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Today, due to the growth of the pharmaceutical industry and the high consumption of drugs, monitoring of drug residues in environmental samples because of their destructive effects on the environment and humans is essential. In the present work, ultrasound‐assisted emulsification‐microextraction coupled with high‐performance liquid chromatography as a simple and fast method was applied for simultaneous determination of paracetamol and caffeine in the aqueous samples. Effective parameters on the extraction efficiencies of these analytes such as type and volume of extraction solvent, pH of sample solution, salt concentration, sonication, and centrifuging times were studied and optimized. Under the optimum conditions, the calibration graphs were linear in the range of 30.0–1100.0 ng/mL for paracetamol and 50.0–400.0 ng/mL for caffeine. The limits of detection were 9.7 and 15.2 ng/mL for paracetamol and caffeine, respectively. The proposed method was successfully applied for the determination of these drugs in different aqueous samples.

A simple, efficient, and rapid sample preparation method based on aeration‐assisted homogeneous liquid–liquid microextraction was developed for determination of curcumin in food samples by high‐performance liquid chromatography. The centrifuge step has been eliminated in this procedure. The effects of some variables, such as pH, volume of extraction solvent, extraction time, and salt effect, were studied through a Box–Behnken design method. Under the optimum conditions, calibration curves of curcumin were linear in the range of 0.08‐4000 μg/mL with R2 = 0.997. Limit of detection and relative standard deviation were 0.019 μg/mL and 3.01%, respectively. The preconcentration factor achieved was 166. The proposed method was successfully applied to determination of curcumin in various food samples.