Protic Ionic Liquid as an Alternative Electrolyte for Simultaneous Electrochemical Determination of Caffeine and Nicotine in Environmental and Food Samples

Caffeine (CAF) and nicotine (NIC) are emerging contaminants and are among the most consumed substances in the world, making it crucial to monitor these contaminants. In this work, an alternative electrolyte, 2-hydroxyethylammonium acetate (2HEAA) was used for the development of an electroanalytical method for determination and quantification of CAF and NIC, simultaneously, using differential pulse voltammetry (DPV). The system with the 2HEAA electrolyte was characterized by cyclic voltammetry and electrochemical impedance spectroscopy, and the DPV parameters were optimized for the best conditions. The method was validated from a calibration curve obtained which showed limit of detection (LOD) of 0.82 and 6.26 μmol L 1 and limit of quantification (LOQ) of 2.73 and 20.8 μmol L-¹ for CAF and NIC, respectively. In the precision analyses, values lower than 10% of relative standard deviation were obtained. In the presence of concomitant inorganic and organic species, the system proved to be selective in the determination of analytes. The method was used to determine the analytes in fortified samples (river water, synthetic urine and commercial milk), obtaining recoveries between 87.25 and 111.40%. The 2HEAA demonstrated high efficiency as an alternative electrolyte with good signal-to-noise ratio, increased analytical sensitivity of the method, in addition to presenting low cost and fast electrolyte preparation.

Keywords:
alkaloids; monitoring; emerging contaminants; 2-hydroxyethylammonium acetate; green chemistry