Simultaneous analysis of uric acid, xanthine and hypoxanthine using voltammetric sensor based on nanocomposite of palygorskite and nitrogen doped graphene

Abnormal level of purines, especially uric acid (UA), xanthine (XA) and hypoxanthine (HX) in organisms is an important marker for early diagnosis of animal (human) disease. In this paper, an simultaneous analysis of UA, XA and HX in biological samples was successfully realized using the fabricated voltammetric sensor based on the nanocomposite of both nano-rod clay mineral palygorskite (Pal) and two-dimensional nano-layered nitrogen doped graphene (NG). A water-soluble carboxymethyl cellulose (CMC) salt was simultaneously decorated both Pal and NG to improve the water dispersibility, and their nanocomposite was characterized. Under optimized conditions, The as-prepared nanocomposite electrode (CMC-Pal-NG/GCE) could realize their simultaneous voltammetric analysis in linear ranges from 0.5 to 60 μM for UA, 0.2 to 20 μM for XA, and 0.6 to 55 μM for HX. The limit of detection of three purines (UA,XA and HX) is calculated to be 0.1 for UA, 0.05 for XA and 0.4 μM for HX, and their possible detailed mechanisms for electro-catalytic oxidation and chemical reaction was discussed, which was successfully empolyed for simultaneous voltammetric analysis of three purines in real samples with good reproducibility, repeatability and stability. Satisfactory results indicated that the obtained nanocomposite will provide a promising candidate for the simultaneous electrochemical determination of UA, XA and HX in analysis of practical samples.