Drug Testing Techniques



ELISA (Enzyme Labeled ImmunoSorbent Assay) is the screening technology used for hair and oral fluid drug testing. This technique involves the mixing of specifically developed antibodies with the patient’s processed hair or oral fluid. These antibodies are designed to attach specifically to drugs or drug metabolites. The specific antibodies will attach to drugs present in the patient’s hair or oral fluid. Automated instrumentation is used to detect this attachment of antibody to drug. If this specific attachment occurs the specimen is considered positive for the drug detected.

EMIT (Enzyme Multiplied Immunoassay Technique) is the screening technology used for urine drug testing. This technique utilizes essentially the same principles as the ELISA testing.

GC/MS (Gas Chromatograph/Mass Spectrometry) is considered a confirmatory testing technique. It is universally considered the “Gold Standard” in drug testing. This procedure involves the purification of a specimen (hair, oral fluid or urine) by the gas chromatograph and the positive identification of the purified drug by the mass spectrometer. The mass spectrometer produces the mass spectrum of the drug undergoing confirmation. The mass spectrum is as unique to a drug as a fingerprint is to an individual. The GC/MS technique provides absolute information about drugs and drug metabolites in biological specimens.

Whereas drug screening, by either ELISA or EMIT, is an extremely reliable indicator of drug use, no screening test provides 100% accuracy. Only GC/MS testing can approach this level of accuracy.