Detection Limit

Detection Limit (DL) - A measure of the capability of an analytical method to distinguish samples that do not contain a specific analyte from samples that contain low concentrations of the analyte; the lowest concentration or amount of the target analyte that can be determined to be different from zero by a single measurement at a stated level of probability. DLs are analyte- and matrix-specific and may be laboratory-dependent. Some of the more commonly used definitions are described below.

Instrument Detection Limit (IDL) - The lowest concentration or mass an instrument can detect above background instrument noise under ideal conditions. Sample preparation is not considered in the determination of an IDL.

Method Detection Limit - A statistically derived estimate of the lowest concentration or mass detectable under method conditions at the concentration evaluated. A series of standards at an estimated limit of detection is analyzed multiple times (usually 7), a standard deviation of these seven replicate analyses is determined and the standard deviation is multiplied by the Student's t-distribution statistic at 6 degrees of freedom (3.14). See Reporting Limit.

Practical Quantitation Limit (PQL) - A measure of the lowest limit of detection under the conditions of a particular method. The PQL is often determined by multiplying the MDL by a factor of between 3 and 10.

Reporting Limit (RL) - For a target analyte, the reporting limit is instrument dependent and based on the lowest point on the calibration curve.

[Category=Quality Assurance ]

Source: Massachusetts Department of Environmental Protection, 19 March 2011 07:27:53, http://www.mass.gov/dep/cleanup/laws/glossa01.htm