Sensitive detection of Ferulic acid using multi-walled carbon nanotube decorated with silver nano-particles modified carbon paste electrode

The electrochemical oxidation of Ferulic acid (FA) was assiduously scrutinized by cyclic voltammetry and more sensitive amperometry technique using silver decorated multi-walled carbon nano-tubes modified carbon paste electrode. The modified electrode showed superior catalytic activity at physiological pH. The synergistic outcome of multiwalled carbon nano-tubes and silver nano-particles resulted in superior electro-catalytic activity and a significant three time increase of anodic peak current sensitivity and a remarkable lower energetics by 120 mV shift in potential thereby decreasing over-potential for electro-oxidation of FA in comparison to bare carbon paste electrode. Under optimized conditions, a linear dynamic range of 4.0 x 10(-8) to 1.0 x 10(-3) M, with a lower detection limit of 3.0 x 10(-8) M (S/N = 3) was obtained. The surface morphology of the sensor was studied using field emission scanning electron microscopy and atomic force microscopy. EDX was used determine the elemental composition of the electrode. The electrochemical impedance study revealed the least charge transfer resistance for the modified electrode. The effect of variation of scan rate, pH and concentration towards the electro-catalytic oxidation of FA was also investigated. Absence of peak for interfering molecules like Ascorbic acid, Uric acid and Glucose makes this sensor unique with significant analytical advantage. The fabricated sensor revealed adequate reproducibility, long term stability and enhanced selectivity in presence of commonly existing interfering molecules. The sensor was employed for the validation of spiked human urine and the wine which gave recoveries ranging from 97.5 to 99.4%, making it a potential alternative tool for the quantitative detection of FA in the biomedical field.