Automated analysis of urinary 3-methoxy-4-hydroxy-mandelic acid using ion-pair chromatography and fluorimetric detection.

A new rapid high-performance liquid chromatographic method, without urine sample pre-treatment and based on isocratic ion-pair elution, fluorimetric detection and column-switching, has been developed for the determination of vanillylmandelic acid. The sensitivity was 0.1 mg/l, and the linearity was excellent in the concentration range tested. For all endogenous substances as well as for all the drugs tested no interferences were observed. Typical concentrations were in the range 0.3-5.5 mg of vanillylmandelic acid per day, depending on the age of subject under investigation.