Ionic Liquid-phase Microextraction Research Articles

Simple and fast spectrophotometric determination of low levels of thiabendazole residues in fruit and vegetables after pre-concentration with ionic liquid phase microextraction

ABSTRACTThere is a great importance of monitoring thiabendazole (TBZ) residues in fruits and vegetables to ensure food safety. Therefore, a new ionic liquid (IL) phase microextraction method using IL, 1-butyl-3-methylimidazoliumhexafluorophosphate [C4mim][PF6], as extracting solvent is proposed for simple and fast determination of low levels of TBZ in fruits and vegetables by spectrophotometry. The method is based on selective complex formation of TBZ with Cu(II) ions in presence of PF6– as counter ion at pH 5.5, and then microextraction of the complex into the fine micro-drops of IL phase. After optimisation of variables affecting microextraction efficiency, the analytical parameters of the method were determined by calibration curves. The method exhibits a linear relationship (0.3–280 μg L−1), low detection limit (0.1 μg L−1), good intra- and inter-day precision (2.4–4.5% as RSDr%, 2.1–5.6% as RSDR%), good recovery (≥95.1–98.2%) and high sensitivity enhancement factor (150) by solvent-based calibration curve. It allows a detection limit of 0.24 μg L−1 and a range of 0.8–250 μg L−1 by the matrix-matched calibration curve. After validation, the method was successfully applied to the determination of TBZ residues with method quantification limits in fruit and vegetables of 2.0 and 2.5 µg kg−1 with and without adding polyvinylpyrrolidone (PVP-15) solution. Recoveries range from 85.5% to 98.2% after spiking (10, 50 and 100 µg kg−1, n: 3).

Ringer tablet-based ionic liquid phase microextraction: Application in extraction and preconcentration of neonicotinoid insecticides from fruit juice and vegetable samples

An efficient, reliable, sensitive, rapid, and green analytical method for the extraction and determination of neonicotinoid insecticides in aqueous samples has been developed using ionic liquid phase microextraction coupled with high performance liquid chromatography–diode array detector. In this method, a few microliters of 1–hexyl–3–methylimidazolium hexafluorophosphate (as an extractant) is added onto a ringer tablet and it is transferred into a conical test tube containing aqueous phase of the analytes. By manually shaking, the ringer tablet is dissolved and the extractant is released into the aqueous phase as very tiny droplets to provide a cloudy solution. After centrifuging the extracted analytes into ionic liquid are collected at the bottom of a conical test tube. Under the optimum extraction conditions, the method showed low limits of detection and quantification between 0.12 and 0.33 and 0.41 and 1.11ngmL–1, respectively. Extraction recoveries and enrichment factors were from 66% to 84% and 655% to 843%, respectively. Finally different aqueous samples were successfully analyzed using the proposed method.

Ionic liquid phase microextraction combined with fluorescence spectrometry for preconcentration and quantitation of carvedilol in pharmaceutical preparations and biological media.

BackgroundCarvedilol belongs to a group of medicines termed non-selective beta-adrenergic blocking agents. In the presented approach, a practical and environmentally friendly microextraction method based on the application of ionic liquids (ILs) was followed by fluorescence spectrometry for trace determination of carvedilol in pharmaceutical and biological media.MethodsA rapid and simple ionic liquid phase microextraction was utilized for preconcentration and extraction of carvedilol. A hydrophobic ionic liquid (IL) was applied as a microextraction solvent. In order to disperse the IL through the aqueous media and extract the analyte of interest, IL was injected into the sample solution and a proper temperature was applied and then for aggregating the IL-phase, the sample was cooled in an ice water-bath. The aqueous media was centrifuged and IL-phase collected at the bottom of the test tube was introduced to the micro-cell of spectrofluorimeter, in order to determine the concentration of the enriched analyte.ResultsMain parameters affecting the accuracy and precision of the proposed approach were investigated and optimized values were obtained. A linear response range of 10–250 μg l−1 and a limit of detection (LOD) of 1.7 μg l−1 were obtained.ConclusionFinally, the presented method was utilized for trace determination of carvedilol in commercial pharmaceutical preparations and biological media.

A novel salt-controlled homogenous ionic liquid phase microextraction based on the salting out effect and optimization of the procedure using the experimental design methodology

A novel salt-controlled homogenous ionic liquid phase microextraction based on the salting out effect, combined with high performance liquid chromatography-diode array detection (HPLC-DAD), was proposed for simultaneous preconcentration and separation of azole compounds from wastewater samples. According to this procedure, 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) and methanol were used as the extraction and consolute solvents; the homogenous solution was also broken by the addition of sodium chloride. Optimization of the conditions for high extraction efficiency was studied simultaneously using experimental designs. A Plackett–Burman design (PBD) was applied to screen the significant factors on the extraction efficiency. A Box–Behnken design (BBD) was then used for the optimization of significant factors and the response surface equations were obtained. Under the best conditions, the detection limits (in the range of 1.25–5 μg L−1), relative standard deviation (RSD% < 11.1) and error percent (between 7.2% and −11.8%) were obtained. Preconcentration factors were obtained in the range of 75–111. Finally, the performance of the proposed method was tested to determine trace amounts of azole compounds in wastewater and satisfactory results were obtained.