The determination of mandelic acid in urine

Abstract

A method is described for the indirect determination of low concentrations of mandelic acid in urine by using gas-liquid chromatography. The method can also be used with ultraviolet spectrophotometry in place of gas chromatography when samples containing no interfering compounds are to be analysed. The mandelic acid is oxidised by potassium periodate, in dilute sulphuric acid solution, to benzaldehyde, which is separated by simultaneous steam-distillation from interfering compounds before being determined; 395-µg amounts in aqueous solution were determined with accuracies of ±0·62 per cent. (ultraviolet spectrophotometry) and ±3·1 per cent. (gas chromatography). Little interference was observed from compounds with structure similar to mandelic acid, although a small constant value for apparent mandelic acid in normal horse urine was found.