Multivariate optimization and validation of a new procedure for simultaneous determination of folic acid and folinic acid based on enhancement effect of n-dodecylpyridinium chloride

The present study is a first report about of an electrochemical sensor for simultaneous determination of folic acid (FA) and calcium folinate (CF). Also, the work is a first successful application of n-dodecylpyridinium chloride (DPC) as a modifier in simultaneous measurement of folates. This study is based on the adsorption of cationic surfactants at the surface of a carbon paste electrode (CPE) to improve the electrochemical response of the tow analytes. The enhancement effect of DPC is compared with CTAB by differential pulse voltammetry (DPV) technique and DPC shows the better results as a modifier. Other novelty of the work is application of multivariate optimization for optimization of effective parameters in the voltammetric peak current of the analytes. Under the optimized conditions, a peak separation of CF and FA is higher than 270 mV. CPE in the presence of DPC shows wide linear responses for CF and FA in the concentration ranges of 0.1-100.0 mu M and 0.05-10.0 mu M with detection limits of 24.0 nM and 7.5 nM (3 sigma), respectively. CPE in the presence of DPC exhibits good repeatability and stability for the two analytes. At the last, CPE in the presence of DPC was successfully applied to the simultaneous detection of FA and CF in urine real samples.