Sensitive and selective folic acid measurement with adsorption effect of N-Dodecylpyridinium chloride at Carbon paste electrode

Folic acid (FA) also called as pteroylglutamic acid (PteGlu), is essential for various biological functions. Deficiency of FA causes anemia, leucopoenia, devolution of mentality, psychosis and increasing probability of heart attack and stroke. It is a necessary vitamin for healthy growth and development of foetus. Therefore, the measurement of FA is a significant research interest and several analytical methods have been reported for the determination of FA, In recent years, electrochemical methods have been used for the measurement of FA with the advantages including cheaper instruments, more convenient procedure, good sensitivity and selectivity. A surfactant, with a hydrophobic C-H chain, can adsorb at the CPE surface via hydrophobic interaction and then change the electrode/solution interface, and finally affects the electrochemical response of drug. Cetyltrimethylammonium bromide (CTAB) and N-Dodecylpyridinium chloride (DPC) are two types of cationic surfactants. CTAB has been widely used for surface modification of electrode, while for DPC, no successful application has been reported. This study reports designing an electrochemical sensor for FA based on adsorption of cationic surfactant at a Carbon paste electrode (CPE) and compares the performance of DPC with CTAB to improve the electrochemical response of folic acid. In this work cyclic voltammetry (CV), differential pulse voltammetry (DPV), chronoamperometry (CA) and chronocoulometry (CC) methods were used and the experiments were performed with a certain electrode composition of 0.05 gr paraffin oil and 0.5 gr high purity graphite powder. After determining the superiority of DPC, for the first time, DPC was successfully used in electrochemical assays. Central composite design (CCD) was used to optimize the experimental parameters. 13th Annual Electrochemistry Seminar of Iran Materials and Energy Research Center (MERC), 22- 23 Nov, 2017 52 Under the optimized condition, the anodic peak current is linear to folic acid concentration in the range from (1.0×10-2 -10.0 μM). The detection limit was 3.1 nM and the relative standard deviation for 10.0 μM of folic acid was 2.3%. After studying the influence of the interfering ions and drugs, it was found that the proposed procedure has excellent selectivity. Finally, the method was successfully applied to the determination of folic acid in pharmaceutical tablets and urine.