Electrochemical determination of ascorbic acid and paracetamol in pharmaceutical formulations using a glassy carbon electrode modified with multi-wall carbon nanotubes dispersed in polyhistidine

DALMASSO PABLO; M. L. PEDANO; G. A. RIVAS

SENSORS AND ACTUATORS B-CHEMICAL

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2012

0925-4005

This work reports on the analytical performance of glassy carbon electrodes (GCE) modified with a disper-sion of multi-wall carbon nanotubes (MWCNT) in polyhistidine (Polyhis) (GCE/MWCNT?Polyhis) for the simultaneous determination of ascorbic acid (AA) and paracetamol (PA). The modified electrode exhibited enhanced current responses and lower oxidation overvoltages, demonstrating excellent catalytic activ-ities towards AA and PA oxidation compared to bare GCE. The linear dependence between the anodic peak currents and the square root of scan rates over the range of 0.005?0.300 V s−1 demonstrate that the electrooxidation of AA and PA occurs under diffusional control. The MWCNT?Polyhis modified GCE dis-played a sensitivity of (3.8 ± 0.1) ×104 A M−1 (r = 0.998) and a detection limit of 0.76 M for the selective determination of AA in the presence of 1.00 × 10−4M PA. Conversely, for the direct quantification of PA in the presence of 5.00 ×10−4M AA, the sensitivity and the detection limit were (6.3 ± 0.2) ×105 A M−1 (r = 0.997) and 32 nM, respectively. The proposed electrochemical sensor was successfully applied for quantifying AA and PA in commercial pharmaceutical formulations without any sample pretreatment −1 demonstrate that the electrooxidation of AA and PA occurs under diffusional control. The MWCNT?Polyhis modified GCE dis-played a sensitivity of (3.8 ± 0.1) ×104 A M−1 (r = 0.998) and a detection limit of 0.76 M for the selective determination of AA in the presence of 1.00 × 10−4M PA. Conversely, for the direct quantification of PA in the presence of 5.00 ×10−4M AA, the sensitivity and the detection limit were (6.3 ± 0.2) ×105 A M−1 (r = 0.997) and 32 nM, respectively. The proposed electrochemical sensor was successfully applied for quantifying AA and PA in commercial pharmaceutical formulations without any sample pretreatment