Determination of uric acid based on carbon nanotube/chitosan composite film modified electrode
XU Junhui， ZHOU Huangxin， WANG Yazhen
Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education， School of Chemistry and Environmental Engineering， Jianghan University， Wuhan 430056， China
Abstract：The carbon nanotube (CNT)/chitosan composite film modified electrode on a glassy carbon electrode had been fabricated. The electrochemical behavior of uric acid was studied at the composite film electrode by cyclic voltammetry and chronocoulometry in detail. The experimental conditions such as supporting electrolytes， pH and accumulation time were optimized. Compared with the bare glassy carbon electrode， the oxidation peak current of uric acid increased greatly， with the negative peak potential shift of about 20 mV， which indicated that CNT/chitosan composite film modified electrode had a good catalytic effect to the electrochemical oxidation of uric acid in pH＝3.95， 0.1 mol/L citric acid salt buffer. The electrochemical behavior of uric acid at this composite film electrode was also characterized by chronocoulometry. The results indicated that oxidation of uric acid involves two-proton two-electron transfer process. Cyclic voltammetry experiment results also showed that the oxidative peak current increased linearly with the concentration of uric acid in the range of 5.0×10－9～5.0×10－7 mol/L and 1.5×10－6～1.0×10－4 mol/L， respectively. One regression equation was i(μA)＝0.8524 c(μmol/L)＋0.1879 with a correlation coefficient of 0.994 7 from 5.0×10－9 to 5.0×10－7 mol/L of UA and another regression equation was i(μA)＝0.04285 c(μmol/L)＋1.299 with a correlation coefficient of 0.988 4 at the range of UA concentration of 1.5×10－6～1.0×10－4 mol/L. The detection limit was 5.0×10－9 mol/L(S/N＝3). The high sensitivity and good selectivity of the composite film electrode was demonstrated by its practical application to the determination of uric acid in urine samples.
2019, Vol. 53 
