Mass spectral peaks, drugs

A second software feature capitalizes on the fact that many potential drug candidates contain atoms that are not naturally occurring in the body and which possess unique isotopic patterns. In particular, chlorine and bromine atoms give unique and distinctive mass spectral signals. The computer can evaluate the sample dataset and find any chromatographic peaks that contain these characteristic isotopic patterns. An example of how these software routines can simplify a complex chromatogram is shown in Fig. 2. This compound contained a tritium label, so the top trace (A) shows peaks corresponding to radioactive metabolites. The second... 

The molecular mass of the isolated Impurity A was confirmed to be 60 Da higher than the drug substance. This mass spectral confirmation on the isolate is critical prior to NMR analysis to assure that the correct peak has been isolated and that there are no changes that are due to contamination or degradant of the sample. Typically, this should be performed on the fraction collected from first preparative injections to confirm peak identity. 

Decision 2002/657/EC and CAC/GL 71-200932 contain additional performance requirements for mass spectral methods used in the confirmation of veterinary drug residues in foods. It should be noted that the performance specifications given for GC-MS methods using El spectra are more stringent than for other techniques, including GC-MS with Cl, LC-MS, and LC-MS/MS. It is also recommended that only ions with an intensity >10% of the base peak should be used as analytical peaks for confirmation. The EU and CAC requirements address performance of both the chromatographic system and the mass spectrometer ... 

The early work on requirements for confirmatory mass spectrometric methods was undertaken to address a regulatory requirement for the analysis of carcinogens established in 1977 by the US Food and Drug Administration. A paper published in 1978 demonstrated the minimum number of peaks and the specifications for relative ion abundances for each peak required to uniquely identify diethylstilbestrol from a GC-MS spectral library containing El spectra of... 

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