Letter: The formation of a M + 2 compound in the analysis of a trimethylsilyl derivative of monocarboxylic acids by gas chromatography electrospray ionization mass spectrometry.

The trimethylsilyl (TMS) derivative is one of the most widely utilized derivatives for analyzing polar compounds by gas chromatography. An ion two mass units higher than the protonated molecular ion was observed in analyzing TMS-monocarboxylic acids by using gas chromatography electrospray ionization mass spectrometry (GC-ESI/MS). The structure of the M + 2 compound was investigated using tandem mass spectrometry and high-resolution mass spectrometry. The results suggest that one methyl group bound to the silicon atom was replaced by a hydroxyl group during the ESI process. One possible mechanism for the formation of the M + 2 compound is proposed. This observation suggests the possibility of synthesizing an organic compound by using ESI.