Development of a stir bar sorptive extraction method coupled to solidification of floating droplets dispersive liquid-liquid microextraction based on deep eutectic solvents for the extraction of acidic pesticides from tomato samples.

A stir bar sorptive extraction method coupled with deep eutectic solvent based solidification of floating organic droplets-dispersive liquid-liquid microextraction has been used for the simultaneous derivatization and extraction of some acidic pesticides in tomato samples. In this method, initially the analytes are adsorbed on a coated stir bar from tomato juice filled in a narrow tube. After extraction, the stir bar is removed and a water-miscible deep eutectic solvent is used to elute the analytes. Afterward, a derivatization agent and a water-immiscible deep eutectic solvent (as an extraction solvent) with melting point near to room temperature are added to the obtained eluant at µL-levels and the obtained mixture is rapidly injected into deionized water. Under the optimum conditions, the introduced method indicated high enhancement (1543-3353) and enrichment (2530-2999) factors, low limits of detection (7-14 ng/L) and quantification (23-47 ng/L), good linearity (r ≥ 0.9982), and satisfactory repeatabilities (relative standard deviation ≤12% for intra- and inter-day precisions at a concentration of 100 ng/L of each analyte). Finally, the proposed method was applied in analysis of the analytes in tomato samples.