TRANSPORT BEHAVIORS OF STEROID-HORMONES FACILITATED BY HTAB MICELLES THROUGH A WATER MEMBRANE

Transport behaviors of steroid hormones were investigated on a liquid membrane system with hexadecyltrimethylammonium bromide (HTAB) micelles as a carrier separating a hexane source phase and a hexane receiving phase. The experimental results are reasonably explained by a model which hormones transferred from the hexane source phase to the water membrane to be entrapped in HTAB micelles in a diffusion layer close to the hexane/ water interface and transported through the membrane in an entrapping form in micelles and also in a free form. According to this analysis, the dynamical parameters for the transport were determined. The most suitable values for a length of the diffusion layer and a diffusion coefficient of HTAB micell were estimated to be 0.01 cm and 4.4×10-6 cm2/s, respectively, from the experimental results of progesterone transport. In the case of hormone with a lower water/hexane partition coefficient, the uptake process from the hexane source phase to the water phase is rate-determining in the transport process and the hormone transport is accelerated by the addition of HTAB, while the rate-determining step is changed to the release process from the water phase to the hexane receiving phase with an increase of the partition coefficient. Then the transport process is governed by the hormone concentration of free form in the water membrane and the hormone transport is decelerated by the addition of HTAB, because the concentration of free form decreases inversely by the entrapping in micelles for the system having the restricted amount of hormone in the hexane source phase. © 1990, The Chemical Society of Japan. All rights reserved.