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How Do Drug Tests Work?

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How Do Drug Tests Work?

Properly administered drug tests start with an initial screening to rapidly identify negatives. If a drug screening shows that there are clearly no drugs in the system, the results are reported. However, because an initial screening is a blunt measurement, non-negative drug screens are then sent for highly sophisticated gas chromatography–mass spectrometry (GC/MS) testing. GC/MS confirmation testing confirms if the result is positive and, furthermore, identifies the specific drug within the class that is present in the specimen.

Nearly all types of drugs that people consume can be detected in the days, weeks, or months that follow by a simple drug test. Whether the drug is obtained by prescription for a medical purpose, purchased on the street for illicit recreational use, or given to someone unknowingly, drugs and their metabolites remain in the body long after the psychoactive effects wear off. Drug tests identify the class of the drug that was consumed as well as the specific metabolite found in the body. Since some of these metabolites may exist in the body naturally, labs establish minimum cutoff levels for each drug class to avoid reporting false positives.

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