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Background Determination of emerging pollutants including pharmaceuticals, pesticides, industrial chemicals and hormones in different environmental samples is very important for human health. Objective Experimental design enabled parameters to be evaluated for their effects onextraction output as well as their interactive effects. Method A multivariate experimental design was used to attain optimum conditions of a dispersive liquid-liquid microextraction method for preconcentration of pesticides and pharmaceuticals for determination by GC-MS. Results The optimum parameters suggested by the design model were 200 µL of chloroform, 1.96 mL of ethanol, and 40 s vortexing period. LOD and LOQ were calculated using linear calibration plots of the analytes developed in the standard concentration range of 2.0 μg/L–2.0 mg/L. Conclusions Enhancement in detection power of the analytes recorded by the optimized method with respect to direct GC-MS determination (based on LOD values) was in the range of 3.6 and 539 folds. Spiked recovery experiments for municipal, medical, and synthetic wastewater samples yielded low recovery results when calculated against aqueous standard solutions. Matrix matched calibration standards were used to mitigate interferences from the waste samples and the percent recoveries obtained were close to 100%. This established accuracy and applicability of the developed method. Highlights The detection limits were found between 0.50 ng/mL and 37 ng/mL. An accurate, simple and sensitive analytical method was developed for the analytes.

Background Pesticides are chemicals used mainly to protect plant crops in order to increase their production efficiency and quality. Objective Switchable-solvent homogeneous liquid-liquid microextraction was optimized using a Box-Behnken experimental design and validated on a gas chromatography mass spectrometry system for the determination of analytes. Method The significance of independent variables (switchable solvent volume, sodium hydroxide volume, and vortex period) and their interactions were evaluated by analysis of variance at 95% confidence limits (α = 0.05). Results The LOD and LOQ ranges of the analytes were found to be 0.42–1.90 µg/L and 1.36–6.33 µg/L, respectively. Percentage recovery results were found to be in the range of 87–113% in spiking experiments. Conclusions A simple, efficient, and accurate analytical method was developed for the simultaneous determination of the selected pesticides. Highlights: Matrix matching was used to enhance quantification accuracy for real samples. Highlights Matrix matching was used to enhance quantification accuracy for real samples.

Determination of nicotine at trace levels in different matrixes is crucial because of nicotine's strongly addictive property. In this study, a simple and fast analytical method was developed using liquid–liquid extraction with GC-MS. Chloroform was used as an extraction solvent. Different parameters for extraction, such as pH of the solution, types and volumes of extraction and supporter solvents for dispersion, extraction period, and salt type and its amount, were optimized. To improve the precision, naphthalene was used as an internal standard. The calibration plot of nicotine was linear from 0.010 to 2.0 mg/L with a correlation coefficient 0.9996. The LOD and LOQ for nicotine after extraction were 2.6 and 8.8 ng/mL, respectively. Under the optimum conditions, tap water, wastewater, and saliva samples were analyzed for their nicotine content. The spiking experiments yielded satisfactory recoveries of 97.6 ± 3.5, 96.8 ± 1.1, and 85.1 ± 1.3% for tap water, wastewater, and saliva samples, respectively.