DETERMINATION OF HYDROPHOBIC SUBSTANCES IN AQUEOUS-ORGANIC AND MICELLAR MEDIA BY USE OF ELECTROCHEMICAL TECHNIQUES

A new electroanalytical methodology for the determination of hormones in micellar media by use of differential pulse polarography (DPP) and adsorptive stripping voltammetry (ASV) is reported. It was applied to the determination of hydroxyprogesterone in Triton X-100 as micellar medium, with a detection limit of 3.6 x 10(-6) M (DPP) and 2.5 x 10(-11) M (ASV). A theoretical explanation for the increased diffusion current of the hormone in the micellar medium is provided and its significance discussed. The electrochemical behavior of this hormone and beta-estradiol in aqueous-organic media was also studied by using DPP and ASV. The detection limits thus obtained for the two compounds were 1.2 x 10(-5) M beta-estradiol and 1.5 x 10(-5) M hydroxyprogesterone by the former technique and 8 x 10(-9) M hydroxyprogesterone by the latter. The beta-estradiol showed no adsorption in any of the assayed media, so the ASV determination of hydroxyprogesterone in its presence was highly selective.