Electrochemical Determination of Vanillylmandelic Acid and Its Analogous Compounds

Determination of vanillylmandelic acid in urine by use of catalytic maximum wave in differential pulse polarography

“…In a more recent application of this technique, a retention time reproducibility of 0.9-1.3% RSD was reported (11). Several authors have used microexponential diluters (12)(13)(14)(15). In such a system, the gradient is formed in a stirred mixing vessel.…”

“…After the initial solvent is introduced via a switching valve, the final solvent is allowed to dilute the initial solvent exponentially. Retention time reproducibilities are reported to be 1.8 (13) or 1-1.5% (14) RSD. A similar approach to gradient elution made use of a series of linked micro-exponential diluters (16,17).…”

“…The velocity of the electrode reaction is limited by formation of the active intermediate complex as shown in eq 3. We have already reported the catalytic effect of 11 different kinds of organic compounds containing VMA in the presence of Mo(VI) and brómate ions (14). Thus, an analogous compound like mandelic acid gives a remarkably "catalytic maximum wave" using a dropping mercury electrode (DME) in the DP mode ( 9), which is about 500-1000 times the oxidation current of VMA on glassy carbon electrode, according to eq 1-4.…”

Functional group analysis

“…Vanillylmandelic acid and related compounds exert a catalytic effect on oxidation of Mo( VI) in the presence of Br03". With differential-pulse polarography, it is possible to determine the concentration of the above acids (27).…”