Gas Chromatographic and Mass Spectrometric Identification of New Specific Derivatives of Prostaglandins A and E: Application to Prostaglandin Profiling in General

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Abstract
The direct derivatization of PGEs and PGAs with a mixture of BSTFA/piperidine has produced two new types of derivatives whose respective mass spectral patterns correspond to those of a 9-enol PGE(TMS)4 and a 11-piperidyl-9-enol PGA(TMS)3 derivative, respectively. The most remarkable characteristic in the case of PGAs lies in the exceedingly simple and specific mass spectral pattern practically composed of a single ionic species at M-173. The reaction mechanisms have been studied in some detail by using (a) different combinations of silylating agent (BSTFA, BSA or TMSI)/piperidine and (b) BSTFA/nonaromatic-containing heterocyclics (piperidine, hexamethylenimine, pyrrolidine, propylenimine or morpholine). BSTFA appears to be the silylating agent required for the quantitative reduction of the 9-keto group of both PGs while in the case of PGAs the earlier suggestion of a nucleophilic addition of piperidine to C-11 applies to other heterocyclics as well. The corresponding mass spectra, herein reported, are almost identical, allowing for the molecular weight differences, to that obtained with the piperidyl derivative. The application of this new derivatization procedure to the concurrent GLC determination of PGAs Es, Fs and Bs facilitates the study of their GLC profiles which, compared to the profiles obtained by combined methoximation silylation, appear to be more convenient for prostaglandin profiling.