ELECTROCATALYTIC OXIDATION AND DETERMINATION OF ASCORBIC ACID BY GLASSY CARBON ELECTRODE MODIFIED WITH BINUCLEAR COPPER(Ⅱ) CO-ORDINATE COMPLEX

A new coordinate complex of LCu2bipy(ClO4)4 was synthesized self-assembly with hydroxyethyl-diethenyl-triamine,α,α′-bipyridyl (abbreviated as L and bipy respectively) and cupric ion,and modified on glassy carbon electrode by electrodeposition.As shown by the result of study on electrochemical behavior,by cyclic voltammetry at scanning rate of 50 mV·s-1 and in the potential range of -0.2-0.8 V,that in a PBS buffer medium of pH 7,the modified electrode showed electrocatalytic oxidation toward ascorbic acid with good reproducibility and high sensitivity.Linear relationship was kept between the values of the catalytic peak current and concentration of ascorbic acid in the range of 4.0×10-5-1.2×10-4mol·L-1,with a detection limit (S/N=3) of 2.5×10-6mol·L-1.In its application to the analysis of 3 kinds of fruit juice sample,values of RSD′s and recoveries obtained were in the range of 1.6%-2.1% and 97.8%-102.1% respectively.