An Improved Spectrophotometric Method for Determination of Total 3-Methoxy- 4-Hydroxyphenylglycol in Urine

A clinically useful spectrophotometric method for the determination of 3-methoxy-4-hydroxyphenyiglycol (MHPC) is presented. After treatment with barium chloride, the urine is hydrolyzed with Glusulase ($-glucuronidase and sulfatase).f The hydrolysate is passed through a column of Amberlite CG-4Bt to remove any 3-methoxy-4-hydroxymandelic acid (MHMA) and the pH is adjusted to neutral. The MHPG is extracted with ethyl acetate and returned into potassium carbonate solu-tion. Conversion of the MHPG to vanillin is accomplished with periodate and the vanillin is subsequentlyextracted with toluene and then potassiumcarbonate solution. The vanillin concentration is determined at 360 nm and 380 nm. The mean recovery of added MHPG standard was 54.9%. The mean daily excretion of MHPG in 23 samplesfrom 10 normal subjects was 1.87 ± 0.6 mg (range 0.81-3.64). In 3 sub-jects with pheochromocytomathe excretion of MHPC was markedly elevated. There was an excellent correlation of the MHMA and MHPG excretion. IT HAS LONG BEEN RECOGNIZED that the chemical determination of the metabolites of biogenic amines, epinephrine and norepinephrine, is important in the diagnosis of a number of metabolic disorders. In 1957 Armstrong et al (1) postulated that 3-methoxy-4-hydroxymandelic acid (MHMA) was a major urinary metabolite of the catecholamines. Axel-rod et al (2) identified 3-methoxy-4-hydroxyphenylglycol sulfate as an o-methylated catecholamine metabolite in 1959 and suggested the alter-nate pathway for epinephrine and norepinephrine