Measurement of Plasma Progesterone and its O-Methyloxime by Gas Chromatography—Nitrogen Detection

A routine method for the quantitation of plasma progesterone, using only 1 ml of sample, has been developed based on gas chromatography—nitrogen detection of the O-methyloxime derivative. Simple solvent extraction of progesterone from plasma using cyclohexane as solvent and medrogestone as internal standard allows measurement at the 3 nmol/l level, while the coefficient of variation at 16, 64, and 127 nmol/l progesterone is 14, 7·5, and 6·5% respectively. Comparison with a radioimmunoassay gave a linear regression equation of Y = 0·84 x + 1·4, Syx = 7·8, r = 0·9255 (n = 55).