Electrochemical investigation of a novel surfactant for sensitive detection of folic acid in pharmaceutical and biological samples by multivariate optimization

The present study is a report about of an electrochemical sensor for folic acid (FA) detection based on the adsorption of a cationic surfactant, n-dodecylpyridinium chloride (DPC), at the surface of a carbon paste electrode (CPE). The DPC performance compares with the cetyltrimethylammonium bromide (CTAB) to improve the electrochemical reaction and response of FA. It is notable for the first time, DPC is successfully utilized in electrochemical analysis. Determination of FA is performed by differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronocoulometry (CC) techniques. Response surface methodology (RSM) and central composite rotatable design (CCRD) is chosen for optimization of effective variables in the voltammetric peak current of FA. Another innovation in this study is the utilization of cubic terms in the experimental design. Under the optimized conditions, the FA oxidation peak current was linear to the FA concentration in the range of 0.01 µM–10.69 μM with the detection limit of 2.9 nM (3σ). After studying the influence of probable interferences, it was found that the offered method has excellent selectivity for FA. Finally, the offered procedure was successfully applied to the FA detection in tablet and urine samples with satisfactory results.