Simultaneous quantification of ascorbic acid, uric acid and nitrite using a clay/porphyrin modified electrode

A chloro meso-tetraphenylporphyrin iron(III)/clay (Fe(III)TPyP-Ba) composite has been prepared using a Cameroonian smectite clay (from Bagba hill, Ba) and was then employed to modify glassy carbon electrodes (GCE). These modified electrodes were successfully used for the simultaneous determination of ascorbic acid (AA), uric acid (UA) and nitrite (NO2-). Fe(III)TPyP-Ba composites were characterized by ultraviolet-visible absorption spectroscopy (UV-vis) and scanning electron microscopy (SEM). The combination of Fe(III)TPyP porphyrin and Ba clay endowed the electrode with a large surface area, good biological compatibility and stability, high selectivity and sensitivity. The linear calibration plots for AA, UA and NO2- were obtained over the range of 5-330 mu M, 0.4-25 mu M and 1-250 mu M with detection limits of 0.95 mu M, 0.06 mu M and 0.5 mu M, respectively. The modified electrode was successfully applied for the determination of AA in a pharmaceutical preparation. (C) 2015 Elsevier B.V. All rights reserved.