Gas chromatography chemical ionization mass spectrometry of prostaglandin Falpha cyclic boronate derivatives.
The electron impact mass spectra of prostaglandins F 1alpha, F 2alpha and F 3alpha methyl ester cyclic 9,11-methane-, n-butane-, cyclohexane- and benzeneboronate 15-trimethylsilyl ethers show base peaks corresponding to [M-(C-16-C-20)]+, i.e. [M-71]+ for prostaglandins F 1alpha and F 2alpha but [M-69]+ for prostaglandin F 3alpha yielding identical ions in the latter two cases. Derivatives of prostaglandin F 2alpha and F 3alpha are difficult to separate by gas chromatography, so that the use of this ion type for single ion monitoring of either prostaglandin (as has been reported) is ambiguous. The chemical ionization mass spectra of these cyclic boronates, however, show distinctive base peaks for prostaglandins F 1alpha, F 2alpha and F 3alpha at m/e 317,315 and 313 respectively, corresponding to [M-RBO2H2-TMSO]+. Fragmentation patterns have been investigated by the use of [3,3,4,4-2H4]prostaglandin F 2alpha and by the formation of [2H9]trimethylsilyl ethers and a [2H3]methyl ester. Cleavage of the C-15-C-16 bond is of minor importance under chemical ionization conditions. The possible value of the [M-RBO2H2-TMSO]+ ions for single ion monitoring is explored: specificity is aided by the formation of the same ions from a series of boronates of characteristic retention indices.
D001896:Boron Compounds; D055598:Chemical Phenomena; D002621:Chemistry; D002849:Chromatography, Gas / Q000379:methods*; D007477:Ions; D013058:Mass Spectrometry / Q000379:methods*; D011460:Prostaglandins F; D011461:Prostaglandins F, Synthetic; D014297:Trimethylsilyl Compounds
D001896:Boron Compounds; D007477:Ions; D011460:Prostaglandins F; D011461:Prostaglandins F, Synthetic; D014297:Trimethylsilyl Compounds