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Putting Technology To Work Environmental Technology Verification Program Advanced Monitoring Systems Center Test/QA Plan for Verification of Test Kits for Detection of Atrazine in Water ElVEFtf ------- TEST/QA PLAN for VERIFICATION OF TEST KITS FOR DETECTION OF ATRAZINE IN WATER September 15,2003 Prepared by Battelle 505 King Avenue Columbus, OH 43201-2693 ------- Table of Contents Page 1.0 Introduction 1 1.2 Test Objective 1 1.3 Organization and Responsibility 2 1.3.1 Battelle 2 1.3.2 Partner Organizations 6 1.3.3 Vendors 6 1.3.4 EPA 7 1.3.5 Subcontract Laboratory 8 2.0 Verification Approach 9 2.1 Scope of Testing 9 2.2 Experimental Design 10 2.3 Test Samples 11 2.3.1 QC Samples 11 2.3.2 PT Samples 12 2.3.3 Environmental Samples 14 2.4 Reference Method 15 3.0 Materials and Equipment 16 3.1 Field Supplies 16 3.2 Laboratory Supplies 16 4.0 Procedures 19 4.1 Environmental Sample Collection and Storage 19 4.2 Equipment Calibration 19 4.3 Test Sample Preparation and Storage 21 4.3.1 Physico-chemical Characterization 21 4.3.2 Sample Preparation 21 4.4 Sample Identification 22 4.5 Sample Analysis 22 4.5.1 Test Kits 22 4.5.2 Reference Method 23 4.6 Schedule 23 5.0 Data Handling and Reporting 25 5.1 Data Acquisition and Review 25 5.2 Data Analysis 27 5.2.1 Accuracy 27 5.2.2 Precision 27 5.2.3 Linearity 28 5.2.4 Method Detection Limit 28 ------- 29 29 29 30 31 31 31 31 32 32 33 34 34 36 5.2.5 Matrix Interferences 5.2.6 False Positives/False Negatives 5.2.7 False Positives/False Negatives Reporting Quality Assurance /Quality Control Sample Chain-of-Custody Procedures Audits 6.2.1 Technical Systems Audit 6.2.2 Data Quality Audit 6.2.3 Performance Evaluation Audit.. Reference Method QC QA/QC Reporting Corrective Action References ------- LIST OF TABLES Table 1. Sample Summary for Verification of Test Kits for Atrazine in Water 13 Table 2. Calibration Procedures for Sample Preparation and Physico-chemical Characterization 20 Table 3. Approximate Schedule of Verification Test Days 24 Table 4. Summary of Data Recording Process for the Verification Test 26 LIST OF FIGURES Figure 1. Organization Chart for the Verification Test 3 ------- ETV Advanced Monitoring Systems Center Test/QA Plan for Verification of Test Kits for Atrazine in Water Version 1.0 September 15, 2003 APPROVAL: Name Company Date ------- DISTRIBUTION LIST Elizabeth A. Betz U.S. Environmental Protection Agency National Exposure Research Laboratory MD-44 Research Triangle Park, NC 27711 Robert Fuerst U.S. Environmental Protection Agency National Exposure Research Laboratory Mail Drop D-205-05 4930 Old Page Road Research Triangle Park, NC 27709 Elin Ulrich U.S. Environmental Protection Agency National Exposure Research Laboratory Mail Drop D-205-05 4930 Old Page Road Research Triangle Park, NC 27709 James Brady Syngenta Crop Protection 410 Swing Road Greensboro, NC 27419 Brian Skoczenski Beacon Analytical 383 Presumpscot St. Portland, ME 04103 Fernando Rubio Abraxis 54 Steamwhistle Drive Warminster, PA 18974 Tom Round Silver Lake Research 911 S. Primrose Ave. Monrovia, CA 91016 Bob Ferguson Strategic Diagnostics Inc. Ill Pencader Drive Newark DE 19702 Kenneth Wood Senior Consultant DuPont Corporate Environmental Engineering Group Brandy wine Building 9212 Wilmington, DE 19898 Marty Link Groundwater Section Nebraska Dept. of Environmental Quality 1200 N St., Suite 400 P.O. Box 98922 Lincoln, NE 68509-8922 Elizabeth Flynt U.S. Environmental Protection Agency Environmental Chemistry Laboratory Bldg. 1105, RoomD416 Stennis Space Center, MS 39529 Geoff Scott In Care of: Paul Pennington NOAA/National Ocean Service 219 Fort Johnson Road Charleston, SC 29412-9110 Craig Adams University of Missouri - Rolla Department of Civil, Architectural & Environmental Engineering Rolla, MO 65409 Joe Peters Alan Cherepon Texas Commission on Environmental Quality Building MC-147 12100 Park 35 Circle Austin, TX 78753 Karen Riggs Amy Dindal Zachary Willenberg Battelle 505 King Ave. Columbus, OH 43201 Patricia White Bo Liu Rosanna Buhl Battelle 397 Washington St. Duxbury, MA 02332 ------- Atrazine Test Kits Test/QA Plan Page 1 of 36 Version 1.0 Date: September 15, 2003 1.0 Introduction 1.1 Test Description This test/quality assurance (QA) plan provides procedures for a performance verification test of test kits for the analysis of atrazine in water. The verification test will be conducted under the auspices of the U.S. Environmental Protection Agency (EPA) through the Environmental Technology Verification (ETV) Program. The purpose of ETV is to provide objective and quality-assured performance data on environmental technologies so that users, developers, regulators, and consultants can make informed decisions about purchasing and applying these technologies. The verification test will be performed by Battelle, which is managing the ETV Advanced Monitoring Systems (AMS) Center through a cooperative agreement with EPA. The scope of the AMS Center covers verification of monitoring technologies for contaminants and natural species in air, water, and soil. In performing the verification test, Battelle will follow the procedures specified in this test/QA plan and will comply with the data quality requirements in the "Quality Management Plan for the ETV Advanced Monitoring Systems Center" (AMS Center QMP).1 1.2 Test Objective The verification of test kits for the detection of atrazine in water will be conducted to determine the analytical and operational performance characteristics of these technologies. These technologies are typically based on immunoassay methods, where specific antibodies are used to detect and measure the analytes of interest. Immunoassay-based test kits utilize a competitive enzyme-linked immunosorbent assay (ELISA), where atrazine in the sample competes with enzyme-labeled atrazine for a limited number of antibody binding sites specific to atrazine. After an incubation period, a magnetic field may be used to separate the bound and unbound atrazine. A simple wash step is typically followed by a color development step. The ------- Atrazine Test Kits Test/QA Plan Page 2 of 36 Version 1.0 Date: September 15, 2003 sample concentration is inversely proportional to color development, with a darker color indicating a lower sample concentration and a lighter color indicating a higher concentration. A variety of quality control (QC), performance test, and environmental water samples will be analyzed to assess the capabilities of the test kits relative to an accepted reference laboratory method. 1.3 Organization and Responsibility The verification test will be performed by Battelle with the assistance of the following partner organizations: National Oceanographic and Atmospheric Administration National Ocean Service (NOAA/NOS), Texas Commission on Environmental Quality (TCEQ), EPA's Environmental Chemistry Laboratory at the Stennis Space Center (Stennis, Mississippi), and the University of Missouri - Rolla. The testing will occur at Battelle's Duxbury, Massachusetts laboratory. The organizational chart provided in Figure 1 identifies the responsibilities of the organizations and individuals associated with the verification test. Roles and responsibilities are defined further below. 1.3.1 Battelle Ms. Patricia White is the AMS Center Verification Test Coordinator. In this role, Ms. White will have overall responsibility for ensuring that the technical, schedule, and cost goals established for the verification test are met. Specifically, Ms. White will: • Assemble a team of qualified technical staff to conduct the verification test. • Direct the team in performing the verification test in accordance with the test/QA plan. • Ensure that all quality procedures specified in the test/QA plan and in the AMS Center QMP are followed. ------- Atrazine Test Kits Test/QA Plan Page 3 of 36 Version 1.0 Date: September 15, 2003 Figure 1. Organization Chart for the Verification Test ------- Atrazine Test Kits Test/QA Plan Page 4 of 36 Version 1.0 Date: September 15, 2003 • Prepare the draft and final test/QA plan, verification reports, and verification statements. • Revise the draft test/QA plan, verification reports, and verification statements in response to reviewers' comments. • Respond to any issues raised in assessment reports and audits, including instituting corrective action as necessary. • Serve as the primary point of contact for vendor representatives. • Coordinate distribution of the final test/QA plan, verification reports and statements. • Establish a budget for the verification test and monitor staff effort to ensure that budget is not exceeded. • Ensure that confidentiality of vendor information is maintained. Ms. Amy Dindal is a Verification Testing Leader for the AMS Center. Ms. Dindal will provide technical guidance and oversee the various stages of verification testing. She will: • Support Ms. White in preparing the test/QA plan and organizing the testing. • Review the draft and final test/QA plan. • Review the draft and final verification reports and verification statements. Ms. Karen Riggs is Battelle's manager for the AMS Center. Ms. Riggs will: • Review the draft and final test/QA plan. • Review the draft and final verification reports and verification statements. • Ensure that necessary Battelle resources, including staff and facilities, are committed to the verification test. • Ensure that vendor confidentiality is maintained. ------- Atrazine Test Kits Test/QA Plan Page 5 of 36 Version 1.0 Date: September 15, 2003 • Support Ms. White in responding to any issues raised in assessment reports and audits. • Maintain communication with EPA's technical and quality managers. Battelle Technical Staff will conduct the testing of the atrazine test kits during the verification test. The responsibilities of the technical staff include: • Assist in the collection, receipt, and storage of environmental samples. • Filter environmental water samples, as required. • Measure physico-chemical parameters on environmental water samples prior to preparation of atrazine-fortified samples. • Prepare the atrazine spiking solution and fortify the test samples as required. • Split and ship water samples to the reference laboratory for measurement of atrazine, and to the subcontract laboratory for analysis of dissolved organic carbon (DOC) as part of the physico-chemical characterization. • Perform test kit analyses, as required. Mr. Zachary Willenberg is Battelle's Quality Manager for the AMS Center. Mr. Willenberg will: • Review the draft and final test/QA plan. • Conduct a technical systems audit once during the verification test, or designate another QA Manager to conduct the audit. • Audit at least 10% of the verification data. • Prepare and distribute an assessment report for each audit. • Verify implementation of any necessary corrective action. ------- Atrazine Test Kits Test/QA Plan Page 6 of 36 Version 1.0 Date: September 15, 2003 • Issue a stop work order if self audits indicate that data quality is being compromised; notify Battelle's AMS Center Manager if a stop work order is issued. • Provide a summary of the QA/QC activities and results for the verification reports. • Review the draft and final verification reports and verification statements. • Assume overall responsibility for ensuring that the test/QA plan is followed. 1.3.2 Partner Organizations The responsibilities of the partner organizations supporting the verification test are as follows: • Review the draft test/QA plan. • Technical staff from NOAA/NOS and the University of Missouri - Rolla will assist in the collection of environmental water samples for analysis in the test and ship them to Battelle. • Technical staff from TCEQ will analyze test samples using the atrazine test kits at Battelle. • The EPA Environmental Chemistry Laboratory at the Stennis Space Center will provide reference laboratory analyses for atrazine in water. 1.3.3 Vendors The responsibilities of the vendor representatives are as follows: • Review the draft test/QA plan. • Approve the test/QA plan prior to test initiation. • Provide off-the-shelf test kits for analysis of all verification test samples. • Provide all other equipment needed to complete the immunoassay analyses, including a spectrophotometer. ------- Atrazine Test Kits Test/QA Plan Page 7 of 36 Version 1.0 Date: September 15, 2003 • If desired, provide training to Battelle and TCEQ personnel on operating the test kits and associated equipment prior to testing. • Review the draft verification report and statement. 1.3.4 EPA EPA's responsibilities in the AMS Center are based on the requirements stated in the "Environmental Technology Verification Program Quality Management Plan" (EPA QMP).2 The roles of the specific EPA staff are as follows: Ms. Elizabeth Betz is EPA's AMS Center Quality Manager. For the verification test, Ms. Betz will: • Review the draft test/QA plan. • Perform at her option one external technical system audit during the verification test. • Notify the EPA AMS Center Manager of the need for a stop work order if external audit indicates that data quality is being compromised. • Prepare and distribute an assessment report summarizing results of external audit. • Review draft verification reports and statements. Mr. Robert Fuerst is EPA's manager for the EPA AMS Center. Mr. Fuerst will: • Review the draft test/QA plan. • Approve the final test/QA plan. • Review the draft verification reports and statements. • Oversee the EPA review process of the verification reports and statements. ------- Atrazine Test Kits Test/QA Plan Page 8 of 36 Version 1.0 Date: September 15, 2003 • Coordinate the submission of verification reports and statements for final EPA approval. 1.3.5 Subcontract Laboratory A subcontract laboratory, Severn-Trent Laboratories (STL) in Burlington, Vermont will be utilized to analyze DOC in environmental samples as part of the physico-chemical characterization. Mr. Kirk Young is STL's project manager. For the verification test, Mr. Young will provide QA-reviewed DOC results as requested for water samples. ------- Atrazine Test Kits Test/QA Plan Page 9 of 36 Version 1.0 Date: September 15, 2003 2.0 Verification Approach 2.1 Scope of Testing This test/QA plan specifically addresses verification of immunoassay test kits that provide qualitative, semi-quantitative, or quantitative measurements of atrazine in water. Test kits that provide qualitative results only indicate the presence or absence of the target analyte relative to a regulatory or health-based concentration level. Test kit methods that provide semi- quantitative results determine the presence or absence of the analyte within a specified concentration interval. Quantitative results can be obtained using test kits that generate a calibration curve using a range of analyte concentrations. The vendor will specify the type of the measurement provided by the test kit to be verified. Qualitative test kits are designed to be operated by non-technical users. Semi-quantitative and quantitative immunoassay test kits will yield more consistent and reliable results when operated by an experienced user. In this verification test, an analyst with previous experience in using immunoassay test kits will analyze all test samples to minimize the error introduced by operator inexperience. Test kits that are specific for atrazine are typically cross-reactive for a variety of triazine analogues, some of which are degradation products of atrazine. Cross-reactivity information is typically provided in the test kit documentation. It is assumed that most users of these kits will perform laboratory analysis of samples that provide a positive immunoassay response to confirm the presence and concentration of atrazine in the sample (i.e., the test kits will be used primarily as a screen for the possible presence of atrazine). As such, this test will not verify all vendor- provided information on cross-reactivity; however, the effect of two cross-reactive atrazine degradation products (hydroxyatrazine and desethyl atrazine) on test kit performance will be verified. It is assumed that most users of these kits will perform laboratory analysis of samples that provide a positive immunoassay response to confirm the presence and concentration of atrazine in the sample (i.e., the test kits will be used primarily as a screen for the possible presence of atrazine). ------- Atrazine Test Kits Test/QA Plan Page 10 of 36 Version 1.0 Date: September 15, 2003 Natural and atrazine-fortified water samples will be analyzed using both the immunoassay test kits and an appropriate reference method. A variety of sample matrices will be tested: ASTM Type I water, fresh pond water, brackish pond water, shallow (i.e., alluvial) groundwater, and chlorinated drinking water. These matrices are examples of water types that are typically monitored using immunoassay test kits to give a sense of the performance using a variety of matrices. However, this is not intended to be an exhaustive study nor to represent all possible water types that could be tested. The performance of each test kit will be evaluated quantitatively by comparing the test kit and reference method results. Each test kit also will be qualitatively evaluated for ease of use, cost, and sample throughput. The test kits will be evaluated for the following parameters: • accuracy • precision • linearity • method detection limit • cross reactivity of hydroxyatrazine and desethyl atrazine • matrix interference effects, and • occurrence of false positive and false negative results. Qualitative technologies will not be evaluated for linearity or method detection limit because they only provide a positive or negative result relative to a specified concentration level. The experimental design is described further below. 2.2 Experimental Design The verification will involve challenging each test kit with a variety of water samples that are intended to represent those typically monitored using the test kits. Sample matrices will include fresh pond water, brackish pond water, alluvial groundwater, and chlorinated drinking water. Natural and atrazine-fortified (i.e., unspiked and spiked) samples of each matrix will be ------- Atrazine Test Kits Test/QA Plan Page 11 of 36 Version 1.0 Date: September 15, 2003 analyzed. ASTM Type I water samples fortified with atrazine or an atrazine degradation product also will be analyzed. Physico-chemical parameters (pH, temperature, salinity, conductivity, alkalinity, and DOC) will be measured in environmental samples to provide supporting characterization data. All samples will be analyzed by each test kit and by the reference method. Each sample will be analyzed in triplicate with each test kit. Samples will be given to the analyst blind and in random order. Test kit and reference method results will be used to assess test kit accuracy and linearity. Replicate sample results will be used to assess test kit precision. Results for replicates of a low- level spiked sample will be used to evaluate the method detection limit. Cross-reactivity of hydroxyatrazine and desethyl atrazine will be assessed by evaluating the test kit results for samples that contain only the degradation compound, but not atrazine. Potential matrix effects will be assessed by comparing accuracy and precision results for environmental samples (i.e., chlorinated drinking water, fresh surface water, brackish surface water and groundwater) to those for ASTM Type I water samples. Performance parameters, such as ease of use and reliability, will be based on documented observations of the analyst. Sample throughput will be estimated based on the time required to analyze a sample set. 2.3 Test Samples Test samples to be used in this verification test will include QC samples, performance test (PT) samples, and environmental water samples. Table 1 lists the number and type of each sample to be analyzed in the verification test. Each type of test sample is described further below. 2.3.1 QC Samples QC samples will include reagent blank (RB) and calibration check samples. The RB samples will be prepared from ASTM Type I water and will be exposed to identical sample ------- Atrazine Test Kits Test/QA Plan Page 12 of 36 Version 1.0 Date: September 15, 2003 preparation and analysis procedures as the test samples, including the addition of all reagents. These samples will be used to help ensure that no sources of contamination are introduced in the sample handling and analysis procedures. At least 10% of the test samples will be RB samples. Calibration check samples may be used to verify that the test kits are properly calibrated and reading within defined control limits. Calibration check samples will be analyzed in accordance with the vendor-provided test kit protocol using standards or calibration check samples supplied by the vendor. 2.3.2 PT Samples PT sample types are listed in Table 1. The first type of PT sample consists of ASTM Type I water spiked at five different atrazine concentration levels. The PT sample concentrations will span the calibration range of the immunoassay test kits. This range includes the EPA maximum contaminant level (MCL) for atrazine in drinking water, which is 3 parts per billion [ppb]3. Three replicates of each PT sample will be analyzed using the test kits. The second type of PT sample is a low-level atrazine fortified sample. Seven replicates of this sample will be analyzed for the method detection limit determination. This sample will be spiked at a level of two times the vendor-stated test kit detection limit. The third type of PT sample is a cross-reactivity check sample. Two samples will consist of ASTM Type I water spiked with two different cross-reactive atrazine degradation products (hydroxyatrazine and desethyl atrazine) at a level of 3 ppb. Three replicates of each cross- reactivity check sample will be analyzed using the test kits. One replicate will be analyzed by the reference method to confirm the absence of atrazine in the samples. All PT samples will be prepared in the Battelle laboratory using a certified, commercially-available standards. PT sample results will be used to assess test kit accuracy, precision, linearity, method detection limit, cross-reactivity, and occurrence of false positive and false negative results using the data analysis methods described in Section 5.2. ------- Table 1. Sample Summary for Verification of Test Kits for Atrazine in Water Total No. Replicates for test kit laboratory reference Type of sample Description analysis analyses Performance Factor1 Quality Control Reagent blanks (10%) minimum 10% frequency 20 1 False positive/negative Calibration check samples As required by the test kit protocol TBD - Performance Test Performance test #1 0.1 ppb atrazine 3 1 Performance test #2 0.5 ppb atrazine 3 1 Accuracy, precision, Performance test #3 1 ppb atrazine 3 1 linearity, false Performance test #4 3 ppb atrazine 3 1 positive/negative Performance test #5 5 ppb atrazine 3 1 Method detection limit Atrazine concentration 2X vendor-stated detection limit 7 Method detection limit Cross-reactivity test #1 3 ppb hydroxyatrazine 3 1 Cross-reactivity, false Cross-reactivity test #2 3 ppb desethyl atrazine 3 1 positive/negative Environmental Fresh water Fresh surface water, unspiked 3 1 Fresh water spike #1 Fresh surface water with 1 ppb atrazine spike 3 1 Fresh water spike #2 Fresh surface water with 3 ppb atrazine spike 3 1 Brackish water Brackish water, unspiked 3 1 Brackish water spike #1 Brackish water with 1 ppb atrazine spike 3 1 Brackish water spike #2 Brackish water with 3 ppb atrazine spike 3 1 Accuracy, precision, matrix effects, false Groundwater Groundwater, unspiked 3 1 positive/negative Groundwater spike #1 Groundwater with 1 ppb atrazine spike 3 1 Groundwater spike #2 Groundwater with 3 ppb atrazine spike 3 1 Treated drinking water Chlorinated drinking water 3 1 Treated drinking water spike #1 Chlorinated drinking water with 1 ppb spike 3 1 Treated drinking water spike #2 Chlorinated drinking water with 3 ppb atrazine spike 3 1 Performance Evaluation Sample - 1 - Total 84 21 - 1 Other performance factors to be evaluated qualitatively include ease of use and reliability. ------- Atrazine Test Kits Test/QA Plan Page 14 of 36 Version 1.0 Date: September 15, 2003 2.3.3 Environmental Samples Environmental samples will be collected from a variety of sources to evaluate the performance of the test kits with various sample matrices. Samples will be collected from the following sources: • Fresh surface water from a South Carolina pond • Brackish surface water from a South Carolina pond • Groundwater from an alluvial aquifer in the Midwest • Chlorinated drinking water from the Battelle laboratory. Some test kit protocols recommend filtration for removal of gross particulate matter prior to sample analysis. Therefore, the fresh and brackish pond water samples will be filtered with a 0.45 pm filter in the laboratory prior to sample spiking/preparation and analysis. After filtration, the following physico-chemical parameters will be measured in each environmental water sample to characterize the sample matrix: pH, temperature, salinity, conductivity, and alkalinity. An aliquot of each environmental sample will be collected and sent to the subcontract laboratory for DOC analysis. The physico-chemical parameters will be measured in the laboratory instead of in the field to provide information about the sample matrix immediately prior to test kit analysis. As shown in Table 1, each environmental water sample also will be fortified with atrazine at two spike levels. The fortified samples will be spiked in the Battelle laboratory to increase the analyte concentration by the amount shown in Table 1. The spike solution will be prepared in the laboratory from a certified, commercially-available atrazine standard. Three replicates of each sample will be analyzed. The data for the environmental samples will be used to assess accuracy, precision, potential matrix effects, and occurrence of false positives and false negatives following the data analysis procedures provided in Section 5.2. ------- Atrazine Test Kits Test/QA Plan Page 15 of 36 Version 1.0 Date: September 15, 2003 2.4 Reference Method The laboratory reference method to be used for this verification test is an EPA standard method for the analysis of drinking water. Each sample will be analyzed using gas chromatography / mass spectrometry (GC/MS) according to EPA Method 525.24. ------- Atrazine Test Kits Test/QA Plan Page 16 of 36 Version 1.0 Date: September 15, 2003 3.0 Materials and Equipment In general, this verification test will rely on test kit materials and equipment provided by the vendors. Battelle will provide the following equipment and materials for the collection, preparation, storage, and shipment of test samples. 3.1 Field Supplies The following supplies will be needed for the collection of field samples: • 1-L or 2-L certified clean amber glass bottles fitted with polytetrafluoroethylene (TFE)-lined screw caps • Solvent-rinsed foil to keep bottle caps contaminant-free during sampling • Disposable latex gloves • Sample labels • Clear packing tape (to affix the sample label to bottle and seal the cooler for sample shipment) • Chain-of-custody forms • Bubble wrap to prevent sample breakage • Coolers and blue ice packs for sample storage and shipping • Address labels for the coolers. 3.2 Laboratory Supplies The following laboratory supplies will be needed for the preparation of the PT and laboratory-fortified environmental samples and sample shipment. Vendors will provide all equipment needed to perform the immunoassay test kit analyses. ------- Atrazine Test Kits Test/QA Plan Page 17 of 36 Version 1.0 Date: September 15, 2003 • ASTM Type I water • Class A volumetric flask • 10-|aL to 500-|iL adjustable pipette and disposable tips • Repeating pipette and disposable tips (volume appropriate for each test kit) • Certified, commercially-available atrazine, hydroxyatrazine and desethyl atrazine standards • Performance evaluation (PE) atrazine standard • Dichloromethane, acetone, and/or methanol, as applicable (pesticide-grade or equivalent) • Glass vials fitted with TFE-lined screw caps for test kit aliquots • Pre-cleaned glass container of sufficient size to prepare atrazine-fortified samples • 1-L certified clean amber glass bottles fitted with TFE-lined screw caps for reference sample aliquots • Pre-cleaned glass container fitted with TFE-lined screw caps for DOC samples (provided by STL Burlington) • Sample filtration equipment • Conductivity meter • Salinity refractometer • Alkalinity meter • pH meter capable of reading pH levels of 1 to 14 • Thermometers to measure air and water temperature • Sample labels ------- Atrazine Test Kits Test/QA Plan Page 18 of 36 Version 1.0 Date: September 15, 2003 Clear packing tape (to affix sample label to bottles and seal cooler for sample shipment) Chain-of-custody forms Bubble wrap to prevent sample breakage Coolers and blue ice packs for sample shipping Address labels for the coolers. ------- Atrazine Test Kits Test/QA Plan Page 19 of 36 Version 1.0 Date: September 15, 2003 4.0 Procedures 4.1 Environmental Sample Collection and Storage Before environmental sample collection, the total volume of sample material needed to complete all required analyses for both the test kit and reference methods at all required spike levels will be determined. Environmental samples will be collected within 21 days of the preparation of atrazine-fortified samples for the verification test. The chlorinated drinking water sample from the Battelle laboratory will be collected directly from the tap into certified clean amber glass bottles. These samples will be stored in the dark at 4°C until test sample preparation (see Section 4.3). Fresh and brackish pond water samples will be collected directly into certified clean amber glass bottles. The samples will be collected at the surface of the water near the shoreline by submerging the containers no more than one inch below the surface of the water. The groundwater sample will be collected directly from a tap at the intake to a power plant in the Midwest, prior to any pretreatment of the water by the power plant. Each sample will be assigned a unique sample identification (ID) number (see Section 4.4). The sample II ) number, date, name of person collecting the sample, sample location, and time of collection will be recorded on a chain-of-custody form for all field samples. All environmental samples collected in the field will be stored at 4°C and shipped to the Battelle laboratory on the day of collection following chain-of-custody procedures (see Section 6.1). 4.2 Equipment Calibration Table 2 identifies the laboratory equipment that require calibration. All equipment will be calibrated according to the criteria provided in Table 2. The spectrophotometer for immunoassay analyses will be provided by the vendor and will be calibrated in accordance with the manufacturer's recommended procedures. ------- Atrazine Test Kits Test/QA Plan Page 20 of 36 Version 1.0 Date: September 15, 2003 Table 2. Calibration Procedures for Sample Preparation and Physico-chemical Characterization Equipment Calibration Frequency Acceptance Criteria Reference Refrigerator Daily Refrigerators: 4 ± 2 °C Battelle SOP 3-095, Use of Laboratory Refrigerators and Freezers Thermometer Glass - annually1 Electronic - quarterly at two temperatures that bracket target temperature(s) against an NIST traceable thermometer Appropriate correction factors applied Battelle SOP 3-018, Calibration of Laboratory Thermometers Variable volume pipettes (i.e., Eppendorf) Monthly 3% of known of true value. ASTM E 542, Standard Practice for Calibration o f Volumetric Apparatus, and E 969, Standard Specification for Volumetric (Transfer) Pipettes. Nonvolumetric glassware/ labware (applicable only when used for measuring volumes) By lot at the time of purchase 3% of known or true value. ASTM E 542, Standard Practice for Calibration of Volumetric Ware Salinity Atago refractometer: Calibrate prior to use or every 30 minutes Reichert-Jung refractometer: Routine calibration quarterly Atago refractometer: adjust the boundary line to 0.0% when calibrated with deionized water. Reichert-Jung refractometer: The instrument should be checked using distilled or deionized water to assure that the reading departs from zero by no more than 0.05%. Battelle SOP 3-051, Use of Salinity Refractometers Conductivity meter Daily One point calibration; within 5 % of the expected value Battelle SOP 3-161, Use of the Cole Parmer TDSTestr 20 Conductivity Meter pH meter Prior to the analysis the pH measurement is within 0.1 pH units Battelle SOP 3-170, Use of the pH Testr2 pH meter Alkalinity meter Prior to the analysis pH standards of 4 and 10 within ± 0.05 pH units Battelle SOP 5-256, Determination of Alkalinity Using the Radiometer Titralab lrrhe criteria are defined for mercury thermometers. Battelle will apply the criteria to all glass thermometers. ------- Atrazine Test Kits Test/QA Plan Page 21 of 36 Version 1.0 Date: September 15, 2003 4.3 Test Sample Preparation and Storage Prior to test kit analysis, environmental samples will be filtered and characterized, and fortified PT samples will be prepared in the laboratory. These procedures are described below. 4.3.1 Physico-chemical Characterization Prior to the physico-chemical characterization, the fresh and brackish pond water will be filtered with a 0.45 |jm filter in the laboratory. All environmental samples will be measured for temperature using a thermometer following Battelle SOP 3-1695, for salinity using a refractometer following Battelle SOP 3-0516, for conductivity using a conductivity meter following Battelle SOP 3-1617, for alkalinity using an alkalinity meter following Battelle SOP 5-2568, and for pH using a pH meter following Battelle SOP 3-1709. All measurements will be recorded manually by the analyst on data sheets designed specifically for this verification test. All instruments used to measure physico-chemical parameters will be calibrated prior to use according to the SOPs (Table 2). Instrument model, serial number, and calibration information will be recorded on data sheets, and calibration records will be maintained in the study files. An aliquot of each environmental sample will be collected and shipped to the subcontract laboratory for DOC analysis according to Method 906010. 4.3.2 Sample Preparation The PT and fortified environmental samples will be prepared from certified, commercially-available standard solutions. The purchased standards will be diluted to the appropriate concentration using pesticide-grade or equivalent solvent in Class A volumetric glassware. All samples will be stored in the dark at 4°C until use. No other preservatives will be added to the samples because atrazine has been shown to be stable in water for up to two years when samples are stored under refrigerated conditions11. The PT and fortified environmental samples will be analyzed within 14 days of sample preparation. ------- Atrazine Test Kits Test/QA Plan Page 22 of 36 Version 1.0 Date: September 15, 2003 Each sample will be split into 1-L and 100-mL aliquots. The 100-mL aliquots will be retained for test kit analysis and stored in the dark at 4°C until use. Two 1-L aliquots will be sent to the EPA Environmental Chemistry Laboratory at the Stennis Space Center for reference analysis. The chlorinated water sample will be treated with sodium sulfite according to Method 525.2 at the reference laboratory prior to analysis. The samples for reference analysis will be stored in the dark in amber glass bottles at 4°C until extraction. The reference method sample extraction will be performed within 14 days of sample preparation (i.e., spiking), and analysis will be performed within 30 days of sample extraction. 4.4 Sample Identification All samples will be assigned a unique sample II ) number at the time of preparation. The sample II ) will include a survey code and sequential number, and will not contain information about the nature of the sample (i.e., the samples will be blind to the test kit analyst). A master log of the sample description, sample ID number, and preparation date will be maintained by Battelle. Each sample container will be labeled with the sample ID, container number (e.g. 1 of 3), preparation date, and initials of the person preparing the sample. 4.5 Sample Analysis 4.5.1 Test Kits Each vendor will provide test kits and other necessary equipment (e.g. vortexer, spectrophotometer) for the analysis of all samples. The full set of samples listed in Table 1 will be analyzed by each test kit. The vendors are encouraged to train the analyst prior to test kit analysis. A technical staff member from a partner organization with previous experience in performing immunoassay analyses will analyze the complete set of samples for each technology. The analyses will be performed according to the vendor's recommended procedures as described ------- Atrazine Test Kits Test/QA Plan Page 23 of 36 Version 1.0 Date: September 15, 2003 in the test kit instructions or user manual. Calibration and maintenance of the test kits will be performed as specified by the vendor. Test kit results will be recorded manually by the analyst on data sheets designed specifically for this verification test. In addition to the test kit results, the data sheets will include records of the time required for sample analysis and operator observations concerning the use of the test kit (e.g. ease of use, maintenance, etc.). 4.5.2 Reference Method The reference method for analysis of atrazine will be performed on a Hewlett-Packard 5971 GC/MS or equivalent by EPA's Environmental Chemistry Laboratory. The reference instrument will be operated according to the recommended procedures in the instrument operating manual, and samples will be analyzed according to EPA Method 525.2, "Determination of Organic Compounds in Drinking Water by Liquid-Solid Extraction and Capillary Column Gas Chromatography/Mass Spectrometry"4. Results from the reference analyses will be recorded electronically and compiled by the laboratory into a report format, including the sample ID and the analyte concentration for each sample. 4.6 Schedule The sample collection, preparation, and analysis are expected to take place over a four- week period. The time period for each activity should be considered approximate. Table 3 lists the activities to be conducted and a nominal schedule. All samples will be analyzed by one test kit before proceeding to the next test kit. Analysis of all samples using a single test kit is expected to take no longer than one day. Test conditions will be kept as similar as possible throughout the duration of the test (e.g., air temperature and lighting conditions) to minimize error introduced by variable test conditions. Participating vendors must provide the test kits and other sample analysis equipment to ------- Atrazine Test Kits Test/QA Plan Page 24 of 36 Version 1.0 Date: September 15, 2003 Battelle one week before the start of sample analysis, so that technical staff may become familiar with the kits and equipment prior to test initiation. This period will also be used to clarify any questions about the test kit's operation. Vendor staff may be present for this familiarization stage and may provide training in the operation of the test kits. During the verification test, the test kits will be operated by partner organization staff. Vendors are encouraged to stay and observe during the duration of the tests. Unused test kits and associated equipment will be returned to the vendors at the completion of testing. Table 3. Approximate Schedule of Verification Test Days Testing Period Test Location Activity Days 1-21 Field locations Collection of environmental samples and shipment to Battelle laboratory Days 14-21 Battelle Laboratory Receive test kits and supplies from vendor; test kit familiarization Day 18 Battelle Laboratory Environmental sample filtration Day 21 Battelle Laboratory Training, environmental sample physico-chemical characterization, test sample preparation, shipment of reference samples and DOC samples to appropriate laboratories Days 22-28 Battelle Laboratory Analysis of all samples using test kits Days 22-52 EPA Environmental Chemistry Laboratory Analysis of reference samples Days 22-52 STL Burlington Analysis of environmental water samples for DOC ------- Atrazine Test Kits Test/QA Plan Page 25 of 36 Version 1.0 Date: September 15, 2003 5.0 Data Handling and Reporting 5.1 Data Acquisition and Review Various types of data will be acquired and recorded electronically or manually by Battelle and partner organization technical staff during this verification test. Table 4 summarizes the types of data to be recorded. All data and observations will be documented on data sheets or in laboratory record books. Results from the laboratory reference instruments will be compiled in electronic format. Records received by or generated by Battelle or partner organization staff in the verification test will be reviewed by a more Battelle senior staff member within two weeks after receipt or generation, respectively, before the records are used to calculate, evaluate, or report verification results. This review will be performed by a Battelle technical staff member involved in the verification test, but not the staff member that originally received or generated the record. The review will be documented by the person performing the review by adding his/her initials and date to a hard copy of the record being reviewed. This hard copy will then be returned to the Battelle staff member who will be storing the record. In addition, data calculations performed by Battelle will be spot-checked by Battelle technical staff to ensure that calculations are performed correctly. Calculations to be checked include and statistical calculations described in this test/QA plan. The data obtained from this verification test will be compiled and reported independently for each test kit. Results for test kits from different vendors will not be compared with each other. ------- Atrazine Test Kits Test/QA Plan Page 26 of 36 Version 1.0 Date: September 15, 2003 Table 4. Summary of Data Recording Process for the Verification Test Data to be Recorded Responsible Party Where Recorded How often Recorded Disposition of data11 Dates and times of test events Battelle or partner organization ETV data sheets Start/end of test, and at each change of a test parameter Used to organize/check test results; manually incorporated in data spreadsheets as necessary Calibration information and results for physico- chemical parameters (temperature, salinity, pH, conductivity, etc.) Battelle ETV data sheets Prior to sample preparation Manually incorporated in data spreadsheets as necessary Sample collection and preparation information, including chain-of- custody Battelle or partner organization ETV data sheets and chain-of- custody forms At time of sample collection and preparation Used to organize/check test results; manually incorporated in data spreadsheets as necessary Test kit procedures and sample results Battelle or partner organization ETV data sheets Throughout test duration Manually incorporated in data spreadsheets Reference method procedures and sample results Battelle or partner organization ETV data sheets, or data acquisition system, as appropriate Throughout sample analysis process Transferred to spreadsheets DOC analysis procedures and sample results Subcontract laboratory ETV data sheets, or data acquisition system, as appropriate Throughout sample analysis process Transferred to spreadsheets (a) All activities subsequent to data recording are carried out by Battelle. ------- Atrazine Test Kits Test/QA Plan Page 27 of 36 Version 1.0 Date: September 15, 2003 5.2 Data Analysis Procedures for analyzing the data produced in the verification test are described in this section. 5.2.1 Accuracy For test kits that provide quantitative results, PT sample accuracy will be assessed relative to the spike level, and environmental sample accuracy will be assessed relative to the reference method results. The results for each set of analyses will be averaged, and the accuracy will be expressed in terms of a percent recovery (R) as calculated from Equation 1: where C is the average concentration measured by the test kit and Cr is the spike level for the PT samples and the reference measurement for the environmental samples. For qualitative results, accuracy will be assessed by determining whether the test kit result agrees with the reference method result. An overall percent agreement will be determined by dividing the number of correct responses to the overall number of analyses. 5.2.2 Precision For test kits that provide quantitative results, the standard deviation (S) of the results for the three replicate samples will be calculated for each sample using Equation 2: where n is the number of replicate samples, Ck is the concentration measured for the kth sample, and C is the average concentration of the replicate samples. The precision for each sample will R = C / CR x 100 (1) 1/2 (2) ------- Atrazine Test Kits Test/QA Plan Page 28 of 36 Version 1.0 Date: September 15, 2003 be reported in terms of the relative standard deviation (RSD) as calculated using Equation 3: RSD = x 100 (3) For test kits that provide qualitative results, precision will be assessed by calculating the percentage of consistent responses. 5.2.3 Linearity For test kits that provide quantitative results, linearity will be assessed by performing a linear regression with the spiked analyte concentration as the independent variable, and the individual test kit result as the dependent variable. Individual replicate results for the five PT samples will be used in the linear regression. Linearity will be expressed in terms of the slope, intercept, and correlation coefficient (r). 5.2.4 Method Detection Limit The method detection limit for each test kit will be assessed using results from seven replicate analyses of a sample spiked at a level of two times the vendor-stated test kit detection limit. The standard deviation of the seven replicate samples will be calculated using Equation 2. The MDL will be calculated using Equation 4: MDL = txS (4) Where t is the Student's t value for a 99% confidence level and S is the standard deviation of the seven replicate samples. ------- Atrazine Test Kits Test/QA Plan Page 29 of 36 Version 1.0 Date: September 15, 2003 5.2.5 Cross Reactivity The cross reactivity of the test kits to the atrazine degradation products hydroxyatrazine and desethyl atrazine will be assessed qualitatively by evaluating the test kit results for samples that contain only the degradation compound, but not atrazine. The reference analysis results will be used to confirm the absence of atrazine in the samples. 5.2.6 Matrix Interferences The potential effect of the sample matrix on the test kit performance will be evaluated qualitatively by comparing the accuracy and precision results for the natural and atrazine-fortified environmental samples to those for the PT samples. 5.2.7 False Positives/False Negatives For quantitative and semi-quantitative technologies, the occurrence of false positive and false negative results will be assessed relative to the test kit's lowest calibration standard. A false positive is defined as a positive test kit result when reference method analysis indicates that the atrazine concentration in the sample is below the test kit's lowest calibration standard. A false negative will be defined as a negative test kit result when the reference method analysis indicates that the atrazine concentration in the sample is above the test kit's lowest calibration standard. For qualitative technologies, a false positive is defined as a positive test kit result when the reference method analysis indicates that the atrazine concentration in the sample is below the threshold value (+10%) of the kit. A false negative is defined as a negative test kit result when the reference method analysis indicates that the atrazine concentration in the sample is above the threshold value (+10%) of the kit. The rate of false positives/false negatives will be expressed as a percentage of total number of samples. Reagent blanks, PT samples, and environmental samples will be included in the analysis. ------- Atrazine Test Kits Test/QA Plan Page 30 of 36 Version 1.0 Date: September 15, 2003 5.3 Reporting The data obtained in the verification test will be compiled separately for each test kit, and the data evaluation methods described in Section 5.2 will be applied to each data set without comparison to any other technology. At no time will data for test kits from different vendors be intercompared or ranked. Following completion of the data evaluation, a draft verification report will be prepared for each test kit. The verification report will describe the verification test procedures and document the results. Each draft verification report will each be submitted to the corresponding vendor for review and comment. Each draft report will be revised in response to the comments provided by the vendor. The revised reports will be submitted for external peer review. The reports will be revised again to address the peer review comments, and then submitted to EPA for final approval. A verification statement will also be prepared for each test kit. The verification statement is a 2- to 3-page summary of the technology, test procedures, and results. The verification statement will follow the same review and revision process as the verification reports. Upon final approval by EPA, each verification statement will be signed by a senior Battelle manager and an EPA laboratory director. Final verification reports and statements will be posted on the ETV website (http://www.epa.gov/etv), and original signed verification statements will be provided to the vendor. ------- Atrazine Test Kits Test/QA Plan Page 31 of 36 Version 1.0 Date: September 15, 2003 6.0 Quality Assurance /Quality Control The QA/QC activities associated with this verification test will focus primarily on sample preparation and handling, data recording and analysis, and reference laboratory analysis. An independent audit covering each of these areas will be performed by the Battelle Quality Manager to ensure the quality of the verification test. 6.1 Sample Chain-of-Custody Procedures Sample custody will be documented throughout collection, shipping, and analysis of the samples. Sample chain-of-custody procedures will be in accordance with the Battelle SOP 6-010, Sample Receipt, Custody, and Handling11. The chain-of-custody form summarizes the samples collected and analyses requested. The custody form will track sample release from the field to the Battelle laboratory, and from the Battelle laboratory to the subcontract laboratory and EPA's Environmental Chemistry Laboratory. Each sample custody form will be signed by the person relinquishing samples once that person has verified that the custody form is accurate. The original sample custody forms accompany the samples; the shipper will keep a copy. Upon receipt at the sample destination, sample custody forms will be signed by the person receiving the samples once that person has verified that all samples identified on the custody forms are present in the shipping container. Any discrepancies will be noted on the form and the sample receiver will immediately contact the Verification Test Coordinator to report missing, broken, or compromised samples. 6.2 Audits 6.2.1 Technical Systems Audit The Battelle Quality Manager or his designee will conduct a technical systems audit at least once during the course of the verification test. The purpose of this audit is to ensure that the ------- Atrazine Test Kits Test/QA Plan Page 32 of 36 Version 1.0 Date: September 15, 2003 verification test is being performed in accordance with this test/QA plan and the AMS Center QMP1, and that all procedures described in this test/QA plan are being followed. This audit will review the standards and methods used, compare actual test procedures to those specified in this test/QA plan, and review data acquisition and handling procedures. An independent technical systems audit may also be performed by EPA Quality Management staff during the verification test at EPA's discretion. 6.2.2 Data Quality Audit At least 10% percent of the data acquired during the verification test will be audited during the verification test. Battelle's Quality Manager or his designee will trace the data from its initial acquisition, through reduction and statistical analysis, to final reporting, to ensure the integrity of the reported results. All calculations performed on the data undergoing the audit will be checked. 6.2.3 Performance Evaluation Audit A performance evaluation (PE) audit will be conducted to assess the quality of the reference measurements made in this verification test. A PE audit involves challenging the reference instrument with a standard that is independent of the one used to calibrate the instrument for the test. For the PE audit, a certified standard will be obtained from a commercial supplier other than the one that supplied the standard for the preparation of PT and fortified environmental samples, or the one used to calibrate the reference instrument. The PE sample result must be within the certified range to be considered acceptable. Failure to achieve this agreement will trigger recalibration of the reference instrument with the original QC standard, and a repeat of the PE comparison. Failure in the second comparison requires obtaining another set of standards, and repeating the performance audit. ------- Atrazine Test Kits Test/QA Plan Page 33 of 36 Version 1.0 Date: September 15, 2003 6.3 Reference Method QC The performance of the reference method will be demonstrated through the analysis of QC samples. Laboratory RB samples will be analyzed to ensure that no sources of contamination are present. If the analysis of a laboratory RB sample indicates a concentration above the method detection limit (MDL) for the reference instrument, then contamination will be suspected. Any contamination source(s) will be corrected, and proper blank readings will be achieved, before proceeding with the reference analyses. The accuracy of the reference method will be verified before the beginning and at the conclusion of each testing day. The instrument to be used for reference analyses will be initially calibrated according to the procedures specified in the reference method. The instrument calibration will be verified using an appropriate calibration check sample. If the result for the calibration check sample differs by more than ±20% from the value of the standard, then the instrument will be recalibrated before continuation of the test. Laboratory matrix spike samples will be analyzed at a frequency of at least 5% to assess whether matrix effects potentially influence the results of the reference analyses. The percent recovery (R) of the laboratory matrix spikes will be calculated from the following Equation 5: C-C ,c. R=— x 100 (5) s where Cs is the analyzed concentration of the spiked sample, C is the analyzed concentration of the unspiked sample, and s is the concentration equivalent of the analyte spike. If the percent recovery of a matrix spike sample falls outside the range from 70-130%, then a matrix effect will be suspected. Analytical duplicates will be analyzed at a frequency of at least 5% to assess analytical precision. The relative percent difference (RPD) between the two duplicates should be within 30%. ------- Atrazine Test Kits Test/QA Plan Page 34 of 36 Version 1.0 Date: September 15, 2003 A Laboratory Fortified Blank (LFB) sample will be analyzed with each set of samples to determine whether the methodology is in control. If the recovery of the LFB falls out of the range of 70-130% of the actual concentration, then work should be stopped until the source of the problem is identified. Upon completion of the data package and draft final report, the EPA Environmental Chemistry Laboratory QA Officer will review all data and results for accuracy, precision, completeness, and representativeness. The QA Officer also will conduct a review of the project with the Lead Chemist and present the findings to the Environmental Chemistry Laboratory Branch Chief for review and comment before approving the final report. The QA Officer may at any time selectively review any data during tabulation, and will be available for consultation with the Lead Chemist regarding any QAPP deviations and corrective action. 6.4 QA/QC Reporting Each assessment and audit will be documented in accordance with Section 3.3.4 of the AMS Center QMP1. The results of the technical systems audit will be submitted to EPA. Assessment reports will include the following: • Identification of any adverse findings or potential problems. • Response to adverse findings or potential problems. • Recommendations for resolving problems. • Confirmation that solutions have been implemented and are effective. • Citation of any noteworthy practices that may be of use to others. 6.5 Corrective Action During the course of any assessment or audit, the Battelle Quality Manager will inform the technical staff of any immediate corrective action that should be taken. If serious quality ------- Atrazine Test Kits Test/QA Plan Page 35 of 36 Version 1.0 Date: September 15, 2003 problems exist, the Battelle Quality Manager is authorized to stop work. Once the assessment report has been prepared, the Verification Test Coordinator will ensure that a response is provided for each adverse finding or potential problem, and will implement any necessary follow-up corrective action. The Battelle Quality Manager will ensure that follow-up corrective action has been taken. ------- Atrazine Test Kits Test/QA Plan Page 36 of 36 Version 1.0 Date: September 15, 2003 7.0 References 1. Quality Management Plan (QMP) for the ETV Advanced Monitoring Systems Center, Version 4.0. EPA Environmental Technology Verification Program, prepared by Battelle, Columbus, Ohio, December, 2002. 2. Environmental Technology Verification Program Quality Management Plan, December 2002 (EPA/600/R-03/021). 3. National Primary Drinking Water Standards, 40 CFR Part 141. 4. U.S. EPA Method 525.2, Determination of Organic Compounds in Drinking Water by Liquid-solid Extraction and Capillary Column Gas Chromatography/Mass Spectrometry, Revision 2.0, 1995. 5. Battelle SOP 3-169. Operation of Digital Thermometers. May 21, 2002. 6. Battelle SOP 3-051. Use of Salinity Refractometers. October 3, 1990. 7. Battelle SOP 3-161. Use of the Cole-Parmer TDSTestr 20 Conductivity Meter. June 17, 1996. 8. Battelle SOP 5-256. Determination of Alkalinity Using the Radiometer Titralab. May 10, 1995. 9. Battelle SOP 3-170. Use of the pH Testr2 pH meter. June 21, 2000. 10. U.S. EPA Method 9060 Total Organic Carbon, Revision 0, September 1986. 11. Ciba Crop Protection Report ABR-94094, Storage Stability of Atrazine, G-30033, G28279, and G28273 in Water Under Refrigerator Storage Conditions, Greensboro, NC as cited in "Interlaboratory Validation of an Atrazine Immunoassay." Journal of the Americal Water Works Association, September 2001. 12. Battelle SOP 6-010. Sample Receipt, Custody, and Handling. August 7, 2000. ------- |