An improved amperometric determination of xanthine with xanthine oxidase nanoparticles for testing of fish meat freshness

The nanoparticles of xanthine oxidase (XODNPs) were prepared by desolvation method and characterized by transmission electron microscopy(TEM) and Fourier transform Infra-red spectroscopy(FTIR). These XODNPs were immobilized directly onto surface of Au electrode via covalent bond. An improved amperometric xanthine biosensor was fabricated using XODNPs modified Au electrode, as working electrode (WE), Ag/AgCl as reference electrode and Pt wire as auxiliary electrode connected through potentiostat.The biosensor showed optimum current at 0.25 V within 5 s, at pH 7.0 and 35 °C.The working range of biosensor was 0.01–1.0 μM with a limit of detection of 0.01 μM.The % recovery of added xanthine (1 and 5 μM) was 94.1 ± 0.2 and 94.8 ± 0.31 respectively. Within and between batch coefficient of variation (CV) were