The title paper reports at direct determination of cholesterol using semi-differential absorptive voltammetry at the static mercury drop electrode. Cholesterol adsorbed on the mercury surface yields two peaks at -1.0 and -1.4 V (vs. SCE), resp. in phosphate buffer solution The reductive current of the first peak is linear over the range of 10-7 to 10-6 mol/dm3. Detection limit of 2.3 ?10-8 mol/dm3 is obtained after 10 min preconcn. The concentration of cholesterol in human serum has been determine by this method. It is demonstrated that the adsorption of cholesterol activates its reductive reaction at the mercury electrode.

Key words: VOLTAMMETRY, ADSORPTION, CHOLESTEROL, POTASSIUM COMPOUNDS, SERUM, ELECTROCHEMICAL ANALYSIS, MERCURY ELECTRODE, ELECTRODE REACTION, MONOHYDRIC PHOSPHATE