High-pressure liquid chromatography analysis of salicylic acid, salicyluric acid, and gentisic acid in biological matrixes.

An assay is reported for salicylic acid and two of its metabolites, salicyluric acid and gentisic acid, in mouse and rat blood, urine, and feces and rat embryos. The procedure involves aqueous dilution of the biological sample, addition of methanol-1% acetic acid (in water) (40:60), centrifugation, and injection of the supernate onto a commerical high-pressure liquid chromatographic column. Detection is via a variable-wavelength UV detector set at 296 nm. Quick and easy sample preparation, good accuracy and precision, and sufficient sensitivity make analysis of large numbers of samples feasible.