Which laboratory technique is considered the gold standard for definitive drug testing?

Gas chromatography-mass spectrometry (GC-MS) is considered the gold standard for definitive drug testing because it offers high specificity and sensitivity, allowing for the accurate identification and quantification of drugs and their metabolites in biological samples. This combination of techniques separates compounds in a sample (gas chromatography) and then provides a detailed molecular mass analysis of these compounds (mass spectrometry).

GC-MS is particularly powerful in drug testing due to its ability to distinguish between substances that may have similar chemical structures but differ in their mass-to-charge ratios, thus preventing false positives that can occur with other techniques. The method can detect a wide variety of substances, including illicit drugs, prescription medications, and even their metabolites, providing comprehensive and reliable results essential for clinical diagnosis and management.

In comparison to other techniques, while enzyme-linked immunosorbent assays (ELISA) are useful for initial screening due to their ease of use and speed, they may lack the specificity required for definitive results. Techniques such as thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC) do offer separation capabilities but do not provide the same level of molecular identification and quantification as GC-MS. Therefore, GC-MS stands out as the gold standard in laboratory drug testing.