In GC-MS confirmation, what combination confirms an analyte's identity?

In GC-MS confirmation, what combination confirms an analyte's identity?

• A. Retention time alone determines identity.
• B. Mass spectral data is used only for calibration, not identity.
• C. Retention time is matched to standards and mass spectral fragmentation patterns are compared to libraries with defined criteria.
• D. Mass spectral data is unused if retention time matches.

Answer: (C)

The key idea is that confirming an analyte’s identity in GC-MS requires two independent lines of evidence: where the compound elutes and how it fragments. The strongest approach is to match the observed retention time to a known standard under the same GC conditions and to compare the observed mass spectral fragmentation pattern to a reference library using predefined criteria. This combination is powerful because retention time alone can drift between runs or be similar for different compounds, and a mass spectrum by itself can be ambiguous due to shared fragments or closely related structures. When the retention time falls within the expected window and the mass spectrum yields a robust library match that meets set criteria, you have high confidence in the identity.

The key idea is that confirming an analyte’s identity in GC-MS requires two independent lines of evidence: where the compound elutes and how it fragments. The strongest approach is to match the observed retention time to a known standard under the same GC conditions and to compare the observed mass spectral fragmentation pattern to a reference library using predefined criteria. This combination is powerful because retention time alone can drift between runs or be similar for different compounds, and a mass spectrum by itself can be ambiguous due to shared fragments or closely related structures. When the retention time falls within the expected window and the mass spectrum yields a robust library match that meets set criteria, you have high confidence in the identity.