Development and validation of a voltammetric method for determination of total phenolic acids in cotton cultivars

Abstract

A highly sensitive and selective differential pulse voltammetric (DPV) method based on the oxidation of caffeic acid in a glassy carbon electrode is presented for determination of total phenolic acids (TPAs). Under optimized conditions (0.2M phosphate buffer, pH 3, 50mV pulse amplitude, 50mVs−1 scan rate), the oxidation peak current (Ipa) of caffeic acid is linear (Ipa(A)=−4.15×10−8+0.97 [Caffeic acid]) to caffeic acid concentration in the range from 1.0×10−7 to 1.0×10−6M, with a correlation coefficient of 0.9985. The detection and quantitation limits obtained were 6.8×10−8M and 1.0×10−7M, respectively. The repeatability and intermediate precision of DPV method were acceptable (Relative Standard Deviation (RSD) <10%). The absence of the matrix effect on the determination of TPAs by DPV method was attested by F-test and t-test (95% confidence level). The method was successfully applied to the determination of TPAs in five cotton cultivars, with recoveries of 94–104% (RSD <2%).