Lithium cobalt phosphate electrode for the simultaneous determination of ascorbic acid, dopamine, and serum uric acid by differential pulse voltammetry.

Lithium cobalt phosphate (LCP) was prepared and modified on the surface of glassy carbon electrode (GCE) to fabricate the electrochemical sensor (LCP/GCE) for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and serum uric acid (UA). The homogenous incorporation of carbon improved the conductivity of LCP. Benefiting from the small particle size distribution, LCP/GCE has a large active surface and responds to AA, DA, and UA sensitively and rapidly. For the simultaneous detection with differential pulse voltammetry the anodic peaks of AA, DA, and UA were well-separated and appeared at ~0 V, ~0.19 V, and ~ 0.33 V (vs. Ag/AgCl), respectively. The linear responses toward AA, DA, and UA were in the range 10 μM-8.0 mM, 10 nM-10 μM, and 0.020 μM-25 μM; the detection limits were estimated to be 8.10 μM, 7.50 nM, and 22.7 nM (S/N = 3), respectively. The excellent selectivity and reproducibility of LCP/GCE enable serum UA to be detected without the interference of AA and DA. The recoveries of DA and AA in the serum sample were in the range 95 to 111%. The results indicate that LCP has the potential to be developed as the sensing devices to be applied to in vitro diagnosis. The lithium-ion battery cathodic material, LCP with the excellent adsorption and catalytic behavior, was utilized to fabricate the electrochemical sensor for the sensitive and simultaneous detection of AA, DA, and UA, which achieved the low detection limits and the wide concentration ranges. LCP/GCE can be used for the quantitative detection of serum UA without the interference of DA and AA. In addition, the recoveries of DA and AA in human serum were satisfactory, which illustrate the reliability of LCP/GCE to be applied to in vitro diagnosis.