Thermospray liquid chromatography/mass spectrometry of prostaglandin methyl ester derivatives: application to the determination of prostaglandins E2 and D2 in rat gastric mucosa.

Methyl ester derivatives of 6-keto prostaglandin (PG) F1 alpha, PGF 2 alpha, PGE2 and PGD2 as well as methyl oximes of 6-keto PGF1 alpha, PGE2 and PGD2 have been analysed by thermospray high-performance liquid chromatography mass spectrometry. These compounds are eluted in a gradient of ammonium acetate buffer-acetonitrile at pH 3.4 using a 5 micron ODS-2 reversed-phase column. The mass spectral patterns of the PG derivatives are discussed relative to those of non-derivatized PGs. In general, the methyl ester derivatives show better characteristics than the non-derivatized PGs for the analysis of these compounds in a biological matrix, both from a chromatographic as well as from a mass spectrometric standpoint. Detection limits between 100 and 600 pg on-column can be achieved. Response curves in the selected ion monitoring mode for PGF2 alpha, PGE2 and PGD2 are linear in the range from 100 pg to 10 ng. The technique has been applied to the analysis of PGE2 and PGD2 in rat gastric mucosa.