Method Number: EPA 200.7 Revision Number: 3.0 Date: September 3, 2010 Clinical Laboratory of San Bernardino, Inc. Standard Operating Procedure for the Determination of Metals by Inductively Coupled Plasma Spectroscopy 1. SCOPE AND APPLICATION: 1.1 This method provides procedures for the determination of dissolved elements in ground waters, surface waters, and drinking water supplies. It may also be used for the determination of total recoverable element concentrations in these waters and wastewaters. Dissolved elements can be determined after suitable filtration and acid preservation. Acid digestion procedures are required prior to the determination of total recoverable elements. To reduce potential interference, dissolved solids should be < 0.2% (w/v). Prepared samples may require dilution prior to analysis to avoid physical interferences. The method is applicable to the following analytes:
Chemical Abstract Services Registry Numbers (CAS-No.) 7429-90-5 7440-39-3 7440-42-8 7440-70-2 7440-48-4 7440-50-8 7439-89-6 7439-95-4 7439-96-5 7439-98-7 7440-41-7 7440-43-9 7440-47-3 7440-02-0 7440-22-4 7440-09-7 7631-86-9 7440-23-5 7440-66-6 Dectection Limit of Reporting (DLR) 50 ppb 100 ppb 100 ppb 1 ppm 10 ppb 50 ppb 100 ppb / 40 ppb 1 ppm 20 ppb / 4 ppb 10 ppb 1.0 ppb 1.0 ppb 10 ppb 10 ppb 10 ppb 1 ppm 0.5 ppm 1 ppm 50 ppb

1.2

1.3 1.4

Analyte Aluminum (Al) Barium (Ba) Boron (B) Calcium (Ca) Cobalt (Co) Copper (Cu) Iron (Fe) Magnesium (Mg) Manganese (Mn) Molybdenum (Mo) Beryllium (Be) Cadmium (Cd) Chromium (Cr) Nickel (Ni) Silver (Ag) Potassium (K) Silica (SiO2) Sodium (Na) Zinc (Zn)

1.5

When using this method for determination of boron, silica, and aluminum in aqueous samples, only plastic, Teflon or quartz labware should be used

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Method Number: EPA 200.7 Revision Number: 3.0 Date: September 3, 2010 from time of sample collection to completion of analysis. For accurate determinations of boron in solid sample extracts at concentration below 100 mg/kg, only quartz beakers should be used in the digestions with immediate transfer of an exact aliquot to a plastic centrifuge tube following dilution of the extract to volume. For these determinations, borosilicate glass must not be used in order to avoid sample contamination of these analytes from the glass. 1.6 This method is applicable to analysis of drinking water for the determination of primary and secondary contaminant metals. All drinking water samples must be pretreated with acid prior to analysis.

2.

REPORTING LIMIT: 2.1 The Detection Limit for Reporting (DLR) is determined as the lowest limit that can be reported that can be reached by the instrument which is usually 3 times higher than the MDL. Experimentally the value can be repeated within a 40% RPD on consistent basis. Refer to table in Section 1.4 for reference. We are reporting at the state DLR levels.

3.

APPLICABLE MATRIX AND MATRICES: 3.1 Please refer to Section 1.1.

4.

SUMMARY OF METHOD: 4.1 This method describes a technique for simultaneous multi element determination of metals and trace elements in solution. The basis of the method is the measurement of atomic emission by an optical spectrometric technique. Samples are nebulized and the aerosol that is produced is transported to the plasma torch where desolvation and excitation occur. Characteristic atomic-line emission spectra are produced by a radio frequency inductively coupled plasma (ICP). The Perkin Elmer combines a polychromator with a solid-state detector in an integrated system optimized for ICP. Background must be measured adjacent to the analyte lines on samples during analysis. The position used must either be free of spectral interference or adequately corrected to reflect the same change in background intensity as occurs at the analyte wavelength measured. Background correction is handled automatically by the instrument.

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Method Number: EPA 200.7 Revision Number: 3.0 Date: September 3, 2010 5. DEFINTIONS: 5.1 Batch – Defined as 10 samples unless otherwise specified. A batch will contain a MBLK, DLR, LCS, LCSD, and Interference check solution, MS, MSD, a beginning and ending calibration verification. Calibration Blank – A volume of de-ionized water acidified with the same acid matrix as in the calibration standards. The calibration blank is used to calibrate the ICP instrument. Calibration Standard (CAL) – A solution prepared from the dilution of stock standard solutions. The CAL solutions are used to calibrate the instrument response with respect to that analyte concentration. It is prepared from the PDS solution standard. Dissolved Analyte – The concentration of analyte that will pass through at 0.45 um membrane filter assembly prior to sample acidification. Laboratory Control Sample (LCS) – An aliquot of reagent water to which known quantities of the method analytes is spiked in the laboratory. The LCS is analyzed exactly like the samples, and its purpose is to determine whether method performance is within acceptable control limits. An SDS is used to spike this solution. Linear Dynamic Range (LDR) – The concentration range over which the analytical curve remains linear. Method Blank (MBLK) – An aliquot of reagent water that is treated exactly like a sample including exposure to all glassware, equipment, reagents, and acids that are used with other samples. The MBLK is used to determine if method analytes or other interferences are present in the laboratory environment, the reagents or equipment. Method Detection Limit (MDL) – The minimum concentration of an analyte that can be identified measured and reported with 99% confidence that the analyte concentration is greater than zero. Matrix Spike (MS) and Matrix Spike Duplicate (MSD) – A sample is spiked with a known concentration of analytes at mid-range of calibration. The SDS is used to spike this sample.

5.2

5.3

5.4 5.5

5.6 5.7

5.8

5.9

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5.10 5.11

Method Number: EPA 200.7 Revision Number: 3.0 Date: September 3, 2010 Primary Dilution Standard (PDS) – A standard which is used in the lab to prepare the calibration standards only. Secondary Dilution Standard (SDS) – A standard which is used to prepare LCS, MS and MSD samples. It is a different lot from PDS and is referred to as a second source standard. Spectral Interference Check Solution (SIC) – A solution of selected method analytes of high level concentrations which is used to evaluate the procedural routine for correcting known inter-element spectral interferences with respect to a defined set of method criteria. Stock Standard Solution – A concentrated solution containing one analyte purchased from a reputable commercial source. Stock standard solutions are used to prepare PDS and SDS and other analyte solutions. Total Recoverable – The concentration of an analyte determined in an unfiltered sample following treatment by refluxing with hot, diluted mineral acid.

5.12

5.13

5.14

6.

CONTAMINATION AND INTERFERENCES: Spectral Interference: 6.1 Can be categorized as an overlap of a spectral line from another element: unresolved overlap of molecular band spectra; background contribution from continuous or recombination phenomena; or background contribution from stray light from the line emission of high concentration elements. The first of these effects can be compensated by utilizing a correction of raw data. The second effect may require selection of an alternative wavelength. The third and fourth effects can generally be compensated by a background correction adjacent to the analyte line. Spectral overlaps may be avoided by using an alternative wavelength, using multiple wavelengths for each element in your method, or can be compensated for by equations that correct for inter-element contributions, which involves measuring the interfering elements. These interferences will produce false-positive or false-negative determinations and be reported as analyte concentrations. Users may apply inter-element correction factors determined on their instruments to compensate off-line or on-line for the effects of interfering elements. When inter-element

6.2

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Method Number: EPA 200.7 Revision Number: 3.0 Date: September 3, 2010 corrections are applied, there is need to verify their accuracy by analyzing spectral interference checks. Physical Interferences: 6.3 Are generally considered to be effects associated with the sample nebulization and transport processes. Such properties as change in viscosity and surface tension can cause significant inaccuracies especially in samples that may contain high dissolved solids and/or high acid concentrations. If these types of interferences are operative, they must be reduced by sample dilution and/or utilization of standard addition techniques. Another problem which can occur from high dissolved solids is salt build up at the tip of the nebulizer. This affects aerosol flow rate causing instrumental drift. Wetting the argon prior to nebulization, use of a tip washer, or sample dilution has been used to control this problem. Also, it has been reported that better control of the argon flow rate improves instrument performance. This is accomplished with the use of mass flow controllers.

Chemical Interferences: 6.4 Are characterized by molecular compound formation, ionization effects and solute vaporization effects. Normally these effects are not pronounced with the ICP technique, however, if observed they can be minimized by careful selection of operating conditions (i.e. incident power, observation position, etc.), by buffering the sample, matrix matching or standard addition procedures. These types of interferences can be high dependent on matrix type and the specific element. Serial Dilution – If the analyte concentration is sufficiently high (a factor of 10X the MDL or greater after dilution), an analysis of a dilution should agree within 10% or the original determination. If not, a chemical or physical interference should be suspected. Analyte addition – A post digestion analyte addition added at a minimum level of 20X the MDL (maximum: 100X) to the original determination should be recovered within established control limits. If not, a matrix effect should be suspected. Wavelength scanning of analyte line region - Can be performed to detect potential spectral interferences.

6.5

6.6

6.7

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6.8

Method Number: EPA 200.7 Revision Number: 3.0 Date: September 3, 2010 Selection of Analyte Wavelength – The most important parameter in the development of an analytical method is the analyte wavelength. The instrument covers the range of wavelengths 165-782 nm and has a resolution of 0.005 – 0.006 nm. The items discussed below should be taken into consideration before making the selection. 6.8.1 Nature of Transition – The spectral lines observed in ICP spectroscopy originates from neutral and singly ionized forms of the elements. It is preferable to employ ion lines whenever other considerations permit as they are usually less affected by small changes in the operating conditions of the plasma. Some elements however do not exhibit ion lines of useful intensity two of which are aluminum and boron. 6.8.2 Background equivalent concentration (BEC) and Detection Limits is employed in emission spectroscopy to compare the signal to background ratio of the various emission wavelengths of an element. It is defined as the intensity of the plasma background at the selected wavelength. The instrument manual describes how to calculate these for each wavelength. Detection limits can be determined from a BEC. A reasonable detection limit can be calculated by dividing the BEC by 10. 6.8.3 Linear Working Range – The upper limits of the linear working range for each element wavelength may vary. If the element concentrations exceed the linear working range of a wavelength it may desirable to utilize a less sensitive wavelength or make an appropriate sample dilution. 6.8.4 Interference Equivalent Concentration (IEC) – The IEC is defined as the intensity change, expressed as milligrams of analyte per liter of solution resulting from the analysis of solution containing 1000mg/L of interferant of the analyte wavelength. The IEC indicates the degree of background interference to be expected at a particular wavelength for a particular matrix component. The Optima 5300 have a special program for setting up and testing IEC corrections. These values can be found in the wavelength calibration tables. 6.8.5 Memory Effects – Memory interferences result when analytes in a previous sample contribute to the signals measured in a new

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Method Number: EPA 200.7 Revision Number: 3.0 Date: September 3, 2010 sample. Memory effects can result from sample deposition on the uptake tubing to the nebulizer and from the buildup of sample material in the plasma torch and spray chamber. The site where these effects occur is dependent on the element and can be minimized by flushing the system with rinse blank between samples. The possibility of memory interferences should be recognized with an analytical run and suitable rinse times should be used to reduce them. The rinse times necessary for particular element must be estimated prior to analysis. 7. APPARATUS AND MATERIALS: 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 7.11 Perkin Elmer Optima 5300 DV simultaneous inductively coupled plasmaatomic emission spectrometer (ICP-AES). Dell Personal Computer. Perkin Elmer software, WinLab32. Perkin Elmer S10 auto-sampler with trays. Polyscience Recirculator cooling system. CETAC ultrasonic NEBULIZER. Peristaltic pump tubing, Blk/Blk for sample. Peristaltic pimp tubing, red/red for waste line. A 50 mL plastic centrifuge tubes. 15 mL plastic centrifuge tubes. Argon gas supply, liquid gas pack, high purity grade (99.9%). Argon gas supply pressure should be 80 psi. Compressed air at 80-100 psi as a shear gas. 25, 50, 100 mL volumetric flask. Brother HL-1440 Laser Printer. 200 – 1000 uL – Mechanical pipettor with disposable tips.

7.12 7.13 7.14 8.

REAGENTS AND STANDARDS:

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Method Number: EPA 200.7 Revision Number: 3.0 Date: September 3, 2010 NOTE: Only high-purity reagents should be used whenever possible. All acids used for this method must be of ultra pure high purity grade. 8.1 8.2 8.3 8.4 8.5 Nitric acid, concentrated – Trace Metals. HCl acid, concentrated – Trace Metals. Reagent water – For all sample preparation and dilutions, de-ionized water required. Stock Standard solutions – Purchased from Absolute Standards in concentrations of 1000 μg/mL containing metal elements. Mixed calibration solutions – Prepare mixed CAL solutions by combining appropriate volumes of the stock standard solutions in volumetric flasks. Refer to Table 3 in Section 17. 8.5.1 Add concentrated nitric acid first to a small volume of water in the flask so that the final concentration of nitric acid will be 2%. Then add the aliquots of stock standard and finally dilute to volume with de-ionized water. 8.5.2 Transfer the freshly prepared CAL solutions to clean polyethylene bottles for storage and label with date, concentration and name. Fresh mixed CAL solutions should be prepared as needed with the realization that concentrations can change on aging. The CAL solutions must be initially verified using a quality control sample. 8.6 Blanks – Three types of blanks are required for this method. A calibration blank is used to establish the analytical calibration curve, a laboratory reagent blank is used to assess possible contamination from the sample preparation procedure and a rinse blank is used to flush the instrument uptake system and nebulizer between standards and samples to reduce memory interferences. 8.6.1 Calibration Blank (CB) – Prepare by diluting a mixture of 20 mL of concentrated Nitric acid to 1000 mL with de-ionized water. Store in a plastic bottle. 8.6.2 Method Blank (MBLK) – Contains all the reagents in the same volumes used in processing the samples. The MBLK must be carried through the entire preparation procedure and analysis scheme. The

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Method Number: EPA 200.7 Revision Number: 3.0 Date: September 3, 2010 final solution should contain the same acid concentrations as sample solutions for analysis. 8.6.3 Rinse Blank – Prepare this wash solution by rinsing the zero position cup with reagent grade water and filling with reagent grade water and adding 4 mL of nitric acid. 8.7 Laboratory Control Sample (LCS) – These solutions are prepared from a source external to the laboratory. Follow the instructions for preparing these solutions provided by the supplier of the samples. Refer to Table 2 in Section 17. Detection Limit for Reporting (DLR) – Refer to Table 1 in Section 17. Spectral Interference Check (SIC) solution aka Interference Check Solution – Follow the instructions provided for preparing and analyzing the interference check solution. When inter-element corrections are applied, SIC solutions are needed. 8.9.1 Containing concentrations of the interfering elements at levels that will provide an adequate test of the correction factors. SIC solutions containing Fe 10 mg/L, Al 25 mg/L, Ca 100 mg/L, Mg 25 mg/L Ba, Co, B, Zn, Cu, Mn, Mo all 1.0 mg/L should be prepared in the same acid mixture as the standards and stored in Teflon bottles. 8.9.2 If the correction routine is operating properly, the determined apparent analyte concentration from analysis of each interference solution should fall within a specific concentration range bracketing the calibration blank. This concentration range is calculated by multiplying the concentration of the interfering element by the value of the correction factor being tested and dividing by 10. If after subtraction of the calibration blank the apparent analyte concentration is outside this range, a change in the correction factor of more than 10% should be suspected. 8.9.3 The cause of the change should be determined and corrected and the correlation factor should be updated.

8.8 8.9

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Method Number: EPA 200.7 Revision Number: 3.0 Date: September 3, 2010 Note: The SIC solution should be analyzed more than once to confirm a change has occurred with adequate rinse time between solutions and before subsequent analysis of the calibration blank. 8.9.4 If the correction factors tested on a daily basis are found to be within 10% criteria for 5 consecutive days the required verification frequency of those factors in compliance may be extended to a weekly basis.

9.

SAMPLE COLLECTION, PRESERVATION, SHIPMENT, AND STORAGE: 9.1 Samples that cannot be acid preserved at the time of collection because of sampling limitations or transport restrictions should be acidified with nitric acid to pH