An Inexpensive Biosensor for Uric Acid Determination in Human Serum by Flow‐Injection Analysis

An inexpensive and easy to construct miniaturized biosensor is described for the determination of uric acid in biological fluids. The amperometric biosensor was prepared by using a carbon paste electrode prepared with uricase from Arthrobacter globiforms and tetracyanoquinodimethane as electron transfer mediator. When incorporated into a flow‐injection system it was enabled to perform 50 measurements/h of uric acid in the analytical range of 1–100 μmol dm −3 with a relative standard deviation of 0.20% ( n =14). The system was applied to human serum samples analysis providing good data correlation with those obtained by the reference spectrophotometric method. A linear relationship AM (μmol dm −3 )=1.02 (±0.05) SP (μmol dm −3 ) −0.12 (±0.13) was obtained evidencing the absence of significant error. The constructed biosensor was successfully used for at least four months (250 assays) with only a 13% of decrease in the enzymatic activity.