A novel organoselenium-based Schiff base for selective separation of copper and zinc from food samples using ultrasonic-assisted solidified floating organic drop microextraction strategy

Herein, we document the development of a novel organoselenium-based Schiff base, 2-((4-((2-hydroxy-4nitrobenzylidene)amino)phenyl)selanyl)-N-phenylacetamide (HOASe), to selectively separate zinc and copper from food samples. To the best of our knowledge, OSe compound has never been used in microextraction procedures before, until today. HOASe was synthesized from aniline by a simple four-step procedure. The structure of HOASe was elucidated by various spectroscopic techniques (e.g., IR, MS, 1H- and 13C NMR). After that, HOASe was used to extract Cu2+ and Zn2+ by ultrasonic-assisted dispersive liquid-liquid microextraction based on the solidification of floating organic drop (UA-DLLME-SFOD) combined with flame atomic absorption spectrometry. Important experimental parameters including amount of the extraction solvent, initial pH, amount of HOASe, ultrasonication time, centrifugation, and salt addition, were studied and optimized to offer quantitative separation of the analytes. The detection limits and the linear ranges for Cu2+ and Zn2+ were 1.9, 8.0 - 400.0, and 2.4, 6 - 150 mu g L-1, respectively. The method's greenness and applicability were assessed using the Analytical GREEnness metric methodology and the Blue Applicability Grade Index, respectively. Finaly, this approach was used for quantification of Cu2+ and Zn2+ in food samples and, therefore, can be further developed for food safety and quality control programs.