Gas chromatography/mass spectrometry is used to confirm positive results in drug screening. Which option describes this practice?

• A. Immunoassay screening is sufficient to confirm results
• B. Gas chromatography/mass spectrometry is used to confirm positive results
• C. Urine dipstick tests confirm results
• D. Blood glucose tests confirm results

Answer: (B)

In drug screening, confirmation hinges on a test with high specificity that can definitively identify the exact substance. Gas chromatography/mass spectrometry does just that: gas chromatography separates the sample’s components, and mass spectrometry provides a precise molecular fingerprint for each drug, allowing both identification and quantification. This reduces false positives that can occur with initial screening methods and provides reliable, defendable results for clinical or legal decisions. The initial step is an immunoassay screening, which is fast and sensitive but can cross-react with similar substances, so positive results are typically sent to GC/MS for confirmation. Other options aren’t used to confirm drug presence: screening tests like immunoassays are not definitive, urine dipstick tests aren’t used for drugs, and blood glucose tests measure glucose, not drugs.