THE DIETHYLHYDROGENSILYL-CYCLIC DIETHYLSILYLIVE DERIVATEVE IN THE GAS CHROMATOGRAPHY-MASS SPECTROMETRY OF THROMBOXANE B₂

Abstract

The diethylhydrogensilyl-cyclic diethylsilylene (DEHS-DES) derivative of thromboxane B₂ (TXB₂) methyl ester-methyloxime was prepared by treating with diazomethane, O-methylhydroxylamine-HCl and then with N, O-bis(diethylhydrogensilyl)trifluoroacetamide (DEHS-BSTFA). The gas chromatogram of the reaction product showed a well-resolved doublet using a 5% phenylmethylsilicon cross-linked fused silica capillary column, corresponding to the syn- and anti-isomers. In their mass spectra, these components showed an ion of at 269 as a base or prominent peak. This ion and many other characteristic ions reflect the TXB₂ system with moderate intensity. The ion at m/z 269 consisted of a fragment of the DES ring moiety and the α-side chain. The mass spectrum of the second eluting component was considerably more complex than that of the first. Almost all of the fragment ions in the mass spectrum of the first eluting component were also observed in that of the second component. When gas chromatography/high resolution-selected ion monitoring (GC/HR-SIM) was carried out at a resolutioin of 8000 to monitor the ion of m/z 269. 1753, specific for the structural integrity of TXB₂, the selected ion recording (SIR) showed a well-shaped doublet with signal to noise ratio (S/N) of greater than 300 after an injection of 25 pg of the derivative.