Phospholipid modified glassy carbon electrode for determination of chili peppers pungency by ex-situ extraction voltammetry

Abstract

Objective determination of chili peppers pungency, for which capsaicinoids (CPDs), predominantly capsaicin (CA) and dihydrocapsaicin (DHC) are responsible, belongs to frequently solved tasks in food and medicinal analysis. In this manuscript, application of ex-situ extractive stripping voltammetry (ExSV) utilizing a phospholipid modified glassy carbon electrode is described.The obtained analytical parameters, e.g., linear dynamic range from 3 to 60 mg L−1, limit of detection 2.1 mg L−1, proved to be fully comparable with those achieved using the direct voltammetric method on a polished glassy carbon electrode and reference HPLC/UV. Although the sensitivity of ExSV was slightly lower compared to the direct method, ExSV provided better selectivity to CPDs due to their lipophilic interactions with the phospholipid layer. Hydrophilic components of the chili pepper samples were not extracted into the phospholipid layer and therefore did not interfere. The developed method was tested on the determination of CPDs in different chili peppers: Foxta, Madras Chilli, Habanero, Carolina Reaper, Bird's eye, Bhut Jolokia, Naga Jolokia extract, and Habanero extract.Furthermore, the electrochemical reactions of CPDs in acidic aqueous-methanolic media were characterized using an electrochemical cell hyphenated with mass spectrometer and the main oxidation products were identified.