infrared radiation source to h eat the reagent to a temperature**  **just below the boiling point. This use prevents th e formation of bubbles that rise**  **and burst at the surface of the liquid. Thus, the aerosolized solution particles are**  **left in solution and prevented from physically tran sporting contaminants**  **throughout the distillation apparatus. Sub-boiling distillation is a slower but very**  **reliable method of purifying all of the common mine ral acids and many organic**  **reagents used in analytical methods. It relies exc lusively on the vapor pressure**  **of the reagent, and contaminant, and can therefore be specifically optimized for**  **purification of the mineral acids if the object is to remove metal ions. Of all acids,**  **nitric acid, for a variety of reasons, can be purif ied to excellent quality. Sources**  **for sub-boiling apparatus equipment and methods for constructing one are**  **provided in the references. Purchasing sub-boiling acids from commercial**  **sources is also an option. Construction or purchas e of sub-boiling reagent**  **purification equipment may be cost effective for so me laboratories depending on**  **the quantity of reagents required for sample throug hput.** 

**3.4.2.3 Materials for Sample Preparation, Storage, and Analysis** 

**For ultra-trace analyses, only certain materials a re preferred for use in the**  **construction of sample vessels and instrument compo nents that come into**  **contact with the sample. Over the past two decades , materials identified as**  **being non-contaminating have become the top choices for bottles, beakers,**  **reaction vessels, storage containers, nebulizers, a nd instrument components for**  **trace and ultra-trace analysis. The materials are the same as those currently**  **being used in many digestion vessels, bomb liners, and microwave vessels. The**  **materials are characterized by being thermally dura ble, chemically resistant or**  **inert, non-contaminating, and possessing appropriat e compression and tensile**  **strength. Table 3-7 lists, in order of preference, several types of, non**  **contaminating materials that are chemically inert t o most acid reactions. These** **SW-846 Update V THREE - 10 Revision 5**

**October 2012 materials have been evaluated and tested extensivel**  **y for their potential to contaminate (References 4, 6, 7, 12, and 13).** 

**With the exception of polyethylene, the materials listed in Table 3-7 are**  **those most commonly used for sample preparation ves sels, both atmospheric**  **pressure vessels and closed vessel liners that come into contact with the sample.** 

**These materials are the most stable to acid reactio ns (with the exception of**  **quartz and glass if hydrofluoric acid is used). Fl uoropolymers are the most**  **common and were adapted from other chemical uses fo r application in pressure**  **systems. The fluoropolymers have the highest range of use temperatures for**  **most plastics, ranging from 270-300 °C. They are a lso chemically inert to the**  **majority of mineral acids and combinations thereof. Sulfuric acid has a boiling**  **point of approximately 330 °C and can damage all fl uoropolymers by melting**  **them. Quartz and glass can safely contain sulfuric acid at these high**  **temperatures, but borosilicate glass is not appropr iate for ultra-trace elemental**  **analysis (References 7 and 13). Glass actually for ms a gel layer that hydrates**  **and leaches, transferring contaminants from the gla ss to the sample solution.**  **While these quantities may be considered minute, th ey would be detected in**  **blanks and samples undergoing ultra-trace analyses.**

**Polyethylene is suitable for storage of diluted sa mples after digestion, but**  **it does not have a thermal-use temperature appropri ate for digestion. It is also**  **not sufficiently inert to be useful as a digestion vessel or vessel liner, similar to**  **polycarbonate and polypropylene. The low cost of p olyethylene and its relative**  **inertness to cool, weakly acidic solutions make it an excellent storage container**  **for trace element solutions (Reference 4).**

**3.4.2.4 Analytical Technique and Synergistic Equipm ent** 

**The fourth significant source of analytical blank contamination is the skill**  **of the analyst and the appropriateness of the techn ique being performed.**  **Analytical blank control has been explained as the combination of atmosphere,**  **reagent, material, and protocol being performed. A lso, the skill and awareness of**  **the analyst as well as the way in which the combina tions of the aforementioned**  **clean chemistry techniques are applied will have a significant effect on the final**  **contamination error and analytical blank control. Sample preparation**  **instrumentation may also assist in these protocols. For example, microwave**  **sample preparation assists each of these parameters in synergistic ways, thus**  **lowering the analytical blank, improving blank prec ision, and enhancing overall**  **quality control and transferability of methods. So me instrumentation and**  **fundamental processes involved in specific sample p reparation procedures**  **assists the analyst by incorporating useful clean c hemistry concepts into** 

**instrumentation and method structure. Such instrum entation is pertinent since**  **microwave methods now exist that provide sample pre paration for leaching or**  **total analysis of many target analytes simultaneous ly. As an example, the skill of**  **the analyst with regard to clean chemistry is assis ted by the method structure**  **and microwave equipment as indicated below:**

• **If a closed or controlled atmospheric microwave ve ssel is prepared in a clean**  **hood and sealed before leaving the clean environmen t, the sample will not be**  **affected by atmospheric contamination during the re action, since it has not** 

**been removed from a clean environment. SW-846 Update V THREE - 11 Revision 5** 

**October 2012** • **The vessel materials described previously might no t normally be used by**  **many laboratories, and therefore the advantages of the fluoropolymers would**  **not be realized if they were not required in most m icrowave reaction vessels**  **as they commonly are.**

• **The time that the sample spends in digestion, leac hing, or extraction may be**  **reduced from hours to minutes, thus reducing the po tential leaching of** 

**contaminants from the container walls.**

• **Because most microwave systems are sealed systems, evaporation of the**  **reagent before it reacts productively is prevented and smaller quantities of**  **reagents are used, thus preventing excess and unnec essary accumulation of** 

**contaminants in the blank.**

**By reducing the exposure variables, the blank vari ability is consequently**  **reduced in size and is more consistent. An example of these components**  **working together has been provided in the literatur e, where analysis under** 

**different conditions has verified these conclusions (References 4, 14 and 15).**  **The example illustrates the isolation of the blank optimization areas:**  **environment, reagents, materials, and analyst skill s. The skill of the analyst is**  **kept more constant as the instrument dictates clean er, chemically-appropriate**  **procedures.**

**3.5 REAGENT PURITY**

**The purity of the reagents used for sample preserv ation, acid digestion, leaching,**  **extraction and analysis is extremely important for preventing or minimizing sample**  **contamination. Reagents have very different puriti es, depending on their processing grade and**  **purpose. Reagent grade, ACS grade or better are re commended for use with most SW-846**  **methods. Sample contamination introduced through s ample preservation, handling, preparation**  **and analysis is assessed from the analysis of metho d blanks.** 

**3.6 SAMPLE DIGESTION METHODS**

**Many of the methods listed below employ HCl in the digestion process. Chlorine is an**  **interferant in ICP-MS analysis and its use in sampl e digestion is discouraged except when**  **absolutely necessary or when the instrument manufac turer has indicated that the use of HCl will**  **not adversely affect the equipment and accurate qua ntitation of the desired target analytes.**  **However, please note that recoveries of certain met als may be biased low when using nitric acid**  **only. Interference from chlorine may be minimized by use of collision or reaction cell** 

**instrumentation.**

**The methods in SW-846 for sample digestion or diss olution include:** 

Method 3005A: **Acid Digestion of Waters for Total Recoverable or D issolved Metals for** 

**Analysis by FLAA or ICP Spectroscopy**

**This method may be used for the preparation of gro und water and surface water samples** 

**for total recoverable and dissolved metal determina tions by FLAA, ICP-OES, or ICP-MS. The**  **unfiltered or filtered sample is heated with dilute HCl and HNO**  **3 prior to metal determination.** **SW-846 Update V THREE - 12 Revision 5**

**October 2012** Method 3010A: **Acid Digestion of Aqueous Samples and Extracts for Total Metals for Analysis** 

**by FLAA or ICP Spectroscopy**

**This method may be used for the preparation of was te samples for total recoverable metal**  **determinations by FLAA, ICP-OES, or ICP-MS. The sa mples are vigorously digested with nitric**  **acid followed by dilution with hydrochloric acid. The method is applicable to aqueous samples,**  **leachates, and mobility-procedure extracts.**

Method 3015A: **Microwave Assisted Acid Digestion of Aqueous Sample s and Extracts** 

**This method may be used for the preparation of aqu eous samples, mobility-procedure**  **extracts, and wastes that contain suspended solids for total recoverable metal determinations**  **by FLAA, GFAA, ICP-OES, or ICP-MS. Nitric acid and hydrochloric acid are added to the**  **sample in a PTFE digestion vessel and heated in a m icrowave unit prior to metals** 

**determination.**

Method 3020A: **Acid Digestion of Aqueous Samples and Extracts fo r Total Metals for Analysis** 

**by GFAA Spectroscopy**

**This method may be used for the preparation of was te samples for total recoverable**  **metals determinations by GFAA or ICP-MS. The sampl es are vigorously digested with nitric**  **acid followed by dilution with nitric acid. The me thod is applicable to aqueous samples,**  **leachates, and mobility-procedure extracts.**

Method 3031: **Acid Digestion of Oils for Metals Analysis by Atomi c Absorption or ICP** 

**Spectrometry**

**This method may be used for the preparation of was te oils, oil sludges, tars, waxes,**  **paints, paint sludges and other viscous petroleum p roducts for analysis by FLAA, GFAA, and**  **ICP-OES. The samples are vigorously digested with nitric acid, sulfuric acid, hydrochloric acid,**  **and potassium permanganate prior to analysis.**

Method 3040A: **Dissolution Procedure for Oils, Greases, or Waxes**

**This method may be used for the preparation of oil y waste samples for determination of**  **soluble metals by FLAA and ICP-OES. The samples ar e dissolved and diluted in organic**  **solvent prior to analysis. The method is applicabl e to the organic extract in the oily waste EP**  **procedure and other samples high in oil, grease, or wax content.** 

Method 3050B: **Acid Digestion of Sediments, Sludges, and Soils**

**This method may be used for the preparation of was te samples for total recoverable**  **metals determinations by FLAA and ICP-OES, or GFAA and ICP-MS depending on the options**  **chosen. The samples are vigorously digested in nit ric acid and hydrogen peroxide followed by**  **dilution with either nitric or hydrochloric acid. The method is applicable to soils, sludges, and**  **solid waste samples.**

Method 3051A: **Microwave Assisted Acid Digestion of Sediments, S ludges, Soils, and Oils** 

**This method may be used for the preparation of slu dges, sediments, soils and oils for total**  **recoverable metal determinations by FLAA, GFAA, ICP -OES or ICP-MS. Nitric acid and**  **hydrochloric acid are added to the representative s ample in a fluorocarbon digestion vessel and**  **heated in a microwave unit prior to metals determin ation.** **SW-846 Update V THREE - 13 Revision 5**

**October 2012** Method 3052: **Microwave Assisted Acid Digestion of Siliceous an d Organically Based Matrices** 

**This method may be used for the preparation of sil iceous and organically based matrices**  **including ash, biological tissue, oil, oil contamin ated soil, sediment, sludge, and soil for total**  **metals analysis by FLAA, CVAA, GFAA, ICP-OES, and I CP-MS. Nitric acid and hydrofluoric**  **acid are added to a representative sample in a fluo rocarbon digestion vessel and heated in a**  **microwave unit prior to analysis.**

Method 3060A: **Alkaline Digestion for Hexavalent Chromium**

**This method may be used for the preparation of soi ls, sludges, sediments and similar** 

**waste materials for hexavalent chromium determinati on. The samples are digested and heated**  **to dissolve the Cr(VI) and stabilize it against red uction to Cr(III).** 

Method 3200: **Mercury Species Fractionation and Quantification b y Microwave Assisted**  **Extraction, Selective Solvent Extraction and/or Sol id Phase Extraction** 

**This method uses sequential extraction and separati on procedures to differentiate**  **mercury species that are present in soils and sedim ents into four distinct fractions: extractable**  **organic mercury, extractable inorganic mercury, sem i-mobile mercury and non-mobile mercury.**  **Extraction is accomplished with the aid of either m icrowave irradiation or ultrasound.**  **Quantification of mercury in the different fraction s may be performed using any appropriate**  **determinative method, (e.g., Method 7473, 1631, or Methods 7470 and 7471). The test method**  **also contains provisions for separating and quantif ying individual extractable mercury species**  **using HPLC.**

**3.7 METHODS FOR DETERMINATION OF INORGANIC ANALYTES**

**This section of the manual contains analytical tec hniques for trace inorganic analyte**  **determinations. Instrumental techniques include:**

**- Inductively coupled argon plasma optical emission spectrometry (ICP-OES),**  **- Inductively coupled plasma mass spectrometry (ICP -MS),**  **- Direct-aspiration or flame atomic absorption spec trophotometry (FLAA),**  **- Graphite furnace atomic absorption spectrophotome try (GFAA),**  **- Hydride-generation atomic absorption spectrometry (HGAA),**  **- Cold-vapor atomic absorption spectrometry (CVAA), - Cold-vapor atomic fluorescence spectrometry (CVAF**  **), - Anodic stripping voltammetry (ASV),**  **- X-ray fluorescence (XRF), - Ion chromatography (IC)**  **- Capillary electrophoresis (CE) - Speciated isotope dilution mass spectrometry (SI**  **DMS) and - Several procedures for hexavalent chromium analys**  **is.**

**Each of these (except the individual hexavalent chr omium analyses) is discussed briefly below.**  **Some advantages, disadvantages, and cautions for th e analysis of wastes are provided.** 

**ICP-OES allows simultaneous or rapid sequential determinat**  **ion of many elements in a short time. Aerosol samples are introduced into an**  **extremely hot plasma source which vaporizes, atomizes, and ionizes the sample compone**  **nts. Upon exiting the plasma, the SW-846 Update V THREE - 14 Revision 5** 

**October 2012 electronically excited analytes emit characteristic**  **photons that are detected via emission spectrometry. A primary disadvantage of ICP-OES is**  **the occurrence of background radiation from other elements and the plasma gases. Although**  **all ICP-OES instruments utilize high resolution optics and background correction to mini**  **mize these interferences, analysis of trace levels of inorganic analytes in the presence of a l**  **arge excess of a single analyte is difficult. Examples would be trace levels of inorganic analyte**  **s in an alloy or trace metals in a limed (high calcium) waste. ICP-OES and FLAA have comparable d**  **etection limits (within a factor of 4) except that ICP-OES exhibits greater sensitivity fo**  **r refractories (Al, Ba, etc.). Further, the wide dynamic ranges and multi-element capabilities make**  **ICP-OES instruments more productive. GFAA, in general, will exhibit lower detection limi**  **ts than either ICP-OES or FLAA.**

**ICP-MS allows sensitive, simultaneous determination of ma**  **ny elements in a short time frame using MS detection in place of OES. In gener**  **al ICP-MS exhibits greater sensitivity than GFAA, FLAA or ICP-OES for most elements. The main**  **disadvantage of ICP-MS is isobaric elemental interferences. These are caused by diffe**  **rent elements or molecular species forming ions with the same nominal mass-to-charge ratio. M**  **athematical correction for interfering ions can minimize these interferences, but the most effe**  **ctive means of removal of molecular isobaric**

**interferences is the collision or reaction cell.**

**FLAA**

**direct-aspiration determinations, as opposed to IC P-OES or ICP-MS, are normally**  **completed as single-element analyses and are relati vely free of interelement spectral**  **interferences. Either a nitrous-oxide/acetylene or air/acetylene flame is used as an energy**  **source for dissociating the aspirated sample into t he free atomic state, making analyte atoms**  **available for absorption of light and spectrophotom etric detection. In the analysis of some**  **elements, the temperature or type of flame used is critical. If the proper flame and analytical**  **conditions are not used, chemical and ionization in terferences can occur.** 

**GFAA**

**replaces the flame with an electrically-heated gra phite furnace. The furnace allows**  **for gradual heating of the sample aliquot in severa l stages. Thus, the processes of dissolution,**  **drying, decomposition of organic and inorganic mole cules and salts, and formation of atoms,**  **which should occur in a flame or plasma in a few mi lliseconds may be allowed to occur over a**  **much longer time period and at controlled temperatu res in the furnace. This allows an**  **experienced analyst to remove unwanted matrix compo nents by using temperature**  **programming and/or matrix modifiers. The major adv antage of this technique is that it affords**  **extremely low detection limits. It is the easiest to perform on relatively clean samples. Because**  **this technique is so sensitive, interferences can b e a real problem; finding the optimum**  **combination of digestion, heating times and tempera tures, and matrix modifiers can be a**  **challenge for complex matrices.**

**HGAA**

**utilizes a chemical reduction to reduce and separa te arsenic, selenium, or antimony**  **selectively from a sample digestate. The technique therefore has the advantage of being able**  **to isolate these elements from complex samples whic h may cause interferences for other**  **analytical procedures. Significant interferences h ave been reported when any of the following is**  **present: (1) easily reduced metals (Cu, Ag, and Hg) ; (2) high concentrations of transition metals**  **(>200 mg/L); (3) oxidizing agents (oxides of nitrog en) remaining following sample digestion.** 

**CVAA**

**uses chemical reduction to reduce mercury to its v olatile elemental form. The**  **procedure is sensitive, though not as sensitive as CVAF, but is subject to interferences from**  **some volatile organics, chlorine, and sulfur compou nds. CVAA may be more appropriate than**  **CVAF for samples with higher mercury concentrations**

**.**

**CVAF uses chemical reduction to reduce mercury to its v**  **olatile elemental form. The procedure is extremely sensitive, approximately one**  **to two orders of magnitude more sensitive than CVAA. CVAF may be more appropriate than CVAA**  **for samples with low mercury SW-846 Update V THREE - 15 Revision 5** 

**October 2012 concentrations. Because of the extreme sensitivity**  **of CVAF, contamination during sampling and analysis is a major concern.** 

**ASV is an electrochemical method that can be used for**  **determining free dissolved metals such as arsenic and mercury. The analyte of interes**  **t is reduced at the electrode surface during a deposition step and oxidized from the electrode d**  **uring a stripping step; the current measured during the stripping step is proportional to the an**  **alyte concentration. ASV detects dissolved divalent mercury species and cannot directly distin**  **guish between organic and inorganic mercury compounds. The sensitivity of this method for merc**  **ury is similar to CVAA. ASV detects dissolved inorganic arsenic species and can disting**  **uish between As(III) and As(V) by adjusting the potential applied during the deposition step.**  **The sensitivity of this method for arsenic is about an order of magnitude more sensitive than ICP**  **-MS, GFAA, or HGAA. This method is subject to interferences from suspended solids, org**  **anics, and other metals. Samples can be modified (e.g., digested, addition of chelating age**  **nt, etc.) to determine the concentration of various species of the analyte of interest (e.g., t**  **otal fraction, methylmercury, etc.)**

**XRF uses sealed radioisotope sources or other suitable**  **X-ray source to irradiate samples with X-rays. When a sample is irradiated with X-ra**  **ys, the source X-rays may undergo either scattering or absorption by sample atoms. This lat**  **er process is known as the photoelectric effect. When an atom absorbs the source X-rays, th**  **e incident radiation dislodges electrons from the innermost shells of the atom, creating vac**  **ancies. The electron vacancies are filled by electrons cascading in from outer electron shells.**  **Electrons in outer shells have higher energy states than inner shell electrons, and the outer sh**  **ell electrons give off energy as they cascade down into the inner shell vacancies. This rearrang**  **ement of electrons results in emission of X rays characteristic of the given atom. The emissio**  **n of X-rays, in this manner, is termed X-ray**

**fluorescence.**

**IC generally refers to the separation of ions through**  **ion exchange chromatography. In this technique, an aqueous sample is injected into a mob**  **ile solution that is carried into a chromatography column. As the sample travels throu**  **gh the column, the sample analytes are temporarily retained on the column, the stationary**  **phase, via electrostatic forces. The separated analytes are identified as they are relea**  **sed from the column based on their retention time. Detection and quantification in IC are most**  **commonly performed using conductivity detection. IC is typically used for the determinat**  **ion of anionic analytes in waste samples.**

**CE refers to the electrophoretic separation of ions d**  **issolved or suspended in an electrolyte. Samples are introduced into a capilla**  **ry tube containing an electrolytic buffer. Under the application of an electric field the cations in**  **the sample migrate toward the negatively charged electrode (cathode) and the anions migrate**  **toward the positively charged electrode (anode). This technique may be coupled with a vari**  **ety of determinative techniques for quantitative analysis. Inorganic anions can be det**  **ermined in environmental samples using CE and indirect UV detection, in which analytes are de**  **tected and quantified based on proportional**

**decreases in the absorbance of the buffer solution. CE is a complementary technique to IC and**  **typically offers shorter analysis times than IC.**

**SIDMS is a quantitative method for determining elemental**  **species based on the measurement of isotope ratio(s) in each species of**  **a nuclide using mass spectrometry after speciated isotope dilution. Samples are mixed with**  **one or more isotopic spikes which have different isotopic abundances and are artificially**  **converted to chemical forms corresponding to the species to be analyzed. The spiked samples are**  **then subjected to the separation of the species and the measurement of the altered isotope**  **ratios in each species. Both species concentrations and species conversions can be mathe**  **matically derived. SW-846 Update V THREE - 16 Revision 5** 

**October 2012 The following methods are included in this section**  **:**

Method 6010D **: Inductively Coupled Plasma-Optical Emission Spect rometry** 

Method 6020B **: Inductively Coupled Plasma-Mass Spectrometry**

Method 6200 **: Field Portable X-Ray Fluorescence Spectrometry fo r the Determination** 

**of Elemental Concentrations in Soil and Sediment**

Method 6500 **: Dissolved Inorganic Anions in Aqueous Matrices by Capillary Ion** 

**Electrophoresis**

Method 6800 **: Elemental and Speciated Isotope Dilution Mass Spe ctrometry** 

Method 7000B **: Flame Atomic Absorption Spectrophotometry**

Method 7010 **: Graphite Furnace Atomic Absorption Spectrophotome try** 

Method 7061A **: Arsenic (Atomic Absorption, Gaseous Hydride)**

Method 7062 **: Antimony and Arsenic (Atomic Absorption, Borohydr ide Reduction)** 

Method 7063 **: Arsenic in Aqueous Samples and Extracts by Anodic Stripping** 

**Voltammetry (ASV)**

Method 7195 **: Chromium, Hexavalent (Coprecipitation)**

Method 7196A **: Chromium, Hexavalent (Colorimetric)**

Method 7197 **: Chromium, Hexavalent (Chelation/Extraction)**

Method 7198 **: Chromium, Hexavalent (Differential Pulse Polarogr aphy)** 

Method 7199 **: Determination of Hexavalent Chromium in Drinking Water,** 

**Groundwater and Industrial Wastewater Effluents by Ion**  **Chromatography**

Method 7470A **: Mercury in Liquid Waste (Manual Cold-Vapor Techni que)** 

Method 7471B **: Mercury in Solid or Semisolid Waste (Manual Cold- Vapor Technique)** 

Method 7472 **: Mercury in Aqueous Samples and Extracts by Anodic Stripping** 

**Voltammetry (ASV)**

Method 7473 **: Mercury in Solids and Solutions by Thermal Decomp osition,** 

**Amalgamation, and Atomic Absorption Spectrophotomet ry**  Method 7474 **: Mercury in Sediment and Tissue Samples by Atomic Fluorescence** 

**Spectrometry**

Method 7580 **: White Phosphorus (P 4**  **) by Solvent Extraction and Gas**

**Chromatography**

Method 7741A **: Selenium (Atomic Absorption, Gaseous Hydride)**

Method 7742 **: Selenium (Atomic Absorption, Borohydride Reductio n)** 

**3.8 REFERENCES FOR PREVIOUS SECTIONS AND THE TABLES AND FIGURES** 

**1. Skoog, D. A., "Principles of Instrumental Analys is," 3rd ed, Saunders College Publishing,**  **Philadelphia, PA, 1985.**

**2. EPA, U.S., "Sampling Ambient Water for Trace Met als at EPA Water Quality Criteria**  **Levels," Method 1669, U.S. Environmental Protection Agency, Office of Water,**  **Washington, D.C., 1996.**

**3. Adeloju, S. B. and Bond, A. M., "Influence of La boratory Environment on the Precision and**  **Accuracy of Trace Element Analysis,"** Anal. Chem. **, 1985,** 57 **, 1728-1733. SW-846 Update V THREE - 17 Revision 5** 

**October 2012 4. Kingston, S. H. M., et al., "Microwave Enhanced**  **Chemistry: Fundamentals, Sample Preparation, and Applications," American Chemical S**  **ociety, Washington, DC, 1997, p.**

**257-279.**

**5. Moody, J. R., "NBS Clean Laboratories for Trace Element Analysis,"**  Anal. Chem. **, 1982,**

54 **, 1358A-1376A.**

**6. Murphy, T., "National Bureau of Standards Specia l Publication 422 Accuracy in Trace**  **Analysis: Sampling, Sample Handling, and Analysis, " National Bureau of Standards,**  **Gaithersburg, MD, 1976, p. 509-539.**

**7. Tolg, G. and Tschopel, P., "Determination of Tra ce Elements," VCH, New York, NY, 1994,**  **p. 1-38.**

**8. Zief, M. and Mitchell, J. W., "Chemical Analysis ," Vol. 47, John Wiley & Sons, New York,**  **NY, 1976.**

**9. Kuehner, E. C., et al., "Production and Analysis of Special High-Purity Acids Purified by**  **Sub-Boiling Distillation,"** Anal. Chem. **, 1972,** 44 **, 2050-2056.**

**10. Moody, J. R., "Purified Reagents for Trace Meta l Analysis,"**  Talanta **, 1982,** 29 **, 1003-1010.**

**11. Kuehner, E. C. and Freeman, D. H., "Purificatio n of Inorganic and Organic Materials,"**  **Marcel Dekker, New York, NY, 1969, p. 297-306.**

**12. Moody, J. R., "The Sampling, Handling and Stora ge of Materials for Trace Analysis,"** 

Philos. Trans. R. Soc. London **, 1982,** 305 **, 669-680.**

**13. Moody, J. R. and Lindstrom, R. M., "Selection a nd Cleaning of Plastic Containers for**  **Storage of Trace Element Samples,"** Anal. Chem. **, 1977,** 49 **, 2264-2267.**

**14. Prevatt, F. J., "Clean Chemistry for Trace Anal ysis,"**  Environmental Testing and Analysis

**, 1995,**  4 **, 24-27.**

**15. Skelly, E. M. and DiStefano, F. T., "Clean Room and Microwave Digestion Techniques:**  **Improvement in Detection Limits for Aluminum Determ ination by GF-AAS,"**  Appl. Spectrosc. **, 1988,** 42 **, 1302-1306.**

**16. Rabinowitz, M. B. and Wetherill, G. W., "Identi fying Sources of Lead Contamination by**  **Stable Isotope Techniques,"** Environ. Sci. Technol. **, 1972,** 6 **, 705-709.**

**17. Maienthal, E. J., "U.S. National Bureau of Stan dards Technical Note 545," National**  **Bureau of Standards, Gaithersburg, MD, 1970, p. 53- 54.** **SW-846 Update V THREE - 18 Revision 5**

**October 2012 18. Boothe, P. N. and Nicolau, B.A. "The Coastal Be**  **nd Bays Project,"** 26th Annual Conference on Analysis of Pollutants in the Environ ment **, Chicago, IL 2003.**

**19. Miller, G. T., "Living in the Environment, Wads worth Inc., Belmont, CA, 1994.** 

**20. Gy, P., "Sampling for Analytical Purposes" Wile y, New York, NY, 1998.** 

**21. Pitard F.F. “Pierre Gy’s Sampling Theory and Sa mpling Practice,” Second Edition, CRC**  **Press, Inc., Boca Raton, FL, 1993.**

**22. EPA, U.S., “Correct Sampling Using the Theories of Pierre Gy,” Office of Research and**  **Development, Las Vegas, NV, 1999.**

**23. EPA, U.S., “Guidance for Obtaining Representati ve Laboratory Analytical Subsamples**  **from Particulate Laboratory Samples.” Office of Re search and Development, 2003.** **SW-846 Update V THREE - 19 Revision 5**

**October 2012 TABLE 3-1** 

**MATERIALS FOR USE IN SAMPLE COLLECTION FOR**

**INORGANIC ANALYTE DETERMINATIONS**

**Analyte Recommended Container Material**

**Metals PTFE, plastic, glass** 

**Chloride PTFE, plastic, glass** 

**Cyanide PTFE, plastic** 

**Fluoride PTFE, plastic** 

**Nitrate PTFE, plastic, glass** 

**pH PTFE, plastic, glass** 

**Specific Conductance PTFE, plastic, glass**

**Sulfate PTFE, plastic, glass** 

**Sulfide PTFE, plastic, glass** 

**a These recommendations are intended as guidance only**  **and not inclusive of all possible analytes and materials. The selection of sample container shoul**  **d be made based on the nature of the sample, the intended end use of the data and the project data q**  **uality objectives. SW-846 Update V THREE - 20 Revision 5** 

**October 2012 TABLE 3-2** 

**RECOMMENDED SAMPLE HOLDING TIMES, PRESERVATION, COL LECTION QUANTITIES,** 

**AND DIGESTION VOLUMES FOR SELECTED INORGANIC ANALYT E DETERMINATIONS IN** 
**AQUEOUS AND SOLID SAMPLES a,b** 

**Analyte Matrix Fraction Minimum** 

**Collection**

**Volume/Mass Preservation** 

**1 Digestion** 

**Volume Holding** 

**Time 2** 

**Metals (except Hg and Cr**  **6+ )**  **Aqueous Total/total**

**recoverable 600 mL HNO**  **3 to pH<2 100 mL 6 months** 

**Dissolved 600 mL Filter on site;**

**HNO 3**  **to pH<2 100 mL 6 months** 

**Suspended 600 mL Filter on site; 100 mL 6 months**

**Solid Total 200 g None 2 g 6 months**

**Hexavalent**

**chromium Aqueous 400 mL ≤6 °C 100 mL 24 hours** 

**Solid 100 g ≤6 °C 30 days to**

**extraction ≤6 °C 2.5 g 7 days from** 

**extraction to analysis** 

**Mercury Aqueous Total 400 mL HNO 3**  **to pH<2 100 mL 28 days**

**Dissolved 400 mL Filter;**

**HNO 3**  **to pH<2 100 mL 28 days** 

**Solid Total 200 g ≤6 °C 0.2 g 28 days**

**Solid Species 200 g ≤6 °C 0.2 g 5 days**

**Chloride Aqueous 50 mL ≤6 °C**

 **28 days**

**Cyanide Aqueous 500 mL ≤6 °C;**

**NaOH to pH>12**   **14 days**

**Solid 100 g ≤6 °C**

 **14 days**

**Fluoride Aqueous 300 mL ≤6 °C**

 **28 days**

**Nitrate Aqueous 1000 mL ≤6 °C**

 **28 days**

**Hexane**

**Extractable**

**Material (HEM; Oil &**  **Grease) Aqueous** 

**Solid 1000 mL** 

**100 g ≤6 °C** 

**HCl or H 2**  **SO 4**  **to pH <2**

**≤6 °C**  **28 days**

**28 days**

**HCl or H 2**  **SO 4**  **to pH <2 when**  **practical SW-846 Update V THREE - 21 Revision 5** 

**October 2012 TABLE 3-2** 

**RECOMMENDED SAMPLE HOLDING TIMES, PRESERVATION, COL LECTION QUANTITIES,** 

**AND DIGESTION VOLUMES FOR SELECTED INORGANIC ANALYT E DETERMINATIONS IN** 
**AQUEOUS AND SOLID SAMPLES a,b** 

**Analyte Matrix Fraction Minimum** 

**Collection**

**Volume/Mass Preservation** 

**1 Digestion** 

**Volume Holding** 

**Time 2** 

**pH Aqueous 25 mL NA**

 **Analyze immediately** 

**Solid 20 g NA** 

 **Analyze immediately** 

**Specific**

**Conductance Aqueous**  **100 mL NA**

 **Analyze immediately** 

**Sulfate Aqueous 50 mL ≤6 °C**

 **28 days**

**Sulfide Aqueous**

**Solid 100 mL** 

**100 g 4 drops 2N** 

**zinc**

**acetate/100 mL sample;** 

**NaOH to pH>9;** 

**Minimize aeration;** 

**Store headspace** 

**free at**

**≤6 °C**

**Fill sample**

**surface with**

**2N zinc**

**acetate until moistened;** 

**Store headspace** 

**free at ≤6 °C** 

 **7 days**

**7 days**

**Organic Carbon, Total**  **(TOC) Aqueous** 

**Solid 200 mL** 

**100 g ≤6 °C** 

**store in dark**

**HCl or H 2**  **SO 4**  **to pH <2;**

**≤6 °C** 

 **28 days**

**28 days**

**a These recommendations are intended as guidance only**  **. The selection of sample and digestion volumes an d**  **preservation and holding times should be made based on the nature of the sample, the intended end use**  **of the data and the data quality objectives.** 

**b Additional sample quantities may need to be collec**  **ted in order to allow for the preparation and analy sis of QC**  **samples, such as matrix spikes and duplicates.**

**1 The exact sample extract, and standard storage temp**  **erature should be based on project-specific require ments** 

**and/or manufacturer’s recommendations for standards . Alternative temperatures may be appropriate base**  **d on demonstrated analyte stability within a matrix, pro**  **vided the data quality objectives for a specific pr oject are still** 

**attainable. SW-846 Update V THREE - 22 Revision 5** 

**October 2012 2**  **A longer holding time may be appropriate if it can be demonstrated that the reported analyte concentr**  **ations are not adversely affected by preservation, storage and ana**  **lyses performed outside the recommended holding tim es.** 

**TABLE 3-3**

**EXAMPLES OF THE ANALYTICAL BLANK INFLUENCE ON**

**ULTRA-TRACE ANALYSIS OF ELEMENTS IN GLASS**

**Conditions Pb (ng) Ag (ng)** 

**Initial analysis of TEG* standard 330 ± 250 970 ± 5** **00**

**Analysis using sub-boiled distilled acids 260 ± 200**
**-**

**Analysis in a Class 100 hood 20 ± 8 207 ± 200**

**Analysis using sub-boiled acids in a Class 100 hood 2 ± 1 3 ± 2** 

*** TEG = Trace element in glass**

**Data are taken from Reference 6.**

**TABLE 3-4**

**EXAMPLES OF LEAD CONCENTRATIONS IN AIR**

**Site Lead Concentration (μg/m**  **3 ) Source** 

**Downtown St. Louis, MO 18.84 Reference 16**

**Rural park, Southeastern MO 0.77 Reference 17**

**NIST Laboratory, MD 0.4 Reference 6 SW-846 Update V THREE - 23 Revision 5** 

**October 2012 TABLE 3-5** 

**CLEANLINESS LEVELS IN INTERNATIONAL STANDARD ISO 14 644-1** 

**ISO**

**classification**

**number Maximum concentration limits (particles/m** 
**- 3**  **of air) for particles equal to and larger than the considered sizes shown below** 

0.1 μm 0.2 μm 0.3 μm 0.5 μm 1 μm 5 μm

ISO Class 1 10 2

ISO Class 2 100 24 10 4

ISO Class 3 1,000 237 102 35 8

ISO Class 4 10,000 2,370 1,020 352 83

ISO Class 5 100,000 23,700 10,200 3,520 832 29

ISO Class 6 1,000,000 237,000 102,000 35,200 8,320 293

ISO Class 7 352,000 83,200 2,930

ISO Class 8 3,520,000 832,000 29,300

ISO Class 9 35,200,000 8,320,000 293,000

**NOTE: Uncertainties related to the measurement pro cess require that concentration data with no more**  **than three significant figures be used in determini ng the classification level** 

**© ISO. This material is reproduced from ISO 14644- 1:1999 with permission of the American**  **National Standards Institute (ANSI) on behalf of th e International Organization for**  **Standardization (ISO). No part of this material ma y be copied or reproduced in any form,**  **electronic retrieval system or otherwise or made av ailable on the Internet, a public network, by**  **satellite or otherwise without the prior written co nsent of ANSI. Copies of this standard may be**  **purchased from ANSI, 25 West 43rd Street, New York, NY 10036, (212) 642-4900,**  **http://webstore.ansi.org. SW-846 Update V THREE - 24 Revision 5** 

**October 2012 TABLE 3-6** 

**PARTICULATE CONCENTRATIONS IN LABORATORY AIR**

**Concentration (μg/m 3**  **)**

**Location Iron Copper Lead Cadmium**

**Ordinary laboratory**  **0.2 0.02 0.4 0.002**

**Clean room 0.001 0.002 0.0002 ND**

**Clean hood 0.0009 0.007 0.0003 0.0002**

**ND = Not Detected**

**Data are taken from Reference 17.**

**TABLE 3-7**

**NON-CONTAMINATING MATERIALS AND FOR USE AS DIGESTIO N VESSELS** 

**AND SAMPLE CONTAINERS IN ULTRA-TRACE ANALYSES**

**Listed from highest to lowest preference for use in sample containment** 

**Fluoropolymers: PFA*, TFM, TFE*, FEP*, Tefzel***

**Quartz - Synthetic**

**Polyethylene (suitable for storage only, not for ac id digestion)** 

**Quartz - Natural**

**Borosilicate Glass**

*** Various forms of PTFE**

**Data are taken from Reference 8. SW-846 Update V THREE - 25 Revision 5** 

**October 2012 FIGURE 3-1** 

**COMPARISON OF CLEAN VERSUS CONVENTIONAL SAMPLING AN D ANALYSIS** 
**TECHNIQUES USED IN THE ANALYSIS OF SOUTH TEXAS ESTU ARY WATERS** 

**Taken from Reference 18.** 0 10 20 30 40

Cd Cu Hg Pb Zn



### ElementConcentration (ppb) 

### Clean Conventional

11 fold 10 fold

36 fold 280 fold 26 fold**SW-846 Update V THREE - 26 Revision 5**

**October 2012 FIGURE 3-2** 

**COMPARISON OF PARTICLE COUNT ANALYSIS OF A CLEAN RO OM AND** 
**A STANDARD LABORATORY AT DUQUESNE UNIVERSITY IN PIT TSBURGH, PA** 

**Taken from Reference 4. SW-846 Update V THREE - 27 Revision 5** 

**October 2012 FIGURE 3-3** 

**PARTICLE SIZE COMPARISON CHART FOR COMMON PARTICULA TES** 

**Taken from Reference 4, 19. SW-846 Update V THREE - 28 Revision 5** 

**October 2012 APPENDIX A** 

**SUMMARY OF UPDATES/CHANGES IN CHAPTER THREE**

**1. The entire document was formatted in Microsoft W ord 2007 .docx format from the**  **original .wpd and .pdf files. 2. The Revision number was changed to Revision 5, u**  **pdated for release October 2012. 3. Minor editorial and grammatical changes were mad**  **e throughout the Chapter.**

**4. Method 3200 was added to Section 3.6. 5. Method numbers were revised to reflect the assig**  **ned number for Update V. 6. Definition for instrument detection limit (IDL)**  **was revised to be consistent with methods**

**6010D and 6020B. 7. The term “accuracy” was replaced by “bias” where**  **appropriate. 8. Definition for linear range was revised to be co**  **nsistent with methods 6010D and 6020B. 9. All references to atomic emission spectrometry w**  **ere changed to optical emission spectrometry throughout the chapter.**  **10. Replaced the definition of interference check s ample (ICS) with the spectral interference**  **check (SIC) solution to be consistent with methods 6010D and 6020B.**  **11. Added a note to clarify the methods that can be used for total acid soluble/recoverable** 

**metals. 12. References 20-22 were added as guidance for min**  **imizing sampling bias. 13. The term “decomposition” was replaced by “diges**  **tion” where appropriate. 14. Descriptions of cold vapor atomic fluorescence**  **and anodic stripping voltammetry were**

**added to Section 3.7. 15. Collision/reaction cell technology was added to**  **Sections 3.6 and 3.7 as an effective method for removing isobaric interferences when ana**  **lyzing by ICP-MS. 16. The terms "analytical" and "analysis" were chan**  **ged to "instrument" or "determinative", where appropriate.**  **17. The term “signal” was changed to “instrument re sponse”.**  **18. The method for assessing sensitivity for ICP-OE S and ICP-MS in Section 3.1 was** 

**modified. 19. The term “optimum concentration range” was remo**  **ved from Section 3.1. 20. Antimony was added to the HGAA method described**  **in Section 3.7. 21. The definition for “laboratory control sample”**  **was revised to recommend the use of a spiking solution from the same source as the calibr**  **ation standards. 22. A minimum collection mass of 100 g was added to**  **Table 3-2 for solid samples collected for sulfide analysis.**