The analysis of uric acid in urine using microchip capillary electrophoresis with electrochemical detection

Clinical studies have linked irregular concentrations of uric acid in urine to several diseases. Conventional methods for the measurement of uric acid are however temperature-dependent, expensive, and require labile reagents. The miniaturization of analytical techniques, specifically capillary electrophoresis, offers an ideal alternative for clinical analyses such as uric acid determination. The added benefits include reduced reagent and analyte consumption, decreased maintenance costs, and increased throughput and portability. A microchip capillary electrophoresis-electrochemical system for the analysis of uric acid in urine is described. The poly(dimethylsiloxane) (PDMS)/glass microchip utilizes amperometric detection via an off-chip platinum working electrode. Linear responses from 1 to 165 microM and 15 to 110 microM were found for dopamine and uric acid, respectively. The limit of detection for both compounds was 1 microM. Once characterized, the system was used to measure the concentration of uric acid in a dilute urine sample in less than 30 s. The measured uric acid concentration was verified with the uricase reaction and found to be acceptable. Six additional urine samples were evaluated with the microchip device and the uric acid concentration for each sample was found to be in the expected clinical concentration range.