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.
This study, a fast, simple, and efficient ultrasound-assisted emulsification microextraction coupled with orthogonal signal correction-moving window partial least squares (OSC-MWPLS) was successfully used to preconcentration and simultaneous spectrophotometric determination of uranium and thorium in water samples. Response surface methodology based on a Box-Behnken design was used to optimize the extraction conditions. The analysis of variance and some statistical tests such as lack-of-fit and coefficient of determination (R 2 ) showed good fit of the experimental data with the second-order polynomial model. Under the optimum conditions, the calibration graphs were linear in the range of 10.0 to 230.0 and 10.0 to 250.0 ng mL −1 with detection limits of 3.11 and 3.56 ng mL −1 (3S b /m) for uranium and thorium, respectively. The preconcentration factor of this method for uranium and thorium reached 192. Repeatability (intra-day) and reproducibility (inter-day) were obtained 1.23% and 2.18% for uranium and 1.34% and 1.95% for thorium, respectively. The OSC was used for preprocessing of data matrices, and also MWPLS regression has been proposed for the selection of informative spectral intervals. In this paper, ultrasound-assisted emulsification microextraction coupled with OSC-MWPLS method was presented for the first time. The root mean square error of prediction for uranium and thorium with PLS, OSC-PLS, and OSC-MWPLS were 11.755, 10.335 and 5.301, 5.399 and 0.974, 0.986 ng mL −1 , respectively. The results indicated that practical and environmentally friendly proposed method could be successfully used to the simultaneous determination of uranium and thorium in different environmental water samples.
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