Estimation of aldosterone, 11-deoxycorticosterone, 18-hydroxy-11-deoxy-corticosterone, corticosterone, cortisol and 11-deoxycortisol in human plasma by gas-liquid chromatography with electron capture detection.

A method for determining the plasma concentrations of six major corticosteroids, aldosterone, 18-hydroxy-11-deoxycorticosterone (18-OH-DOC), corticosterone, deoxycorticosterone (DOC), cortisol and 11-deoxycortisol using gas-liquid chromatography with electron capture detection is described. Esterification of suitable derivatives of these compounds with heptafluorobutyric anhydride (HFB) allowed detection of quantitities of steroid, ranging from 0-3 pg for androstenetrione HFB (from cortisol) to 2-3 pg for corticosterone HFB. No detectable reagent blank was obtained for any compound when water was used instead of plasma and this was also the case when plasma from an adrenalectomized subject was analysed, with the exception of 18-OH-DOC where a reproducible but negligibly small blank occurred. Coefficients of variation for replicate determinations ranged from 8% for corticosterone to 17% for aldosterone. Concentrations in a series of normal human plasma samples were as follows: aldosterone, 4-0- 18-0 ng/100 ml; 18-OH-DOC, 20-16- ng/ml; corticosterone, 0-08 - 0.-80 mug/100 ml; DOC, 2-8 - 16-0 ng/100 ml; cortisol, 2-5 - 10-0 mug/100 ml; and 11-deoxycortisol, 40-0 - 400-0 ng/100 ml. When seven normal subjects were treated with dexamethasone concentrations of DOC, cortisol and 11-deoxycortisol fell to below the limit of the normal range, those of 18-OH-DOC and corticosterone were at the lower end of the normal range while the concentration of aldosterone was not significantly affected.