Glossary

GC-MS (gas chromatography–mass spectrometry)

A confirmation method that separates and identifies individual analytes by mass-to-charge ratio.

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GC-MS is one of the two principal confirmation technologies in federally regulated workplace drug testing. It is highly specific, capable of distinguishing structurally similar molecules that an immunoassay screen cannot.

Related terms & pages

Glossary

LC-MS/MS (liquid chromatography–tandem mass spectrometry)

A confirmation method that uses two stages of mass analysis, often used for fentanyl and other low-cutoff analytes.

 Glossary

Immunoassay

The initial screening method that uses antibodies to detect drug classes — fast but less specific than confirmation.

 Glossary

Confirmation test

A second-stage analysis that confirms (or rejects) an initial non-negative screening result.