Ferrocene-based electroactive derivatizing reagents for the rapid selective screening of alcohols and phenols in natural product mixtures using electrospray-tandem mass spectrometry

The alcohols and phenols of oil of cloves, lemon oil, rose absolut, and oil of peppermint were derivatized with ferroceneoyl azide to generate their ferroceneoyl carbamates. These derivatives are selectively detected at the attomole level, in nanomolar concentrations by electrospray-tandem mass spectrometry (ES-MS/MS) without the need for sample cleanup. The ES-MS/MS analyses of the four essential oils revealed all the expected alcohols, and, in the case of lemon oil, it detected alpha-terpineol as a trace component that was not readily observed by GC-MS. The ES-MS/MS analyses complements the more conventional GC-MS analysis. The ES-MS method has the advantage of speed, selectivity, and sensitivity over GCMS for detection of a targeted alcohol of a specific mass or structural type. The ES-MS method does not require a chromatographic separation of the components to accomplish its task. In contrast, GC-MS remains the preferred method for the determination of the total constituents of an oil. The ES-MS method may produce artifact ions, especially if the sample is wet and an excess of the ferroceneoyl azide is used; however, the artifacts did not interfere with the analyses.