Quantitative analysis of 11 alpha-hydroxy-9,15-dioxo-2,3,4,5,20-pentanor-19-carboxyprostanoic acid, the major urinary metabolite of E prostaglandins in man.

A system for the assay of the major metabolite of E prostaglandins (PGE-M) in human urine was developed. The metabolite, as the dimethyl ester-bis(O-methyloxime)-trimethylsilyl ether derivative, was quantified by gas chromatography-mass spectrometry with selected ion monitoring. The internal standard was the diethyl ester analog. A linear response ratio over the range 10 to 300 ng of injected prostaglandin was demonstrated in calibrations with authentic material. The 20-ml specimens of urine were extracted with Amberlite XAD-2, methylated, chromatographed over octadecasilyl-silica, silicic acid, and Lipidex-5000, and then methoximated, trimethylsilylated, and instrumentally analyzed. The interassay coefficient of variation, for analysis of four identical urine specimens, was 11% and the intraassay coefficient of variation ranged from 1 to 5%. Specificity, accuracy, and precision of the method were verified by recovery of PGE-M from four different 80-ml urine pools. Each pool was divided into four equal portions, and different amounts of PGE-M were added to three. The recovery of authentic, underivatized PGE-M added to urine was 103.2 +/- 3.3% (mean +/- SE, N = 12). The plot of recovered versus added PGE-M followed the equation y = 1.003x + 1.83, with R = 0.9974.