Use of magnetic effervescent tablet-assisted ionic liquid dispersive liquid-liquid microextraction to extract fungicides from environmental waters with the aid of experimental design methodology

Photodegradation of multiclass fungicides in the aquatic environment and determination by liquid chromatography-tandem mass spectrometry

The photodegradation behaviour for nine widespread fungicides (benalaxyl, cyprodinil, dimethomorph, fenhexamide, iprovalicarb, kresoxim-methyl, metalaxyl, myclobutanil and tebuconazole) was evaluated in different types of water. Two different systems, direct UV photolysis and UVC/H₂O₂ advanced oxidation process (AOP), were applied for the photodegradation tests. For the monitoring of the target compound degradation, a method based on direct injection liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. Several fungicide photodegradation by-products were tentatively identified by high-resolution mass spectrometry (HRMS) as well. For the photolysis studies, the efficiency of different types of radiation, UVC (λ = 254 nm) and UVA (λ = 365 nm), was compared. UVC photolysis provided the highest removal with a complete degradation for fenhexamide and kresoxim-methyl, and percentages between 48 and 78% for the other compounds, excluding iprovalicarb and myclobutanil with removals <35%, after 30 min of irradiation. Besides, the photodegradation tests were performed with different initial concentrations of fungicides, and the efficiency of two photoreactor systems was compared. In all cases, the kinetics followed pseudo-first order, and the half-life times could also be calculated. The addition of H₂O₂ under UVC light allowed an improvement of the reaction kinetics, especially for the most recalcitrant fungicides, obtaining in all cases removals higher than 82% in less than 6 min. Finally, in order to evaluate the suitability of the proposed systems, both UVC photolysis and UVC/H₂O₂ system were tested in different real water matrices (wastewater, tap water, swimming pool water and river water), showing that the UVC/H₂O₂ system had the highest removal efficiency in less than 6 min, for all water samples.

Rapid analysis of fungicides in tea infusions using ionic liquid immobilized fabric phase sorptive extraction with the assistance of surfactant fungicides analysis using IL-FPSE assisted with surfactant

A green, simple, inexpensive, and sensitive ionic liquid immobilized fabric phase sorptive extraction method coupled with high performance liquid chromatography was developed for rapid screening and simultaneous determination of four fungicides (azoxystrobin, chlorothalonil, cyprodinil and trifloxystrobin) residues in tea infusions. This IL modified extraction fiber is capable of extracting target analytes directly from complicated tea water matrices with the addition of surfactant. A series of extraction conditions were investigated by one-factor-at-a-time approach and orthogonal test. After a series experiments, the optimum conditions were found to be 10% [HIMIM]NTf₂ as coating solution, 2min vortex time, 500μL acetonitrile as dispersive solvent and 2min desorption time. Under the above conditions, the proposed technique was applied to detect fungicides from real tea water samples with satisfactory results.

Headspace single drop microextraction versus dispersive liquid-liquid microextraction using magnetic ionic liquid extraction solvents

A headspace single drop microextraction (HS-SDME) method and a dispersive liquid-liquid microextraction (DLLME) method were developed using two tetrachloromanganate ([MnCl₄^2-])-based magnetic ionic liquids (MIL) as extraction solvents for the determination of twelve aromatic compounds, including four polyaromatic hydrocarbons, by reversed phase high-performance liquid chromatography (HPLC). The analytical performance of the developed HS-SDME method was compared to the DLLME approach employing the same MILs. In the HS-SDME approach, the magnetic field generated by the magnet was exploited to suspend the MIL solvent from the tip of a rod magnet. The utilization of MILs in HS-SDME resulted in a highly stable microdroplet under elevated temperatures and long extraction times, overcoming a common challenge encountered in traditional SDME approaches of droplet instability. The low UV absorbance of the [MnCl₄^2-]-based MILs permitted direct analysis of the analyte enriched extraction solvent by HPLC. In HS-SDME, the effects of ionic strength of the sample solution, temperature of the extraction system, extraction time, stir rate, and headspace volume on extraction efficiencies were examined. Coefficients of determination (R²) ranged from 0.994 to 0.999 and limits of detection (LODs) varied from 0.04 to 1.0μgL^-1 with relative recoveries from lake water ranging from 70.2% to 109.6%. For the DLLME method, parameters including disperser solvent type and volume, ionic strength of the sample solution, mass of extraction solvent, and extraction time were studied and optimized. Coefficients of determination for the DLLME method varied from 0.997 to 0.999 with LODs ranging from 0.05 to 1.0μgL^-1. Relative recoveries from lake water samples ranged from 68.7% to 104.5%. Overall, the DLLME approach permitted faster extraction times and higher enrichment factors for analytes with low vapor pressure whereas the HS-SDME approach exhibited better extraction efficiencies for analytes with relatively higher vapor pressure.

Magnetic effervescent tablet-assisted ionic liquid dispersive liquid-liquid microextraction of selenium for speciation in foods and beverages

A novel, simple and rapid method based on magnetic effervescent tablet-assisted ionic liquid dispersive liquid-liquid microextraction (MEA-IL-DLLME) followed by graphite furnace atomic absorption spectrometry (GFAAS) determination was established for the speciation of selenium in various food and beverage samples. In the procedure, a special magnetic effervescent tablet containing CO2 sources (sodium carbonate and sodium dihydrogenphosphate), ionic liquids and Fe3O4 magnetic nanoparticles (MNPs) was used to combine extractant dispersion and magnetic recovery procedures into a single step. The parameters influencing the microextraction efficiency, such as pH of the sample solution, volume of ionic liquid, amount of MNPs, concentration of the chelating agent, salt effect and matrix effect were investigated and optimised. Under the optimised conditions, the limits of detection (LODs) for Se(IV) were 0.021 μg l(-)(1) and the linear dynamic range was 0.05-5.0 μg l(-)(1). The relative standard deviation for seven replicate measurements of 1.0 μg l(-)(1) of Se(IV) was 2.9%. The accuracy of the developed method was evaluated by analysis of the standard reference materials (GBW10016 tea, GBW10017 milk powder, GBW10043 Liaoning rice, GBW10046 Henan wheat, GBW10048 celery). The proposed method was successfully applied to food and beverage samples including black tea, milk powder, mushroom, soybean, bamboo shoots, energy drink, bottled water, carbonated drink and mineral water for the speciation of Se(IV) and Se(VI) with satisfactory relative recoveries (92.0-108.1%).