After an initial immunoassay screen for drugs of abuse yields a positive result, which method is most commonly used to confirm the identity of the specific drug?

After an initial immunoassay screen for drugs of abuse yields a positive result, which method is most commonly used to confirm the identity of the specific drug?

• A. GC with mass spectrometry
• B. Scanning calorimetry
• C. Ion-specific electrode
• D. Immunoassay

Answer: (A)

After a positive immunoassay drug screen, the goal is to identify the exact drug with high specificity. Gas chromatography coupled with mass spectrometry does this by first separating the sample’s components and then producing a mass spectrum for each component. The resulting spectral pattern is compared to reference libraries, providing definitive identification and reliable quantitation in many cases. Immunoassays are great for screening but can cross-react and yield false positives, which is why they aren’t used for confirmation. Scanning calorimetry looks at thermal properties and isn’t suitable for identifying drugs in biological samples, and ion-specific electrodes aren’t applicable to the broad range of drug compounds in complex matrices. So, GC-MS is the best confirmatory method.

After a positive immunoassay drug screen, the goal is to identify the exact drug with high specificity. Gas chromatography coupled with mass spectrometry does this by first separating the sample’s components and then producing a mass spectrum for each component. The resulting spectral pattern is compared to reference libraries, providing definitive identification and reliable quantitation in many cases. Immunoassays are great for screening but can cross-react and yield false positives, which is why they aren’t used for confirmation. Scanning calorimetry looks at thermal properties and isn’t suitable for identifying drugs in biological samples, and ion-specific electrodes aren’t applicable to the broad range of drug compounds in complex matrices. So, GC-MS is the best confirmatory method.