Method Validation

Abstract

Method validation is an important component of the quality assurance program in a forensic toxicology laboratory. The extent of validation that is required is based on the type of method being evaluated. A qualitative screening method requires less validation than a quantitative confirmation method. For example, all methods require at a minimum precision and accuracy studies, specificity studies, and carryover studies. Precision should be evaluated within a single batch and between batches. A quantitative method will also require determination of limit of detection, limit of quantitation, linearity range, selectivity, specimen stability, and extract stability. A method employing liquid chromatography- mass spectrometry or tandem mass spectrometry requires ion suppression or ion enhancement studies as well. Changes to the analytical method necessitate additional validation, the extent of which depends on the nature of the change.