Electrochemical Determination of Tert-Butylhydroquinone (TBHQ) in Edible Oil by Differential Pulse Voltammetry (DPV) at Modified Screen-Printed Carbon Electrodes (SPCEs) with a Three-Dimensional Standard Curved Surface Method

Reliable quantitative analysis using electrochemical sensors remains a challenge due to the differences in the effective area after surface modification of the electrodes, resulting in poor precision of the signals between electrodes. Herein, a novel quantitative approach called standard curved surface for the electrochemical detection is reported which does not require identical electrodes, high modification, or the use of internal standards that may cause calibration interferences. The technique is based upon the principle that the current is linearly correlated with the electroactive area of the electrodes. By introducing the electroactive area as a new variable into the standard curve, a three-dimensional standard curved surface was obtained to correct for differences among electrodes, thereby improving the accuracy of electrochemical detection. Furthermore, it was applied to the determination of tert-butylhydroquinone (TBHQ) in edible oil. Compared with the traditional standard curve, the reported method reduced the relative standard deviation values from 13.22% to 4.01%. The current response was linear with the concentration of TBHQ between 5 × 10−6 and 1.25 × 10−3 mol/L. The limit of detection was 1.07 × 10−6 mol/L and the spike recovery was from 90.44% to 112.09%. Therefore, a universal calibration method has been reported with expected additional applications for electrochemical sensors.