Air assisted emulsification liquid-liquid microextraction based on deep eutectic solvent for preconcentration of methadone in water and biological samples

Air-assisted liquid-liquid microextraction based on solidification of floating deep eutectic solvent for the analysis of ultraviolet filters in water samples by high performance liquid chromatography with the aid of response surface methodology

For this work, a novel air-assisted liquid-liquid microextraction based on solidification of floating deep eutectic solvent (AA-LLME-SFDES), coupled with a high performance liquid chromatography (HPLC) method was developed for the detection of benzophenone and salicylate ultraviolet filters in water samples. Three types of fatty acid-based hydrophobic deep eutectic solvents (DESs) with low viscosity, low-density, and melting point close to room temperature were prepared and employed as extraction solvents. This air-assisted liquid-liquid microextraction was carried out in a glass centrifuge tube. Subsequently, the glass tube was introduced into ice-water bath and held for 3 min, during which the upper DES phase was solidified. The water phase was easily extracted using a syringe equipped with a long needle, and later, the glass tube was removed from ice-water bath. The solidified DES phase was immediately melted at room temperature and used for HPLC analysis. The response surface methodology was employed to optimize some influencing parameters such as the volume of the extraction solvent, the pH value of sample solution, the number of extraction cycles, and the addition of salt. A quadratic model, namely a central composite design, was used to replace the conventional single factor analysis. It was found that under optimal conditions, the limits of determination and quantification were 0.045-0.54 µg L^-1 and 0.15-2.0 µg L^-1, respectively. The relative standard deviations for inter-day (n = 5) and intra-day (n = 5) precision were ≤ 4.2%, whereas the enrichment factors for the ultraviolet filters were obtained from 41 to 50. Furthermore, this novel method was successfully employed for the detection of benzophenone and salicylate ultraviolet filters from real water samples. The recoveries ranged from 87.5% to 105.8%, whereas the RSDs were lower than 3.6%.

Air-assisted ionic liquid dispersive liquid-liquid microextraction based on solidification of the aqueous phase for the determination of triazole fungicides in water samples by high-performance liquid chromatography

A simple, rapid, and environmentally friendly approach was introduced to determine triazole fungicides in water samples by air-assisted ionic liquid dispersive liquid-liquid microextraction based on solidification of the aqueous phase using high-performance liquid chromatography-diode array detection. Ionic liquid was applied as the extraction solvent rather than a high-toxicity extraction solvent. The air-assisted dispersion method induced a trace amount of the ionic liquid to disperse as small droplets in the water sample, which significantly increased the contact area between the organic phase and the aqueous phase for the rapid transfer of target fungicides without using a dispersion solvent or auxiliary extraction devices. The solidification of the aqueous phase facilitated the collection of extraction solvent. The type of extraction solvent, the volume ratio of the extraction solvent to the water sample, the number of extraction cycles, the addition of NaCl, and pH values were evaluated. The recoveries were 72.65-100.13% with a relative standard deviation of 0.92% to 5.99%. The limits of quantification varied from 0.65 ng mL^-1 to 1.83 ng mL^-1. This approach can be used to determine fungicides in ground, river, and lake water samples.

Alternative Green Extraction Phases Applied to Microextraction Techniques for Organic Compound Determination

The use of green extraction phases has gained much attention in different fields of study, including in sample preparation for the determination of organic compounds by chromatography techniques. Green extraction phases are considered as an alternative to conventional phases due to several advantages such as non-toxicity, biodegradability, low cost and ease of preparation. In addition, the use of greener extraction phases reinforces the environmentally-friendly features of microextraction techniques. Thus, this work presents a review about new materials that have been used in extraction phases applied to liquid and sorbent-based microextractions of organic compounds in different matrices.

Ionic deep eutectic solvents for the extraction and separation of natural products

Room ionic liquids (ILs) used as green solvents have received considerable attention and wide application in different research and industrial fields, such as chemistry, biology, catalysis, energy, and even environmental sciences. Recently, a new class of sustainable solvents named deep eutectic solvents (DESs) have been developed, which share the promising solvent characteristics of ILs, such as thermal and chemical stability, low vapor pressure and design ability. In addition, the major advantages of DESs over ILs are their lower prices and easier preparation. Therefore, DESs have been considered to be a potential alternative to replace conventional organic solvents and ILs. Currently, the developed DESs may be classified into ionic and nonionic liquids. Typically, choline chloride (ChCl)/urea (1:2) is an ionic DES, while glucose/sucrose (1:1) is a nonionic DES. Although several reviews have covered advancements in DESs, in this review, we aim to provide a general insight into DESs, particularly ionic DESs, like choline-based DES, in terms of their preparation and application in the extraction of natural products (NPs) mainly from traditional Chinese medicines and the recovery of extracted compounds from their extracts. Additionally, various factors affecting the extraction efficiency of DESs are discussed.

Determination of microcystins in water samples by deep eutectic solvent-based vortex-assisted liquid–liquid microextraction coupled with ultrahigh-performance liquid chromatography-high resolution mass spectrometry

An eco-friendly and efficient DES-based VALLME coupled UHPLC-ESI(+)-qTOF-MS method was developed to determine MC-YR and MC-LR in surface water samples.

A highly efficient vortex-assisted liquid–liquid microextraction based on natural deep eutectic solvent for the determination of Sudan I in food samples

A natural deep eutectic solvent (NADES) composed of choline chloride (ChCl) and sesamol was successfully employed in the vortex-assisted liquid–liquid microextraction (VALLME) of food toxicant Sudan I (1-phenylazo-2-naphthalenol) in food samples for HPLC-UV analysis. Sesamol-based NADESs exhibited better Sudan I extraction abilities than other deep eutectic solvents and conventional organic solvents. ¹H NMR and 2D NOESY spectra were used to characterize the sesamol-based NADESs, indicating that hydrogen bonds were formed between ChCl and sesamol. The developed VALLME method showed a high extraction efficiency (near 100%) within 60 s at room temperature. Under the optimized extraction conditions, this established method showed good linearity (r² = 1.000) and a low limit of detection (LOD) of 0.02 mg kg⁻¹. The recoveries were in the range of 93–118%, and the intra-day and inter-day precisions were less than 4.5%. The developed method was successfully applied to the determination of Sudan I in various food samples, including chili oil, chili sauce, and duck egg yolk. This method gave a higher recovery than that of the EU recommended method when applied to sample analysis.

A highly efficient vortex-assisted liquid–liquid microextraction based on natural deep eutectic solvent was developed for the determination of Sudan I.

Deep Eutectic Solvent Based Air Assisted Ligandless Emulsification Liquid-Liquid Microextraction for Preconcentration of Some Heavy Metals in Biological and Environmental Samples

In this study, a deep eutectic solvent (DES) based on air-assisted ligandless emulsification liquid-liquid microextraction method (DES-AA-LL-ELLME) was considered for preconcentration and extraction of some metals (Cd, Ni, Pb and Cu). A 1:1 mixture of the synthesized DES and triethylamine was added as an extractant to extract metal ions in the absence of chelating agent. Tetrahydrofuran as the aprotic solvent provided a turbid state. To disperse the aggregated DES droplets into the aqueous phase, air-assisted was performed. The influence of several effective parameters was monitored. Under optimum conditions, limits of detection were found in the range of 0.31-0.99 µg L^-1 with preconcentration factor from 67 to 69. The relative standard deviation (n = 10) was in the range of 2.1%-3.1% for all analytes. This procedure was applied to determine some metals in both biological and environmental samples with appropriate recoveries about 98.7%-106%.

Development of a new emulsification microextraction method based on solidification of settled organic drop: application of a novel ultra-hydrophobic tailor-made deep eutectic solvent

In this research, a new microextraction method based on the solidification of settled organic drop (SSOD) was developed by coupling a novel tailor-made ultra-hydrophobic deep eutectic solvent (DES) with effervescence assisted emulsification microextraction.

Dispersion of magnetic graphene oxide nanoparticles coated with a deep eutectic solvent using ultrasound assistance for preconcentration of methadone in biological and water samples followed by GC-FID and GC-MS

Magnetic graphene nanoparticles coated with a new deep eutectic solvent (Fe₃O₄@GO-DES) were developed for efficient preconcentration of methadone. The extracted methadone was then analyzed by gas chromatography-flame ionization detection (GC-FID) or gas chromatography-mass spectrometry (GC-MS). Fe₃O₄@GO-DES were characterized by Fourier transform IR and X-ray diffraction techniques. Ultrasound was used to enhance the dispersion of the sorbent, with a high extraction recovery. Some parameters affecting the extraction recovery, such as pH, type of deep eutectic solvent, sample volume, amount of sorbent, extraction time, and type of eluent, were investigated. Under optimum conditions, the method developed was linear in the concentration range from 3 to 45,000 μg L^-1 for GC-FID and from 0.1 to 500 μg L^-1 for GC-MS, with a detection limit of 0.8 μg L^-1 for GC-FID and 0.03 μg L^-1 for GC-MS. The relative standard deviations (n = 6) as the intraday and interday precisions of the methadone spike at a concentration of 100 μg L^-1 were 5.8% and 8.4% respectively for GC-FID. The preconcentration factor was 250. Relative recoveries from spiked plasma, urine, and water samples ranged from 95.1% to 101.5%.