Mass spectrometry of prostaglandins, leukotrienes and steroids as their allyldimethylsilyl ether derivatives

Abstract

Allyldimethylsilyl ethers of prostaglandin E₂ and F_2α, leukotriene B₄ and 5β‐pregnane‐3α, 20α‐diol were prepared at room temperature in good yields with the novel reagent N, O‐bis(allyldimethylsilyl)‐trifluoroacetamide. The gas chromatographic properties of the derivatives of prostaglandins and the steroid were found to be excellent whereas those of leukotriene B₄ were found to be less than satisfactory. The mass spectra of the allyldimethylsilyl ether derivatives of the compounds studied show intense ions in their upper mass region derived from the elimination of an allyl radical. In the mass spectrum of the derivative of leukotriene B₄, the formation of a conjugated carbonium ion by α‐cleavage is a major process. The detection limits for a quantitative assay were established by performing selected ion monitoring on the most intense ion in the upper mass region of respective mass spectrum. Detection limits in the low picogram range were obtained for the prostaglandins and the steroid but the allyldimethylsilyl ether derivative of leukotriene B₄ exhibited a far higher detection limit. It is concluded for the latter compound that the detection limit depends primarily on the gas chromatographic properties.