THE DETERMINATION OF 5α-ANDROSTANE-3α,17β-DIOL IN HUMAN PLASMA BY RADIOIMMUNOASSAY

1978 ◽  
Vol 88 (4) ◽  
pp. 778-786 ◽  
Author(s):  
P. Laband ◽  
J. A. F. Tresguerres ◽  
B. P. Lisboa ◽  
U. Volkwein ◽  
J. Tamm
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Human Plasma ◽  
Cross Reactions ◽  
Idiopathic Hirsutism ◽  
Coefficients Of Variation ◽  
The Cross ◽  
Normal Males ◽  
Layer Chromatography

ABSTRACT Antibodies have been raised in rabbits against 3α,17β-dihydroxy-5α-androstane-6-0-carboxymethyloxime coupled with Cohn's fraction IV-4. The antiserum exhibited significant cross reactions with 5β-androstane-3α,17β-diol, 5α-dihydrotestosterone, and testosterone. No cross reactions were observed with 5α-androstane-3β,17β-diol and 5-androstene-3β,17β-diol. The methodological criteria for the measurement of 5α-androstane-3α,17β-diol in human plasma were as follows: The specificity was ensured by separating the cross reacting steroids by thin layer chromatography. The intraassay and interassay coefficients of variation were found to be 6.2 and 10.2 %, respectively. The sensitivity was 30 pg. The recovery of different amounts of 5α-androstane-3α,17β-diol added to human plasma (80, 120, and 200 pg) yielded 91.3, 92.5, and 93.5%, respectively. The following concentrations of 5α-androstane-3α,17β-diol have been determined in human plasma (mean ± sd, ng/dl): Normal males: 18.98 ± 5.9; normal females: 2.65 ± 0.27; females with idiopathic hirsutism: 11.9 ± 6.4; pre-pubertal children: not detectable.

Improvement of Chemical Analysis of Antibiotics. Part XIX1: Determination of Tetracycline Antibiotics in Milk by Liquid Chromatography and Thin-Layer Chromatography/Fast Atom Bombardment Mass Spectrometry

1994 ◽  
Vol 77 (4) ◽  
pp. 891-895 ◽  
Author(s):  
Hisao Oka ◽  
Yoshttomo Ikai ◽  
Junko Hayakawa ◽  
Katsuyoshi Masuda ◽  
Ken-Ichi Harada ◽  
...  
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Mass Spectra ◽  
High Sensitivity ◽  
Tetracycline Antibiotics ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic ◽  
Layer Chromatography ◽  
Fab Mass Spectra

Abstract A precise liquid chromatographic (LC) determination with high sensitivity and a reliable mass spectrometric (MS) confirmation were established for the determination of tetracycline antibiotics (TCs) in milk. The determination of the TCs was based on C18 cartridge cleanup followed by LC separation. Recoveries of TCs from milk fortified at 20 ppb were 73.0–81.8%, and coefficients of variation were 2.6–4.6%. With this method, concentrations of oxytetracycline and tetracycline as low as 10 ppb and chlortetracycline and doxycycline as low as 20 ppb were determined readily. Thin-layer chromatography (TLC)Zfast atom bombardment (FAB) MS with a condensation technique was used to confirm TCs in milk. After the C18 cartridge cleanup, separation on a C18 TLC plate, and application of the sample condensation technique, FAB mass spectra were measured. TCs in milk at 50 ppb were reliably confirmed by TLC/FABMS.

scholarly journals Determination of Cortisol in Human Plasma by Radioimmunoassay

1977 ◽  
Vol 14 (1-6) ◽  
pp. 343-349 ◽  
Author(s):  
G. F. Read ◽  
Diana R. Fahmy ◽  
R. F. Walker
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Human Plasma ◽  
Plasma Cortisol ◽  
Specific Radioimmunoassay ◽  
Precision And Accuracy ◽  
Layer Chromatography

A radioimmunoassay for plasma cortisol featuring the gamma-emitting radioligand 125I-iodohistamine, coupled to cortisol-3-(O-carboxymethyl)-oxime, is described. The new procedure retains much of the specificity associated with the use of anti-cortisol-3-BSA sera with tritium-labelled radioligands, and has the further advantages that running costs are lower and there is a greater potential for automation. Cortisol values obtained by this procedure agree well with those obtained by a published specific radioimmunoassay using the tritiated cortisol radioligand. Specificity of the procedure was checked by comparing values obtained with and without thin-layer chromatography purification: correlation was excellent (r = 0·96). Satisfactory levels of sensitivity, precision, and accuracy were obtained.

Determination of Aflatoxins in Vegetable Oils

1985 ◽  
Vol 68 (1) ◽  
pp. 136-137
Author(s):  
Noah Miller ◽  
Helena E Pretorius ◽  
Donald W Trinder
Keyword(s):  
Liquid Chromatography ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Vegetable Oils ◽  
Simple Method ◽  
Silica Column ◽  
Coefficients Of Variation ◽  
Layer Chromatography ◽  
Chloroform Methanol

Abstract A simple method is proposed for determination of aflatoxins in vegetable oils. The method was successfully applied to both crude and degummed oils. The oil sample, dissolved in hexane, was applied to a silica column and washed with ether, toluene, and chloroform; aflatoxins were eluted from the column with chloroform-methanol (97 + 3). As quantitated by thin layer chromatography and liquid chromatography, the oils analyzed contained aflatoxin Bx at levels of 5-200 αg/kg. Recoveries of aflatoxin Bi standards added to aflatoxin-free oils were between 89.5 and 93.5%, with coefficients of variation of 6.3- 8.0%.

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