A method with high sensitivity, good accuracy and fast response is of ever increasing importance for the simultaneous detection of AA, DA and UA. In this paper, a simple and sensitive electrochemical sensor, which based on the polyvinylpyrrolidone (PVP)-graphene composite film modified glassy carbon electrode (PVP-GR/GCE), was presented for detecting ascorbic acid (AA), dopamine (DA) and uric acid (UA) simultaneously. The PVP-GR/GCE has excellent electrocatalytic activity for the oxidation of AA, DA and UA. The second-order derivative linear sweep voltammetry was used for the electrochemical measurements. The peak potential differences of DA-AA, DA-UA, and UA-AA (measured on the PVP-GR/GCE) were 212, 130 and 342 mV respectively. Besides, the over potential of AA, DA and UA reduced obviously, so did the peak current increase. Under the optimum conditions, the linear ranges of AA, DA and UA were 4.0 μM-1.0 mM, 0.02-100 μM, and 0.04-100 μM, respectively. The detection limits were 0.8 μM, 0.002 μM and 0.02 μM for AA, DA, and UA. The electrochemical sensor presented the advantages of high sensitivity and selectivity, excellent reproducibility and long-term stability. Furthermore, the sensor was successfully applied to the analysis of real samples.

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A new electrochemical sensor for the quick determination of both paracetamol (ACOP) and ascorbic acid (AA) was prepared using an acetylene black paste electrode modified with polyvinylpyrrolidone and graphene composite (PVP-GR/ABPE). Second derivative linear sweep voltammetry (SDLSV) and cyclic voltammetry (CV) were then used to investigate the electrochemical behavior of both ACOP and AA on this PVP-GR/ABPE. The results demonstrate that the two analytes have good resolution and strong electrochemical signal responses. Due to the interconnected effects of PVP, GR, and AB ternary composite, the designed electrode has several beneficial characteristicsincluding good adsorption ability, significant specific surface area, and good conductivity. The voltammetric responses of ACOP and AA on the PVP-GR/ABPE show that the modified electrode displayed good electrocatalytic properties for the chemical reactions of both ACOP and AA, with the linear range of 0.01-100 μM for ACOP and the linear range of 6-1000 μM for AA. The detection limits of 6.0 nM (ACOP) and 1.0 μM (AA) were obtained, respectively. The sensor has successfully been used in the measurement of ACOP and AA in real samples, indicating that this method is potentially applicable for routine biomedical and chemical sensing in vitro diagnostically.