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Environmental Sampling and Analytical Methods (ESAM) Program

Quality Control Guidelines for SAM Biotoxin Methods

There are several quality control (QC) considerations that apply when using the methods listed in EPA's Selected Analytical Methods for Environmental Remediation and Recovery (SAM). Having data of known and documented quality is critical so that public officials can accurately assess the activities that may be needed in remediating a site during and following emergency situations. Having such data requires that laboratories: (1) conduct the necessary QC to ensure that measurement systems are in control and operating properly; (2) properly document results of the analyses; and (3) properly document measurement system evaluation of the analysis-specific QC. Information regarding EPA's data quality objectives (DQO) process, considerations and planning is available at Quality Management Tools - Systematic Planning. Ensuring data quality also requires that laboratory results are properly evaluated and the results of the data quality evaluation are included within the data report when transmitted to decision makers. See: Quality Management Tools - Systematic Planning.

The level or amount of QC needed often depends on the intended purpose of the data that are generated. Various levels of QC may be required if the data are generated during presence/absence determinations versus confirmatory analyses. The specific needs for data generation should be identified. QC requirements and DQO's should be derived based on those needs and should be applied consistently across laboratories when multiple laboratories are used. For example, during rapid sample screening, minimal QC samples (e.g., blanks, replicates) and documentation might be required to ensure data quality. Sample analyses for environmental evaluation during site assessment through site clearance might require increased QC (e.g., demonstrations of method sensitivity, precision, and accuracy).

While method-specific QC requirements may be included in many of the procedures and will be referenced in any analytical protocols developed to address the specific analytes and sample types of concern, the following describes a minimum set of QC samples and procedures that should be conducted for all analyses. Individual methods, sampling and analysis protocols, or contractual statements of work also should be consulted to determine any additional QC that may be needed. QC tests should be run as frequently as necessary to ensure the reliability of analytical results. In general, sufficient QC includes an initial demonstration of measurement system capability as well as ongoing assessments to ensure the continued reliability of the analytical results.

Examples of sufficient QC for presumptive tests include:
  • Method blanks
  • Positive test samples / negative test samples
  • Calibration check samples
  • Use of test kits and reagents prior to expiration date
  • Accurate temperature controls
Examples of sufficient QC for confirmatory tests include:
  • Demonstration that the measurement system is operating properly
    • Initial calibration
    • Method blanks
  • Demonstration of measurement system suitability for intended use
    • Precision and recovery (verify measurement system has adequate accuracy)
    • Analyte/sample type/level of concern-specific QC samples (verify that measurement system has adequate sensitivity at levels of concern)
  • Demonstration of continued measurement system reliability
    • Matrix spike (MS)/matrix spike duplicate(MSD) recovery and precision
    • QC samples (system accuracy and sensitivity at levels of concern)
    • Continuing calibration verification
    • Method blanks

Please note: The appropriate  Technical Contacts page of this website should be consulted regarding appropriate Quality assurance (QA)/QC procedures prior to sample analysis. These contacts will consult with the EPA Environmental Response Laboratory Network (ERLN) and Water Laboratory Alliance (WLA) coordinators responsible for laboratory activities during the specific event to ensure QA/QC procedures are performed consistently across laboratories. EPA program offices will be responsible for ensuring that the QA/QC practices are implemented.

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