Single-drop coacervative microextraction of organic compounds prior to liquid chromatography

A review of green solvent extraction techniques and their use in antibiotic residue analysis

Antibiotic residues are being continuously recognized in the aquatic environment and in food. Though the concentration of antibiotic residues is typically low, adverse effects on the environment and human health have been observed. Hence, an efficient method to determine numerous antibiotic residues should be simple, inexpensive, selective, with high throughput and with low detection limits. Liquid-based extractions have been exceedingly used for clean-up and preconcentration of antibiotics prior to chromatographic analysis. In order to make methods more green and environmentally sustainable, conventional hazardous organic solvents can be replaced with green solvents. This review presents sampling strategies as well as comprehensive and up-to-date methods for chemical analysis of antibiotic residues in different sample matrices. Particularly, solvent-based sample preparation techniques using green solvents are discussed along with applications in antibiotic residue analysis.

Recent Application of Deep Eutectic Solvents as Green Solvent in Dispersive Liquid-Liquid Microextraction of Trace Level Chemical Contaminants in Food and Water

As growing concerns on green, cost-effective, and time-saving chemistry analysis methods, deep eutectic solvents (DESs) are considered to be promising green alternatives to conventional solvents in dispersive liquid-liquid microextraction (DLLME) of trace level chemical contaminants in food and water, due to their biodegradability, low cost, and simple preparation. In the past few years, numerous innovative researches have focused on preconcentration of trace level chemical contaminants using DESs as extractant. In this context, this review aims to summarize the updated state-of-the-art effort dedicated to preconcentration of trace level chemical contaminants in food and water sample using DESs as extractants in DLLME. Furthermore, the major impact factors affecting the preconcentration efficiency and process mechanisms are thoroughly analyzed and discussed. Finally, prospects and challenges in application of DESs as solvents in DLLME to enrich trace level chemical contaminants are extensively elucidated and critically reviewed.

Twenty years of supramolecular solvents in sample preparation for chromatography: achievements and challenges ahead

Supramolecular solvents (SUPRAS) have progressively become a suitable alternative to organic solvents for sample preparation in chromatographic analysis. The inherent properties of these nanostructured solvents (e.g. different polarity microenvironments, multiple binding sites, possibility of tailoring their properties, etc.) offer multiple opportunities for the development of innovative sample treatment platforms not approachable by conventional solvents. In this review, major achievements attained in the combination SUPRAS-chromatography in the last 20 years as well as the challenges that should be addressed in the near future are critically discussed. Among achievements, particular attention is paid to the theoretical and practical knowledge gained that has helped make substantial progress in the area. In this respect, advances in the understanding of the mechanisms involved in SUPRAS formation and SUPRAS-solute interactions driving extractions are discussed, with a view to the setting up of knowledge-based extraction procedures. Likewise, the strategies followed to improve the compatibility of SUPRAS extracts with liquid and gas chromatography and adapt SUPRAS-based extractions to different formats are presented. Ongoing efforts to apply SUPRAS in multicomponent extractions and synthesize tailored SUPRAS for the development of innovative sample treatments are highlighted. Among challenges identified, discussion is focused on the automation of SUPRAS-based sample treatment and the elucidation of SUPRAS nanostructures, which are considered essential for their acceptance in routine labs and the design of tailored SUPRAS with programmed functions. Graphical abstract.

Multifunctional vesicular coacervates as engineered supramolecular solvents for wastewater treatment

In this study, multifunctional supramolecular solvents (SUPRASs) able to simultaneously extract ionic, polar and hydrophobic organic compounds from wastewater have been developed. SUPRASs were synthesized in aqueous solutions containing mixtures of carboxylic acids and carboxylates that underwent spontaneous self-assembly and coacervation under the addition of tetraalkylammonium ions. These SUPRAS consisted of coacervate droplets made up of large unilamellar vesicular aggregates bridged by tetraalkylammonium ions. Both, the high kinetic stability of vesicles and their strong interaction with tetraalkylammonium ions through different bonds working cooperatively, made supramolecular nanostructures in the SUPRAS chemically stable, which minimized the presence of solvent residues in the treated water. The suitability of the synthesized SUPRASs to behave as multifunctional extractants in water treatment was investigated by their application to the removal of anionic, cationic and ionizable dyes and PAHs. All the variables affecting the extraction process were optimized (i.e. chain length of the tetraalkylammonium ion, fractional SUPRAS phase volume, pH, ionic strength, pollutant concentration and stirring time/rate). All the pollutants selected were efficiently removed at room temperature and a fractional SUPRAS phase volume of 0.01. Applicability of the SUPRAS-based treatment to the efficient removal of dyes in textile effluents and benzo(a)pyrene in tap water was proved. Overall, the low cost, easy synthesis and high removal efficiency of these engineered SUPRASs make them highly promising for application in comprehensive wastewater treatments.

Development of supramolecular solvent based microextraction prior to high performance liquid chromatography for simultaneous determination of phenols in environmental water

SUPRAS based microextraction for phenols.

Highly selective amino-functionalized magnetic molecularly imprinted polymers: absorbents for dispersive solid phase extraction and trace level analysis of chlorophenols in seawater

Three-in-one dispersive magnetic solid phase extraction system for preconcentration of trace-level CPs in seawater was established by using as-prepared molecularly imprinted magnetic polymers with effective, fast, and accurate for routine analyses.

Chlorophenol's ultra-trace analysis in environmental samples by chitosan-zinc oxide nanorod composite as a novel coating for solid phase micro-extraction combined with high performance liquid chromatography

In this study, a simple, novel, and efficient preconcentration method has been developed for the determination of some chlorophenols (4-chlorophenol, 2,5-dichlorophenol, 2,3-dichlorophenol, and 2,4,6-trichlorophenol) using a direct solid phase microextraction (D-SPME) based on chitosan-ZnO nanorod composite combined with high performance liquid chromatography (HPLC). A one step-novel hydrothermal method was demonstrated on the fabrication of ZnO nanorods arrayed on the fused silica fiber in the chitosan hydrogel solution (CZNC) as a new coating of SPME fiber. The coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) instruments. The CZNC coating has combined the merits of both ZnO nanorods and chitosan hydrogel; it has several improvements such as increased extraction efficiency of chlorophenols and longer life time (over 80 cycles of D-SPME-HPLC operation). Experimental design method was used for optimization of extraction conditions and determination of four chlorophenols in water samples by SPME-HPLC-UV method. The calibration curves were linear from 5 to 1000 µg L(-1) for analytes, and the limits of detection were between 0.1 and 2 µg L(-1). Single fiber repeatability and fiber-to-fiber reproducibility were in the range of 5.8-10.2% and 8.8-14.5%, respectively. The spiked recoveries at 50 µg L(-1) for environmental water sample were in the range of 93-102%.

Microextraction techniques coupled to liquid chromatography with mass spectrometry for the determination of organic micropollutants in environmental water samples

Until recently, sample preparation was carried out using traditional techniques, such as liquid–liquid extraction (LLE), that use large volumes of organic solvents. Solid-phase extraction (SPE) uses much less solvent than LLE, although the volume can still be significant. These preparation methods are expensive, time-consuming and environmentally unfriendly. Recently, a great effort has been made to develop new analytical methodologies able to perform direct analyses using miniaturised equipment, thereby achieving high enrichment factors, minimising solvent consumption and reducing waste. These microextraction techniques improve the performance during sample preparation, particularly in complex water environmental samples, such as wastewaters, surface and ground waters, tap waters, sea and river waters. Liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS) and time-of-flight mass spectrometric (TOF/MS) techniques can be used when analysing a broad range of organic micropollutants. Before separating and detecting these compounds in environmental samples, the target analytes must be extracted and pre-concentrated to make them detectable. In this work, we review the most recent applications of microextraction preparation techniques in different water environmental matrices to determine organic micropollutants: solid-phase microextraction SPME, in-tube solid-phase microextraction (IT-SPME), stir bar sorptive extraction (SBSE) and liquid-phase microextraction (LPME). Several groups of compounds are considered organic micropollutants because these are being released continuously into the environment. Many of these compounds are considered emerging contaminants. These analytes are generally compounds that are not covered by the existing regulations and are now detected more frequently in different environmental compartments. Pharmaceuticals, surfactants, personal care products and other chemicals are considered micropollutants. These compounds must be monitored because, although they are detected in low concentrations, they might be harmful toward ecosystems.

An improved ionic liquid-based headspace single-drop microextraction-liquid chromatography method for the analysis of camphor and trans-anethole in compound liquorice tablets

A simple, accurate and sensitive ionic liquid-based headspace single-drop microextraction procedure followed by high-performance liquid chromatography was developed and validated for the determination of camphor and trans-anethole in compound liquorice tablets. The volume of the ionic liquid microdrop was increased to 12 µL by modifying the device of the suspended drop. The stability of the microdrop and the sensitivity of the method were improved. Under the optimum experimental conditions, the calculated calibration curves gave acceptable linearity for camphor and trans-anethole with correlation coefficients of 0.9990 and 0.9998, respectively. The repeatability of the proposed method, expressed as relative standard deviation, was below 4.5% (n = 5). The limits of detection for the two target analytes were found to be 9.77 and 1.95 × 10(-2) μg/mL, respectively. In this study, the separation, purification and enrichment were achieved in one step in an airtight system, which reduced the interferences caused by other complicated constituents, increased the signal-to-noise of the method and ensured the accuracy of the results because there was no loss of volatile components. It is expected to be widely applied for sample pretreatment of volatile components with high boiling points in samples with complicated matrices such as the extractions of plants or Chinese traditional drugs.