Magnetic Polyamide Nanocomposites for the Microextraction of Benzophenones from Water Samples.

In this article, the influence of the monomers on the extraction efficiency and the effect of the addition of surfactants during the synthesis have also been considered. The sorption capacity of the resulting nanocomposites has been evaluated, in the dispersive micro-solid phase extraction format, by determining that of six benzophenones in water using ultra performance liquid chromatography (UPLC) combined with photodiode array detection. Under the optimum conditions, the limits of detection were in the range of 0.5⁻4.3 ng/mL and the repeatability, expressed as the relative standard deviation (RSD), varied between 1.5% and 5.6%. The proposed method has been applied for the analysis of real water samples, providing relative recoveries in the interval of 84⁻105.

Dispersive liquid-liquid microextraction based on liquid anion exchanger for the direct extraction of inorganic anions.

For the first time, the possibility of the use of liquid anion exchangers in dispersive liquid-liquid microextraction for the direct extraction of some inorganic anions (nitrite, nitrate, and iodide) was evaluated. In this technique, chloroform containing a liquid anion exchanger (trioctylamine) was used as extractant. The mixture of the extractant and disperser solvent (acetonitrile) was injected into the acidic sample solution. The protonated trioctylamine formed a water-insoluble salt with the inorganic anions (analytes). After the phase separation and stripping of the analytes from the extractant, the analytes were determined by liquid chromatography with UV detection. Various parameters affecting the extraction efficiency were investigated. Under the optimum conditions, broad linear dynamic ranges, with determination coefficients (r2) higher than 0.998, and enrichment factors between 94 and 244 were obtained. The limits of detection and quantification were in the range of 0.1-0.5 and 0.4-1.7 µg L-1, respectively. Also, the values of intra- and inter-day relative standard deviations were 3.5-5.8% and 5.5-7.8%, respectively. Various real water samples including sea, tap, river, spring and mineral water were analyzed by the method. The method was sensitive, simple, inexpensive and capable of the simultaneous extraction and determination of the selected inorganic anions.

Comparison of three different dispersive liquid-liquid microextraction modes performed on their most usual configurations for the extraction of phenolic, neutral aromatic, and amino compounds from waters.

In this work we seek clues to select the appropriate dispersive liquid-liquid microextraction mode for extracting three categories of compounds. For this purpose, three common dispersive liquid-liquid microextraction modes were compared under optimized conditions. Traditional dispersive liquid-liquid microextraction, in situ ionic liquid dispersive liquid-liquid microextraction, and conventional ionic liquid dispersive liquid-liquid microextraction using chloroform, 1-butyl-3-methylimidazolium tetrafluoroborate, and 1-hexyl-3-methylimidazolium hexafluorophosphate as the extraction solvent, respectively, were considered in this work. Phenolic, neutral aromatic, and amino compounds (each category included six members) were studied as analytes. The analytes in the extracts were determined by high-performance liquid chromatography with UV detection. For the analytes with polar functionalities, the in situ ionic liquid dispersive liquid-liquid microextraction mode mostly led to better results. In contrast, for neutral hydrocarbons without polar functionalities, traditional dispersive liquid-liquid microextraction using chloroform produced better results. In this case, where dispersion forces were the dominant interactions in the extraction, the refractive index of solvent and analyte predicted the extraction performance better than the octanol/water partition coefficient. It was also revealed that none of the methods were successful in extracting hydrophilic analytes (compounds with the log octanol/water partition coefficient <2). The results of this study could be helpful in selecting a dispersive liquid-liquid microextraction mode for the extraction of various groups of compounds.

Recycling polymer residues to synthesize magnetic nanocomposites for dispersive micro-solid phase extraction.

The ubiquitous presence of plastics, an obvious consequence of their usefulness and low price, has turned them into a problem of environmental and safety concern. The new plastic economy, an initiative recently launched by the World Economic Forum and Ellen MacArthur Foundation, with analytical support from McKinsey & Company, promotes a change in the use of plastic worldwide around three main pillars: redesign, reusing and recycling. Recycled plastics, with the aim of extending their life spam, can be used to synthesize materials for analytical purposes. In this article polystyrene (PS) trays, previously used for food packaging, are proposed as polymeric source for the synthesis of magnetic nanocomposites. The synthesis plays with the solubility of PS in different solvents in such a way that PS is gelated in the presence of cobalt ferrite nanoparticles which are finally embedded in the polymeric network. The extraction capability of the magnetic PS nanocomposite was evaluated using the determination of four parabens (methylparaben, ethylparaben, propylparaben and butylparaben) in water using liquid chromatography-tandem mass spectrometry as model analytical problem. Under the optimum conditions, limits of detection and quantification were in the range of 0.05-0.15 and 0.15-0.5ng/mL, respectively. The precisions, expressed as relative standard deviation (RSD), varied between 4.4% and 8.5% and the relative recoveries for analysis of the water samples were in the interval 81.2-104.5%.

Suitability of dispersive liquid-liquid microextraction for the in situ silylation of chlorophenols in water samples before gas chromatography with mass spectrometry.

Trace analysis of chlorophenols in water was performed by simultaneous silylation and dispersive liquid-liquid microextraction followed by gas chromatography with mass spectrometry. Dispersive liquid-liquid microextraction was carried out using an organic solvent lighter than water (n-hexane). The effect of different silylating reagents on the method efficiency was investigated. The influence of derivatization reagent volume, presence of catalyst and derivatization/extraction time on the yield of the derivatization reaction was studied. Different parameters affecting extraction efficiency such as kind and volume of extraction and disperser solvents, pH of the sample and addition of salt were also investigated and optimized. Under the optimum conditions, the calibration graphs were linear in the range of 0.05-100 ng/mL and the limit of detection was 0.01 ng/mL. The enrichment factors were 242, 351, and 363 for 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol, respectively. The values of intra- and inter-day relative standard deviations were in the range of 3.0-6.4 and 6.1-9.9%, respectively. The applicability of the method was investigated by analyzing water and wastewater samples.

Low-density solvent-based dispersive liquid-liquid microextraction followed by high performance liquid chromatography for determination of warfarin in human plasma.

Extraction and determination of warfarin, a widely used anticoagulant drug, in human plasma were performed using a new generation of dispersive liquid-liquid microextraction (DLLME) and high performance liquid chromatography (HPLC). The extraction procedure is based on extraction solvents lighter than water and performing of extraction in a specially designed extraction cell. Some important parameters, including kind and volume of extraction and disperser solvents, pH of the sample solution, salt concentration in the sample solution and extraction time were investigated and optimized. Under the optimized conditions (150 µL 1-octanol as extraction solvent, 150 µL methanol as disperser solvent, pH(sample)=2.3, extraction time of 2 min, without salt addition), limit of detection (LOD) of 5 ng mL⁻¹ and extraction recovery of 91.0% were obtained. The calibration curve was linear within the range of 15-3000 ng mL⁻¹ with the square of correlation coefficient (R²) of 0.998. Repeatability and reproducibility of method based on five replicate extraction and determination were 2.8% and 6.5%, respectively. The proposed method was applied successfully for the determination of warfarin in plasma sample from a patient under treatment with this drug, and was demonstrated to be sensitive, efficient, and convenient.

Three-phase hollow fiber liquid phase microextraction of warfarin from human plasma and its determination by high-performance liquid chromatography.

A simple, inexpensive and efficient sample preparation technique, three-phase hollow fiber liquid phase microextraction (HF-LPME), followed by high-performance liquid chromatography-ultra violet detection (HPLC-UV) was used for the analysis of warfarin in human plasma. Warfarin was extracted from 11.0 ml of aqueous solution with pH=2.3 (donor phase) into 1-octanol immobilized in the wall pores of a porous hollow fiber and then extracted into the acceptor phase with pH=11.0 located in the lumen of the hollow fiber. After the extraction, the acceptor phase was directly injected into the HPLC system for quantification. Different factors affecting the HF-LPME including nature of organic extraction solvent, pH of donor and acceptor phases, stirring rate, extraction time and salt addition to the sample solution (donor phase) were investigated and optimized. Under the optimized conditions (1-octanol as organic solvent, pH(donor)=2.3, pH(acceptor)=11.0, stirring speed of 1000 rpm, extraction time of 30 min, without addition of salt), limit of detection (LOD) of 5 ng ml(-1) and enrichment factor of 225 were obtained. The calibration curve was linear within the range of 15-550 ng ml(-1) with the square of correlation coefficient of 0.9984. The values of intra-day relative standard deviation (RSD) and inter-day RSD were 4.2% and 11.1%, respectively. The method was applied successfully for the analysis of warfarin in plasma sample from a patient under treatment with this drug and excellent sample clean-up was observed.