Chromium, Hexavalentnewtowncreek.info/docs2/2 Remedial Investigation/Phase 2 Remedial Investigation...

Alpha Analytical, Inc. ID No.:2204 Facility: Westborough, MA Revision 4 Department:Wet Chemistry Published Date:11/26/2013 8:00:04 AM Title: Hexavalent Chromium of 13

Printouts of this document may be out of date and should be considered uncontrolled. To accomplish work, the published version of the document should be viewed online.

Document Type: SOP-Technical Pre-Qualtrax Document ID: SOP 07-12

Chromium, Hexavalent

References: 3500 Cr-D, Standard Methods, 18th Edition (1992)

7196A, SW-846, Test Methods for Evaluating Solid Waste: Physical/Chemical Methods, EPA SW-846, Update III, 1997.

3060A, SW-846, Test Methods for Evaluating Solid Waste: Physical/Chemical Methods, EPA SW-846, Update III, 1997.

1. Scope and Application

Matrices: This method is applicable for the determination of hexavalent chromium in a natural or treated water or in a soil or solid matrix.

Definitions: See Alpha Analytical Quality Manual Appendix A

The data report packages present the documentation of any method modification related to the samples tested. Depending upon the nature of the modification and the extent of intended use, the laboratory may be required to demonstrate that the modifications will produce equivalent results for the matrix. Approval of all method modifications is by one of the following laboratory personnel before performing the modification: Area Supervisor, Laboratory Services Manager, Laboratory Director, or Quality Assurance Officer.

This method is restricted to use by or under the supervision of analysts experienced in the operation of the Spectrophotometer and in the interpretation of Spectrophotometric data. Each analyst must demonstrate the ability to generate acceptable results with this method by performing an initial demonstration of capability, analyzing a proficiency test sample and completing the record of training.

After initial demonstration, ongoing demonstration is based on acceptable laboratory performance of at least a quarterly laboratory control sample or acceptable performance from an annual proficiency test sample. A major modification to this procedure requires demonstration of performance. The identification of major method modification requiring performance demonstration is directed by the QA Officer and/or Laboratory Director on a case by case basis.

The hexavalent chromium concentration of U.S. drinking waters has been reported to vary between 3 and 40µg/L with a mean of 3.2µg/L. Chromium salts are used extensively in industrial processes and may enter a water supply through the discharge of wastes. Chromate compounds frequently are added to cooling water for corrosion control. Chromium may exist in water supplies in both the hexavalent and the trivalent state although the trivalent form rarely occurs in potable water.

2. Summary of Method

This procedure measures only hexavalent chromium (Cr6+

). The hexavalent chromium is determined colorimetrically by reaction with diphenylcarbazide in acid solution. A very sensitive red-violet color of unknown composition is produced, and its absorbance is measured photometrically at 540nm.

2.1 Method Modifications from Reference

The coloring reagent used for the standards in the calibration curve and for the samples is made by dissolving 1 gram of 1,5-diphenylcarbazine in 250mL of acetone, whereas the reference method 7196A dissolves 1 gram in 200mL of acetone.

Alpha uses a smaller sample volume for analysis; therefore reagent volumes are reduced accordingly.

2.5 cm ( not 1cm) absorption cell is used for water samples to increase sensitivity.




3. Reporting Limits

The RDL reported is 0.01mg/L for 50mL of an aqueous sample. The RDL reported is 0.8mg/Kg for 2.5g of a soil/solid sample. The RDLs are not adjusted for % Moisture.

4. Interferences

4.1 Background Color

Turbidity and background sample color are removed by filtering the sample through a 0.45µm filter. In cases when filtration alone is not sufficient, background interference can be subtracted out by adding all reagents to the sample except diphenylcarbazide solution, measuring the background absorbance, and then subtracting this value from the colored sample absorbance value.

4.2 Other Metals

The reaction with diphenylcarbazide is nearly specific for chromium. Hexavalent molybdenum and mercury salts will react to form color with the reagent but the intensities are much lower than that for chromium at the specified pH. Concentrations as high as 200 mg/L of Mo or Hg can be tolerated. Vanadium interferes strongly but concentrations up to 10 times that of chromium will not cause trouble. Potential interference from permanganate is eliminated by prior reduction with azide. Iron in concentrations greater than 1mg/L may produce a yellow color but the ferric ion (Fe

3+) color is not strong and no difficulty is encountered normally if the

absorbance is measured photometrically at the appropriate wavelength. Interfering amounts of molybdenum, vanadium, iron, and copper can be removed by extraction of the cupferrates of these metals into chloroform (CHCl3). A procedure for this extraction is provided in the reference but do not use it unless necessary because residual cupferron and CHCl3 in the aqueous solution complicate the later oxidation. Therefore, follow the extraction by additional treatment with acid fuming to decompose these compounds.

4.3 Reducing/oxidizing tendency of sample matrix When analyzing a sample digest for total Cr(VI), it is appropriate to determine the reducing/oxidizing tendency of each sample matrix, if the matrix spike for that sample matrix has failed the quality control acceptance criteria for this method. Determination of the Reducing/oxidizing potential for failing matrix spike samples can be accomplished by characterization of each sample for additional parameters, such as pH (Method 9045) and Oxidation Reduction Potential (ORP) (ASTM 1498-93 –aqueous samples). Method 9045 (Section 7.2 of Method 9045) is referenced as the preparatory method for soil samples. The ORP and temperature probes are inserted directly into the soil slurry derived from the pH analysis. The displayed ORP value is allowed to equilibrate and the resulting measurement is recorded. Analysis of these parameters establishes the tendency of Cr(VI) to exist or not exist in the unspiked sample(s) and assists in the interpretation of QC data for matrix spike recoveries outside conventionally accepted criteria for total metals.

4.4 Soluble Cr(III) concentration For waste materials or soils containing soluble Cr(III) concentrations greater than four times the laboratory Cr(VI) reporting limit, Cr(VI) results obtained using this method may be biased high due to method-induced oxidation. The addition of Mg

2+ in a phosphate buffer to the alkaline

extraction solution has been shown to suppress this oxidation. If an analytical method for Cr(VI) is used that can correct for possible method induced oxidation/reduction, then the Mg

2+ addition

is optional. The presence of soluble Cr(III) can be approximated by extracting the sample with deionized water.




5. Health and Safety

The toxicity or carcinogenicity of each reagent and standard used in this method is not fully established; however, each chemical compound must be treated as a potential health hazard. From this viewpoint, exposure to these chemicals must be reduced to the lowest possible level by whatever means available. A reference file of material data handling sheets is available to all personnel involved in the chemical analysis. Additional references to laboratory safety are available in the Chemical Hygiene Plan.

All personnel handling environmental samples known to contain or to have been in contact with municipal waste must follow safety practices for handling known disease causative agents.

6. Sample Collection, Preservation, Shipping and Handling

6.1 Sample Collection

Samples are collected in plastic or glass containers with teflon-lined caps. Sample containers must not contain any stainless steel. Separate container has to be provided for MCP HexCr ( see MCP addendum)

6.2 Sample Preservation

Samples are unpreserved and refrigerated at 4 ± 2 °C.

6.3 Sample Shipping

No special shipping requirements.

6.4 Sample Handling

Aqueous samples must be analyzed within 24 hours of collection. Soil and solid samples must be digested within 30 days of collection. The extracts must be analyzed within 168 hours (7 days) after extraction.

7. Equipment and Supplies

7.1 Spectrophotometer: Genesys 10 Vis: for use at 540nm, with a light path of 1cm or longer.

7.2 100 ml digestion cups

7.3 pH Meter: Calibrated.

7.4 Volumetric flasks: 1000mL and 100mL.

7.5 Filtration apparatus.

7.6 0.45µm Membrane filters.

7.7 Hot block Model # SC151 with Stir Base Stirring device (part #SC160)

7.8 Balance.

7.9 Thermometers.

7.10 Volumetric pipets: various volumes.

7.11 50mL Centrifuge Tubes.

7.12 100mL Graduated cylinder




7.13 pH paper range 1-14.

8. Reagents and Standards

8.1 1000ppm Stock Hexavalent Chromium Solution (for calibration and LCS): Commercial purchase. Expire upon manufacturer’s expiration date. Use different lots for calibration and LCS.

8.2 1ppm Working Standard Hexavalent Chromium Solution (for calibration): Dilute 1.00mL stock chromium solution (Section 8.1) to 1000mL with DI. Store at room temperature. Expires three months from the date of preparation.

8.3 10ppm Working Standard Hexavalent Chromium Solution (for LCS/ICV): Dilute 1.00mL stock chromium solution (Section 8.1) to 100mL with DI. Store at room temperature. Expires six months from the date of preparation

8.4 Nitric acid, HNO3, concentrated. Do not use if has a yellow tinge. Expires upon

manufacturer’s expiration date.

8.5 Nitric Acid, 50%: Into a 500mL volumetric flask, dilute 250mL of Concentrated Nitric Acid

with 250mL of DI water. Expires six months from the date of preparation.

8.6 Sulfuric acid, H2SO4, concentrated.

8.7 Sulfuric acid, H2SO4, 10%: Dilute 50mL concentrated H2SO4 to 500mL with DI water.

Expires six months from the date of preparation.

8.8 Diphenylcarbazide solution: Dissolve 1.0g 1,5-diphenylcarbazide (1,5-diphenylcarbo-

hydrazide) in 250mL acetone. Store in a plastic bottle cover with aluminum foil or away from light. Discard when solution becomes discolored.

8.9 Sodium carbonate: Na2CO3, anhydrous, analytical reagent grade. Store at 20 – 25°C in

a tightly sealed container.

8.10Sodium hydroxide: NaOH, analytical reagent grade. Store at 20 – 25°C in a tightly

sealed container.

8.11 Magnesium Chloride: MgCl2 (anhydrous), analytical reagent grade. 392.18mg MgCl2 is

equivalent to 100mg Mg2+

. Store at 20 – 25°C in a tightly sealed container. As an alternate, use 0.8366g MgCl2 · 6 H2O.

8.12 Phosphate Buffer:

8.12.1 K2HPO4: Analytical reagent grade.

8.12.2 KH2PO4: Analytical reagent grade.

8.12.3 0.5M K2HPO4 / 0.5M KH2PO4 buffer: Dissolve 87.09g K2HPO4 and 68.04g KH2PO4 into 700mL of DI water. Transfer to a 1L volumetric flask and dilute to volume. (When prepared accordingly, the buffer solution has an approximate pH value of 7.) Store at 20 – 25°C in a tightly sealed container. Expire one year from prep.

8.13 Lead Chromate: PbCrO4, analytical reagent grade. Store under dry conditions at 20 –

25°C in a tightly sealed container. Expires upon manufacturer’s expiration date.




8.13.1 Soil matrix insoluble spiking solution: Add 10 – 20mg PbCrO4 (Section 8.12) to a separate aliquot of sample. This spike is used to evaluate the dissolution during the digestion process.

8.14 Digestion solution: Dissolve 20.0 ± 0.05g NaOH and 30.0 ± 0.05g Na2CO3 in deionized

water in a one-liter volumetric flask and dilute to the mark. Store the solution in a tightly capped polyethylene bottle at 20 – 25 °C and prepare fresh monthly. The pH of the digestion solution must be checked before using. The pH must be 11.5 or greater; if not, discard.

8.15 Potassium Dichromate, K2Cr2O7, spiking solution (1000mg/L Cr (VI)): Commercial purchase. Expire upon manufacturer’s expiration date.

8.15.1 100mg/L Cr (VI): Add 10.0mL of the 1000mg/L K2Cr2O7 spiking solution (Section 8.14) to a 100mL volumetric flask and dilute to volume with deionized water. Mix well.

8.15.2 5ppm: To a 100mL volumetric flask, add 5mL of 100ppm spiking solution (Section 8.15.1), bring to volume with DI.

8.15.3 Soil sample soluble spike: Add 1 ml of 1000mg/L Cr (VI) spiking solution (Section 8.15) to 2.5g of sample.

8.15.4 Post spike soil sample: Add 1 ml of 100mg/L Cr(VI) solution (section 8.15.1) to 25 ml extracted sample.

8.15.5 Aqueous sample spike: Add 1ml of 5 ppm (section 8.15.2) to 50 ml of sample.

8.16 ICV and CCV Standards: Commercially prepared solution of known hexavalent

chromium concentration. A Certificate of Analysis is kept on file. This solution is diluted with DI to a concentration 0.2 ppm on each day of use.

8.17 Acetone: Analytical reagent grade.

9. Quality Control

The laboratory must maintain records to document the quality of data that is generated. Ongoing data

quality checks are compared with established performance criteria to determine if the results of analyses

meet the performance characteristics of the method.

9.1 Blank(s)

One preparation blank is digested and analyzed per batch of 20 samples or less for method 3500. Method 7196: batch size is 10 samples or less. The concentration of the Blank must be less than the RDL, or one-tenth the regulatory limit or action level, whichever is greater, otherwise the entire batch must be redigested and reanalyzed.

The ICB consists of DI water that has been colored and analyzed as per Section 10.3.4. Results must be less than the RDL, otherwise another ICB is colored and analyzed. It failure continues, a new calibration curve is generated (Section 10.1).

9.2 Laboratory Control Sample (LCS)

One LCS is prepared and analyzed per batch of 20 samples or less for method 3500. Method 7196: batch size is 10 samples or less.




The LCS for aqueous samples consists of the ICV (Section 10.2). LCS recovery for liquids must be within 85 – 115%, otherwise the entire sample batch must be redigested and reanalyzed. For solids samples, a soluble LCS and insoluble LCS must be digested per batch of 20 samples or less (Refer to Section 10.3.3.1) LCS recovery for solids must be within 80 – 120%, otherwise the sample batch must be redigested and reanalyzed.

Note: SRM HexCr standard made by ERA is used for soil LCS: use 0.3-0.5 g, based on certified value. Expires upon manufacturer’s expiration date.

9.3 Initial Calibration Verification (ICV)

Refer to Section 10.2

9.4 Continuing Calibration Verification (CCV)

Refer to Section 10.4

9.5 Matrix Spike

9.5.1 Aqueous samples One sample per delivery group per batch of 20 samples ( method 3500) or 10 samples ( method 7196) or less is required to be spiked.

Example: If a batch consists of 6 liquid samples (3 wastewater from Client A and 3 wastewater from Client B), then one wastewater from Client A and one wastewater from Client B each require spiking.

The spike is prepared by adding 1mL of 5ppm aqueous spiking solution (Section 8.14.2) to 50mL of sample. Spike recovery must be within 85 – 115. If spike recovery is outside of the range, adjust sample pH to 8.5 then add 1 ml of 5 ppm spiking solution and reanalyze. If spike recovery still outside of the range, then dilute sample and retest both diluted sample and spiked diluted sample. Report sample results at the dilution for which the spike recovered at 85 – 115%. Sample dilutions can be made with DI, up to 200X or up to the client’s specified detection limits. If interferences remain after dilutions, and spike recovery is still less than 85% for aqueous samples, refer to Section 10.3.5.

9.5.2 Soil / solid matrix samples

Two spikes per batch of 10 samples or less are required; one with a soluble spike and one with an insoluble spike (Section 10.3.3.1). The acceptance range for spike recovery is 75 – 125%. If recoveries are not within the specified limits, then the matrix spike(s) and the associated samples must be re-homogenized/re-digested/re-analyzed. If upon reanalysis, it is found that the recoveries are acceptable, then the data is submitted with the new spike results. If it is found that the recoveries are still unacceptable upon redigestion, then it is




assumed that the sample matrix is suspect and the pH and ORP are measured at once for the sample that was spiked. If prior knowledge of an interfering sample matrix is known, then matrix spike duplicates (MSD) are set for the soluble and insoluble matrix spikes, along with the pH and ORP analyses for the samples to be spiked. Failure of the MS/MSD will verify that the sample matrix interferes with the digestion, and will not necessitate a re-digestion of the sample and matrix spikes.

9.6 Laboratory Duplicate

Analyze one sample in duplicate per batch of 20 samples (method 3500) or 10 samples (method 7196) or less. The %RPD must be < 20% for aqueous samples and < 20% for solid samples, if both the original sample and the duplicate results are greater than or equal to four times the

reporting limit. A control limit of ± the laboratory reporting limit is used when either the original sample result or the duplicate sample result is less than four times the laboratory reporting limit.

9.7 Method-specific Quality Control Samples

Not applicable.

9.8 Method Sequence

• Sample preparation (digestion and/or pH adjustment and filtration)

• Coloring procedure

• Analysis on Spectrophotometer

• Verification

• Calculation

10. Procedure

10.1 Equipment Set-up

10.1.1 A calibration curve is generated at a minimum of once per year, as follows: 10.1.1.1 For Liquid: Pipet the following volumes of the 1ppm working standard (Section 8.2)

into separate 50mL volumetric flasks: 0.25 ml, 0.5 ml, 1 ml, 2.5 ml, 5 ml, 10 ml and 25 ml. Bring each to volume with DI to give the following concentrations respectively: 0.005ppm, 0.01ppm, 0.02 ppm, 0.05 ppm, 0.10ppm, 0.20ppm and 0.50ppm. Include a 50mL DI blank and proceed with subsequent treatment of the standards in the same manner as samples (Section 10.3.2).

10.1.1.2 For Soil: Prepare seven 100 ml dijestion cups, weigh 0.8366g of MgCl2 · 6 H2O into

each cup, then pipet following volumes of the 10 ppm working standard ( section 8.3) into separate digestion cups:0 ml, 0.1mL, 0.5mL, 1.0mL, 2.0mL, 5.0 ml and 10mL. To all digestion cups add 50 ml of digestion solution and 0.5 ml of phosphate buffer. Proceed to soil/solid digestion and extraction procedure( sections 10.3.3.2 to 10.3.3.7)




10.1.1.3 Develop color for standards and blank as in Section 10.3.4. 10.1.1.4 Construct a calibration curve by plotting the absorbance values against mg/L

hexavalent chromium. An acceptable curve must have a calibration coefficient of > 0.995. This calibration curve is valid for one year, unless failure of an ICV requires construction of a new calibration curve.

10.2 Initial Calibration

A non-digested, colored ICV (Section 8.16) (from a different source than was used for the calibration standards) must be recovered between 85 – 115%. If these criteria are not met, then the ICV is re-analyzed. If failure repeats, then the ICV is re-made and re-analyzed. If failure continues, prepare a new calibration curve (Section 10.1). See Section 12 for corrective actions.

10.3 Equipment Operation and Sample Processing

10.3.1 Treatment of sample: If interfering amounts of molybdenum, vanadium, copper, or iron are present, then follow the removal procedures as stated in the reference method.

10.3.2 Aqueous Samples:

Samples containing sediment, floating or suspended matter, or turbidity are filtered through a 0.45µm membrane filter prior to pH adjustment. If background interferences persist, measure an absorbance reading before adding diphenylcarbazide reagent (Section 10.3.4) and correct the absorbance of the final colored solution by subtracting the absorbance measured previously.

Proceed to Section 10.3.4.

10.3.3 Solid / soil sample digestion and extraction procedure:

10.3.3.1 Samples: Thoroughly mix the sample and weigh 2.5g into a 100 ml digestion cup. Add 0.8366 g of MgCl2·6H20.

Blank: Weigh 2.5g Ottawa Sand into a 100ml digestion cup, add 0.8366g of MgCl2·6H20.

Insoluble LCS: Weigh 2.5g Ottawa Sand into a 100 ml digestion cup, add 0.3-0.5 g of SRM ( ERA catalog # 921)

and 0.8366g of MgCl2·6H20.

Soluble LCS: Weigh 2.5g Ottawa Sand into a 100ml digestion cup, add 0.8366 g of MgCl2·6H20 and 1.0mL 1000ppm K2Cr2O7. (Section 8.15).

Matrix Spike, insoluble: Thoroughly mix the sample and weigh 2.5g into a 100 ml digestion cup. Add 0.8366 g of MgCl2·6H20 and 0.01 – 0.02g PbCrO4

(Section

8.13.1).

Matrix Spike, soluble: Thoroughly mix the sample and weigh 2.5g into a 100mL digestion cup. Add 0.8366 g of MgCl2·6H20 and 1.0mL 1000ppm K2Cr2O7. (Section 8.15).

To all samples and QC samples, add 50mL of digestion solution (8.14) and 0.5mL of phosphate buffer (Section 8.12.3).

10.3.3.2 Stir the sample on a stir plate (unheated) for at least 5 minutes.

10.3.3.3 Place samples on hot block with Stirring base; heat samples for 1 hour at 90 – 95 °C ( after temperature reached 90°C)

10.3.3.4 While still stirring, allow to cool to room temperature. Transfer the contents of the digestion vessel to 50 ml centrifuge tube then centrifuge in 10minute.Pour




centrifuged solution back to original cup. Save the solid centrifuged material from the matrix spikes for possible later analysis for assessing low Cr (VI) recoveries.

Store the centrifuged solid at 4 ±2°C.

10.3.3.5 Under a fume hood, while constantly stirring, very slowly add 50% HNO3 (Section 8.4) to the centrifuged liquid to carefully adjust the pH to 7.5 ± 0.5. If the pH drops below 7.0, discard the solution and re-digest.

10.3.3.5.1 If a precipitate forms, filter the sample again through a 0.45µm membrane filter into a clean 250mL beaker.

10.3.3.6 Remove the stir-bar and rinse, and transfer quantitatively to a 100mL volumetric flask or 100 ml graduated cylinder. Bring to volume with DI.

10.3.3.7 Proceed with coloring and analysis as described in Section 10.3.4.

10.3.4 Color development and measurement:

Place 45mL of sample or standard solution into a 50mL centrifuge tube. Adjust to pH 2 ± 0.5 with 0.6N H2SO4 (Section 8.6). Record pH on excel format. Add 1mL Diphenylcarbazide solution (Section 8.7) and adjust to 50mL with DI water. Mix and let stand 5 – 10 minutes for full color development.

Set the spectrophotometer to zero at 540 nm, utilizing the colored reagent blank in a 1cm absorption cell for soil samples and 2.5 cm absorption call for waters. Next, transfer a suitable portion of each colored standard solution or sample to a 1cm absorption cell for soils and 2.5 cm absorption cell for waters. Measure and record each absorbance at 540nm. Determine mg/L chromium present by reference to the calibration curve (Section 10.1.1.3).

10.3.4.1 Dilute samples volumetrically with DI water if they are more concentrated than the highest standard in the calibration curve.

10.3.5 Verification of Samples

10.3.5.1 For aqueous and soil samples, verification is required to ensure that neither a reducing condition nor a chemical interference is affecting color development. This is accomplished by analyzing a second 10mL aliquot of the pH adjusted filtrate of the soluble spike. 1mL of 100ppm K2Cr2O7 solution (Section 8.15.1) is added to the filtrate and analyzed. To verify the absence of an interference, the spike recovery must be between 85% and 115%.

If the spike recovery is less than 85%, the presence of an interference or reducing condition is verified. Client Services must be notified and a narrative included on the final report that indicates “verification of this sample indicates the presence of a reducing condition or a chemical interference that could affect the results”.

10.3.5.2 If addition of the spike extends the concentration beyond the calibration curve, the analysis solution must be diluted with a blank solution and the calculated results adjusted accordingly.

10.3.5.3 If the result of verification indicates a suppressive interference, the sample must be diluted and reanalyzed.

10.3.5.4 If the interference persists after sample dilution then an alternative method must be considered. See the Inorganics Supervisor for further instruction.

Aqueous samples with acidic extracts that yield recoveries of less than 85% are re-tested to determine if the low spike recovery is due to the presence of residual




reducing agent. This determination is performed by first making an aliquot of the extract alkaline (pH 8.0-8.5) using 1N NaOH. The pH is recorded in the laboratory notebook. This aliquot is respiked and analyzed. If a spike recovery of 85-115% is obtained on the alkaline aliquot of an acidic extract that initially was found to contain less than 5 mg/L Cr(VI), one can conclude that the analytical method has been verified.

10.3.5.5 If the spike recovery is still below 85%, then the presence of reducing agent is confirmed. Client Services must be notified and a narrative included on the final report that indicates “verification of this sample indicates the presence of a reducing condition or a chemical interference that could affect the results”.

10.4 Continuing Calibration

The calibration curve must be verified after every 10 samples or less, with a recovery of 85 – 115% of a non-digested, colored ICV/CCV standard (Section 8.15). If these criteria are not met, then the CCV is re-analyzed. If failure repeats, then the CCV is re-made and re-analyzed. If failure continues, prepare a new calibration curve (Section 10.1). See Section 12 for corrective actions.

10.5 Preventive Maintenance

The Spectrophotometer is calibrated on a semi-annual basis by an instrument service company. Records are kept on file.

11. Data Evaluation, Calculations and Reporting

For aqueous samples:

mg Cr

+6/L = absorbance – y-intercept x dilution

slope

For solid samples:

mg Cr

+6/Kg = absorbance – y-intercept x dilution x 0.1L (final volume)

slope weight (Kg) of sample

12. Contingencies for Handling Out-of-Control Data or Unacceptable Data

Holding time exceedence, improper preservation and observed sample headspace are noted on the nonconformance report form.




Perform routine preventative maintenance following manufacturer's specification. Record all maintenance in the instrument logbook.

Review of standards, blanks and standard response for acceptable performance occurs for each batch of samples. Record any trends or unusual performance on a nonconformance action form.

If the CV or LCS recovery falls outside the designated acceptance range, the laboratory performance is judged to be out of control, and the problem must be immediately identified and corrected. The analytical result in the unspiked samples is suspect and is only reported for regulatory compliance purposes with the appropriate nonconformance action form. Immediate corrective action includes reanalyzing all affected samples by using any retained sample before the expiration of the holding time.

Failure of the LCS for method 3060A requires that the entire sample batch be re-digested and re-analyzed.

If the method blank for method 3060A is greater than the reporting limit, then the following action must be taken. Samples that are non-detect may be reported, and the method blank result is narrated on the final report. If the sample concentration is greater than 10X the concentration of the method blank, then the sample may be reported, and the method blank is narrated on the final report. If the sample(s) concentration are above the reporting limit, but are not greater than 10X the concentration of the method blank, then those samples must be re-digested and re-analyzed. In this case, it is not necessary to submit a narrative unless there is a problem with the hold time, or there is not enough sample to re-digest. The Client Services Department must be made aware of the situation, and if the data is released then the method blank non-conformance is narrated.

The ICV for the analysis must have a recovery of 85-115%. If the ICV fails, it must be re-made and re-analyzed. If the failure persists, then a new calibration curve is constructed.

The ICB for the analysis must be below the detection limit for the analysis. If the ICB fails this requirement, then fresh blank must be colored and analyzed, if this does not solve the problem then a new calibration curve must be constructed.

If the CCV or the CCB fail, pour out a fresh aliquot of CCV and CCB and re-color and re-analyze. If the CCV or the CCB does not pass, then construct a new calibration curve and re-analyze the samples that followed the last acceptable CCV/CCB.

A duplicate result that is outside of the controls limits for this method must be narrated. The sample must be examined to determine the cause of the poor duplication. If it is determined that the poor duplication was due to analyst technique, then the sample and its duplicate are re-digested and re-analyzed. Otherwise, narrate the non-conformance on the final report.

If the matrix spike (aqueous samples) falls outside of the acceptable range of the method, then the analyst must go to the verification (section 10.3.5) part of this method. Poor spike recoveries must be narrated on the final report. Upon Client authorization, hexachromes with poor spike recoveries can be analyzed for total chromium by ICP-AES (Method 6010). The sample must be processed according to the Total Chromium procedure employed and the digestion procedure necessary. Clients will be invoiced for the Total Chromium analysis. Solids and soils digested under 3060A that have failing matrix spike recoveries must be re-digested and re-analyzed to determine if the failure is do to poor technique or the sample matrix. If upon reanalysis, it is found that the recoveries are acceptable, then the data is submitted with the new spike results. If it is found that the recoveries are still unacceptable upon redigestion, then it is assumed that the sample matrix is suspect and the pH and ORP are measured at once for the sample that was spiked. A “Change Order” is submitted to the Client Services Department, and the pH and ORP products are added to the applicable job. The pH and ORP results are evaluated against the Eh/pH Phase Diagram (Figure 1), and the result (reducing or oxidizing) is included in a sample narrative explaining the poor spike recovery.




13. Method Performance

13.1 Method Detection Limit Study (MDL) / Limit of Detection Study (LOD) / Limit of Quantitation (LOQ)

The laboratory follows the procedure to determine the MDL, LOD, and/or LOQ as outlined in Alpha SOP/1732. These studies performed by the laboratory are maintained on file for review.

13.2 Demonstration of Capability Studies

Refer to Alpha SOP/1734,1739 for further information regarding IDC/DOC Generation.

13.2.1 Initial (IDC)

The analyst must make an initial, one-time, demonstration of the ability to generate acceptable accuracy and precision with this method, prior to the processing of any samples.

13.2.2 Continuing (DOC)

The analyst must make a continuing, annual, demonstration of the ability to generate acceptable accuracy and precision with this method.

14. Pollution Prevention and Waste Management

Refer to Alpha’s Chemical Hygiene Plan and Waste Management and Disposal SOP for further pollution prevention and waste management information.

15. Referenced Documents

Chemical Hygiene Plan

SOP/1732 MDL/LOD/LOQ Generation

SOP/1734,1739 IDC/DOC Generation

SOP/1728 Waste Management and Disposal SOP

16. Attachments

Figure 1: Eh/pH Phase Diagram

FIGURE 1 Eh/pH PHASE DIAGRAM

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