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, S yx = 7·8, r = 0·9255 (n = 55).
Abstract Bei der Oxidation des Pregnenols (I) mit Bleitetraacetat und Jod erhält man das Lacton (IIa), das auch aus (IIb) durch Hydrolyse und Methylierung hergestellt werden kann.
The excretion of 6-sulphatoxy melatonin in urine has been shown to provide a reliable index of melatonin production in man. Daily measurements made in two healthy ovulating women showed that both the total amount excreted/day and the proportion excreted during the sleep period remained relatively constant for each subject throughout the menstrual cycle. These data do not support the view that there are changes in melatonin production which correlate with cyclical reproductive endocrine function in the human.
Intraindividual variation (CVi) for glycohemoglobin (GHb) was estimated from serial measurements in patients with diabetes in either stable or variable clinical control. GHb determinations were performed by an affinity column procedure with an analytical imprecision of 4.9% (weighted average; GHb 8.2-14.7%). Within the groups of patients, both a short- (28-32 days) and long-term (approximately 85 days) sampling protocol was used. The derived CVi for each category was 4.2% (n = 16, stable, short-term), 7.1% (n = 23, stable, long-term), 5.1% (n = 13, variable, short-term), and 9.8% (n = 21, variable, long-term). The mean GHb within each category was similar (approximately 11%), and there was no statistically significant difference in GHb values between categories. The results establish that the CVi for GHb is affected by both clinical control and the sampling time interval. These findings have important implications for the estimation of significant differences between serial GHb measurements and the setting of appropriate analytical precision goals.
Abstract The formation of the trimethylsilyl cation in the electron impact mass spectra of t ‐butyldimethylsilyl derivatives is shown to involve rearrangement of the t ‐butyl group bound to silicon.
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