Plasma vitamin A analysis by liquid chromatography: Probucol interference
The analysis of plasma retinol by high-performance liquid chromatography (HPLC) has recently become a widely accepted routine method. Many of the published reports involve reverse phase separations using methanol or methanol/water mixtures with ultraviolet (UV) detection. This experimental technique has the advantage of allowing simultaneous determinations of vitamin A (retinol) and vitamin E (α-tocopherol). The accuracy of all analytical chromatography methods is vitally dependent on the purity of the observed chromatographic peak. Constant awareness must be maintained for the presence of extraneous compounds which can coelute with the analyte of interest. This is of particular importance when dealing with pathological samples where the patients may be receiving drugs whose effect on the analysis is unknown. This note reports the interference of probucol (4,4'-(isopropylidenedithio)bis(2,6-di-t-butylphenol)) an anticholesterolaemic agent (Fig.1), on plasma vitamin A analysis.