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Environmental Sampling and Analytical Methods (ESAM) Program

Quality Control Guidelines for SAM Pathogen 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). Generation of analytical data of known and documented quality is a critical factor in the accurate assessment of and appropriate response to emergency situations. The generation of data of sufficient quality requires that analytical laboratories: (1) have appropriately trained and proficient personnel; (2) acquire and maintain required supplies, equipment and reagents; (3) conduct the appropriate QC procedures to ensure that all measurement systems are in control and operating properly; (4) properly document all analytical results; (5) properly document analytical QC procedures and corrective actions; and (6) maintain personnel training and proficiency testing records. Information regarding EPA's data quality objectives (DQO) process, considerations and planning is available at Quality Management Tools - Systematic Planning. See: Quality Management Tools - Systematic Planning.

The level or amount of QC needed depends on the intended purpose of the data generated. Various levels of QC may be required if the data are generated for presence/absence determinations versus quantitative results. Specific data needs should be identified and QC requirements, based on those needs, applied consistently across laboratories when multiple laboratories are used. The individual methods listed, sampling and analytical protocols or contractual statements of work should be consulted to determine if additional QC procedures are required.

Method-specific QC requirements are described in many of the methods and will be included in protocols developed to address specific pathogen/sample type combinations of concern. In general, analytical QC requirements for pathogen methods include an initial demonstration of measurement system capability, as well as the capability of the laboratory and the analyst to perform the method with the required precision and accuracy. In addition, for molecular techniques (e.g., PCR) general guidelines are provided in EPA's Quality Assurance/Quality Control Guidance for Laboratories Performing PCR Analyses on Environmental Samples. See: Quality Assurance/Quality Control Guidance for Laboratories Performing PCR Analyses on Environmental Samples.

Ongoing analysis of control samples to ensure the continued reliability of the analytical results should also be performed. At a minimum, the following QC analyses should be conducted on an ongoing basis:

  • Media and reagent sterility checks
  • Positive and negative controls
  • Method blanks
  • Reference matrix spikes to evaluate initial and ongoing method/analyst performance, if available
  • Matrix spikes (where possible) to evaluate method performance in the sample type of interest
  • Matrix spike duplicates and/or sample replicates to assess method precision
  • Instrument calibration checks and temperature controls

QC procedures and proper maintenance of ancillary laboratory equipment (e.g., thermometers, autoclaves) should be performed as frequently as necessary to ensure the reliability of analytical results.

Please note: The appropriate Technical Contacts should be consulted regarding appropriate QA/QC procedures prior to sample analysis. These contacts should also be consulted regarding any method deviations or modifications, sample problems or interferences, QC requirements, the use of potential alternative methods, or the need to address analytes or sample types other than those listed in SAM. As previously indicated, any deviations from the recommended method(s) should be reported immediately to ensure data comparability is maintained. Method deviations or modifications must be approved by the ERLN or WLA prior to use.

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