Interference by the pigments of liver extract in the spectrophotometric determination of riboflavine by the method of the British Pharmacopoeia 1968 is obviated by chromatography on a column of activated acidic alumina with the mixture chloroform-ethanol (98 per cent.)-glacial acetic acid (50 + 50 + 0·3 v/v); riboflavine passes through the column while liver pigments are retained. The eluate is concentrated by evaporation, buffered at pH 4, then measured spectrophotometrically at wavelength 444 nm.