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The page below is a sample from the LabCE course Drug Testing Methods in the Clinical Toxicology Laboratory. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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Confirmatory Testing

Samples that screen positive (at or above the cutoff) for target drugs, metabolites, or classes of drugs are considered presumptive positive and should be analyzed by a more specific methodology. Analytical methods developed and validated for gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) are employed by the vast majority of clinical laboratories to confirm the presence of specific drugs and/or metabolites.