scholarly journals Ultramicro determination of plasma testosterone by electron-capture detection of testosterone diheptafluorobutyrate

1968 ◽  
Vol 107 (2) ◽  
pp. 285-292 ◽  
Author(s):  
D. Exley
Keyword(s):  
Electron Capture ◽  
Accurate Determination ◽  
Internal Standard ◽  
High Sensitivity ◽  
Electron Capture Detection ◽  
Plasma Testosterone ◽  
Gas Liquid Chromatography ◽  
Radioactive Label ◽  
Peripheral Plasma

1. A new highly sensitive and accurate ultramicro method for the estimation of testosterone in human peripheral plasma is described. The method uses paper-and thin-layer-chromatographic separation of plasma testosterone, which is determined as testosterone diheptafluorobutyrate by electron-capture detection after gas–liquid chromatography. 2. The average difference between duplicates is ±2% (range 1–5%) with as little as 2·5ml. of human male peripheral plasma. With 10ml. of plasma the method is sensitive enough for the accurate determination of testosterone in human female plasma. The high order of accuracy is achieved by the use of a radioactive label and an internal standard for gas chromatography, and by obtaining several gas chromatograms from the same plasma sample. 3. As little as 40μμg. of peripheral plasma testosterone can be detected. The method is 20 times as sensitive as electron-capture techniques with the monochloroacetate derivative. 4. The method is simpler and quicker than double-isotope-derivative methods, and slightly more sensitive. The advantages of the method, which is specific for testosterone, are its high sensitivity and accuracy, which are achieved with relative convenience.

scholarly journals Determination of δ-aminolaevulinic acid in biological fluids by gas-liquid chromatography with electron-capture detection

1984 ◽  
Vol 219 (3) ◽  
pp. 883-889 ◽  
Author(s):  
A Gorchein
Keyword(s):  
Cerebrospinal Fluid ◽  
Liquid Chromatography ◽  
Electron Capture ◽  
Biological Fluids ◽  
Internal Standard ◽  
Electron Capture Detection ◽  
Gas Liquid Chromatography ◽  
Aminolaevulinic Acid ◽  
Highly Sensitive

A derivative of delta-aminolaevulinic acid (AmLev), 2-methyl-3-acetyl-4-(3-propionic acid pentafluorobenzyl ester)pyrrole, with favourable properties for g.l.c. with electron-capture detection, was synthesized. Less than 1 pg could be detected on the column. 6-Amino-5-oxohexanoic acid formed the analogous derivative under similar conditions and was used as the internal standard in the development of a highly sensitive and specific assay for AmLev. The method has been applied to peripheral-venous and umbilical-cord plasma and to cerebrospinal fluid of normal and porphyric subjects.

DETERMINATION OF PLASMA OESTRIOL IN NORMAL PREGNANCY AND LABOUR USING GAS-LIQUID CHROMATOGRAPHY

1971 ◽  
Vol 51 (3) ◽  
pp. 447-454 ◽  
Author(s):  
W. COOPER ◽  
M. G. COYLE ◽  
J. A. MILLS
Keyword(s):  
Gas Chromatography ◽  
Liquid Chromatography ◽  
Quantitative Determination ◽  
Internal Standard ◽  
Normal Pregnancy ◽  
Gas Liquid Chromatography ◽  
Chemical Purification ◽  
Peripheral Plasma ◽  
Pregnancy And Delivery

SUMMARY A method is described for estimating oestriol in 2–10 ml samples of human pregnancy peripheral plasma. It incorporates acid hydrolysis, chemical purification, methylation, chromatography on alumina columns, formation of a derivative and quantitative determination by gas chromatography. A radioactive internal standard was added to correct for procedural losses. Plasma oestriol determinations in five normal patients throughout pregnancy and delivery are reported.

PERINIDATORY OVARIAN OESTROGEN SECRETION IN THE PREGNANT RAT, DETERMINED BY GAS CHROMATOGRAPHY WITH ELECTRON CAPTURE DETECTION

1972 ◽  
Vol 53 (2) ◽  
pp. 249-260 ◽  
Author(s):  
A. NIMROD ◽  
SHOSHANA LADANY ◽  
H. R. LINDNER
Keyword(s):  
Electron Capture ◽  
Venous Blood ◽  
Electron Capture Detection ◽  
Vaginal Smear ◽  
Specific Method ◽  
Gas Liquid Chromatography ◽  
Uterine Receptivity ◽  
Pregnant Rat ◽  
Ovum Implantation

SUMMARY A sensitive and specific method is described for the determination of oestradiol-17β and oestrone in blood by gas-liquid chromatography with the use of an electron capture detector. The rate of secretion of these steroids into the ovarian venous blood of rats was determined on the day of pro-oestrus (six animals) and at various times during the first 8 days of pregnancy (240 animals). Oestradiol output (pg/ovary/30 min, mean ± s.e.m.) was low during day 1 (the day sperm were present in the morning vaginal smear) and until 11.00 h on day 2 (59 ± 13), but rose rapidly and significantly on the afternoon of day 2 (299 ± 46). From day 3 to day 8 an increased secretion rate was maintained (451 ± 26), though this was well below the level found on the day of pro-oestrus (mean 8·8 ng oestradiol and 1·2 ng oestrone/ovary/30 min). Oestradiol secretion during early pregnancy tended to be higher in the afternoon than in the morning. Oestrone output roughly paralleled that of oestradiol, but was only about one third as high. No distinct peak in the rate of secretion of either steroid was demonstrable on day 4. The results strengthen the view that ovarian oestrogen secretion has an essential role in ovum implantation in the rat, but are incompatible with the hypothesis that the time of uterine receptivity to the blastocyst and of uterine sensitivity to atraumatic deciduoma induction is determined by a discrete discharge of oestradiol or oestrone from the ovary on the afternoon of the 4th day post coitum — the so-called 'oestrogen surge' theory.

DETERMINATION OF DEHYDROEPIANDROSTERONE AND DEHYDROEPIANDROSTERONE SULPHATE IN HUMAN PLASMA USING ELECTRON CAPTURE DETECTION OF 4-ANDROSTENE-3,6,17-TRIONE AFTER GAS-LIQUID CHROMATOGRAPHY

1972 ◽  
Vol 53 (3) ◽  
pp. 461-474 ◽  
Author(s):  
F. H. de JONG ◽  
H. J. van der MOLEN
Keyword(s):  
Liquid Chromatography ◽  
Electron Capture ◽  
Plasma Concentrations ◽  
Mean Value ◽  
Electron Capture Detection ◽  
Gas Liquid Chromatography ◽  
Mean Values ◽  
Peripheral Plasma ◽  
Competitive Protein Binding ◽  
The Mean

SUMMARY A method for the measurement of dehydroepiandrosterone (DHA) and of its sulphate (DHAS) in human peripheral plasma is described and evaluated. After isolation of DHA from the sample the steroid is oxidized to 4-androstene-3,6,17-trione, which is measured with an electron capture detector after gas—liquid chromatography. It is possible to detect 100 pg 4-androstene-3,6,17-trione. The smallest amount of DHA per sample that can be distinguished from zero is approximately 4 ng, when recovery (27·9 ± 8·8%) and method blank (0·23 ± 0·38 ng) are taken into account. The oxidation to 4-ene-3,6-diones is specific for steroidal 5-en-3-ols. Specificity for DHA is ensured by several chromatographic steps. Repeated estimation of 10 ng DHA gave a mean value of 9·6 ± 1·45 (s.d.) ng (n = 35). Mean concentrations and their standard deviations for DHA and DHAS in peripheral plasma from 18 individuals were 0·50 ± 0·25 and 78 ± 40 μg/100 ml, respectively, at 08.30 h and 0·32 ± 0·17 and 84 ± 34 μg/100 ml, respectively, at 17.00 h of the same day. Levels of plasma cortisol in the same plasma samples estimated with a competitive protein-binding method were 16·7 ± 1·8 and 11·9 ± 3·8 μg/100 ml, respectively. No significant differences between the sexes were observed by any of the three assays. The mean values of the plasma concentrations of cortisol and DHA in the morning were significantly higher than those in the evening (P < 0·001 and P < 0·005, respectively). In contrast, the mean value of the plasma levels of DHAS in the morning was significantly lower than that in the evening (P < 0·025).

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