Abstract
Sterols with not any or isolated double bonds in the steroid skeleton are problematic analytes, as they rarely exhibit electrochemical/fluorescent activity or sufficient absorbance in UV spectra. In this contribution the possibilities of their electrooxidation on platinum, glassy carbon, and boron-doped diamond electrodes were investigated in acetonitrile and mixed media of acetonitrile:water.
Their presence in solution can be traced either as well-developed anodic voltammetric signal at reasonable potentials of around +1.2 V / +1.6 V (vs. Ag/0,01 mol l(-1) AgNO3/1 mol l(-1) NaClO4) when using minimal content of water in acetonitrile or as earlier onset of anodic current compared to supporting electrolyte solution in non-aqueous media.
Voltammetric methods based on evaluation of these signals exhibit detection limit in the micromolar range for cholesterol and bile acids. Factors influencing the stability of this signal, including the pretreatment of the electrode surface and structure of the particular sterols will be discussed.