Amperometric detection of Uric Acid and Hypoxantine with Xanthine oxidase immobilized and carbon based screen-printed electrode for fish freshness determination

摘要

A continuous system for the detemination of fish freshness with carbon-based screen-printed electrode was developed and applied to the determination of the freshness indicator K = 100 (HxR + Hx) / (IMP + HxR + Hx), where IMP, HxR and Hx are Inosine monophosphate. Inosine and Hypoxanthine, respectively. Hypoxanthine and related compounds determination was based on Uric acid (AU) detection at a potential of 450 mV vs Ag/AgCl. Xanthine oxidase (XO) was immobilized in a reactor with CPG aminopropylsilane in a FLA assembly. Higher reproducibility and lifetime was obtained and optimum conditions were found for the determination of AU, Hx, HxR and IMP. Calibration graphs are linear up to 50 muM with detection limit of 1 muM for 50 mul injection. One assay is completed within 30 seconds. The reproducibility of 20 muM of Hx was obtaned with CV 2percent.