Development of ternary H-point standard addition method for simultaneous analysis of curcuminoids by differential pulse voltammetry.

Turmeric (Curcuma longa L.) rhizome is one of the most famous plants that has been widely used in food, medicine, and industry. Its quality deeply depends on the presence of curcuminoids and their ratios. As their structures are very similar to each other, this work reported simple, accurate, fast, and sensitive method based on developed ternary H-point standard for differential pulse voltammetry (t-HPSAM-DPV). For electrochemical determination of three analytes in the sample, three standards were added simultaneously. This method was developed for detection of three curcuminoids including curcumin (CU), desmethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC) in real samples. The precision of method has RSD% < 5.5 % and the accuracy of proposed method has relative error lower than 7.0 %. Also, intra and inter-day precisions have provided the mean RSD% < 4.50. The LOD values were obtained for CU, DMC and BDMC are 0.6 × 10-6, 0.57 × 10-6 and 0.42 × 10-6, respectively. Compared with other reported HPLC methods, the results revealed a reasonable accurate precision for proposed method. Under optimized experimental conditions, t-HPSMA significantly resolved overlapping of DPV peaks of CU, DMC, and BDMC. This method can be successfully used for ternary analysis of analytes using one standard addition to the real samples.