Comparative electrochemical study of oxidative nicarbazin determination in non-aqueous media: Differential pulse voltammetry vs. capillary electrophoresis with amperometric detection

Background: Electrochemistry offers a range of powerful techniques for solving analytical problems, each with its own advantages and limitations that can significantly affect the information obtained. These variations lead to diverse requirements for newly developed methods. Applying multiple electrochemical techniques simultaneously can optimize information extraction from a sample, aiding in the selection of the best analytical approach. Results: In this study, we present the first investigation of the oxidation of the coccidiostat nicarbazin, along with a comparative evaluation of two established electrochemical methods with complementary strengths: differential pulse voltammetry (DPV) and capillary electrophoresis coupled with amperometric detection (CE-AD). We thoroughly examine the oxidative determination of nicarbazin in poultry feed samples using acetonitrile based media. DPV allows for rapid and efficient analysis, while CE-AD excels in handling complex samples with electrochemically active species due to its high separation efficiency. Both methods exhibit limits of detection (LODs) in the low micromolar range. To provide a comprehensive understanding of the nicarbazin oxidation process, the final reaction products were analyzed by mass spectrometry, identifying 4-nitroaniline and (4nitrophenyl)formamide as key product compounds. Significance and novelty: This pioneering research on the anodic detection of nicarbazin includes a detailed analysis of the components in the studied equimolar mixture. The developed protocols, combined with straightforward sample preparation, enable the successful determination of nicarbazin levels below those allowed by EU regulations.