Selective electrochemical determination of uric acid in the presence of ascorbic acid using a carbon paste electrode modified with beta-cyclodextrin

摘要

Uric acid (UA) was determined in the presence of ascorbic acid (AA) by using a carbon paste electrode modified superficially by a beta-cyclodextrin film (CPE/beta-CD). The surface carbon paste electrode was prepared applying a 30 cycles potential program and using a 1 M HCIO4 + 0.01 M beta-CD electrolytic solution. The UA and AA solutions were used to evaluate the electrode selectivity and sensitivity by cyclic voltammetric and amperometric methods. In these experiments the detection limit for UA was (4.6 +/- 0.01) x 10(-6) M and the RSD calculated from the amperometric curves was 10%. From the data obtained it was possible to quantify UA in the urine and saliva samples. Selective detection of UA was improved by formation of an inclusion complex between beta-CD and UA. The results show that the CPE/beta-CD is a good candidate due to its selectivity and sensitivity in the UA determination in complex samples like the biological fluids.