•A novel magnetic effervescent tablet was prepared for the detection of fungicides.•Extractions were screened by PB design and optimized through CCD design.•Analytes could be rapidly and efficiently extracted upon field inspection.•The extractant could be separated without centrifugation.In this work, a novel effervescence-assisted microextraction technique was proposed for the detection of four fungicides. This method combines ionic liquid-based dispersive liquid–liquid microextraction with the magnetic retrieval of the extractant. A magnetic effervescent tablet composed of Fe3O4 magnetic nanoparticles, sodium carbonate, sodium dihydrogen phosphate and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonimide) was used for extractant dispersion and retrieval. The main factors affecting the extraction efficiency were screened by a Plackett–Burman design and optimized by a central composite design. Under the optimum conditions, good linearity was obtained for all analytes in pure water model and real water samples. Just for the pure water, the recoveries were between 84.6% and 112.8%, the limits of detection were between 0.02 and 0.10 μg L−1 and the intra-day precision and inter-day precision both are lower than 4.9%. This optimized method was successfully applied in the analysis of four fungicides (azoxystrobin, triazolone, cyprodinil, trifloxystrobin) in environmental water samples and the recoveries ranged between 70.7% and 105%. The procedure promising to be a time-saving, environmentally friendly, and efficient field sampling technique.

A novel liquid phase microextraction method based on the solidification of floated ionic liquids (SFIL-LPME) was developed to determine four phthalate esters (diethyl phthalate, diallyl phthalate, benzyl butyl phthalate, and dicyclohexyl phthalate) in environmental waters and bottle beverages and subsequently separate them using high-performance liquid chromatography. In this work, we customized a tributyldodecylphosphonium tetrafluoroborate ([P4 4 4 12][BF4]) ionic liquid (IL) to obtain a low density such that it can be solidified at a low temperature, and then used as an extraction solvent in liquid-phase microextraction based on the solidification of floated organic drops (SFO-LPME). This means that more potential ILs can be customized to broaden extraction solvents in SFO-LPME. To identify the significant factors that affect extraction efficiency, parameters such as the volume of [P4 4 4 12][BF4], the extraction time, the rotation speed, the extraction temperature and the ionic strength were optimized using a Plackett–Burman design. A central composite design was then used to optimize the identified significant factors to study the effect of interactions on the experiment. Under these optimized conditions, the extraction recoveries of the four phthalate esters in water samples ranged from 73.0 to 94.6% and in bottled beverage were from 70.2 to 101.3%, with relative standard deviations (RSDs) ranging from 0.6 to 8.2% and 0.6 to 7.8%. Good linearity for both water samples and bottled beverages were obtained in the range of 5–500 μg L−1, with correlation coefficients greater than 0.9993. The limits of detection for the four phthalate esters varied from 0.27 to 1.1 μg L−1 for water samples and 1.22 to 2.36 μg L−1 for bottled beverages. The two developed methods were then successfully applied to the determination of phthalate esters in environmental waters and bottled beverages.

A novel in situ metathesis reaction combined with an ultrasound-assisted dispersive liquid–liquid microextraction based on the solidification of sedimentary ionic liquids (in situ UA-SSIL-DLLME) was combined with high-performance liquid chromatography (HPLC) to detect four triazole pesticides in water and juice samples. In this method, the hydrophobic ionic liquid [P4448][PF6], formed in situ by the hydrophilic ionic liquid [P4448]Br and the anion-exchange reagent KPF6, was used as the microextraction solvent. The extraction procedure was assisted by ultrasound at 50 W for 5 min. After centrifugation and cooling, [P4448][PF6] was sedimented at the bottom and easily collected by decanting the aqueous phase directly. Various parameters affecting the extraction efficiency, such as the quantity of [P4448]Br, the molar ratio of [P4448]Br to KPF6, salt addition, ultrasound time, centrifugation rate and time, and sample pH, were evaluated. Good linearities with correlation coefficients greater than 0.99 were obtained under the optimum conditions. The limits of detection varied between 0.90 and 1.38 μg L−1, and the enrichment factors were in the range of 94–101. The recoveries of these four triazole pesticides ranged from 85.18% to 91.14%, with relative standard deviations less than 4.86% and 5.87% for intra-day (n = 3) and inter-day (n = 3), respectively. The proposed method was then successfully applied to analyze the target compounds in environmental water and juice samples.

This paper presents a study of the performance of ultrasound-enhanced temperature-controlled (UETC) ionic liquid dispersive liquid–liquid microextraction (IL-DLLME). The use of ultrasonication and heating can enhance the ability of the ionic liquid to extract the analytes. Various parameters that would affect the extraction efficiency, such as the type and volume of the extraction and dispersing solvents, salt concentration, pH value, centrifugation time, effect of temperature on UETC-IL-DLLME, were investigated and optimized. Under the optimal extraction conditions, good enrichment factors (178–197) and recoveries (88.9–98.5%) were obtained. Good linearity was obtained in the range of 4–500 μg L−1 for myclobutanil and in the range of 6–500 μg L−1 for uniconazole, penconazole, tebuconazole and hexaconazole. Based on the optimized conditions, the UETC-IL-DLLME method was applied and combined with high-performance liquid chromatography with diode array detection (HPLC-DAD) to determine the presence of five triazole fungicides. The results showed that the method we proposed could effectively determine the target fungicides in rat blood samples.

An ultrasound-assisted dispersive liquid–liquid microextraction (UADLLME) was developed as a simple, sensitive, and robust method for the simultaneous determination of quinocetone (QCT) and three of its synthesized desoxy metabolites in swine urine samples via high-performance liquid chromatography (HPLC). Experimental parameters were optimized using the one-factor-at-a-time approach and were followed using an orthogonal array design. The results indicate that ultrasonic irradiation significantly affects the DLLME extraction efficiency. Moreover, the intermolecular binding energies and octanol–water partition ratio (Kow) of the target analytes were calculated using the density functional theory and the atom-additive method, respectively. A high correlation was found between the extraction efficiency and the calculated results, which may serve as a scientific guideline in the determination of the target analyte selectivity of DLLME. The feasibility of UADLLME with HPLC for the simultaneous determination of QCT and its desoxy metabolites in blank swine urine samples was then investigated. Higher enrichment factors (118–175), low limits of detection (0.06–0.12 ng mL−1), and high precisions (relative standard deviation < 2.5%) were obtained. Calibration curves were performed in the 0.5–500 ng mL−1 range and displayed good linearity. In addition, the proposed method was successfully applied to the pharmacokinetic study of QCT and its desoxy metabolites in real urine samples. The results show that UADLLME has a potential application in the pharmacokinetic and residue studies of quinoxaline-N-dioxides derivatives in biological fluid samples.Highlights► Ultrasound-assisted (UA) DLLME was used for determination of Quinoxaline-N-dioxide drugs in swine urine samples. ► Orthogonal array design was performed to evaluated experimental parameters. ► Calculated intermolecular binding energies and Kow were obtained to investigate target analyte selectivity.

Heats of formation have been calculated by the DFT method for a number of furan derivatives. It is found that, with the isodesmic reaction, the calculations are in good agreement with the available experimental data. These results suggest that a combination of DFT methods with the isodesmic reaction afford accurate thermochemical data for relatively substituted furan derivatives. In this study, the MPW1PW91 method was found to be the most suitable method in predicting the enthalpy of formation of the furan derivatives.

The pKa value of perchloric acid was successfully calculated with high accuracy by using high-level ab initio methods, including G2 and CBS-QB3, DFT-based method, complete basis sets (CBS), and Gaussian-n methods. Solvation energies were calculated using the CPCM and IEF-PCM continuum models at the HF and B3LYP levels. Excellent agreement (to within 0.2 pKa units) was obtained between the calculated and experimentally determined values.

This paper presents a study of the performance of ultrasound-enhanced temperature-controlled (UETC) ionic liquid dispersive liquid–liquid microextraction (IL-DLLME). The use of ultrasonication and heating can enhance the ability of the ionic liquid to extract the analytes. Various parameters that would affect the extraction efficiency, such as the type and volume of the extraction and dispersing solvents, salt concentration, pH value, centrifugation time, effect of temperature on UETC-IL-DLLME, were investigated and optimized. Under the optimal extraction conditions, good enrichment factors (178–197) and recoveries (88.9–98.5%) were obtained. Good linearity was obtained in the range of 4–500 μg L−1 for myclobutanil and in the range of 6–500 μg L−1 for uniconazole, penconazole, tebuconazole and hexaconazole. Based on the optimized conditions, the UETC-IL-DLLME method was applied and combined with high-performance liquid chromatography with diode array detection (HPLC-DAD) to determine the presence of five triazole fungicides. The results showed that the method we proposed could effectively determine the target fungicides in rat blood samples.