Poly(ionic liquids)‐coated stainless‐steel wires packed into a polyether ether ketone tube for in‐tube solid‐phase microextraction

An in‐tube solid‐phase microextraction device was developed by packing poly(ionic liquids)‐coated stainless‐steel wires into a polyether ether ketone tube. An anion‐exchange process was performed to enhance the extraction performance. Surface properties of poly(ionic liquids)‐coated stainless‐steel wires were characterized by scanning electron microscopy and energy dispersive X‐ray spectrometry. The extraction device was connected to high‐performance liquid chromatography equipment to build an online enrichment and analysis system. Ten polycyclic aromatic hydrocarbons were used as model analytes, and important conditions including extraction time and desorption time were optimized. The enrichment factors from 268 to 2497, linear range of 0.03–20 μg/L, detection limits of 0.010–0.020 μg/L, extraction and preparation repeatability with relative standard deviation less than 1.8 and 19%, respectively were given by the established online analysis method. It has been used to detect polycyclic aromatic hydrocarbons in environmental samples, with the relative recovery (5, 10 μg/L) in the range of 85.1–118.9%.     

Coating of optical fiber with a smart thermosensitive polymer for the separation of phthalate esters by solid‐phase microextraction

A solid‐phase microextraction fiber was prepared by coating an optical fiber with a temperature‐sensitive polymer to determine phthalate esters. N‐Isopropylacrylamide and N,N′‐methylenebisacrylamide were used as the monomer and the cross linker, respectively. The fabricated fiber was characterized by FTIR spectroscopy, thermogravimetric analysis, and scanning electron microscopy. During extraction, important factors such as extraction time, pH, temperature, and ionic strength were optimized. The fabricated fiber, which is firm, inexpensive, stable, and efficient, is a vital material used in solid‐phase microextraction. Under optimum conditions, the calibration curve was linear and in the range of 1–20 μg/L (r² = 0.9747). The high extraction efficiency was obtained for phthalates with a detection limit of 0.12 μg/L. The fabricated fiber was successfully applied to the solid‐phase micro extraction of phthalates from water samples after its extraction, followed by gas chromatography with flame ionization detection.     

A novel sorbent based on carbon nanotube/amino‐functionalized sol–gel for the headspace solid‐phase microextraction of α‐bisabolol from medicinal plant samples using experimental design

A novel sol–gel coating on a stainless‐steel fiber was developed for the first time for the headspace solid‐phase microextraction and determination of α‐bisabolol with gas chromatography and flame ionization detection. The parameters influencing the efficiency of solid‐phase microextraction process, such as extraction time and temperature, pH, and ionic strength, were optimized by the experimental design method. Under optimized conditions, the linear range was between 0.0027 and 100 μg/mL. The relative standard deviations determined at 0.01 and 1.0 μg/mL concentration levels (n = 3), respectively, were as follows: intraday relative standard deviations 3.4 and 3.3%; interday relative standard deviations 5.0 and 4.3%; and fiber‐to‐fiber relative standard deviations 6.0 and 3.5%. The relative recovery values were 90.3 and 101.4% at 0.01 and 1.0 μg/mL spiking levels, respectively. The proposed method was successfully applied to various real samples containing α‐bisabolol.     

Dendrimer‐reinforced sol–gel based hollow fiber solid‐phase microextraction for citalopram determination using response surface methodology

The inclusion of a polyamidoamine dendrimer in a silica sol–gel yielded a solid nanosorbent that was used for the preconcentration, extraction, and determination of citalopram in hospital waste water, hemodialysis solution, and some drinking water. The method was developed by applying a novel nanosorbent for the solid‐phase microextraction of citalopram, containing a silica sol–gel reinforced by polyamidoamine second‐generation dendrimer, which was protected by a polypropylene hollow fiber. Plackett–Burman design and central composite design were utilized to evaluate the significance of several factors on the extraction efficiency. The adsorption mechanism and thermodynamic and kinetic aspects were studied. The adsorption process was exothermic and well fitted to the Bangham equation kinetic model. Under optimal conditions, the presented method was liner in the range of 0.05–100 μg/mL. The limits of detection of quantification of citalopram were 0.0095 and 0.031 μg m/L, respectively.     

Ionic liquid chemically bonded basalt fibers for in‐tube solid‐phase microextraction

Ionic liquids have been widely used in different fields by advantage of their specific properties. In this work, 1‐methyl‐3‐(3‐trimethoxysilyl propyl)imidazolium chloride was prepared and chemically bonded onto basalt fibers for in‐tube solid‐phase microextraction. Through combining in‐tube extraction device with high‐performance liquid chromatography equipped with a diode array detector, an online enrichment and analysis method for eight polycyclic aromatic hydrocarbons was established under the optimum conditions. A good enrichment factor (52–814), good linearity (0.10–15 and 0.20–15 μg/L), low limits of detection (0.03–0.05 μg/L), and low limits of quantitation (0.10–0.20 μg/L) were achieved using a sample volume of 50 mL. Analysis method was applied to the real samples including the groundwater and wastewater from a chemical industry park, some target analytes were detected and the relative recoveries were in the range of 80.4–116.8%.     

Ion‐pair‐based hollow‐fiber liquid‐phase microextraction combined with high‐performance liquid chromatography for the simultaneous determination of urinary benzene,toluene, and styrene metabolites

In the current study, a novel technique for extraction and determination of trans,trans‐muconic acid, hippuric acid, and mandelic acid was developed by means of ion‐pair‐based hollow fiber liquid‐phase microextraction in the three‐phase mode. Important factors affecting the extraction efficiency of the method were investigated and optimized. These metabolites were extracted from 10 mL of the source phase into a supported liquid membrane containing 1‐octanol and 10% w/v of Aliquat 336 as the ionic carrier followed by high‐performance liquid chromatography analysis. The organic phase immobilized in the pores of a hollow fiber was back‐extracted into 24 μL of a solution containing 3.0 mol/L sodium chloride placed inside the lumen of the fiber. A very high preconcentration of 212‐ to 440‐fold, limit of detection of 0.1–7 μg/L, and relative recovery of 87–95% were obtained under the optimized conditions of this method. The relative standard deviation values for within‐day and between‐day precisions were calculated at 2.9–8.5 and 4.3–11.2%, respectively. The method was successfully applied to urine samples from volunteers at different work environments. The results demonstrated that the method can be used as a sensitive and effective technique for the determination of the metabolites in urine.     

Speciation analysis of mercury by dispersive solid‐phase extraction coupled with capillary electrophoresis

A pretreatment method of dispersive solid‐phase extraction (DSPE) along with back‐extraction followed by CE‐UV detector was developed for the determination of mercury species in water samples. Sulfhydryl‐functionalized SiO₂ microspheres (SiO₂−SH) were synthesized and used as DSPE adsorbents for selective extraction and enrichment of three organic mercury species namely ethylmercury (EtHg), methylmercury (MeHg), and phenylmercury (PhHg), along with L‐cysteine (L‐cys) containing hydrochloric acid as back‐extraction solvent. Several main extraction parameters were systematically investigated including sample pH, amount of adsorbent, extraction and back‐extraction time, volume of eluent, and concentration of hydrochloric acid. Under optimal conditions, good linearity was achieved with correlation coefficients over 0.9990, in the range of 4−200 μg/L for EtHg, and 2−200 μg/L for MeHg and PhHg. The LODs were obtained of 1.07, 0.34, and 0.24 μg/L for EtHg, MeHg, and PhHg, respectively, as well as the LOQs were 3.57, 1.13, and 0.79 μg/L, respectively, with enrichment factors ranging from 109 to 184. Recoveries were attained with tap and lake water samples in a range of 62.3−107.2%, with relative standard deviations of 3.5–10.1%. The results proved that the method of SiO₂−SH based DSPE coupled with CE‐UV was a simple, rapid, cost‐effective, and eco‐friendly alternative for the determination of mercury species in water samples.     

Microwave‐assisted preparation of poly(ionic liquids)‐modified magnetic nanoparticles for pesticide extraction

Novel poly(ionic liquids) were synthesized and immobilized on prepared magnetic nanoparticles, which were used to extract pesticides from fruit and vegetable samples by dispersive solid‐phase extraction prior to high‐performance liquid chromatography analysis. Compared with monomeric ionic liquids, poly(ionic liquids) have a larger effective contact area and higher viscosity, so they can achieve higher extraction efficiency and be used repeatedly without a decrease in analyte recovery. The immobilized poly(ionic liquids) were rapidly separated from the sample matrix, providing a simple approach for sample pretreatment. The nature and volume of the desorption solvent and amount of poly(ionic liquid)‐modified magnetic material were optimized for the extraction process. Under optimum conditions, calibration curves were linear (R² > 0.9988) for pesticide concentrations in the range of 0.100–10.000 μg/L. The relative standard deviations for repeated determinations of the four analytes were 2.29–3.31%. The limits of detection and quantification were 0.29–0.88 and 0.97–2.93 μg/L, respectively. Our results demonstrate that the developed poly(ionic liquid)‐modified material is an effective absorbent to extract pesticides from fruit and vegetable samples.     

Introduction of a coiled solid‐phase microextraction fiber based on a coating of animal bone waste for chromatographic analysis

We attempt to introduce animal bone waste as a coating material with an organic−inorganic structure for the fabrication of a coiled solid‐phase microextraction fiber for the first time. The coiled fiber was simply prepared with the use of copper wire and coated with bone waste suspension through the dip‐coating method. The bone waste coating was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction analysis. It was applied as new type of solid‐phase microextraction fiber for preconcentration of polycyclic aromatic hydrocarbons before determination by high‐performance liquid chromatography with UV detection. A wide linear range 0.01–99.0 μg/L and limits of detection in the range 3.0–11.1 ng/L were obtained at optimized conditions. The bone waste coated coiled solid‐phase microextraction fiber has promise in sample preparation techniques because it is cost effective, available, stable in aqueous and organic solutions, environmentally friendly, and easy to fabricate and operate.     

In‐situ preparation of porous monolithic polymer inside hollow fiber as a micro‐solid phase extraction device for glucocorticoids in cosmetics

Glucocorticoids have a certain whitening effect on the skin. However, frequent and long‐term use of cosmetics including glucocorticoids is harmful to health. Herein, we proposed a novel micro‐solid phase extraction method for the detection of prednisolone acetate, prednisone, and prednisolone in cosmetics coupled with high‐performance liquid chromatography. In this method, porous monolithic polymer micro‐extraction bars were prepared by “one‐step, one‐pot” in situ photopolymerization combined with sacrificial support in hollow fiber under water atmosphere. The crucial factors such as pH of sample solution, extraction, and elution times that influence micro‐extraction were optimized and found to be 9.0, 2 h, and 32 min, respectively. Under the optimum experimental conditions, the linear range of the calibration curves were from 5.0 to 2000 µg/L with correlation coefficients (R²) between 0.9922 and 0.9996. The limit of detection and limit of quantification were 1.5 µg/L and 5.0 µg/L, respectively, and the recoveries were found to be in range of 69.0–113.3%. The analysis of precision for intraday and interday were less than 10.40 and 10.59%. The device has been successfully achieved photopolymerization under water atmosphere. The results indicated that this method is simple, accurate, and satisfactory for the pretreatment and determination of glucocorticoids in complex cosmetics samples.     

Reversed‐phase ion‐pair solid‐phase extraction and ion chromatography analysis of pyrrolidinium ionic liquid cations in environmental water samples

A method of reversed‐phase ion‐pair solid‐phase extraction combined with ion chromatography for determination of pyrrolidinium ionic liquid cations (N‐methyl‐N‐ethyl pyrrolidinium, N‐methyl‐N‐propyl pyrrolidinium, and N‐methyl‐N‐butyl pyrrolidinium) in water samples was developed in this study. First, ion‐pair reagent sodium heptanesulfonate was added to the water samples after static, centrifugation and filteration. Then, pyrrolidinium cations in the samples were enriched and purified by a reversed‐phase solid‐phase extraction column, and eluted from the column with methanol aqueous solution as eluent. Finally, the eluate collected was analyzed by ion chromatography. The separation and direct conductivity detection of these pyrrolidinium cations by ion‐exchange column using 1.0 mM methanesulfonic acid (in water)/acetonitrile (97:3, v:v) as mobile phase was achieved within 10 min. By using this method, pyrrolidinium cations in Songhua River and Hulan River were successfully extracted with the recoveries ranging from 74.2 to 97.1% and the enrichment factor assessed as 60. Pyrrolidinium cations with the concentration of 0.001?0.03 mg/L can be enriched and detected in the water samples. The developed method for the determination of pyrrolidinium ionic liquid cations in water samples is simple and reliable, which provides a reference for the study of the potential impact of ionic liquids on the environment.     

Development of a solid‐phase microextraction fiber by the chemical binding of graphene oxide on a silver‐coated stainless‐steel wire with an ionic liquid as the crosslinking agent

Graphene oxide was bonded onto a silver‐coated stainless‐steel wire using an ionic liquid as the crosslinking agent by a layer‐by‐layer strategy. The novel solid‐phase microextraction fiber was characterized by scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and Raman microscopy. A multilayer graphene oxide layer was closely coated onto the supporting substrate. The thickness of the coating was about 4 μm. Coupled with gas chromatography, the fiber was evaluated using five polycyclic aromatic hydrocarbons (fluorene, anthracene, fluoranthene, 1,2‐benzophenanthrene, and benzo(a)pyrene) as model analytes in direct‐immersion mode. The main conditions (extraction time, extraction temperature, ionic strength, and desorption time) were optimized by a factor‐by‐factor optimization. The as‐established method exhibited a wide linearity range (0.5–200 μg/L) and low limits of determination (0.05–0.10 μg/L). It was applied to analyze environmental water samples of rain and river water. Three kinds of the model analytes were quantified and the recoveries of samples spiked at 10 μg/L were in the range of 92.3–120 and 93.8–115%, respectively. The obtained results indicated the fiber was efficient for solid‐phase microextraction analysis.     

Microwave‐assisted preparation of poly(ionic liquids)‐modified polystyrene magnetic nanospheres for phthalate esters extraction from beverages

The fabrication of novel poly(ionic liquids)‐modified polystyrene (PSt) magnetic nanospheres (PILs‐PMNPs) by a one‐pot miniemulsion copolymerization reaction was achieved through an efficient microwave‐assisted synthesis method. The morphology, structure, and magnetic behavior of the as‐prepared magnetic materials were characterized by using transmission electron microscopy, vibrating sample magnetometry, etc. The magnetic materials were utilized as sorbents for the extraction of phthalate esters (PAEs) from beverage samples followed by high‐performance ultrafast liquid chromatography analysis. Significant extraction parameters that could affect the extraction efficiencies were investigated particularly. Under optimum conditions, good linearity was obtained in the concentration range of 0.5–50 (dimethyl phthalate), 0.3–50 (diethyl phthalate), 0.2–50 (butyl benzyl phthalate), and 0.4–50 μg/L (di‐n‐butyl phthalate), with correlation coefficients R ² > 0.9989. Limits of detection were in the range 125–350 pg. The proposed method was successfully applied to determine PAEs from beverage samples with satisfactory recovery ranging from 77.8 to 102.1% and relative standard deviations ranging from 3.7 to 8.4%. Comparisons of extraction efficiency with PSt‐modified MNPs as sorbents were performed. The results demonstrated that PILs‐PMNPs possessed an excellent adsorption capability toward the trace PAE analytes.     

Extraction and determination of trace amounts of three anticancer pharmaceuticals in urine by three‐phase hollow fiber liquid‐phase microextraction based on two immiscible organic solvents followed by high‐performance liquid chromatography

An automated three‐phase hollow fiber liquid‐phase microextraction based on two immiscible organic solvents followed by high‐performance liquid chromatography with UV–Vis detection method was applied for the extraction and determination of exemestane, letrozole, and paclitaxel in water and urine samples. n‐Dodecane was selected as the supported liquid membrane and its polarity was justified by trioctylphosphine oxide. Acetonitrile was used as an organic acceptor phase with desirable immiscibility having n‐dodecane. All the effective parameters of the microextraction procedure such as type of the organic acceptor phase, the supported liquid membrane composition, extraction time, pH of the donor phase, hollow fiber length, stirring rate, and ionic strength were evaluated and optimized separately by a one variable at‐a‐time method. Under the optimal conditions, the linear dynamic ranges were 1.8–200 (R² = 0.9991), 0.9–200 (R² = 0.9987) and 1.2–200 μg/L (R² = 0.9983), and the limits of detection were 0.6, 0.3, and 0.4 μg/L for exemestane, letrozole, and paclitaxel, respectively. To evaluate the capability of the proposed method in the analysis of biological samples, three different urinary samples were analyzed under the optimal conditions. The relative recoveries of the three pharmaceuticals were in the range of 91–107.3% for these three analytes.     

Basalt fibers grafted with a poly(ionic liquids) coating for in‐tube solid‐phase microextraction

To improve the durability and extraction efficiency of an ionic liquid coating, 1‐dodecyl‐3‐vinylimidazolium bromide was polymerized and grafted onto basalt fibers for in‐tube solid‐phase microextraction. To develop an extraction tube, basalt fibers grafted with the poly(ionic liquids) coating were filled into a polyether ether ketone tube with a 0.75 mm inner diameter. The extraction tube was connected to high‐performance liquid chromatography system equipped with a sampling pump to build an online enrichment and analysis system. Using four common phthalates as model analytes, the extraction tube was investigated by the online analysis system. Good enrichment performance was exhibited by high enrichment factors ranging from 851 to 1858. Under the optimum conditions, an online analysis method was established, and good linearity (0.03–12 and 0.15–12 μg/L) and low limits of detection (0.01–0.05 μg/L) were achieved. This analysis method was applied to real samples including water in a disposable plastic box and the bottled water, some targets were detected but not quantified, and the relative recoveries spiked at 2, 5 and 10 μg/L were in the range of 86.4–119.5%.     

On‐line extraction and determination of two herbicides: Comparison between two modes of three‐phase hollow fiber microextraction

Two different modes of three‐phase hollow fiber liquid‐phase microextraction were studied for the extraction of two herbicides, bensulfuron‐methyl and linuron. In these two modes, the acceptor phases in the lumen of the hollow fiber were aqueous and organic solvents. The extraction and determination were performed using an automated hollow fiber microextraction instrument followed by high‐performance liquid chromatography. For both three‐phase hollow fiber liquid‐phase microextraction modes, the effect of the main parameters on the extraction efficiency were investigated and optimized by central composite design. Under optimal conditions, both modes showed good linearity and repeatability, but the three‐phase hollow fiber liquid‐phase microextraction based on two immiscible organic solvents has a better extraction efficiency and figures of merit. The calibration curves for three‐phase hollow fiber liquid‐phase microextraction with an organic acceptor phase were linear in the range of 0.3–200 and 0.1–150 μg/L and the limits of detection were 0.1 and 0.06 μg/L for bensulfuron‐methyl and linuron, respectively. For the conventional three‐phase hollow fiber liquid‐phase microextraction, the calibration curves were linear in the range of 3.0–250 and 15–400 μg/L and LODs were 1.0 and 5.0 μg/L for bensulfuron‐methyl and linuron, respectively. The real sample analysis was carried out by three‐phase hollow fiber liquid phase microextraction based on two immiscible organic solvents because of its more favorable characteristics.     

Sensitive determination of typical phenols in environmental water samples by magnetic solid‐phase extraction with polyaniline@SiO2@Fe as the adsorbents before HPLC

A novel magnetic core–shell material polyaniline@SiO₂@Fe (PANI@SiO₂@Fe) has been successfully synthesized and investigated as an effective adsorbent for the magnetic solid‐phase extraction of typical endocrine disrupting compounds such as bisphenol A, tetrabromobisphenol A, and 4‐nonylphenol from water samples. The morphology of the as‐prepared PANI@SiO₂@Fe was characterized by transmission electron microscopy and X‐ray diffraction. The main parameters that influenced the enrichment performance such as the kind of eluent, amount of adsorbent, volume of eluent, adsorption time, elution time, ionic strength, pH, concentration of humic acid, and sample volume were investigated. Under the optimal conditions, a good linear relationship was found in the range of 0.05–100 μg/L for bisphenol A, 0.05–300 μg/L for tetrabromobisphenol A, and 0.05–250 μg/L for 4‐nonylphenol, respectively. The correlation coefficients are all above 0.995. The limits of detection were in the range of 0.009–0.04 μg/L, and precisions were under 3.73% (n  = 6). The real water analysis indicated that the spiked recoveries were in the range of 92.9–98.9% (n  = 3). All these results indicated that the developed method was an efficient tool for the analysis of bisphenol A, tetrabromobisphenol A, and 4‐nonylphenol.     

Magnetic micro‐solid‐phase extraction based on magnetite‐MCM‐41 with gas chromatography–mass spectrometry for the determination of antidepressant drugs in biological fluids

A new facile magnetic micro‐solid‐phase extraction coupled to gas chromatography and mass spectrometry detection was developed for the extraction and determination of selected antidepressant drugs in biological fluids using magnetite‐MCM‐41 as adsorbent. The synthesized sorbent was characterized by several spectroscopic techniques. The maximum extraction efficiency for extraction of 500 μg/L antidepressant drugs from aqueous solution was obtained with 15 mg of magnetite‐MCM‐41 at pH 12. The analyte was desorbed using 100 μL of acetonitrile prior to gas chromatography determination. This method was rapid in which the adsorption procedure was completed in 60 s. Under the optimized conditions using 15 mL of antidepressant drugs sample, the calibration curve showed good linearity in the range of 0.05–500 μg/L (r ² = 0.996–0.999). Good limits of detection (0.008–0.010 μg/L) were obtained for the analytes with good relative standard deviations of <8.0% (n  = 5) for the determination of 0.1, 5.0, and 500.0 μg/L of antidepressant drugs. This method was successfully applied to the determination of amitriptyline and chlorpromazine in plasma and urine samples. The recoveries of spiked plasma and urine samples were in the range of 86.1–115.4%. Results indicate that magnetite micro‐solid‐phase extraction with gas chromatography and mass spectrometry is a convenient, fast, and economical method for the extraction and determination of amitriptyline and chlorpromazine in biological samples.     

Long‐chain ionic liquid based mixed hemimicelles and magnetic dispersed solid‐phase extraction for the extraction of fluorescent whitening agents in paper materials

A novel mixed hemimicelles and magnetic dispersive solid‐phase extraction method based on long‐chain ionic liquids for the extraction of five fluorescent whitening agents was established. The factors influenced on extraction efficiency were investigated. Under the optimal conditions, namely, the pH of sample solution at 8.0, the concentration of long chain ionic liquid at 0.5 mmol/L, the amount of Fe₃O₄ nanoparticle at 12 mg, extraction time at 10 min, pH 6.0 of methanol as eluent, and the desorption time at 1 min, satisfactory results were obtained. Wide linear ranges (0.02–10 ng/mL) and good linearity were attained (0.9997–0.9999). The intraday and interday RSDs were 2.1–8.3%. Limits of detection were 0.004–0.01 ng/mL, which were decreased by almost an order of magnitude compared to direct detection without extraction. The present method was applied to extract the fluorescent whitening agents in two kinds of paper samples, obtaining satisfactory results. All showed results illustrated that the detection sensitivity was improved and the proposed method was a good choice for the enriching and monitoring of trace fluorescent whitening agents.     

Optimization of multiwalled carbon nanotubes reinforced hollow‐fiber solid–liquid‐phase microextraction for the determination of polycyclic aromatic hydrocarbons in environmental water samples using experimental design

A novel design of hollow‐fiber liquid‐phase microextraction containing multiwalled carbon nanotubes as a solid sorbent, which is immobilized in the pore and lumen of hollow fiber by the sol–gel technique, was developed for the pre‐concentration and determination of polycyclic aromatic hydrocarbons in environmental water samples. The proposed method utilized both solid‐ and liquid‐phase microextraction media. Parameters that affect the extraction of polycyclic aromatic hydrocarbons were optimized in two successive steps as follows. Firstly, a methodology based on a quarter factorial design was used to choose the significant variables. Then, these significant factors were optimized utilizing central composite design. Under the optimized condition (extraction time = 25 min, amount of multiwalled carbon nanotubes = 78 mg, sample volume = 8 mL, and desorption time = 5 min), the calibration curves showed high linearity (R ² = 0.99) in the range of 0.01–500 ng/mL and the limits of detection were in the range of 0.007–1.47 ng/mL. The obtained extraction recoveries for 10 ng/mL of polycyclic aromatic hydrocarbons standard solution were in the range of 85–92%. Replicating the experiment under these conditions five times gave relative standard deviations lower than 6%. Finally, the method was successfully applied for pre‐concentration and determination of polycyclic aromatic hydrocarbons in environmental water samples.