Specific determination of 3-methoxy-4-hydroxyphenylethylene glycol in urine by liquid chromatography with post-column reaction.

We describe a "high-performance" liquid-chromatographic method for determining 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) in human urine. MHPG is separated on a reversed-phase column with isocratic elution, oxidized with sodium metaperiodate, and its absorbance measured at 365 nm. This method shows higher specificity, less interference for MHPG than methods involving electrochemical or fluorescence detection. Post-column derivatization of MHPG with periodate yields vanillin. The detection limit (twice the signal-to-noise ratio) in urine samples was 0.08 mg/L. Mean analytical recovery was 72%. Within-assay and day-to-day CVs were 2.9% and 6.5%, respectively. Reference intervals for MHPG in 24-h urine from apparently healthy subjects were 0.85-3.24 mg/day for men and 0.63-2.20 mg/day for women. In terms of creatinine excretion, the respective reference intervals were 0.55-1.99 and 0.70-1.96 mg per gram of creatinine.