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-4hydroxyphenyiglycol (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 3methoxy-4-hydroxymandelic acid (MHMA) and the pH is adjusted to neutral. The MHPG is extracted with ethyl acetate and returned into potassium carbonate solution. 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 subjects with pheochromocytomathe excretion of MHPC was markedly elevated. There was an excellent correlation of the MHMA and MHPG excretion.