METHOD 200.5 DETERMINATION OF TRACE ELEMENTS IN DRINKING WATER BY AXIALLY VIEWED INDUCTIVELY COUPLED PLASMA - ATOMIC EMISSION SPECTROMETRY

Revision 4.2

October 2003

Theodore D. Martin

NATIONAL EXPOSURE RESEARCH LABORATORY OFFICE OF RESEARCH AND DEVELOPMENT U. S. ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OHIO 45268

200.5-1METHOD 200.5 DETERMINATION OF TRACE ELEMENTS IN DRINKING WATER BY AXIALLY VIEWED INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROMETRY

1.0 SCOPE AND APPLICATION 1.1 Axially viewed inductively coupled plasm a -atom i c em ission spectrom e try (AVICP-AES) is used to determ ine trace elem ents, as well as water m a trix elem ents, in drinking water and drinking water supplies. This m e thod is applicable to the following analytes:

))))))))))))))))))))))))))))))))))))))))))))))))))))))))))) Chem ical Abstract Services Analyte Abbreviation Registry Num b ers (CASRN)

))))))))))))))))))))))))))))))))))))))))))))))))))))))))))) Alum inum (Al) 7429-90-5 Antim ony* (Sb) 7440-36-0 Arsenic* (As) 7440-38-2 Barium * ( Ba) 7440-39-3 Beryllium * (Be) 7440-41-7 Boron ( B) 7440-42-8 Cadm ium * (Cd) 7440-43-9 Calcium ( Ca) 7440-70-2 Chrom i um * ( Cr) 7440-47-3 Copper* (Cu) 7440-50-8 Iron ( Fe) 7439-89-6 Lead* ( Pb) 7439-92-1 Magnesium (Mg) 7439-95-4 Manganese (Mn) 7439-96-5 Nickel (Ni) 7440-02-0 Selenium * ( Se) 7782-49-2 Silica ( SiO 2 ) 7631-86-9 Silver (Ag) 7440-22-4 Sodium (Na) 7440-23-5 Tin ( Sn) 7440-31-5 Vanadium (V) 7440-62-2 Zinc (Zn) 7440-66-6

S))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))Q * Designated prim ary drinking water contam inant. 1.2 For reference where this m e thod is approved for use in com p liance m onitoring program (e.g., Safe Drinking W a ter Act [SDWA]) consult both the appropriate sections of the Code of Federal Re gulation (40 CFR Part 141 § 141.23) and the latest Federal Register announcem ents.

200.5-21.3 This m e thod provides a specific procedure utilizing axially-viewed plasm aatom ic em ission signals generated only by pneum atic nebulization for the analysis of all analytes. Som e AVICP-AES instrum e nts are so conf igured that the em itted signal can also be viewed alternately or sim u ltaneously in a radial m anner. Radiallyviewed signals for the determ ination of drinking water m a trix elem ents (Ca, Mg and Na) and silica are acceptable. The Ca and Mg data can be used in the calculation of hardness. 1.4 Wh en viewing sodium em ission from the axial configuration, the ratio of signal intensity to analyte concentration is not a linear response. Therefore, sodium should be calibrated using m u ltiple standard solutions of increasing concentration to properly define the response ratio at various levels of concentration (see Sect. 7.8.2). 1.5 For drinking water com p liance m onitoring, a “total” elem ent determ ination (dissolved + suspended fractions) is required. Wh en the m easured turbidity on an acid preserved sam p le is < 1 NTU, direct analysis, without sam p le digestion, is perm itted with the use of som e approved spectrochem ical m e thods. However, when using this m e thod, all sam p les are digested and preconcentrated prior to analysis using the total recoverable digestion (1) step described in Section 11.1. Preconcentrating the sam p le prior to analysis increases analytical sensitivity f o r m eeting the m e thod detection lim it (MDL) requirem e nts given in Section 1.12. Thus, when using this m e thod, the need to m easure sam p le turbidity prior to m e tal analysis is elim inated. 1.6 Operative m atrix effects can occur from elevated dissolved solids. Using this technique, m a trix effects have been observed when the concentration of calcium and/or the com b ined concentrations of the m atrix elem ents (Ca, Mg, and Na) and silica exceed 125 m g /L and 250 m g /L, respectively. To verify that a m atrix effect is not operative, an LFM (see Sect. 9.4) m u st be analyzed when a prim ary contam inant (see Sect. 1.1) concentration exceeds 80% of the established m a xim um contam inant level (MCL) or action level. If the absence of a m a trix interference can not be verified, the sam p le m u st be analyzed by m e thod of standard additions (MSA; see Sect. 11.3) or another approved m e thod (see Sect. 1.7 for special requirem e nts for lead). 1.7 Wh en determ ining lead by this m e thod, the instrum e nt m u st be capable of analyzing silica as well. Levels of silica that exceed 30 m g /L, when preconcentrated 2X, cause a suppressive effect on lead determ inations. For sam p les containing silica above 30 m g /L and lead concentrations $ 10 μg/L, lead m u st be determ ined by m e thod of standard additions (MSA; see Sect. 11.3) or by another approved com p liance m onitoring m e thod. If the laboratory can not determ ine silica when using this m e thod, this m e thod can not be used for com p liance m onitoring of lead. 1.8 Wh en determ ining boron and silica, only plastic or PTFE labware should be used from tim e of sam p le collection to com p letion of analysis. In this m e thod, glassware is specifically avoided and only the use of m e tal-free plastic labware is recomm e nded. Borosilicate glass should be avoided to prevent contam ination of these analytes.

200.5-31.9 The total recoverable sam p le digestion procedure given in Section 11.1 is suitable for the determ ination of silver in aqueous sam p les containing concentrations up to 0.1 m g /L. Also, sam p les prepared using the procedure m ay be analyzed for thallium using EPA Method 200.9 (2)

. 1.10 Com p liance m onitoring data for m e tal contam inants are norm a lly reported in units of m g /L; however, the data for the total recoverable analytes in this m e thod are noted in units of μg/L. This difference is done to reduce or elim inate the listing of non-significant zeros. Wh en data are reported for com p liance m onitoring, the data should be reported in the sam e units used to express the established MCL and to the appropriate num erical level of significance. 1.11 MDLs for trace elem ents and linear ranges for the drinking water m a trix elem ents will vary with the wavelength selected and the spectrom e ter conf iguration and operating conditions. Table 4 provides determ ined MDLs for the listed wavelengths utilizing the instrum e nt operating conditions given in Table 3. These values are provided for com p arative purposes for user self-evaluation when com p leting the m andatory initial dem onstration of perf orm ance. Meeting the exact sam e lim its listed in Table 4 is not necessarily a requirem e nt for the use of this m e thod. Users of this m e thod m u st docum ent and have on file the required initial dem onstration perform ance data described in Section 9.2 prior to using the m e thod for analysis (see Sect. 1.12). 1.12 Users of this m e thod for the purpose of SDWAcom p liance m onitoring m u st achieve and docum ent MDLs for As, Be, Cd, Sb, Se, and Pb that are # a value of 1/5 their respective MCL or action level. 2.0 SUMMARY OF METHOD 2.1 A 50 m L aliquot of a well-m i xed, non-filtered, acid preserved aqueous sam p le is accurately transferred to a clean 50-m L plastic disposable digestion tube containing a m i xture of nitric and hydrochloric acids. The aliquot is heated to 95 °C (± 2 °C), evaporated to approxim ately 25 m L , covered with a ribbed plastic watch glass and subjected to total recoverable solubilization with gentle refluxing for 30 m i nutes. The sam p le is allowed to cool and diluted to 25 m L with reagent water to ef f e ct a 2X preconcentration. The sam p le is capped, m i xed and now ready for analysis (The tim e required to com p lete the sam p le preparation step is approxim a tely 2.5 hours). 2.2 The analytical determ inative step described in this m e thod involves m u lti-elem ental determ inations by AVICP-AES using sequential or sim u ltaneous instrum e nts. The instrum e nts m easure characteristic atom ic-line em ission spectra by optical spectrom e try. Standard and sam p le solutions are nebulized by pneum atic nebulization and the resulting aerosol is transported by argon carrier-gas to the plasm atorch. Elem ent specific em ission spectra are produced by a radio-frequency inductively coupled plasm a . The spectra are dispersed by a grating spectrom e ter, and the intensities of the line spectra are m onitored at specif i c wavelengths by a photosensitive device. Photo currents from the photosensitive device are processed and controlled by a com puter system

. A background correction technique is

200.5-4required to com p ensate for variable background contribution to the determ ination of the analytes. Background should be m easured adjacent to the analyte wavelength during analysis. Possible interferences that can occur m u st be considered and addressed appropriately as discussed in Section 4. 3.0 DEFINITIONS 3.1 CALIBRATION BLANK - A volum e of reagent water acidified with the sam e acid m atrix reagents as in the calibration standards. The calibration blank is a zero standard and is used to calibrate the AVICP instrum e nt (Sects. 7.9.1). 3.2 CALIBRATION STANDARD (CAL) - A solution prepared from the dilution of stock standard solutions. The CAL solutions contain the acid m a trix reagents and are used to calibrate the instrum e nt response with respect to analyte concentration (Sect. 7.8.1). 3.3 DISSOLVED ANALYTE - The concentration of analyte in an aqueous sam p le that will pass through a 0.45- : m m e m b rane f ilter assem b ly prior to sam p le acidif ication. 3.4 FIELD REAGENT BLANK (FRB) - An aliquot of reagent water that is placed in a sam p le container in the laboratory and treated as a sam p le in all respects, including shipm e nt to the sam p ling site, exposure to the sam p ling site conditions, storage, acid preservation, and all analytical procedures. The FRB is used to determ ine if m e thod analytes or interferences are present in the field environm ent (Sect. 8.2). 3.5 INSTRUMENT DETECTION LIMIT (IDL) - The concentration equivalent to the analyte signal which is equal to three tim es the standard deviation of a series of ten replicate m easurem ents of the calibration blank signal at the sam e wavelength. 3.6 INSTRUMENT PERFORMANCE CHECK (IPC) SOLUTION - A solution of m e thod analytes in the acid m a trix reagents used to evaluate the perform ance of the instrum e nt system with respect to a defined set of m e thod criteria (Sects. 7.10.3 & 9.3.4). 3.7 LABORATORY DUPLICATES (LD1 and LD2) - Two aliquots of the sam e sam p le taken in the laboratory and analyzed separately with identical procedures. Analyses of LD1 and LD2 indicates precision associ ated with laboratory procedures, but not with sam p le collection, preservation, or storage procedures. 3.8 LABORATORY FORTIFIED BLANK (LFB) - An aliquot of LRB to which known quantities of the m e thod analytes are added in the laboratory. The LFB is analyzed exactly like a sam p le, and its purpose is to determ ine whether the m e thodology is in control and whether the laboratory is capable of m aking accurate and precise m easurem ents (Sects. 7.9.3 & 9.3.2). 3.9 LABORATORY FORTIFIED SAMPLE MA TRIX (LFM) - An aliquot of a drinking water or drinking water supply sam p le to which known quantities of the m e thod analytes are added in the laboratory. The LFM is analyzed exactly like a

200.5-5sam p le, and its purpose is to determ ine whether the sam p le m a trix contributes bias to the analytical results. The background concentrations of the analytes in the sam p le m atrix m u st be determ ined in a separate aliquot and the m easured values in the LFM corrected for background concentrations (Sects. 1.6, 1.7 & 9.4). 3.10 LABORATORY REAGENT BLANK (LRB) - An aliquot of reagent water that is treated exactly as a sam p le including exposure to all labware, equipm ent, and reagents, that are used with other sam p les. The LRB is used to determ ine if m e thod analytes or other interferences are present in the laboratory environm ent, reagents, or apparatus (Sects. 7.9.2 & 9.3.1). 3.11 LINEAR DYNAMIC RANGE (LDR) - The concentration range over which the instrum e nt response to an analyte is linear (Sect. 9.2.2). 3.12 MAXIMUM CONTAMINANT LEVEL (MCL) - The m a xim um perm issible level of a contam inant in water which is delivered to any user of a public water system

. 3.13 METHOD DETECTION LIMIT (MDL) - The m i nim um concentration of an analyte that can be identified, m easured, and reported with 99% confidence that the analyte concentration is greater than zero (Sects. 1.11, 1.12, 9.2.5 and Table 4). 3.14 PLASMA SOLUTION - A solution used to determ ine the nebulizer argon flow rate or gas pressure that will produce the optim um net-signal-to-noise (S-B/B) needed for the m o st requiring analyte included in the analytical schem e (Sects. 7.11 & 10.2). 3.15 QUALITY CONTROL SAMPLE (QCS) - A solution of m e thod analytes of known concentrations which is used to fortify an aliquot of LRB or sam p le m a trix. The QCS is obtained from a source external to the laboratory and different from the source of calibration standards. It is used to check either laboratory or instrum e nt perform ance (Sects. 7.10.4 & 9.2.4). 3.16 SPECTRAL INTERFERENCE CHECK (SIC) SOLUTION - A solution of selected m e thod analytes of higher concentrations which is used to evaluate the procedural routine for correcting known interelem e nt sp ectral interferences with respect to a defined set of m e thod criteria (Sects. 4.1 & 9.3.5). 3.17 STANDARD ADDITION - The addition of a known am ount of analyte to the sam p le in order to determ ine the relative response of the detector to an analyte within the sam p le m atrix. The relative response is then used to assess either an operative m atrix effect or the sam p le analyte concentration (Sects. 1.6 & 11.3). 3.18 STOCK STANDARD SOLUTION - A concentrated solution containing one or m o re m e thod analytes prepared in the laboratory using assayed reference m a terials or purchased from a reputable comm e rcial source (Sect. 7.7). 3.19 TOTAL RECOVERABLE ANALYTE - For this m e thod, the concentration of analyte determ ined by the analysis of an unf iltered acid preserved drinking water

200.5-6sam p le following digestion by refluxing with hot dilute m i neral acid(s) as specified in the m e thod (Sects. 1.5 & 11.1). Data are reported as a “total” elem ent determ ination - the com b ined concentrations of the dissolved and suspended fractions of the sam p le. 4.0 INTERFERENCES 4.1 Spectral interferences are caused by background em ission from continuous or recom b ination phenom ena, stray light from the line em ission of high concentration elem ents, overlap of a spectral line from another elem ent, or unresolved overlap of m o lecular band spectra. Except for interference from background em ission and possible stray light, which can usually be com p ensated for by subtracting the background em ission adjacent to the analyte wavelength peak, spectral interferences associated with the analysis of drinking water are m i nim a l. However, the absence of interelem e nt spectral interference should be verified. Criteria for determining an interelement spectral interference is an apparent positive or negative concentration on the analyte that is ou tside the 3-sigma control limits of the calibration blank for the analyte. Wh en an instrum e nt equipped with a conventional diffraction grating that provides 0.016 nm first order resolution is used with the wavelengths in the noted spectral order and background correction locations given in Table 1, no detectable concom itant interelem e nt spectral interferences occurs between the trace elem ent analytes listed in this m e thod at concentrations # 20 m g /L. Since concentrations of trace elem ents in drinking water and drinking water supplies are far below the level of 20 m g /L, an interelem e nt correction routine for trace analytes would be unnecessary for an instrum e nt so configured. On the other hand, the concentration of the water m a trix elem ents can be in excess of 100 m g /L. Fortunately, the m a trix elem ents are not spectrally rich and have f e w prom inent lines to cause interelem e nt spectral interf erence. Using this m e thod and analyzing single elem ent solutions of 300 m g /L Ca, 200 m g /L Mg, 200 m g /L Na, and 100 m g /L Si, no spectral enhancem ent of other m e thod analytes were observed, thus not requiring interelem e nt corrections. However, there are three concerns worth noting: (1) yttrium , a comm only used internal standard, proved an interference in the spectral region recomm e nded for background correction on the listed Ag wavelength (328.068 nm ), (2) a sim ilar situation occurs from m o lybdenum on the spectral region recomm e nded for background correction on the V wavelength (292.402 nm ), and (3) the listed Fe wavelength (271.441 nm ) experiences an apparent concentration increase of approxim a tely 8% from cobalt (271.442 nm ) when the two analytes are present in equal concentration. Therefore, a quality control check sam p le containing both iron and cobalt or both vanadium and m o lybdenum should notbe used to confirm the calibration standards when the Fe 271.441 nm and V 292.402 nm wavelengths are utilized. Note : If wavelengths, noted spectral order, and background correction locations different from those listed in Table 1 are used with this m e thod, and/or the optical resolution of the instrum e nt utilized does not provide 0.016 nm first order resolution or better, the absence of interelem e nt spectral interference m u st be confirm e d by com p leting spectral scans over the wavelength area and background correction locations to be utilized. The spectral scans should be com p leted using single

200.5-7elem ent solutions of both trace and water m a trix elem ents of concentrations noted above that will verify nonexistent apparent analyte concentrations. If an interelem e nt spectral interf erence is detected, a correction routine that is operative during analysis m u st be used with daily verification using SIC solutions, to dem onstrate that the routine m eets the above criteria. 4.2 Physical interferences are effects associated with the sam p le nebulization and transport processes. Changes in viscosity and surface tension can cause significant inaccuracies, especially in sam p les containing high dissolved solids or high acid concentrations. Physical interferences of the types described above have not been evident in the analysis of m o st drinking waters. However, the use of a peristaltic pum p to regulate solution uptake rate and the use of m a ss flow controllers that provide better control of the argon flow rates, especially for the nebulizer, im prove instrum e nt stability and precision. 4.3 Chem ical interferences include m o lecular-com pound form ation, ionization effects, and solute-vaporization effects. In general, chem ical interferences are highly dependent on m atrix type and the specific elem ent. In radial ICP-AES, one way of controlling these effects is careful selection of the observation height in the plasm a . However, f o r increased sensitivity, the total em ission of the plasm ais observed in AVICP-AES, thus elim inating this useful option. To counteract ionization and m atrix interferences in AVICP-AES, som e laboratories routinely use an ionization buffer along with an internal standard added to both standards and sam p les alike in the sam p le train using a peristaltic pum p and m i xing tee. Use of an ionization buf f e r is perm itted with this m e thod provided the addition does not cause an interelem e nt spectral interference with a m e thod analyte. However, in drinking water analyses the use of an internal standard with pneum atic nebulization is discouraged because it is not necessary and adds additional variance to the determ ination. The above stated chem ical interferences have not been observed using this m e thod for drinking water analyses when the operating conditions and preparations procedures are followed as written. 4.4 Mem o ry interferences result when analytes in a previous sam p le contribute to the signals m easured in a new sam p le. Mem o ry effects can result from sam p le deposition on the uptake tubing to the nebulizer and from the buildup of sam p le m aterial in the plasm atorch and spray cham ber. The site where these effects occur is dependent on the elem ent and can be m i nim i zed by flushing the system with a rinse blank between sam p les (Sect. 7.9.4). The rinse tim es necessary for a particular elem ent should be estim ated prior to analysis. For the water m a trix elem ents this m ay be achieved by aspirating a single elem ent standard solution corresponding to their LDRs (Sect. 3.11), while for the trace contam inants single elem ent solutions containing 10 m g /L are sufficient. The aspiration tim e should be the sam e as a norm a l sam p le analysis period, followed by analysis of the rinse blank at designated intervals. The length of tim e required to reduce analyte signal to within a factor of 10 tim es the calibration blank should be noted. Until the required rinse tim e is established, this m e thod requires a rinse period using the rinse blank of at least 30 sec between sam p les and standards. If a m e m o ry interference is suspected, the sam p le should be re-analyzed after a long rinse period.

200.5-85.0 SAFETY 5.1 The toxicity or carcinogenicity of each reagent used in this m e thod have not been fully established. Each chem ical should be regarded as a potential health hazard and exposure to these com pounds should be as low as reasonably achievable. Each laboratory is responsible for m a intaining a current awareness file of OSHA regulations regarding the safe handling of the chem icals specified in this m e thod (3-5)

. A reference file of m aterial data handling sheets should also be m a de available to all personnel involved in the chem ical analysis. Specifically, concentrated nitric and hydrochloric acids are m oderately toxic and extrem ely irritating to skin and m u cus m e m b ranes. Use these reagents in a fum e hood whenever possible and if eye or skin contact occurs, flush with large volum es of water. Always wear safety glasses or a shield for eye protection, protective clothing and observe proper m i xing when working with these reagents. 5.2 Acidification of sam p les should be done in a fum e hood. 5.3 The inductively coupled plasm ashould only be viewed with proper eye protection f r om the ultraviolet em issions. 5.4 It is the responsibility of the user of this m e thod to com p ly with relevant disposal and waste regulations. For guidance see Sections 14.0 and 15.0. 6.0 EQUIPMENT AND SUPPLIES 6.1 Axially viewed inductively coupled plasm aem ission spectrom e ter: 6.1.1 Com puter-controlled em ission spectrom e ter with background-correction capability. The spectrom e ter m u st be capable of m eeting and com p lying with the requirem e nts described and referenced in Section 2.2. 6.1.2 Radio-frequency generator com p liant with FCC regulations. 6.1.3 Argon gas supply - High purity grade (99.99%). Wh en analyses are conducted frequently, liquid argon is m o re econom ical and requires less frequent replacem ent of tanks than com p ressed argon in conventional cylinders. 6.1.4 A variable speed peristaltic pum p is required to deliver both standard and sam p le solutions to the nebulizer. 6.1.5 (optional) A m a ss flow controller to regulate or m onitor the argon flow rate of the aerosol transport gas is highly recomm e nded. Use of a m a ss flow controller will provide m o re exacting control of reproducible plasm a conditions. 6.2 An analytical balance with capability to m easure to 0.1 m g, for use in preparing

200.5-9standards and for weighing sam p les as m ay be required. 6.3 A tem p erature adjustable hot plate for preparing stock standard solutions. 6.4 A tem p erature adjustable block digester capable of m a intaining a tem p erature of 95 o C for use with 50-m L plastic disposable digestion tube. 6.5 A gravity convection drying oven with therm o static control capable of m a intaining 180 o C ± 5 o C. 6.6 Air displacem ent pipetters capable of delivering volum es ranging from 50 : L to 10.0 m L with an assortm e nt of high quality disposable pipet tips. 6.7 Labware - For determ ination of trace levels of elem ents, contam ination and loss are of prim e consideration. Potential contam ination sources include im properly cleaned laboratory apparatus and general contam ination within the laboratory environm ent from dust, etc. A clean laboratory work area designated for trace elem ent sam p le handling should be used. Sam p le containers can introduce positive and negative errors in the determ ination of trace elem ents by (1) contributing contam inants through surface desorption or leaching, and (2) depleting elem ent concentrations through adsorption processes. All reusable labware (polyethylene, polym ethylpentene, PTFE, FEP, etc.) and pl astic disposable digestion tubes, caps, and watch glasses should be sufficiently clean for the task objectives. Several cleaning procedures can provide clean labware. The procedure recomm e nded for reusable labware includes washing with a detergent solution, rinsing with tap water, and soaking for 4 h or m o re in a m i xture of 5% (v/v) HNO 3 and 5% (v/v) HCl, rinsing with reagent water and storing clean. (If digested LRBs indicate random contam ination, the plastic disposable digestion tubes, caps, and watch glasses should be cleaned with 2% (v/v) HNO 3 and rinsed with reagent water prior to use.) Chrom i c acid cleaning solutions m u st be avoided because chrom i um is an analyte. 6.7.1 Plastic volum etric labware - PMP (polym ethylpentene) or equivalent m e tal free plastic volum etric flasks (50-m L to 500-m L capacities), graduated cylinders (50-m L ), and disposable m e tal-free plastic digestion tubes with caps and watch glass covers. 6.7.2 (optional) PTFE Griffin beakers, 250-m L with PTFE covers for preparing stock standards and reagents. 6.7.3 Narrow-m outh storage bottles, FEP (fluorinated ethylene propylene) and LDPE (low density polyethylene) with screw closure, 60-m L to 500-m L capacities. 6.7.4 One-piece stem FEP wash bottle with screw closure, 125-m L capacity. 7.0 REAGENTS AND STANDARDS 7.1 Reagents m ay contain elem ental im purities which m i ght af f ect analytical data. Only

200.5-10high-purity reagents that conform to the Am erican Chem ical Society specifications m

u st be used whenever possible. If the purity of a reagent is in question, analyze for contam ination. All acids used for this m e thod should be of ultra high-purity grade or equivalent. Trace m e tal grade acid m ay also be used if it can be verified by analysis to be free of contam ination. Suitable acids are available from a num ber of m anufacturers. Redistilled acids prepared by sub-boiling distillation are acceptable. 7.2 Hydrochloric acid, concentrated (sp.gr. 1.19) - HCl. 7.2.1 Hydrochloric acid (1+1) - Add 250 m L concentrated HCl to 200 m L reagent water and dilute to 500 m L

. 7.2.2 Hydrochloric acid (1+20) - Add 10 m L concentrated HCl to 200 m L reagent water. 7.3 Nitric acid, concentrated (sp.gr. 1.41) - HNO 3 . 7.3.1 Nitric acid (1+1) - Add 250 m L concentrated HNO 3 to 200 m L reagent water and dilute to 500 m L

. 7.3.2 Nitric acid (1+2) - Add 100 m L concentrated HNO 3 to 200 m L reagent water. 7.3.3 Nitric acid (1+5) - Add 50 m L concentrated HNO 3 to 250 m L reagent water. 7.3.4 Nitric acid (1+9) - Add 10 m L concentrated HNO 3 to 90 m L reagent water. 7.4 Reagent water. All references to reagent water in this m e thod refer to ASTM Type I grade water (6)

. 7.5 Amm onium hydroxide, concentrated (sp. gr. 0.902). 7.6 Tartaric acid, ACS reagent grade. 7.7 Standard Stock Solutions - Stock standards m ay be purchased or prepared from ultra-high purity grade chem icals (99.99 to 99.999% pure). All com pounds m u st be dried for 1 h at 105 o C, unless otherwise specified. It is recomm e nded that stock solutions be stored in acid-cleaned, never-used LDPE bottles f o r storage. Replace stock standards when succeeding dilutions for preparation of calibration standards can not be verified (see Sect. 9.2.4). CAUTION : M any of these chem icals are extrem ely toxic if inhaled or swallowed (Sect. 5.1). W a sh hands thoroughly after handling. Typical stock solution preparation procedures follow for 500-m L quantities, but for the purpose of pollution prevention, the analyst is encouraged to prepare sm aller quantities when possible. Concentrations are calculated based upon the weight of the pure elem ent or upon the weight of the com pound m u ltiplied by the fraction of the analyte in the com pound.

200.5-117.7.1 Alum inum solution, stock, 1 m L = 1000 : g Al: Dissolve 0.500 g of alum inum m e tal, weighed accurately to at least three significant figures, in an acid m i xture of 4.0 m L of (1+1) HCl and 1.0 m L of concentrated HN0 3 in a beaker. W arm beaker slowly to effect solution. Wh en dissolution is com p lete, transfer solution quantitatively to a 500-m L PMP flask, add an additional 5.0 m L of (1+1) HCl and dilute to volum e with reagent water. 7.7.2 Antim ony solution, stock, 1 m L = 1000 : g Sb: Dissolve 0.500 g of antim ony powder, weighed accurately to at least three significant figures, in 10.0 m L (1+1) HNO 3 and 5.0 m L concentrated HCl in a beaker. Add 50 m L reagent water and 0.75 g tartaric acid. W arm solution slightly to effect com p lete dissolution. Cool solution and add reagent water to volum e in a 500-m L PMP volum etric flask. 7.7.3 Arsenic solution, stock, 1 m L = 1000 : g As: Dissolve 0.660 g of As 2 O 3 (As fraction = 0.7574), weighed accurately to at least three significant figures, in 50 m L of reagent water containing 5.0 m L concentrated NH 4 OH in a beaker. W arm the solution gently to effect dissolution. Acidify the solution with 10.0 m L concentrated HNO 3 and dilute to volum e in a 500-m L PMP volum etric flask with reagent water. 7.7.4 Barium solution, stock, 1 m L = 1000 : g Ba: Dissolve 0.719 g BaCO 3 (Ba fraction = 0.6960), weighed accurately to at least three significant figures, in a beaker containing 75 m L (1+2) HNO 3 with heating and stirring to degas and dissolve com pound. Let solution cool and dilute with reagent water in 500-m L PMP volum etric flask. 7.7.5 Beryllium solution, stock, 1 m L = 1000 : g Be: DO NOT DRY

. Dissolve 9.823 g BeSO 4 •4 H 2 O (Be fraction = 0.0509), weighed accurately to at least four significant figures, in reagent water, add 5.0 m L concentrated HNO 3 , and dilute to volum e in a 500-m L PMP volum etric flask with reagent water. 7.7.6 Boron solution, stock, 1 m L = 1000 : g B: DO NOT DRY

. Dissolve 2.859 g anhydrous H 3 BO 3 (B fraction = 0.1749), weighed accurately to at least four significant figures, in reagent water and dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.7 Cadm ium solution, stock, 1 m L = 1000 : g Cd: Dissolve 0.500 g Cd m e tal, acid cleaned with (1+9) HNO 3 , weighed accurately to at least three significant figures, in 25 m L (1+1) HNO 3 in a beaker with heating to effect dissolution. Let solution cool and dilute with reagent water in a 500-m L PMP volum etric flask. 7.7.8 Calcium solution, stock, 1 m L = 1000 : g Ca: Suspend 1.249 g CaCO 3 (Ca fraction = 0.4005), dried at 180 °C for 1 h before weighing, weighed accurately to at least four significant figures, in reagent water and dissolve

200.5-12cautiously with a m i nim um am ount of (1+1) HNO 3 . Add 5.0 m L concentrated HNO 3 and dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.9 Chrom i um solution, stock, 1 m L = 1000 : g Cr: Dissolve 0.962 g CrO 3 (Cr fraction = 0.5200), weighed accurately to at least three significant figures, in 60 m L (1+5) HNO 3 . Wh en dissolution is com p lete, dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.10 Copper solution, stock, 1 m L = 1000 : g Cu: Dissolve 0.500 g Cu m e tal, acid cleaned with (1+9) HNO 3 , weighed accurately to at least three significant figures, in 25 m L (1+1) HNO 3 in a beaker with heating to effect dissolution. Let solution cool and dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.11 Iron solution, stock, 1 m L = 1000 : g Fe: Dissolve 0.500 g Fe m e tal, acid cleaned with (1+1) HCl, weighed accurately to three significant figures, in 50 m L (1+1) HCl in a beaker with heating to effect dissolution. Let solution cool and dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.12 Lead solution, stock, 1 m L = 1000 : g Pb: Dissolve 0.799 g Pb(NO 3 ) 2 (Pb fraction = 0.6256), weighed accurately to at least three significant figures, in a m i nim um am ount of (1+1) HNO 3 . Add 10.0 m L (1+1) HNO 3 and dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.13 Magnesium solution, stock, 1 m L = 1000 : g Mg: Dissolve 0.500 g of cleanly polished Mg ribbon, accurately weighed to at least three significant figures, in slow lyadded 2.5 m L (1+1) HCl ( CAUTION: reaction is vigorous). Add 10.0 m L (1+1) HNO 3 and dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.14 Manganese solution, stock, 1 m L = 1000 : g Mn: Dissolve 0.500 g of m anganese m e tal, weighed accurately to at least three significant figures, in 25 m L (1+1) HNO 3 and dilute to volum e in a 500-m L PMP volum etric fl ask with reagent water. 7.7.15 Nickel solution, stock, 1 m L = 1000 : g Ni: Dissolve 0.500 g of nickel m e tal, weighed accurately to at least three significant figures, in 10.0 m L hot concentrated HNO 3 , cool, and dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.16 Selenium solution, stock, 1 m L = 1000 : g Se: Dissolve 0.703 g SeO 2 (Se fraction = 0.7116), weighed accurately to at least three significant figures, in 100 m L reagent water and dilute to volum e in a 500-m L PMP volum etric flask with reagent water. 7.7.17 Silica solution, stock, 1 m L = 1000 : g SiO 2 : DO NOT DRY

. Dissolve

200.5-131.482 g (NH 4 ) 2 SiF 6 , weighed accurately to at least four significant figures, in 100 m L (1+20) HCl in a beaker with heating at 85 °C to effect dissolution. Let solution cool and dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.18 Silver solution, stock, 1 m L = 1000 : g Ag: Dissolve 0.500 g Ag m e tal, weighed accurately to at least three significant figures, in 50 m L (1+1) HNO 3 in a beaker with heating to effect dissolution. Let solution cool and dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.19 Sodium solution, stock, 1 m L = 1000 : g Na: Dissolve 1.271 g NaCl (Na fraction = 0.3934), weighed accurately to at least four significant figures, in reagent water. Add 5.0 m L concentrated HNO 3 and dilute to volum e in a 500-m L PMP volum etric flask with reagent water. 7.7.20 Tin solution, stock, 1 m L = 1000 : g Sn: Dissolve 0.500 g Sn shot, weighed accurately to at least three significant figures, in an acid m i xture of 5.0 m L concentrated HCl and 1.0 m L (1+1) HNO 3 in a beaker with heating to effect dissolution. Let solution cool, add 100 m L concentrated HCl, and dilute to volum e in a 500-m L PMP volum etric flask with reagent water. 7.7.21 Vanadium solution, stock, 1 m L = 1000 : g V: Dissolve 0.500 g V m e tal, acid cleaned with (1+9) HNO 3 , weighed accurately to at least three significant figures, in 25 m L (1+1) HNO 3 in a beaker with heating to effect dissolution. Let solution cool and dilute in a 500-m L PMP volum etric flask with reagent water. 7.7.22 Zinc solution, stock, 1 m L = 1000 : g Zn: Dissolve 0.500 g Zn m e tal, acid cleaned with (1+9) HNO 3 , weighed accurately to at least three significant figures, in 25 m L (1+1) HNO 3 in a beaker with heating to effect dissolution. Let solution cool and dilute in a 500-m L PMP volum etric flask with reagent water. 7.8 Calibration Standard Solutions. 7.8.1 Mixed Calibration Standard Solutions - For total recoverable analyses prepare m i xed calibration standard solutions by com b ining appropriate volum es of the stock solutions in 500-m L PMP volum etric flasks containing 20 m L (1+1) HNO 3 and 10 m L (1+1) HCl and dilute to volum e with reagent water. Prior to preparing the m i xed standards, each stock solution should be analyzed separately to determ ine possible spectral interferences or the presence of im purities. Care should be taken when preparing the m i xed standards to ensure that the elem ents are com p atible and stable together. To m i nim i ze the opportunity for contam ination by the containers, it is recomm e nded to transfer the m i xed-standard solutions to acid-cleaned, never-used FEP fluorocarbon (FEP) bottles for storage. Fresh m i xed standards should be prepared, as needed, with the realization

200.5-14that concentrations can change on aging. Calibration standards not prepared f r om prim ary standards m u st be initially verif i ed using a certif ied reference solution. Recomm e nded wavelengths and calibration concentrations are listed in Table 1. Typical calibration standard com b inations are given in Table 2. 7.8.2 Sodium Multi-point Calibration Standards - To determ ine elevated concentrations of Na in drinking water and drinking water supplies using the recomm e nded wavelength, Na is determ ined using a m u lti-point analytical calibration usable to 160 m g /L. Prepare in a m i xture of 2% HNO 3 (v/v) and 1% HCl (v/v) a calibration blank and six calibration standards at concentrations of 5, 10, 20, 40, 80, and 160 m g /L, respectively. To create the m u lti-point calibration, curve-fit the response of the blank and standards and store as a com puter file. This calibration is standardized before each period of analysis using the calibration blank and the m i xed calibration standard solution containing 20 m g /L Na (Sect. 7.8.1). A new m u lti-point calibration should be prepared whenever there is a change in analytical perform ance caused by either a change in instrum e nt hardware or operating conditions. (Of the 990 ground water sam p les analyzed in the National Inorganic Radionuclide Survey, Na was reported below 90 m g /L in 84% of the sam p les.) 7.9 Blanks - Four types of blanks are required for this m e thod. The calibration blank is used in establishing the analytical curve, the laboratory reagent blank is used to assess possible contam ination from the labor atory procedure, the laboratory fortified blank is used to assess routine laboratory perform ance and a rinse blank is used to flush the uptake system to reduce m e m o ry interferences. 7.9.1 The calibration blank is prepared by diluting 20 m L (1+1) HNO 3 and 10 m L (1+1) HCl in a 500-m L PMP volum etric flask to volum e with reagent water. Store the prepared blank solution to an acid-cleaned, never-used 500-m L FEP bottle. This bottle should be dedicated for reuse and storage of

this solution. 7.9.2 The laboratory reagent blank (LRB) is prepared by carrying 50 m L of reagent water through the entire analytical procedure. The LRB m u st contain all the reagents in the sam e volum es as used in processing the sam p les. 7.9.3 The laboratory fortified blank (LFB) is prepared in the sam e m anner as the LRB, and fortified by adding 1.0 m L of the fortifying solution (7.10.1) to 50 m L of LRB. The LFB m u st be carried through the entire analytical procedure. The analyte concentrations fortified in the LFB are as follows: 4 μg/L Be; 5 μg/L Cd; 6 μg/L Sb; 10 μg/L As; 15 μg/L Pb; 50 μg/L Ag, Mn, Se, Sn and V; 100 μg/L B, Cr and Ni; 200 μg/L Al; 300 μg/L Fe; 1000 μg/L Ba, Cu and Zn.

200.5-157.9.4 The rinse blank is prepared by acidifying reagent water in an acid-cleaned LDPE bottle to concentrations of 2% (v/v) HNO 3 + 2% (v/v) HCl. 7.10 Quality Control Solutions. 7.10.1 Fortifying solution - The fortifying solution is used to prepare the laboratory fortified blank (LFB) and laboratory fortified m a trix (LFM) solutions. The fortifying solution should be prepared in a 100-m L PMP volum etric flask, containing a m i xture of 4 m L (1+1) HNO 3 and 2 m L (1+1) HCl, by com b ining the following listed aliquot volum es of each stock standard and the low-level stock fortifying solution (7.10.2) and diluting to volum e with reagent water: 5 m L Ba, Cu & Zn and the lowlevel stock fortifying solution; 1.5 m L Fe; 1.0 m L Al; 0.5 m L B, Cr & Ni; and 0.25 m L Ag, Mn, Se, Sn & V. Store in a new, acid-cleaned LDPE bottle. The analyte concentrations in the f o rtif ying solution are as f o llows: 50 m g /L Ba, Cu & Zn; 15 m g /L Fe; 10 m g /L Al ; 5.0 m g /L B, Cr & Ni; 2.5 m g /L Ag, Mn, Se, Sn & V; 0.75 m g /L Pb; 0.50 m g /L As; 0.30 m g /L Sb; 0.25 m g /L Cd; and 0.20 m g /L Be. 7.10.2 Low-level stock fortifying solution - The low-level stock fortifying solution is used to prepare the fortifying solution described in Section 7.10.1. The low-level stock fortifying solution is prepared in a 50-m L PMP volum etric flask, containing a m i xture of 2 m L (1+1) HNO 3 and 1 m L (1+1) HCl, by com b ining the following listed aliquot volum es of each stock standard and diluting to volum e with reagent water: 750 μL Pb (15 m g /L); 500 μL As (10 m g /L); 300 μL Sb (6 m g /L); 250 μL Cd (5 m g /L); and 200 μL Be (4 m g /L). (The concentration in parenthesis is that of the analyte in the low-level stock.) Store in a new, acid-cleaned LDPE bottle dedicated for reuse and repeated storage of this solution. 7.10.3 Instrum e nt Perform ance Check (IPC) Solution - The IPC solution is used to periodically verify instrum e nt perform ance during analysis. It should be prepared by com b ining m e thod analytes at appropriate concentrations in the sam e acid m i xture (2% HNO 3 + 1% HCl) as the calibration standards. Silver should be lim ited to < 100 μg/L; while Al and Fe should be m a de to a concentration of 2 m g /L; Ca, Mg, and SiO 2 m a de to 5 m g /L; and Na to a concentration of 10 m g /L. For all other analytes, a concentration of 200 μg/L is recomm e nded. The IPC should be prepared in a PMP (m etal-free plastic) volum etric flask to avoid B and SiO 2 contam ination. Store the IPC solution in a new, acid-cleaned FEP bottle dedicated for reuse and repeated storage of this solution. NOTE: If the instrum e nt readout system incorporates the use of a dilution factor (0.5) to report original sam p le concentration prior to processing, and the IPC solution is analyzed in the sam e m anner as the sam p les, the reported IPC concentrations will be half the concentrations listed above. 7.10.4 Quality Control Sam p le (QCS) - Analysis of a QCS is required for initial

200.5-16and periodic verification of calibration standards or stock standard solutions in order to verify instrum e nt perform ance. The QCS m u st be obtained from outside source differentfrom the standard stock solutions and prepared in a PMP volum etric flask using the sam e acid m i xture as the calibration standards. The concentration of the analytes in the QCS solution should be sufficient to m eet the data quality objectives given in Section 9.2.4. The concentrations m ay range from 200 μg/L for sensitive analytes such as Be and Cd to > 2.0 m g /L for Al, Ca, Fe, Mg, Na, and SiO 2 . However, the concentration of Ag should be lim ited to 0.1 m g /L or less to ensure com p lete solubility and stability. The QCS solution should be stored in a new, acid-cleaned LDPE bottle and analyzed as needed to m eet data-quality needs. A fresh solution should be prepared quarterly or m o re frequently as needed. 7.11 Plasm aSolution - The plasm asolution is used for determ ining the nebulizer argon flow rate or gas pressure that will produce the optim um net-signal-to-background noise (S-B/B) ratio needed for the m o st requiring analytes included in the m e thod without degrading the perform ance of the other analytes. The two analytes that present the greatest challenge are Sb and As because of the low MCLs and lim ited analytical sensitivity. The com b ined 1 m g /L solution is prepared by adding 100 μL of the Sb stock standard (7.7.2) and a 100 μL of the As stock standard (7.7.3) to a m i xture of 4 m L (1+1) HNO 3 and 2 m L (1+1) HCL in a 100-m L PMP volum etric and diluting to volum e with reagent water. Store the solution in a new, acid-cleaned LPDE bottle for repeated use as necessary. 8.0 SAMPLE COLLECTION, PRESERVATION, AND STORAGE 8.1 For the determ ination of trace and water m a trix elem ents in drinking water and drinking water supplies, sam p les are notf iltered, but acidif i ed with (1+1) nitric acid to a pH < 2 (3 m L of [1+1] acid per liter of sam p le should be sufficient). Preservation m ay be done at the tim e of collection; however, to avoid the hazards of strong acids in the field, transport restrictions and possible contam ination, it is recomm e nded that the sam p les be returned to the laboratory within two weeks of collection and acid preserved upon receipt in the laboratory. Following acidification, the sam p le should be m i xed, held for sixteen hours, and then verified to be pH < 2 just prior to withdrawing an aliquot for sam p le processing. If for som e reason, such as high alkalinity, the sam p le pH is verified to be > 2, m o re acid m u st be added and the sam p le held for sixteen hours until verified to be pH < 2. If properly preserved, the sam p le can be held up to 6 m onths. 8.2 If required by the data user, a field reagent blank (Sect. 3.4) should be prepared and analyzed in the sam e m anner as a collected sam p le. Use the sam e type of container and acid as used in sam p le collection. 9.0 QUALITY CONTROL 9.1 Each laboratory using this m e thod is required to operate a form al quality control (QC) program

. The m i nim um requirem e nts of this program consists of an initial

200.5-17dem onstration of laboratory capability, and the periodic analysis of laboratory reagent blanks, fortified blanks and other laboratory solutions as a continuing check on perform ance. The laboratory is required to m a intain perform ance records that def i ne the quality of the data thus generated. 9.2 Initial Dem onstration of Perf orm ance (m andatory). 9.2.1 The initial dem onstration of perform ance is used to characterize instrum e nt perform ance (determ i nation of linear dynam i c ranges and analysis of quality control sam p les) and laboratory perf orm ance (determ i nation of m e thod detection lim its) prior to analyses conducted by this m e thod. 9.2.2 Linear dynam i c range (LDR) - The upper lim it of the LDR m u st be established for each wavelength used for the analysis of the drinking water m atrix analytes: Ca, Mg and silica. It m u st be determ ined from a linear calibration prepared using the established instrum e nt operating conditions. The LDR should be determ ined by analyzing succeedingly higher standard concentrations of the analyte until the observed analyte concentration is no m o re than 10% below the stated concentration of the standard. Determ ined LDRs m u st be docum ented and kept on file. The LDR which m ay be used for the analysis of sam p les should be judged by the analyst from the resulting data. Determ ined sam p le analyte concentrations that are greater than 90% of the determ ined upper LDR lim it m u st be diluted and reanalyzed. The LDRs should be verified as required for certification or whenever, in the judgm ent of the analyst, a change in analytical perform ance caused by either a change in instrum e nt hardware or operating conditions would dictate they be redeterm ined. 9.2.3 Non-linear dynam i c range - The upper lim it of the non-linear calibration used for the determ ination of Na is the highest standard used to describe the calibration curve. The non-linear calibration m u st be established using the sam e instrum e nt operating conditions used for analysis. Determ ined sam p le concentrations that are > 10% above the upper lim it for Na m u st be diluted and reanalyzed. The upper lim it should be verified as required for certification or whenever, in the judgm ent of the analyst, a change in analytical perform ance caused by either a change in instrum e nt hardware or operating conditions would dictate they be redeterm ined. 9.2.4 Quality control sam p le (QCS) - Wh en beginning the use of this m e thod, on a quarterly basis, after the preparation of stock or calibration standard solutions, or as required to m eet data-quality needs, verif ythe calibration standards and acceptable instrum e nt perform ance with the preparation and analysis of a QCS (Sect. 7.10.4.) To verify the calibration standards, the determ ined m ean concentrations from 3 analyses of the QCS m u st be within ± 5% of the stated values. If the calibration standard can not be verified, perform ance of the determ inative step of the m e thod is unacceptable. The source of the problem m u st be identified and corrected before either proceeding on with the initial determ ination of m e thod

200.5-18detection lim its or continuing with on-going analyses. 9.2.5 Method detection lim it (MDL) - MDLs m u st be established for all wavelengths utilized for trace elem ent determ inations in total recoverable digestates. MDLs are determ ined using reagent water (blank) fortified to a concentration ranging from the instrum e nt detection lim it (IDL) to approxim ately two tim es the IDL (7) (see Table 4 for typical levels). To determ ine MDL values, take seven replicate aliquots of the fortified reagent water and process through the entire total recoverable analytical procedure. Perform all calculations defined in the m e thod and report the concentration values in the appropriate units. Calculate the MDL as f o llows: MDL = (t) x (S) where: t = students' t value for a 99% confidence level and a standard deviation estim ate with n-1 degrees of freedom (t = 3.14 for seven replicates). S = standard deviation of the replicate analyses. Note: If the relative standard deviation (RSD) from the analyses of the seven aliquots is < 10% and neither random nor reagent contam ination is operative, the concentration used to determ ine the analyte MDL m ay have been inappropriately high for the determ ination. If so, this could result in the calculation of an unrealistically low MDL. In this case the MDL determ ination should be repeated using a lower concentration. Although data can be reported down to the MDL, the associated variability (RSD $ 30%) at the MDL concentration is very high. A m o re realistic reporting lim it is the estim ated upper lim it of the 95% confidence interval about the MDL. This lim it is based on the 97.5 percentile of chi square over associated 6 degrees of f

r eedom and is com puted by m u ltiplying the MDL by a factor of 2.2 (8)

. Typical single laboratory MDLs and reporting lim its values using this m e thod are given in Table 4. The MDLs m u st be suf f i cient to m eet data quality needs and detect analytes at the required levels according to com p liance m onitoring regulation (Sect. 1.2). Specifically, the determ ined MDLs for the analytes: As, Be, Cd, Sb, Se and Pb m u st be # 1/5 their respective MCL or action level before this m e thod can be used for com p liance m onitoring. MDLs should be determ ined as required for laboratory certification, when a new operator begins work or whenever, in the judgm ent of the analyst, a change in analytical perform ance caused by either a change in instrum e nt hardware or operating conditions would dictate they be redeterm ined. 9.3 Assessing Laboratory Perform ance (m andatory) 9.3.1 Laboratory reagent blank (LRB) - The laboratory m u st analyze at least one LRB (Sect. 7.9.2) with each batch of 20 or fewer sam p les. LRB data are

200.5-19used to assess contam ination from the laboratory environm ent. LRB values that exceed the MDL indicate laboratory or reagent contam ination should be suspected. Wh en LRB values for the trace analytes are above the calculated reporting lim it (2.2 tim es the analyte MDL), fresh aliquots of the sam p les m u st be prepared and analyzed again for the affected analytes after the source of contam ination has been corrected and acceptable LRB values have been obtained. 9.3.2 Laboratory fortified blank (LFB) - The laboratory m u st analyze at least one LFB (Sect. 7.9.3) with each batch of sam p les. Calculate accuracy as percent recovery using the following equation: LFB R =

S)))))))))Q X 100 s where: R = percent recovery. LFB = laboratory fortified blank determ ined concentration.

s = concentration equivalent of analyte added to fortify the LRB solution. If the recovery of any analyte falls outside the required control lim its of 90-110%, that analyte is judged to be out of control, and the source of the problem should be identified and resolved before continuing analyses. 9.3.3 The laboratory m u st use LFB analyses data to assess laboratory perform ance against the appropriate required control lim its of 90-110% (see Sect.9.3.2). Wh en sufficient internal perform ance data becom e available (usually a m i nim um of twenty to thirty analyses), optional control lim its can be developed from the m ean percent recovery (x) and the standard deviation (S) of the m ean percent recovery. These data can be used to establish the upper and lower control lim its as follows: UPPER CONTROL LIMIT = x + 3S LOW E R CONTROL LIMIT = x

! 3S The optional control lim its m u st be equal to or better than the appropriate required control lim its. After each five to ten new recovery m easurem ents, new control lim its can be calculated using only the m o st recent twenty to thirty data points. Also, the standard deviation (S) data should be used to establish an on-going precision statem ent for the level of concentrations included in the LFB. These data m u st be kept on file and be available for review. 9.3.4 Instrum e nt perform ance check (IPC) solution - The laboratory m u st initially and periodically verify that the instrum e nt calibration is within required control lim its. For all determ inations the laboratory m u st analyze the IPC solution (Sect. 7.10.3) and a portion of the calibration blank imm e diately

200.5-20following calibration, after every tenth sam p le and at the end of the sam p le run. Analysis of the calibration blank should always be less than the calculated reporting lim it (2.2 tim es the analyte MDL) for the trace elem ents. Analysis of the IPC solution imm e diately f o llowing calibration m

u st verify that the instrum e nt is within ± 5% of calibration. Subsequent analyses of the IPC solution m u st be within ± 10% of calibration. If the calibration can not be verified within the specified lim its, reanalyze both the IPC solution and the calibration blank. If the second analysis confirm s calibration to be outside the lim its, sam p le analysis m u st be discontinued, the cause determ ined, corrected and/or the instrum e nt recalibrated. All sam p les following the last acceptable IPC solution analysis m u st be reanalyzed. The analyses data of the IPC solution should be kept on file with the sam p le analyses data. 9.3.5 Spectral interference check (SIC) solution - For this m e thod using the listed wavelengths, the specified background locations, and an instrum e nt with first order resolution of 0.016 nm or better, verification of interelem e nt spectral interference is not required. However, if m e thod flexibility, allowing the use of different wavelengths, spectral orders, and background correction locations requires an interelem e nt correction routine for spectral interference, it m u st be verified daily with the use of SIC solutions (see Sect. 4.1 for listed criteria and description of required testing). 9.4 Assessing Total Recoverable Analyte Recovery and Data Quality 9.4.1 Sam p le non-hom ogeneity and the chem ical nature of the sam p le m a trix can af

f ect analyte recovery and the quality of the data. In the analysis of finished drinking water, these aspects are rarely an issue. However, source water for a drinking water supply can have varying turbidity. Taking separate aliquots from the sam p le for replicate and fortified analyses can, in som e cases, assess the effect. Unless otherwise specified by the data user, laboratory or program , the following laboratory fortified m a trix (LFM) procedure (Sect. 9.4.2) is required. 9.4.2 The laboratory m u st add a known am ount of each analyte to a m i nim um of 10% of the routine sam p les. The LFM aliquot m u st be a duplicate of the aliquot used for sam p le analysis and fortified prior to sam p le preparation. The added analyte concentration m u st be the sam e as that used in the laboratory fortified blank (Sect. 7.9.3). Over tim e, sam p les from all routine sam p le sources should be fortified. 9.4.3 Calculate the percent recovery for each analyte, corrected for analyte background concentrations greater than the calculated reporting lim it m easured in the unfortified sam p le, and com p are these values to the designated LFM recovery range of 85-115%. Percent recovery m ay be calculated using the following equation:

200.5-21C s - C R =

S))))))Q x 100 s where: R = percent recovery. C s = f o rtif ied sam p le concentration. C = sam p le background concentration (>2.2 X MDL). s = concentration equivalent of analyte added to fortify the sam p le. 9.4.4 If the recovery of any analyte falls outside the designated LFM recovery range, and the laboratory perform ance for that analyte is shown to be in control (Sect. 9.3), the recovery problem encountered with the fortified sam p le is judged to be m a trix related, not system related. If the analyte in question is a prim ary contam inant (Sect. 1.1), under certain circum stances additional analyses m ay be required (see Sects. 1.6 and 1.7). For a prim ary contam inant not requiring additional analysis, for a secondary contam inant, or non-regulated analyte, the data user should be inform ed that the result for that analyte is suspect due to m a trix effects. 9.4.5 Wh ere reference m aterials are available, they should be analyzed to provide additional perform ance data. The analysis of reference sam p les is a valuable tool f o r dem onstrating the ability to perf orm the m e thod acceptably. 10.0 CALIBRATION AND STANDARDIZ A TION 10.1 Specific wavelengths and calibration concentrations are listed in Table 1. Other wavelengths m ay be substituted if they can provide the needed sensitivity and are corrected for spectral interference (see Sect. 4.1). However, because of the difference am ong various m akes and m odels of spectrom e ters, specific instrum e nt operating conditions are not required. The instrum e nt and operating conditions utilized for determ ination m u st be capable of providing data of acceptable quality (see Sect. 1.12) to the drinking water program and data user. The analyst should follow the instructions provided by the instrum e nt m anufacturer; however, instrum e nt operating conditions used to collect the single laboratory perform ance data included in this m e thod are listed in Table 3 and are provided as a recomm e ndation. Once operating conditions are established, it is intended that daily calibration will be accom p lished using a calibration blank and a single analyte concentration. 10.2 Prior to using this m e thod, optim ize the plasm aoperating conditions. The purpose of plasm aoptim ization is to provide a m a xim um net signal-to-background ratio (S-B/B) for the determ ination of As and Sb, the m o st requiring elem ents in the analytical array. The use of a m a ss flow controller to regulate or m onitor the nebulizer gas f l ow rate greatly f acilitates the procedure. The f o llowing procedure is recomm e nded:

200.5-2210.2.1 Ignite the plasm a , and using the conditions listed in Table 3 as a guide, select appropriate incident rf power and plasm agas flows. Allow the instrum e nt to becom e therm a lly stable before beginning. This usually requires approxim ately 30 m i nutes of operation. Set the aerosol argon flow rate through the nebulizer at approxim a tely 650 m L per m i nute or at the instrum e nt m anufacturer’s recomm e nded pressure setting if the flow rate can not be m easured. Following the instrum e nt m anufacture’s instructions, optically profile the instrum e nt to provide m a xim um signal for all wavelengths. Wh ile aspirating reagent water and using the As channel signal, adjust the horizontal and vertical position of the torch to provide m i nim um signal intensity. This should align the optics with the center of the sam p le channel of the plasm aand m i nim i ze background noise. 10.2.2 After profiling the torch, aspirate the plasm asolution (Sect. 7.11) and while following the instrum e nt m anufacturer' s instructions, adjust the aerosol carrier gas flow rate through the nebulizer and collect signal intensity readings (S) at equal increm ental f l ow settings on either side of the initial flow rate setting. Suggested flow rates (m L/m i n) settings are: 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690 and 700. (NOTE: If nebulizer flow rates can not be m easured, increm ental pressure settings that control flow should be used.) After acid rinsing to elim inate any possible m e m o ry effect, repeat the sam e operation using an acid blank solution and collect the blank signal intensity readings (B) at the sam e respective flow settings. Calculate the S-B/B ratio for As and Sb at each flow setting. Plot, on the sam e graph, the calculated ratios and the blank intensity readings versus the argon flow rates. The intensity counts for the blank signal should decrease at a uniform rate as the argon flow rate increases, while the calculated S-B/B ratios for Sb should increase. At the lower flow rate settings, the As ratios should rem a in nearly constant; however, at som e point the As ratio will start to decrease with an increase in f l ow rate. The f l ow rate where the As ratio begins to decrease (2% or m o re) is the lim iting flow and the flow rate just prior to the lim iting flow should be selected for routine operation. Record the nebulizer gas flow rate or pressure setting for future reference. If the nebulizer is replaced with a new or different nebulizer, repeat this optim ization procedure. 10.2.3 After establishing the nebulizer gas flow rate, determ ine the solution uptake rate of the nebulizer in m L /m in by aspirating a known volum e calibration blank for a period of at least 3 m i nutes. Divide the spent volum e by the aspiration tim e (in m i nutes) and record the uptake rate. Set the peristaltic pum p to deliver the uptake rate in a steady even flow. 10.2.4 The final instrum e nt operating condition, selected as being optim um , should provide acceptable instrum e nt detection lim its and m e thod detection lim its for all trace analytes. Refer to Table 4 for com p arison of IDLs and MDLs, respectively. 10.2.5 Before daily calibration and after the instrum e nt warm up period, the

200.5-23nebulizer gas flow should be reset to the determ ined optim ized flow. If a m a ss flow controller is being used, it should be reset to the recorded optim ized flow rate. In order to m a intain reliable MDLs, the nebulizer gas flow rate should be the sam e from day-to-day (<2% change). 10.3 Before using the procedure (Sect. 11.0) to analyze sam p les, there m u st be data available docum enting initial dem onstration of perf orm ance. The required data and procedures are described in Sections 9.2.2, 9.2.3, 9.2.4, and 9.2.5. These data m u st be generated using the sam e instrum e nt operating conditions and respective calibration routines used for sam p le analysis (see Sect. 11.2). These docum ented data m u st be kept on file and be available for review by the data user. 10.4 After com p leting the initial dem onstration of perform ance, but before analyzing sam p les, the laboratory, if needed, m u st establish and initially verif ythe interelem e nt spectral interf erence correction routine to be used during sam p le analysis. A general description concerning spectral interference and the analytical requirem e nts for background correction are given in Sections 4.1 and 9.3.5. Once established, the entire routine m u st be verified on a daily basis by analyzing SIC solution(s) resulting in response data that falls within the 3-sigm a control lim its of the calibration blank of the analyte (Sect. 4.1). 11.0 PROCEDURE 11.1 Sam p le Preparation (Total Recoverable Digestion) - For the determ ination of trace analytes and water m atrix elem ents in drinking water and source water supply, using a 50-m L PMP graduated cylinder, transfer a 50 m L (± 0.5 m L ) aliquot froma wellm i xed, acid preserved sam p le to a 50-m L cl ean digestion tube containing a m i xture of 1.0 m L (1+1) HNO 3 (Sect. 7.3.1) and 0.5 m L (1+1) HCl (Sect. 7.2.1). (The acids should be added to the digestion tube using an air displacem ent pipetter - see Sect. 6.6.) Place the digestion tube in the block digester (Sect. 6.4). (The block digester should be located in a clean fum e hood.) Power the digestion block to preselected settings to evaporate the sam p le at a tem p erature of 95 °C (± 2 °C). Preconcentrate the sam p le until the volum e has been reduced to approxim ately 25 m L

. Cover the digestion tube with a plastic watch glass and reflux the sam p le for 30 m i nutes. (The tim e required to com p lete this step should approxim ate 2.5 h.) Once the refluxing step is com p lete, rem ove the digestion tube from the block digester and allow the sam p le to cool. Wh en cool, using the volum e gradation m arks on the digestion tube, adjust the sam p le volum e to 25 m L with reagent water (Sect. 7.4). Cap the digestion tube and m i x. The sam p le is now ready for analysis. Because the effects of various m atrices on the stability of analytes in low concentration can not be characterized, all analyses should be perform e d as soon as possible after the com p leted preparation. 11.2 Sam p le Analysis 11.2.1 Prior to daily calibration of the instrum e nt, inspect the sam p le introduction system , including the nebulizer, torch, injector tube and uptake tubing, for salt deposits, dirt and debris that would restrict solution flow and affect

200.5-24instrum e nt perform ance. Clean the system when needed or on a daily basis. 11.2.2 Configure the instrum e nt system to the selected power and operating conditions as determ ined in Sections 10.1 and 10.2. 11.2.3 The instrum e nt should be allowed to becom e therm a lly stable before calibration and analyses. This usually requires at least 30 m i nutes of operation. After instrum e nt warm up, com p lete any required optical profiling or alignm ent routines particular to the instrum e nt. 11.2.4 For initial and daily operation, calibrate the instrum e nt according to the instrum e nt m anufacturer' s recomm e nded procedures, using m i xed calibration standard solutions (Sect. 7.8.1) and the calibration blank (Sect. 7.9.1). A peristaltic pum p m u st be used to introduce all solutions to the nebulizer. To allow equilibrium to be reached in the plasm a , aspirate all solutions for 20 sec after reaching the plasm abefore beginning integration of the background corrected signal to accum u late data. To reduce m easurem ent variance, use the average value of replicate integration periods of the signal to be correlated to analyte concentration. (Suggested data collection period for all determ inations: 5 replicate 24 sec periods [8 sec on the wavelength peak and 8 sec on each BKGD location] = 120 sec.) Flush the system with the rinse blank (Sect. 7.9.4) for a m i nim um of 30 seconds (Sect. 4.4) between each standard. 11.2.5 After com p letion of the initial requirem e nts of this m e thod (Sects. 10.3 and 10.4), sam p les should be analyzed in the sam e operational m anner used in the calibration routine with the rinse blank also being used between all sam p le solutions and quality control check solutions. 11.2.6 During sam p le analysis the laboratory m u st com p ly with the required quality control described in Sections 9.3 and 9.4. 11.2.7 Determ ined water m a trix elem ent concentrations that are 90% or m o re of the upper lim it of the analyte LDR, or in the case of Na above the m u ltipoint calibration range, m u st be diluted with reagent water that has been acidified in the sam e m anner as the calibration blank and reanalyzed. 11.2.8 To ensure an accurate determ ination for com p liance m onitoring, a prim ary contam inant m u st be reanalyzed by either m e thod of standard additions (see Sect.11.3), or by another approved m e thod, when the concentration of that prim ary contam inant determ ined by the norm a l analytical routine (Sect. 11.2) is $ 80% of the established MCL, or action level, and the required LFM analysis does not verify the absence of a m atrix interference (see Sects. 1.6 & 9.4). 11.2.9 Report data as directed in Section 12. 11.3 If the m e thod of standard additions (MSA) is used, standards are added at one or

200.5-25m o re levels to portions of a prepared sam p le. This technique (9) com p ensates for enhancem ent or depression of an analyte signal by a m a trix. It will not correct f o r additive interferences such as contam ination, interelem e nt interferences, or baseline shif ts. This technique is valid in the linear range when the interf erence ef f ect is constant over the range, the added analyte responds the sam e as the endogenous analyte, and the signal is corrected f o r additive interf erences. The sim p lest version of this technique is the single-addition m e thod. This procedure calls for two identical aliquots of the sam p le solution to be taken. To the first aliquot, a sm all volum e of standard is added, while to the second aliquot, a volum e of acid blank is added equal to the standard addition. The sam p le concentration is calculated by the f o llowing: S 2 x V 1 x C Sam p le Conc = S)))))))))))Q

μg/L (S 1 -S 2 ) x V 2 where: C = Concentration of the standard solution (μg/L) S 1 = Signal for fortified aliquot S 2 = Signal for unfortified aliquot V 1 = Volum e of the standard addition (L) V 2 = Volum e of the sam p le aliquot (L) used for MSA

12.0 DATA ANALYSIS AND CALCULATIONS 12.1 Sam p le data for the water m a trix elem ents (Ca, Mg and Na) and silica should be reported in units of m g /L. For com p liance m onitoring, total recoverable trace elem ents should be reported in the sam e units used to express the MCL or action level. If there is no established MCL, the trace elem ent should be reported in μg/L. 12.2 For water m atrix analytes, m u ltiply the solution analyte concentrations by the dilution factor, 0.5, and report the data with allowance for sam p le dilution when analyte concentrations exceed 90% or m o re of the LDR upper lim it, and in the case of Na when the analytical range is exceeded. Round the data to the thousandth place and report up to three significant figures. Do not report analyte concentrations below the IDL. 12.3 For total recoverable trace elem ent analytes, m u ltiply solution analyte concentrations by the dilution factor 0.5, round off the data values (μg/L) to the nearest tenths place and report analyte concentrations up to three significant figures. For drinking water com p liance m onitoring, do not report data below the analyte reporting lim it calculated from the laboratory determ ined MDL data (see Sect. 9.2.5). Typical MDLs and calculated reporting lim its are given in Table 4. 12.4 The QC data obtained during the analyses provide an indication of the quality of the sam p le data and should be provided with the sam p le results.

200.5-2613.0 METHOD PERFORMANCE 13.1 Listed in Table 4 are typical single laboratory total recoverable MDLs for the sam p le procedure given in Sections 11.1, followed by analysis using pneum atic nebulization. They were determ ined for the recomm e nded wavelengths using sim u ltaneous AVICP-AES and the operating conditions given in Table 3. The MDLs were determ ined in reagent blank m a trix (best case situation) f o rtif ied with the respective analyte concentration also listed in Table 4. 13.2 Data obtained from single laboratory m e thod testing are summ arized in Tables 5 and 6. Table 5 lists precision (RSD) and average recovery data for SRM 1643c that was analyzed along with the drinking water sam p les listed in Table 6. The drinking water sam p les were prepared using the procedure given in Section 11.1. Table 6 lists data for 4 different tap water m a trices (two well water supplies, one surface water supply, and a hom e cistern supply). Fi ve unfortified aliquots were prepared to determ ine sam p le background concentrations and four aliquots for each LFM. For prim ary and secondary contam inants, the LFMs were fortified to a concentration equivalent to the respective analyte MCL. Data f o r the analysis of the water m atrix elem ents and silica are listed at the bottom of sam p le data sheet. 14.0 POLLUTION PREVENTION 14.1 Pollution prevention encom p asses any technique that reduces or elim inates the quantity or toxicity of waste at the pointof generation. Num e rous opportunities for pollution prevention exist in laboratory operation. The EPA has established a preferred hierarchy of environm ental m anagem e nt techniques that places pollution prevention as the m anagem e nt option of first choice. Wh enever feasible, laboratory personnel should use pollution prevention techniques to address their waste generation (e.g., Sect. 7.7). Wh en wastes cannot be feasibly reduced at the source, the Agency recomm e nds recycling as the next best option. 14.2 For inform ation about pollution prevention that m ay be applicable to laboratories and research institutions, consult Less is Better: Laboratory Chemical Management for Waste Reduction , available from the Am erican Chem ical Society' s Departm e nt of Governm e nt Relations and Science Policy, 1155 16th Street N.W ., W a shington D.C. 20036, or on-line at http://m em bership.acs.org/c/ccs/pub_9.htm

. 15.0 WASTE MANAGEMENT 15.1 The Environm ental Protection Agency requires that laboratory waste m anagem e nt practices be conducted consistent with all applicable rules and regulations. The Agency urges laboratories to protect the air, water, and land by m i nim i zing and controlling all releases from hoods and bench operations, com p lying with the letter and spirit of any sewer discharge perm its and regulations, and by com p lying with all solid and hazardous waste regulations, particularly the hazardous waste identification rules and land disposal restrictions. For further inform ation on waste m anagem e nt consult The Waste Management Manual for Laboratory Personnel , available from the Am erican Chem ical Society at the address listed in the

200.5-27Section 14.2. 16.0 REFERENCES 1. U.S. Environm ental Protection Agenc y. Sam p le Preparation Procedure for Spectrochem ical Determ ination of Total Recoverable Elem ents - Method 200.2, Revision 2.8, May 1994 (EPA-600/R-94/111). 2. U.S. Environm ental Protection Agency. Determ ination of Trace Elem ents by Stabilized Tem p erature Graphite Furnace Atom ic Absorption - Method 200.9, Revision 2.2, May 1994 (EPA-600/R-94/111). 3. Carcinogens - W o rking W ith Carcinogens, Departm e nt of Health, Education, and W e lf are, Public Health Service, Center f o r Disease Control, National Institute f o r Occupational Safety and Health, Publication No. 77-206, Aug. 1977. Available from the National Technical Inform ation Service (NTIS) as PB-277256. 4. OSHA Safety and Health Standards, Ge neral Industry, (29 CFR 1910), Occupational Safety and Health Adm i nistration, OSHA 2206, (Revised, January 1976). 5. Safety in Academ ic Chem istry Laboratories, Am erican Chem ical Society Publication, Comm ittee on Chem ical Safety, 3rd Edition, 1979. 6. Am erican Society for Testing and Materi als. Standard Specification for Reagent W ater, D1193-77. Annual Book of ASTM Standards, Vol. 11.01. Philadelphia, PA, 1991. 7. Code of Federal Regulations 40 , Ch. 1, Pt. 136 Appendix B. 8. Glaser, J.A.,D.L. Foerst, G.D. McKee, S.A. Quave, and W

. L. Budde, “Trace Analyses for W a stewaters,” Environ. Sci. Technol ., 15 (1981) 1426-1435. 9. W i nefordner, J.D., Trace Analysis: Spectroscopic Methods for Elem ents, Chem ical Analysis, Vol. 46, pp. 41-42.

200.5-2817.0 TABLES, DIAGRAMS, FLOWCHARTS, AND VALIDATION DATA

TABLE 1. WAVELENGTHS, BACKGROUND CORRECTION LOCATIONS, AND RECOMMENDED CALIBRATION

W4444444444444444444444444444 4444444444444 4444444444444444444444444444U

Location For BKGD. Calibrate b Analyte W avelength a Correction to (nm ) (nm ) (m g/L)

Alum inum Antim ony Arsenic Barium Beryllium Boron Cadm ium Calcium Chrom i um Copper Iron Lead Magnesium Manganese Nickel Selenium Silica (SiO 2 ) Silver Sodium Tin Vanadium Zinc 308.215 +0.033 5 206.833x2 -0.009 0.5 189.042x2 -0.009 0.5 493.409 +0.033 1 313.042 +0.033 0.1 249.678x2 +0.016 1 226.502x2 +0.016 0.1 315.887 +0.033 20 267.716 +0.033 0.5 324.754 +0.033 2 271.441 +0.033 5 220.353x2 +0.016 0.5 279.079 +0.033 20 257.610 +0.033 0.5 231.604x2 +0.016 0.5 196.090x2 -0.009 0.5 251.611 +0.033 21.4 328.068 +0.033 0.1 330.232 +0.033 20 189.980 -0.018 0.2 292.402 +0.033 0.5 206.200 +0.033 0.5

W444444444444444444444444444444444444444444444444444444444444444U

a The wavelengths listed in the noted spectral order are recomm e nded because of their sensitivity and overall acceptability. Other wavelengths m ay be substituted if they can provide the needed sensitivity and are treated with the sam e corrective techniques f o r spectral interference (see Sect. 4.1). b Suggested concentration for instrum e nt calibration. Other calibration lim its in the linear ranges m ay be used.

200.5-29TABLE 2. MIXED STANDARD SOLUTIONS

Solution a Analytes I A s, Be, Cd, Pb, Sb, Se, V, and Zn II Ba, Cr, Fe, Mn, Ni, Sn, and SiO 2 III Al, Cu, Ca, Mg, and Na IV Ag and B

a See Section 7.8.1

TABLE 3. AXIALLY VIEWED INDUCTIVELY COUPLED PLASMA INSTRUMENT OPERATING CONDITIONS

rf power 950 watts Argon supply liquid argon Argon pressure 60 psi Coolant argon flow rate 20 L/m i n Aerosol carrier argon pressure 27 psi flow rate 635 m L /m in Auxiliary (plasm a) argon flow rate 0.5 L/m i n Sam p le uptake rate controlled to 1.6 m L /m in

200.5-30TABLE 4. DETECTION AND REPORTING LIMITS

INSTRUMENT (a) MDL METHOD CALCULATED (b) DETECT. LIMIT SPIKE DETECTION LIMIT REPORTING ANALYTE g /L Ag - 0.2 0.5 0.2 0.5 Al - 3 4.0 2.2 4.9 As - 2 2.5 1.4 3.1 B - 0.5 0.8 0.3 0.7 Ba - 0.03 0.08 0.05 0.2 Be - 0.03 0.04 0.02 0.1 Ca 0.02 - - - - Cd - 0.2 0.4 0.1 0.3 Cr - 0.2 0.4 0.2 0.5 Cu - 0.2 0.4 0.3 0.7 Fe - 5 1 0 3.3 7.3 Mg 0.02 - - - - Mn - 0.07 0.08 0.06 0.2 Na 0.4 - - - - Ni - 0.6 1.3 0.6 1.4 Pb - 1 3.0 1.1 2.5 Sb - 1 2.0 0.9 2.0 Se - 2 3.0 1.3 2.9 SiO 2 0.01 - - - - Sn - 1 1.0 0.5 1.1 V - 0.2 0.6 0.2 0.5 Zn - 0.4 0.6 0.4 0.9 m μg/L LIMIT, (MDL), μg/L μg/L μg/L

a Instrum e nt detection lim its are used as reporting lim its f o r m atrix elem ents. b The listed calculated reporting lim its have been rounded up to the tenths place to fully m e et the 2.2 m u ltiple criteria and to elim inate the listing of insignificant num bers. Because of rounding up to the tenths place, the reporting lim its listed for Ba and Be are m u ltiples of 4 and 5 tim es their respective MDLs.

200.5-31TABLE 5. SRM(1643c) PRECISION AND ACCURACY DATA

NIST - 1643c DETERMINED AVERAGE CERTIFIED VALUE CONC. STD. RECOVERY RSD Ag 2.21 2.1 0.82 95% Al 114.6 125 5.1 As 82.1 83.7 1.9 B 119.0 114 0.5 96% Ba 49.6 49.2 99% Be 23.2 22.5 97% Cd 12.2 11.9 0.13 Cr 19.0 18.0 0.21 103% Cu 22.3 22.9 99% Fe 106.9 106 2.8 99% Mn 35.1 34.5 98% Ni 60.6 57.4 95% Pb 35.3 34.4 97% Se 12.7 11.9 94% V 31.4 28.3 Zn 73.9 74.4 0.52 μg/L μg/L 0.30 ± 3.9% 5.1 ± 4.1% 109% 1.2 ± 2.2% 102% 1.4 ± 0.4% 3.1 ± 0.52 1.0% 2.2 ± 0.33 1.5% 1.0 ± 1.1% 98% 0.6 ± 1.2% 2.8 ± 0.74 3.2% 3.0 ± 2.7% 2.2 ± 0.4 1.2% 7.3 ± 0.58 1.0% 0.9 ± 1.2 3.5% 0.7 ± 0.7 5.9% 2.8 ± 0.5% 93% 0.15 0.9 ± 0.7% 101% ANALYTE DEV. % %

NIST - 1643c DETERMINED AVERAGE CERTIFIED VALUE CONC. STD. RECOVERY RSD ANALYTE m g /L m g /L DEV. % % Ca 36.8 37.0 101% 0.9% Mg 9.45 9.61 0.16 102% 1.6% Na 12.19 12.6 103% 0.7% 1.4 ± 0.32 0.27 ± 0.36 ± 0.09

200.5-32TABLE 6. TRACE ELEMENT PRECISION AND RECOVERY DATA

TAP WA TER - REGION 5 SURFACE WA TER SUPPLY

__________________________________________________________________________________ SAMPLE

CONC. STD. Spike ANALYTE μg/L DEV. μg/L AVERAGE RECOVERY (%) RSD (%) Ag <0.5

- 100 100 1.2 Al 18 1.3 200 105 1.5 As <3.1

- 10.0 105 4.2 B 34.8 0.9 100 101 1.5 Ba 37.7 0.4 2000 100 1.3 Be <0.1

- 4.0 100 1.4 Cd <0.3

- 5.0 98 1.8 Cr <0.5

- 100 99 1.3 Cu 3.3 0.09 1000 101 1.3 Fe <7.3

- 300 99 1.5 Mn 0.4 0.01 50 98 1.1 Ni 1.5 0.1 100 99 1.0 Pb <2.5

- 15.0 100 2.2 Sb <2.0

- 6.0 100 5.3 Se <2.9

- 5 0 104 2.0 Sn <1.1

- 5 0 102 2.0 V < 0.5

- 5 0 100 1.4 Zn 5.6 0.1 2000 99 1.0

< Sam p le concentration below the calculated reporting lim it.

Analysis of W ater Matrix Elem ents Sam p le RSD Analyte Conc. m g /L (%)

Ca 34.6 1.4 Mg 9.64 1.6 Na 26.4 2.9 SiO 2 5.23 1.6

200.5-33TABLE 6. TRACE ELEMENT PRECISION AND RECOVERY DATA (Cont’d.)

TAP WA TER - REGION 5 W ELL WA TER SUPPLY

__________________________________________________________________________________ SAMPLE

CONC. STD. Spike ANALYTE μg/L DEV. μg/L AVERAGE RECOVERY (%) RSD (%) Ag <0.5

- 100 97 1.2 Al <4.9

- 200 103 1.1 As 17.7 0.3 10.0 101 1.2 B 96.0 0.7 100 102 0.9 Ba 107 0.7 2000 97 1.0 Be <0.1

- 4.0 97 1.4 Cd <0.3

- 5.0 96 1.9 Cr <0.5

- 100 93 1.3 Cu <0.7

- 1000 98 1.1 Fe 552 2.7 300 103 1.1 Mn 15.0 0.1 50 95 1.1 Ni <1.4

- 100 94 1.3 Pb <2.5

- 15.0 97 4.7 Sb <2.0

- 6.0 97 7.4 Se <2.9

- 5 0 101 1.2 Sn <1.1

- 5 0 102 1.2 V < 0.5

- 5 0 95 1.3 Zn 6.2 0.36 2000 95 1.5

< Sam p le concentration below the calculated reporting lim it.

Analysis of W ater Matrix Elem ents Sam p le RSD Analyte Conc. m g /L (%)

Ca 69.9 0.6 Mg 28.0 0.7 Na 57.9 1.9 SiO 2 12.3 0.8

200.5-34TABLE 6. TRACE ELEMENT PRECISION AND RECOVERY DATA (Cont’d.)

TAP WA TER - REGION 6 W ELL WA TER SUPPLY

__________________________________________________________________________________ SAMPLE

CONC. STD. Spike ANALYTE μg/L DEV. μg/L AVERAGE RECOVERY (%) RSD (%) Ag <0.5

- 100 100 1.2 Al <4.9

- 200 102 1.6 As <3.1

- 10.0 101 2.3 B 56.4 1.2 100 104 1.4 Ba 203 3.6 2000 100 1.4 Be <0.1

- 4.0 102 1.4 Cd <0.3

- 5.0 96 1.9 Cr 1.3 0.07 100 96 1.1 Cu 155 2.7 1000 100 1.3 Fe 8.6 1.9 300 96 1.7 Mn 0.6 0.02 50 97 1.3 Ni 3.3 0.2 100 98 1.4 Pb <2.5

- 15.0 105 2.5 Sb <2.0

- 6.0 98 3.6 Se 4.1 0.5 50 100 1.1 Sn 4.4 0.1 50 102 1.0 V 11.5 0.2 50 98 1.4 Zn 26.4 0.5 2000 98 1.4

< Sam p le concentration below the calculated reporting lim it.

Analysis of W ater Matrix Elem ents Sam p le RSD Analyte Conc. m g /L (%)

Ca 44.6 1.6 Mg 9.26 1.6 Na 41.0 1.7 SiO 2 26.2 1.6

200.5-35TABLE 6. TRACE ELEMENT PRECISION AND RECOVERY DATA (Cont’d.)

TAP WA TER - CISTERN WA TER SUPPLY

__________________________________________________________________________________ SAMPLE

CONC. STD. Spike ANALYTE μg/L DEV. μg/L AVERAGE RECOVERY (%) RSD (%) Ag <0.5

- 100 98 1.2 Al 31.3 0.9 200 104 1.7 As <3.1

- 10.0 102 7.8 B 6.6 0.2 100 100 1.2 Ba 3.3 0.05 2000 98 1.4 Be <0.1

- 4.0 96 1.2 Cd <0.3

- 5.0 94 1.1 Cr <0.5

- 100 95 1.1 Cu 262 1.5 1000 99 1.7 Fe 13 1.9 300 95 1.3 Mn 0.6 0.01 50 94 1.2 Ni <1.4

- 100 95 1.7 Pb <2.5

- 15.0 101 1.6 Sb <2.0

- 6.0 103 3.2 Se <2.9

- 5 0 95 1.2 Sn <1.1

- 5 0 95 1.6 V < 0.5

- 5 0 97 1.3 Zn 14.2 3.4 2000 95 1.2

< Sam p le concentration below the calculated reporting lim it.

Analysis of W ater Matrix Elem ents Sam p le RSD Analyte Conc. m g /L (%)

Ca 10.1 0.7 Mg 0.68 1.0 Na 2.3 1.1 SiO 2 2.07 0.6

200.5-36