Adsorptive stripping voltammetric determination of carbofuran in herbs on chromatographic sorbent modified electrode

Abstract The determination of carbofuran (CBF) in herbs (wild chamomile and Saint-John's-wort) was developed using a carbon-containing electrode (CCE) modified with carbon ink (CI) containing chromatographic sorbent (CS) based on chromaton (Ch), polyethylene glycol (PEG), and iron acetylacetonate (Fe(AA)3). The surface morphology of the Ch/PEG/Fe(AA)3/CI/CCE was investigated by scanning electron microscopy (SEM) in backscattered-electron (BSE) mode and by electrochemical impedance spectroscopy (EIS). Electrochemically inactive CBF was converted to an electrochemically active phenolic analogue CBFP by an alkaline hydrolysis. The electrochemical behavior of CBFP at Ch/PEG/Fe(AA)3/CI/CCE was studied by cyclic voltammetry (CV) in a phosphate buffer solution (PBS) pH 6.86 in the potential range from -0.4 to 1.2 V. Under the optimal experimental conditions, linear concentration dependences in the concentration range from 0.25 to 10 µmol·L-1 were obtained by linear scan voltammetry in the first derivative mode (LSVFD) with limit of detection (LOD) 0.08 µmol·L-1. The proposed Ch/PEG/Fe(AA)3/CI/CCE demonstrated good sensitivity and selectivity for the determination of CBF after its conversion to CBFP. The use of sorbents as modifying agents of electrodes for the determination of carbamate pesticides opens up the possibilities for “green” electroanalytical chemistry.