Which MS technique is typically used for drug analysis?

• A. MALDI-ToF MS
• B. GC-MS
• C. HPLC-MS
• D. Isotope Dilution MS

Answer: (B)

Drug analysis benefits from a separation method paired with a mass spectrometer that can provide unique fragmentation patterns for identification. GC-MS is especially well suited for this because many small drug molecules are volatile or can be made volatile through derivatization, allowing clean, reproducible separation by gas chromatography. When the separated compounds enter the mass spectrometer, electron impact or other ionization produces characteristic fragment ions that serve as a precise and specific fingerprint for each drug. This combination gives strong qualitative certainty and robust quantitative performance, backed by extensive spectral libraries and well-established analytical workflows in toxicology and forensic labs.

MALDI-ToF is tailored for large biomolecules like proteins and peptides, not routine small-molecule drug analysis. HPLC-MS (LC-MS) is highly versatile and widely used, particularly for non-volatile or thermally labile drugs, and is becoming more common in modern labs, but historically GC-MS has been the standard for many standard drugs due to its strong separation and spectral library support. Isotope dilution MS refers to using isotopically labeled internal standards to improve quantitation within a method (often GC-MS or LC-MS), rather than a standalone technique.