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

Abstract

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±1.84 ng f g wet brain, respectively. Simultaneously, their precursors DOPA, DA, NE, DOPAC, HVA, 3MT and NMN, and indolamine 5HT and its metabolite 5HIAA may also be determined by the same chromatographic run.

Stability of Catecholamines, Indolamines and Related Metabolites in the Process of Sample Preparation with Ultrasonication and an Analysis by High-Performance Liquid Chromatography

“…The chromatographic conditions were described in our recent report. 2 Chromatograms are not shown in this paper.…”

“…1,2 In conclusion, most monoamines and related compounds may be decomposed by an ultrasonic physicochemical effect during the process of sample preparation. A better condition for an ultrasonic treatment includes two points: take thermo-control at 3˚C and use a short time course, such as less than 10 min.…”

“…[1][2][3][4][5] During the work of analyzing neuroamines in brain tissue, urine or plasma using HPLC with electrochemical detection (ECD), we prepared these biological samples and noticed the influence of ultrasonication, that is, it badly decreased the recovery of compounds of interest. Until recently, however, the influence of ultrasonication on the stability of catecholamines, indolamines and related metabolites had not been investigated.…”

Simultaneous determination of 3,4-dihydroxymandelic acid, 4-hydroxy-3-methoxymandelic acid, 3,4-dihydroxyphenylglycol, 4-hydroxy-3-methoxyphenylglycol, and their precursors, in human urine by HPLC with electrochemical detection

“…Applying this technique, we applied 0.4 V and -0.3 V, respectively, to the conditioning cell and the second working electrode of the analytical cell. To select a high-efficiency potential for the first working electrode we investigated the effect of three potentials on the reduction current [21]. As shown by the curve obtained, a potential of 0.2 V was chosen.…”