High-Performance Anion Exchange Chromatography Electrochemical Determination of Uric Acid as a Contamination Marker

This study presents the first instance of determining environmental uric acid in urban dust using high-performance anion exchange chromatography coupled with electrochemical detection. The optimum chromatographic conditions were identified as a 10 mm × 4.6 mm, 10 µm anion exchange column with a mobile phase of pH 8 50 mM phosphate buffer. Cyclic voltametric investigations over a pH range of 2 to 12 showed that uric acid gave a single diffusion-controlled peak. Hydrodynamic voltametric studies of uric acid using a mobile phase of 50 mM pH 8.0 phosphate buffer over the range 0.0 V to +1.4 V (vs. stainless steel) showed a similar single oxidation wave, which plateaued at potentials more positive than +0.7 V (vs. stainless steel). An applied potential of +0.90 V (vs. stainless steel) was chosen for further investigations, and a linear range of 0.10 to 100 mg/L was obtained, with a detection limit of 0.866 mg/L based on a signal-to-noise ratio of 3. Dust wipe samples were extracted in pH 8, 50 mM phosphate buffer with the aid of sonication. Recoveries of 99.6% (% CV = 4.52%) were achieved for the dust wipe fortified with 16.8 µg of uric acid. Nitrate, nitrite, chloride, acetate, and sulfate ions were found not to interfere. The dust wipe samples were found to have uric acid levels of between 32.6 µg/m2 and 3.98 mg/m2.