Enhanced detection and structural characterization of flavonoids by complexation with N,O-bis(trimethysilyl)trifluoroacetamide using electrospray ionization mass spectrometry.

Many natural products contain flavonoids that display biological effects when ingested by humans and animals. Flavonoids have received a great deal of research interest, especially for possible cancer and heart disease-preventive properties. The content and the quality of each flavonoid may be a key to their biological effects. The recent development of electrospray ionization mass spectrometry (ESI-MS/MS) has made it possible to use it to study molecular interactions. In the present work, we investigated the derivatization procedures for three flavonoids (chrysin, genistein, and luteolin) by using ESI-MS/MS. Each flavonoid and the derivatization reagent, N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), are mixed using acetonitrile and the mixture is introduced through an electrospray needle. The signal intensities for the derivative ions significantly increased, almost two or three orders of magnitude increased as compared to those for the protonated molecular ions of the flavonoids. Mass spectra of trimethylsilyl derivatives are fragmented at a fixed pattern by collision induced dissociation to obtain the structural relevance of the derivative flavonoids. Further fragmentation studies have been performed and results are discussed in detail. The results in the positive mode detection show that better high intensity data and more simplification of peaks appeared than that for the underivatized cases.