Uric acid determination in the presence of ascorbic acid using self-assembled submonolayer of dimercaptothiadiazole-modified gold electrodes

This article reports the determination of uric acid (UA) in the presence of ascorbic acid (AA) using a self-assembled submonolayer of heteroaromatic dithiol, 2,5-dimercapto-1,3,4-thiadiazole (DMcT), on gold (Au) electrode. Submonolayer to multilayers of DMcT can be prepared on Au electrode by varying the soaking time of Au electrode in 1 mM aqueous solution of DMcT. The formation of submonolayer, monolayer, and multilayers of DMcT on Au electrode was confirmed from its reductive desorption measurements and electrochemical blocking behavior toward ferricyanide. Interestingly, submonolayer of DMcT separates the voltammetric signal of UA from AA by 210 mV, whereas monolayer and multilayers of DMcT fail to separate them. The voltammetric signals of AA and UA are highly stable and reproducible at submonolayer of DMcT. Fast electron transfer, weak hydrogen bonding interactions with AA and UA, and prevention of fouling effect caused by oxidized product of AA can be achieved at submonolayer of DMcT, and thus it successfully separates the voltammetric signals of AA and UA. The practical application of the current system is demonstrated by measuring the concentration of UA in human urine samples without any treatment. (c) 2006 Elsevier Inc. All rights reserved.