Section 771. Chemical testing: limit of detection and limit of quantitation

A. General. All procedures used shall be documented. Documentation shall include the quality system matrix type. All supporting data shall be retained.

B. Limit of detection (LOD). The laboratory shall utilize a test method that provides an LOD that is appropriate and relevant for the intended use of the data. An LOD is not required for a test method when test results are not reported outside of the calibration range. LODs shall be determined by the protocol in the mandated test method or applicable regulation. If the protocol for determining LODs is not specified, the selection of the procedure shall reflect instrument limitations and the intended application of the test method.

1. The LOD shall be initially determined for the compounds of interest in each test method in a quality system matrix in which there are no target analytes or interferences at a concentration that would impact the results. Alternatively the LOD shall be determined in the quality system matrix of interest (see definition of matrix).

2. LODs shall be determined each time there is a change in the test method that affects how the test is performed, or when a change in instrumentation occurs that affects the sensitivity of the analysis.

3. The LOD shall be verified annually for each quality system matrix, method and analyte according to the procedure specified in 1VAC30-45-760 B 1.

C. Limit of quantitation (LOQ).

1. Any established LOQ shall be above the LOD.

2. The LOQ shall be verified annually for each quality system matrix, method and analyte according to the procedure specified in 1VAC30-45-760 B 2. Alternatively, the annual LOQ verification is not required if the LOD is reevaluated or verified according to subdivision B 3 of this section.

Historical Notes

Derived from Volume 25, Issue 07, eff. January 1, 2009; amended, Virginia Register Volume 32, Issue 22, eff. September 1, 2016.

Statutory Authority

§ 2.2-1105 of the Code of Virginia.