Which statement best describes the relationship between gas chromatography and mass spectrometry in drug identification?

Which statement best describes the relationship between gas chromatography and mass spectrometry in drug identification?

• A. Gas chromatography provides definitive identification; mass spectrometry only separates compounds.
• B. Mass spectrometry identifies substances based on color changes.
• C. Gas chromatography separates compounds; mass spectrometry provides specific identification by mass.
• D. Both only provide qualitative results.

Answer: (C)

The key idea is how GC and MS work together in drug identification: one handles separation, the other provides specific identification based on mass data. Gas chromatography separates components as they travel through a column, giving each compound a distinct retention time. Mass spectrometry then analyzes the separated compounds to produce mass spectra—the unique pattern of fragment masses that identifies a substance by its mass. So, GC does the separating, while MS provides the precise identification by mass, often by matching the spectrum to a library. This is why the statement that GC separates compounds and MS offers specific identification by mass is the best description. Color changes are not part of mass spectrometry, and GC-MS can yield quantitative results with proper calibration, not just qualitative ones.

The key idea is how GC and MS work together in drug identification: one handles separation, the other provides specific identification based on mass data. Gas chromatography separates components as they travel through a column, giving each compound a distinct retention time. Mass spectrometry then analyzes the separated compounds to produce mass spectra—the unique pattern of fragment masses that identifies a substance by its mass. So, GC does the separating, while MS provides the precise identification by mass, often by matching the spectrum to a library. This is why the statement that GC separates compounds and MS offers specific identification by mass is the best description. Color changes are not part of mass spectrometry, and GC-MS can yield quantitative results with proper calibration, not just qualitative ones.