Optimization deep eutectic solvent-based ultrasound-assisted liquid-liquid microextraction by using the desirability function approach for extraction and preconcentration of organophosphorus pesticides from fruit juice samples

•Deep eutectic solvent was easily prepared by mixing choline chloride with phenol.•Deep eutectic solvent was used for microextraction of OPPs from fruit juice samples.•Central composite design with desirability function was used for the optimization.•The analysis of OPPs in fruit juice samples was done without any dilution.•Low detection limits, wide linear ranges, and good precision were obtained. A deep eutectic solvent-based ultrasound-assisted liquid-liquid microextraction (DES-UALLME) followed by quantitative analysis using HPLC-UV has been developed for the determination of organophosphorus pesticides (phosalone and chlorpyrifos) in fruit juice samples (red grape juice and sour cherry juice). In DES-UALLME, ultrasonication was applied to transfer the aggregated of DES into tiny droplets. The parameters that influence on extraction efficiency were studied and optimized by central composite design (CCD) in combination with a desirability function approach. The optimum conditions obtained by multivariate optimization were 408 μL of DES, 560 μL of THF, pH of 5.92, and an ultrasonication time of 12.31 min. Under the optimized condition, wide linear range (1–500 ng mL−1), low detection limits (0.070 and 0.096 ng mL−1), high enrichment factors, and good extraction recoveries were obtained. The procedure was successfully applied for the determination of phosalone and chlorpyrifos in red grape juice and sour cherry juice samples with satisfactory relative recoveries (87.3–116.7 %).