GAS CHROMATOGRAPHY-MASS SPECTROMETRY OF O-METHYLOXIME DERIVATIVES OF PROSTAGLANDINS

O-methyloxime trimethylsilyl ether derivatives and O-methyloxime acetyl derivatives of prostaglandins containing a β-ketol system in the five membered ring and in some cases an additional keto group in the side chain have been found to be stable during gas chromatography. GLC data obtained under different conditions are presented. The mass spectrometric fragmentation of the compounds has been investigated using derivatives deuterated in the methyl ester group, the methoxime group, the trimethylsilyl ether groups or the acetyl groups. The molecular ion can generally be seen. Eliminations characteristic for trimethylsilyl ether and acetyl derivatives were observed and in addition 1β-cleavage at the methoxime group. The latter reaction was in some cases accompanied by transfer of hydrogen to the charge retaining ion and loss of CH3O from the methoxime group. These reactions are of value for determination of location of keto groups and of the nature of substituents. © 1969.