Determination of rifaximin in rat serum by ionic liquid based dispersive liquid-liquid microextraction combined with RP-HPLC

An efficient and environmental friendly ionic liquid based dispersive liquid-liquid microextraction procedure was optimized for determination of rifaximin in rat serum by reverse phase high-performance liquid chromatography. The effect of ionic liquids, dispersive solvents, extractant/disperser ratio, and salt concentrations on sample recovery and enrichment factors were studied. Among the five ionic liquids studied in the present investigation, 1-butyl-3-methylimidazolium hexafluorophosphate was found to be most effective for extraction of rifaximin. The recovery was found to be more than 98% using 1-butyl-3-methylimidazolium hexafluorophosphate and methanol as extraction and dispersive solvents, at an extractant/disperser ratio of 0.43. The recovery was further enhanced to 99.5% by the addition of 5.0% NaCl solution. A threefold enhancement in detection limit was achieved when compared to protein precipitation. The ionic liquid containing the extracted rifaximin was directly injected into HPLC system. The linear relationship was observed in the range of 0.03-10.0 μg/mL with the correlation coefficient (r(2) ) 0.9998. Limits of detection and quantification were found to be 0.01 and 0.03 μg/mL, respectively. The relative standard deviation was 2.5%. The method was validated and applied to study pharmacokinetics of rifaxmin in rat serum.     

Determination of triazine herbicides in juice samples by microwave‐assisted ionic liquid/ionic liquid dispersive liquid–liquid microextraction coupled with high‐performance liquid chromatography

A novel microextraction method, termed microwave‐assisted ionic liquid/ionic liquid dispersive liquid–liquid microextraction, has been developed for the rapid enrichment and analysis of triazine herbicides in fruit juice samples by high‐performance liquid chromatography. Instead of using hazardous organic solvents, two kinds of ionic liquids, a hydrophobic ionic liquid (1‐hexyl‐3‐methylimidazolium hexafluorophosphate) and a hydrophilic ionic liquid (1‐butyl‐3‐methylimidazolium tetrafluoroborate), were used as the extraction solvent and dispersion agent, respectively, in this method. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of 1‐hexyl‐3‐methylimidazolium hexafluorophosphate dispersed entirely into sample solution with the help of 1‐butyl‐3‐methylimidazolium tetrafluoroborate. In addition, an ion‐pairing agent (NH₄PF₆) was introduced to improve recoveries of the ionic liquid phase. Several experimental parameters that might affect the extraction efficiency were investigated. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 5.00–250.00 μg/L, with the correlation coefficients of 0.9982–0.9997. The practical application of this effective and green method is demonstrated by the successful analysis of triazine herbicides in four juice samples, with satisfactory recoveries (76.7–105.7%) and relative standard deviations (lower than 6.6%). In general, this method is fast, effective, and robust to determine triazine herbicides in juice samples.     

Ionic‐liquid‐based dispersive liquid–liquid microextraction coupled with high‐performance liquid chromatography for the forensic determination of methamphetamine in human urine

Determination of methamphetamine in forensic laboratories is a major issue due to its health and social harm. In this work, a simple, sensitive, and environmentally friendly method based on ionic liquid dispersive liquid–liquid microextraction combined with high‐performance liquid chromatography was established for the analysis of methamphetamine in human urine. 1‐Octyl‐3‐methylimidazolium hexafluorophosphate with the help of disperser solvent methanol was selected as the microextraction solvent in this process. Various parameters affecting the extraction efficiency of methamphetamine were investigated systemically, including extraction solvent and its volume, disperser solvent and its volume, sample pH, extraction temperature, and centrifugal time. Under the optimized conditions, a good linearity was obtained in the concentration range of 10–1000 ng/mL with determination coefficient >0.99. The limit of detection calculated at a signal‐to‐noise ratio of 3 was 1.7 ng/mL and the relative standard deviations for six replicate experiments at three different concentration levels of 100, 500, and 1000 ng/mL were 6.4, 4.5, and 4.7%, respectively. Meanwhile, up to 220‐fold enrichment factor of methamphetamine and acceptable extraction recovery (>80.0%) could be achieved. Furthermore, this method has been successfully employed for the sensitive detection of a urine sample from a suspected drug abuser.     

Ionic liquid‐based microwave‐assisted surfactant‐improved dispersive liquid–liquid microextraction and derivatization of aminoglycosides in milk samples

A green and simple method, ionic liquid‐based microwave‐assisted surfactant‐improved dispersive liquid–liquid microextraction and derivatization was developed for the determination of aminoglycosides in milk samples. Nonionic surfactant Triton X‐100 and ionic liquid 1‐hexyl‐3‐methylimidazolium hexafluorophosphate were used as the disperser and extraction solvent, respectively. Extraction, preconcentration, and derivatization of aminoglycosides were carried out in a single step. Several experimental parameters, including type and volume of extraction solvent, type and concentration of surfactant, microwave power and irradiation time, concentration of derivatization reagent, and pH value and volume of buffer were investigated and optimized. Under the optimum experimental conditions, the linearities for determining the analytes were in the range 0.4–10.0 ng/mL for tobramycin, 1.0–25.0 ng/mL for neomycin, and 2.0–50.0 ng/mL for gentamicin, with the correlation coefficients ranging from 0.9991 to 0.9998. The LODs for the analytes were between 0.11 and 0.50 ng/mL. The present method was applied to the analysis of different milk samples, and the recoveries of aminoglycosides obtained were in the range 96.4–105.4% with the RSDs lower than 5.5%. The results showed that the present method was a rapid, convenient, and environmentally friendly method for the determination of aminoglycosides in milk samples.     

In situ ionic liquid dispersive liquid–liquid microextraction combined with ultra high performance liquid chromatography for determination of neonicotinoid insecticides in honey samples

An efficient in situ ionic liquid dispersive liquid–liquid microextraction followed by ultra‐performance liquid chromatography was developed to determine four neonicotinoid insecticides in wild and commercial honey samples. In this method, a hydrophobic ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate, formed by in situ reaction between potassium hexafluorophosphate and 1‐butyl‐3‐methylimidazolium bromide in sample solution, was used as the extraction solvent. In comparison with the traditional dispersive liquid–liquid microextraction method, the developed method required no dispersive solvent. To achieve high extraction efficiency and enrichment factor, the effects of various experimental parameters were studied in detail. Under the optimized conditions, the limits of detection and quantification were in the ranges of 0.30–0.62 and 1.20–2.50 μg/L, respectively. The method showed high enrichment factors (74–115) with the recoveries between 81.0 and 103.4%. The proposed method was finally applied to different wild and commercial honey samples.     

Determination of atenolol in human plasma using ionic‐liquid‐based ultrasound‐assisted in situ solvent formation microextraction followed by high‐performance liquid chromatography

An efficient analytical method called ionic‐liquid‐based ultrasound‐assisted in situ solvent formation microextraction followed by high‐performance liquid chromatography was developed for the determination of atenolol in human plasma. A hydrophobic ionic liquid (1‐butyl‐3‐methylimidazolium hexafluorophosphate) was formed by the addition of a hydrophilic ionic liquid (1‐butyl‐3‐methylimidazolium tetrafluoroborate) to a sample solution containing an ion‐pairing agent during microextraction. The analyte was extracted into the ionic liquid phase while the microextraction solvent was dispersed throughout the sample by utilizing ultrasound. The sample was then centrifuged, and the extracting phase retracted into the microsyringe and injected to liquid chromatography. After optimization, the calibration curve showed linearity in the range of 2–750 ng/mL with the regression coefficient corresponding to 0.998. The limits of detection (S/N = 3) and quantification (S/N = 10) were 0.5 and 2 ng/mL, respectively. A reasonable relative recovery range of 90–96.7% and satisfactory intra‐assay (4.8–5.1%, n = 6) and interassay (5.0–5.6%, n = 9) precision along with a substantial sample clean‐up demonstrated good performance of the procedure. It was applied for the determination of atenolol in human plasma after oral administration and some pharmacokinetic data were obtained.     

In situ ionic‐liquid‐dispersive liquid–liquid microextraction of Sudan dyes from liquid samples

In situ ionic‐liquid‐dispersive liquid–liquid microextraction was introduced for extracting Sudan dyes from different liquid samples followed by detection using ultrafast liquid chromatography. The extraction and metathesis reaction can be performed simultaneously, the extraction time was shortened notably and higher enrichment factors can be obtained compared with traditional dispersive liquid–liquid microextraction. When the extraction was coupled with ultrafast liquid chromatography, a green, convenient, cheap, and efficient method for the determination of Sudan dyes was developed. The effects of various experimental factors, including type of extraction solvent, amount of 1‐hexyl‐3‐methylimidazolium chloride, ratio of ammonium hexafluorophosphate to 1‐hexyl‐3‐methylimidazolium chloride, pH value, salt concentration in sample solution, extraction time and centrifugation time were investigated and optimized for the extraction of four kinds of Sudan dyes. The limits of detection for Sudan I, II, III, and IV were 0.324, 0.299, 0.390, and 0.655 ng/mL, respectively. Recoveries obtained by analyzing the seven spiked samples were between 65.95 and 112.82%. The consumption of organic solvent (120 μL acetonitrile per sample) was very low, so it could be considered as a green analytical method.     

Double dispersant‐assisted ionic liquid dispersive liquid–liquid microextraction coupled with capillary electrophoresis for the determination of benzophenone‐type ultraviolet filters in sunscreen cosmetic product

In this work, double dispersant‐assisted ionic liquid dispersive liquid–liquid microextraction coupled with micellar electrokinetic chromatography was developed to determine four UV filters (benzophenone, 4‐hydroxybenzophenone, 2,4‐dihydroxybenzophenone, and 2‐hydroxy‐4‐methoxybenzophenone). 1‐Hexyl‐3‐methylimidazolium hexafluorophosphate was used as the extraction solvent. The main novelty of the present work was that acetonitrile‐Triton X‐114 was used as double disperser solvent. Parameters affected the extraction efficiency were investigated and optimized. Under the optimum conditions, enrichment factors were in the range of 25.3?40.5. The limits of detection and quantitation, calculated at a S/N of three and ten, were 3.9?6.7 ng/mL and 13.0?22.3 ng/mL. The linearity of the method was in the range of 0.02?2 μg/mL for 2, 4‐dihydroxybenzophenone and 4‐hydroxybenzophenone, 0.01?2 μg/mL for benzophenone and 2‐hydroxy‐4‐methoxybenzophenone, with correlation coefficient (R²) of 0.9984?0.9991. The proposed method was successfully applied to the determination of four benzophenone‐type UV filters in six kinds of sunscreen cosmetic products, with yielded relative recoveries ranging from 80.2 to 117.7%.     

Ionic liquid foam floatation coupled with ionic liquid dispersive liquid–liquid microextraction for the separation and determination of estrogens in water samples by high‐performance liquid chromatography with fluorescence detection

An ionic liquid foam floatation coupled with ionic liquid dispersive liquid–liquid microextraction method was proposed for the extraction and concentration of 17‐α‐estradiol, 17‐β‐estradiol‐benzoate, and quinestrol in environmental water samples by high‐performance liquid chromatography with fluorescence detection. 1‐Hexyl‐3‐methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion‐pairing and salting‐out agent NH₄PF₆ was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1‐hexyl‐3‐methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid–liquid microextraction was widened.     

Ionic liquids dispersive liquid–liquid microextraction and high‐performance liquid chromatographic determination of irbesartan and valsartan in human urine

An environmentally friendly ionic liquids dispersive liquid–liquid microextraction (IL‐DLLME) method coupled with high‐performance liquid chromatography (HPLC) for the determination of antihypertensive drugs irbesartan and valsartan in human urine samples was developed. The HPLC separations were accomplished in less than 10 min using a reversed‐phase C₁₈ column (250 × 4.60 mm i.d., 5 µm) with a mobile phase containing 0.3 % formic acid solution and methanol (v/v, 3:7; flow rate, 1.0 mL/min). UV absorption responses at 236 nm were linear over a wide concentration range from 50 µg/mL to the detection limits of 3.3 µg/L for valsartan and 1.5 µg/L for irbesartan. The effective parameters on IL‐DLLME, such as ionic liquid types and their amounts, disperser solvent types and their volume, pH of the sample and extraction time were studied and optimized. The developed IL‐DLLME‐HPLC was successfully applied for evaluation of the urine irbesartan and valsartan profile following oral capsules administration. Copyright © 2012 John Wiley & Sons, Ltd.     

Ionic‐liquid‐based dispersive liquid–liquid microextraction for high‐throughput multiple food contaminant screening

This paper describes an innovation of dispersive liquid–liquid microextraction enabling multiple‐component analysis of eight high‐priority food contaminants in two chemically distinctive families: Sudan dyes and phthalate plasticizers. To provide convenient sample handling for solid and solid‐containing matrices, a modified dispersive liquid–liquid microextraction procedure used an extractant precoated frit to perform simultaneous filtration, solvent mixing, and phase dispersion in one simple step. A binary ionic liquid extractant system was carefully tuned to deliver high quality analysis based only on affordable LC with diode array detector instrumentation. The method is comprehensively validated for robust quantification with good precision (6.9–9.8% RSD) in a linear 2–1000 μg/L range. Having accomplished enrichment factors up to 451, the treatment enables sensitive detection at 0.09–1.01 μg/L levels. Analysis of six high‐risk solid condiments and sauces further verified its practical applicability within a 70–120% recovery range. Compared to other approaches, the current dispersive liquid–liquid microextraction treatment offers major advantages in terms of minimal solvent (1.5 mL) and sample (0.1 g) consumption, ultra‐high analytical throughput (6 min), and the ability to handle complex solid matrices. The idea of performing simultaneous analysis for multiple contaminants presented here fosters a more effective mode of operation in food control routines.     

Effect of Ionic Liquid Structure on the Electrochemical Response of Dopamine at Room Temperature Ionic Liquid‐modified Carbon Paste Electrodes (IL–CPE)

In this work 12 different ionic liquids (ILs) have been used added as co‐binders in the preparation of modified carbon paste electrodes (IL–CPEs) used for the voltammetric analysis of dopamine in Britton‐Robinson buffer. The ionic liquids studied were selected based on three main criteria: (1) increasing chain length of alkyl substituents (studying 1‐ethylimidazolium and ethyl, propyl, butyl, hexyl and decylmethylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids); (2) nature of the counter ion (dicyanamide, bis(trifluoromethylsulfonyl)imide and hexafluorophosphate) in 1‐butyl‐3‐methylimidazolium ionic liquids; and (3) cation ring structures (1‐butyl‐3‐methylimidazolium, 1‐butyl‐1‐methylpiperidinium, 1‐butyl‐1‐methylpyrrolidinium and 1‐butyl‐3‐methylpyridinium) in bis(trifluoromethylsulfonyl)imide or hexafluorophosphate (1‐butyl‐3‐methylimidazolium or 1‐butyl‐3‐methylpyridinium as cations) ionic liquids. The use of IL as co‐binders in IL–CPE results in a general enhancement of both the sensitivity and the reversibility of dopamine oxidation. In square wave voltammetry experiments, the peak current increased up to a 400 % when 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide was used as co‐binder, as compared to the response found with the unmodified CPE. Experimental data provide evidence that electrostatic and steric effects are the most important ones vis‐à‐vis these electrocatalytic effects on the anodic oxidation of dopamine on IL–CPE. The relative hydrophilicity of dicyanamide anions reduced the electrocatalytic effects of the corresponding ionic liquids, while the use of 1‐ethyl‐3‐methylimidazolium hexafluorophosphate or 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (two relatively small and highly hydrophobic ionic liquids) as co‐binders in IL–CPE resulted in the highest electrocatalytic activity among all of the IL–CPE studied.     

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.     

Synthesis of 2‐Phenylthiazoles from α‐Tosyloxyketones and Thiobenzamide in [Bmim][PF6] Ionic Liquid at Ambient Temperature

The room temperature ionic liquid, 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate [bmim][PF₆] is used as a ‘green’ recyclable alternative to classical molecular solvents for the cyclocondensation of α‐tosyloxyketones with thiobenzamide to prepare 2‐phenylthiazoles in good yields.     

An efficient biosorption‐based dispersive liquid‐liquid microextraction with extractant removal by magnetic nanoparticles for quantification of bisphenol A in water samples by gas chromatography‐mass spectrometry detection

In this work, a simple, fast, sensitive, and environmentally friendly method was developed for preconcentration and quantitative measurement of bisphenol A in water samples using gas chromatography with mass spectrometry. The preconcentration approach, namely biosorption‐based dispersive liquid‐liquid microextraction with extractant removal by magnetic nanoparticles was performed based on the formation of microdroplet of rhamnolipid biosurfactant throughout the aqueous samples, which accelerates the mass transfer process between the extraction solvent and sample solution. The process is then followed by the application of magnetic nanoparticles for easy retrieval of the analyte‐containing extraction solvent. Several important variables were optimized comprehensively including type of disperser solvent and desorption solvent, rhamnolipid concentration, volume of disperser solvent, amount of magnetic nanoparticles, extraction time, desorption time, ionic strength, and sample pH. Under the optimized microextraction and gas chromatography with mass spectrometry conditions, the method demonstrated good linearity over the range of 0.5–500 µg/L with a coefficient of determination of R² = 0.9904, low limit of detection (0.15 µg/L) and limit of quantification (0.50 µg/L) of bisphenol A, good analyte recoveries (84–120%) and acceptable relative standard deviation (1.8–14.9%, n = 6). The proposed method was successfully applied to three environmental water samples, and bisphenol A was detected in all samples.     

Temperature‐controlled ionic liquid dispersive liquid‐phase microextraction for the sensitive determination of triclosan and triclocarban in environmental water samples prior to HPLC‐ESI‐MS/MS

A novel dispersive liquid‐phase microextraction method without dispersive solvents has been developed for the enrichment and sensitive determination of triclosan and triclocarban in environmental water samples prior to HPLC‐ESI‐MS/MS. This method used only green solvent 1‐hexyl‐3‐methylimidazolium hexafluorophosphate as extraction solvent and overcame the demerits of the use of toxic solvents and the instability of the suspending drop in single drop liquid‐phase microextraction. Important factors that may influence the enrichment efficiencies, such as volume of ionic liquid, pH of solutions, extraction time, centrifuging time and temperature, were systematically investigated and optimized. Under optimum conditions, linearity of the method was observed in the range of 0.1–20 μg/L for triclocarban and 0.5–100 μg/L for triclosan, respectively, with adequate correlation coefficients (R>0.9990). The proposed method has been found to have excellent detection sensitivity with LODs of 0.04 and 0.3 μg/L, and precisions of 4.7 and 6.0% (RSDs, n=5) for triclocarban and triclosan, respectively. This method has been successfully applied to analyze real water samples and satisfactory results were achieved.     

Solubilization of fullerene into ionic liquids by the use of fluoroalkyl end‐capped oligomers

Fluoroalkyl end‐capped oligomers were solubilized into a variety of ionic liquids such as N‐methylpyrazolium tetrafluoroborate, 3‐methylpyrazolium tetrafluoroborate and 1‐butyl‐3‐methylimidazolium hexafluorophosphate, and these fluorinated oligomers were able to reduce the surface tension of these ionic liquids. Interestingly, these fluorinated oligomers were able to solubilize fullerene into ionic liquids effectively. Fluoroalkyl end‐capped fullerene co‐oligomers, which were prepared by the oligomerizations of fluoroalkanoyl peroxides with radical polymerizable monomers such as acryloylmorpholine in the presence of fullerene, were more effective in solubilizing fullerene into ionic liquids compared to the corresponding fluoroalkyl end‐capped homo‐oligomers possessing no fullerene units. Fluoroalkyl end‐capped fullerene co‐oligomers/fullerene/ionic liquid complexes thus obtained were applied to the arrangements of fullerenes above the poly(methyl methacrylate) (PMMA) surface, and the higher fluorescent intensity of fullerene was obtained in the modified PMMA surface, although the reverse side of this modified film surface afforded an extremely weak fluorescent intensity. Copyright © 2005 John Wiley & Sons, Ltd.     

Ultrasound‐assisted temperature‐controlled ionic liquid emulsification microextraction coupled with capillary electrophoresis for the determination of parabens in personal care products

We developed a CE and ultrasound‐assisted temperature‐controlled ionic liquid emulsification microextraction method for the determination of four parabens (methyl paraben, ethyl paraben, propyl paraben, and butyl paraben) in personal care products including mouthwash and toning lotion. In the proposed extraction procedure, ionic liquid (IL, 1‐octyl‐3‐methylimidazolium hexafluorophosphate) was used as extraction solvent, moreover, no disperser solvent was needed. Parameters affecting the extraction efficiency including volume of IL, heating temperature, ultrasonic time, extraction time, sample pH, ionic strength, and centrifugation time were optimized. Under the optimized conditions, the method was found to be linear over the range of 3–500 ng/mL with coefficient of determination (R²) in the range of 0.9990–0.9998. The LODs and LOQs for the four parabens were 0.45–0.72 ng/mL and 1.50–2.40 ng/mL, respectively. Intraday and interday precisions (RSDs, n = 5) were in the range of 5.4–6.8% and 7.0–8.7%, respectively. The recoveries of parabens at different spiked levels ranged from 71.9 to 119.2% with RSDs less than 9.5%.     

Investigation of ionic liquids under Bi‐ion and Bi‐cluster ions bombardment by ToF‐SIMS

A systematic study of five different imidazolium‐based room temperature ionic liquids, 1‐butyl‐3‐methylimidazolium acetate, 1‐butyl‐3‐methylimidazolium nitrate, 1‐butyl‐3‐methylimidazolium iodide, 1‐butyl‐3‐methylimidazolium hexafluorophosphate and 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide were carried out by means of time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) in positive and negative ion mode. The compounds were measured under Bi‐ion and Bi‐cluster ions (Bi_2–7⁺, Bi_{3, 5}²⁺) bombardment, and spectral information and general rules for the fragmentation pattern are presented. Evidence for hydrogen bonding, due to high molecular secondary cluster ions, could be found. Hydrogen bonding strength could be estimated by ToF‐SIMS via correlation of the anionic yield enhancement with solvent parameters. Copyright © 2010 John Wiley & Sons, Ltd.     

Using magnetic core‐shell nanoparticles coated with an ionic liquid dispersion assisted by effervescence powder for the micro‐solid‐phase extraction of four beta blockers from human plasma by ultra high performance liquid chromatography with mass spectrometry detection

In this work, a novel, efficient, and green sorbent, SiO₂@Fe₃O₄ has been created and functionalized with 1‐butyl‐3‐methylimidazolium hexafluorophosphate as an ionic liquid. This sorbent was applied for microextraction of four beta blockers, propranolol, metoprolol, atenolol, and alprenolol with bupivacaine as internal standard from human plasma followed by liquid chromatography with mass spectrometric detection. A mixture of sodium bicarbonate and sodium dihydrogen phosphate was used as an extractant dispersive agent (effervescent power) to enhance the interaction between the magnetic sorbent and analytes. Main affecting parameters on microextraction and elution were optimized. Figures of merit for dispersive solid phase extraction with ionic liquid coated magnetic nanoparticles assisted by effervescent powder were calculated under the optimized conditions. The detection limits for propranolol, metoprolol, atenolol, and alprenolol were found at 0.33, 0.62, 0.03, and 0.44 ng/mL, respectively. For all analytes, good linearity was obtained. Intra‐ (n = 5) and interday (n = 10) precision were both under 6.3% while the preconcentration factors were obtained in the range between 15–18. The extraction efficiencies for each analyte ranged from 75 to 91%. The method was successfully applied for determination of trace amounts of the beta blockers in human plasma samples.