Simultaneous Determination of 3,4-Dihydroxyphenylglycol, 4-Hydroxy-3-methoxymandelic Acid, 4-Hydroxy-3-methoxy- phenylglycol and Their Precursors in Rat-Brain Tissue by High-Performance Liquid Chromatography with Electrochemical Detection

A method was developed for the quantification of 3,4-dihydroxyphenylglycol (DHPG), 4-hydroxy-3-methoxymandelic acid (VMA), 4-hydroxy-3-methoxyphenylglycol (MHPG). The separation and determination of these compounds in biological samples were previously thought to be very difficult. In this work the separation has been well achieved by high-performance liquid chromatography on a reversed-phase column using three mobile phases with a step-wise gradient elution mode. The condition for coulometric detection has been developed for an effective determination of these compounds. In the analysis of the rat-brain tissue, DHPG, VMA and MHPG were separated and determined successfully. The average levels of DHPG, VMA, and MHPG in nine different rat-brain tissue samples were 11.8±0.57, 2.13±0.13 and 6.77±1.84ng/g wet brain, respectively. Simultaneously, their precursors DOPA, DA, NE, DOP AC, HVA, 3MT and NMN, and indolamine 5HT and its metabolite 5HIAA may also be determined by the same chromatographic run.