Determination of urinary vanilmandelic acid and homovanillic acid by high performance liquid chromatography with amperometric detection.

A method was developed for the simultaneous determination of urinary vanilmandelic acid and homovanillic acid, which included a two step prepurification and a reversed-phase high-performance liquid chromatography with amperometric detection. Conditions were evaluated for performing measurements with the amperometric detector free from electric interference. The method was linear between 2.5 and 100 mumol/l vanilmandelic acid and homovanillic acid with good precision (CV always less than 10%). The correlation between the present determination of vanilmandelic acid and the procedure of Pisano et al. ((1962) Clin. Chim. Acta 7, 285-291) was very good (r = 0.931). No interfering substances could be detected.