A screen-printed electrode modified with silver nanoparticles and carbon nanofibers in a nafion matrix for ionic liquid-based dispersive liquid-liquid microextraction and voltammetric assay of heterocyclic amine 8-MeIQx in food.

An electrochemical method is described for the determination of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (8-MeIQx) which is a heterocyclic aromatic amine formed in cooked food samples. The method uses a screen-printed carbon nanofiber electrode that is modified with silver nanoparticles (AgNPs) in a Nafion matrix. The surface of the modified electrode was characterized by UV-vis spectrometry, dynamic light scattering, scanning electron microscopy and Raman spectroscopy. The average size of the AgNPs is 14 nm. The modified electrode exhibits good properties in terms of reversibility, fast kinetics of electron transfer, and large electroactive area toward the reduction of 8-MeIQx. Differential pulse voltammetry is the most suitable electrochemical technique for quantification of 8-MeIQx, best at a voltage of -0.21 V (versus Ag reference electrode). The first derivative serves as the analytical signal that increases linearly in the 0.015-40 mg L 8-MeIQx concentration range, with a 5 μg L detection limit. A dispersive liquid-liquid microextraction procedure assisted via ionic liquid was developed to isolate the analyte from real samples. The whole extraction-preconcentration and voltammetric method allows to determine 30 and 70 μg L in (spiked) bouillon cube, meat broth, beer and wine, with recoveries in the 93.6-110.4% range. Graphical abstractSchematic presentation for the analysis of aromatic amine 8-MeIQx, resultant compound from cooking meat. Extracted sample solution was placed onto modified electrode surface thus obtaining voltammetric analytical signal. So, quantification atrelevant levels can be performed.