Simultaneous extraction and quantification of albendazole and triclabendazole using vortex‐assisted hollow‐fiber liquid‐phase microextraction combined with high‐performance liquid chromatography

A novel, simple, and rapid vortex‐assisted hollow‐fiber liquid‐phase microextraction method was developed for the simultaneous extraction of albendazole and triclabendazole from various matrices before their determination by high‐performance liquid chromatography with fluorescence detection. Several factors influencing the microextraction efficiency including sample pH, nature and volume of extraction solvent, ionic strength, vortex time, and sample volume were investigated and optimized. Under the optimal conditions, the limits of detection were 0.08 and 0.12 μg/L for albendazole and triclabendazole, respectively. The calibration curves were linear in the concentration ranges of 0.3–50.0 and 0.4–50.0 μg/L with the coefficients of determination of 0.9999 and 0.9995 for albendazole and triclabendazole, respectively. The interday and intraday relative standard deviations for albendazole and triclabendazole at three concentration levels (1.0, 10.0, and 30.0 μg/L) were in the range of 6.0–11.0 and 5.0–7.9%, respectively. The developed method was successfully applied to determine albendazole and triclabendazole in water, milk, honey, and urine samples.     

Homogeneous liquid‐phase microextraction followed by filtration‐based phase separation coupled to high‐performance liquid chromatography

A simple homogenous liquid‐phase microextraction methodology applying octanoic acid as the extraction phase was introduced for determination of chlorobenzenes. In this approach, phase separation phenomenon occurred by changing pH of the solution. The extraction phase was isolated based on filtration of emulsion instead of centrifugation and it was introduced to the high‐performance liquid chromatography instrument as an on‐line procedure. This method was used for extraction and determination of five chlorobenzenes in different samples. Experimental design and response surface methodology were used for the optimization of various parameters influencing the extraction efficiency of the method. Under optimal conditions, chlorobenzenes were effectively extracted, and preconcentration factors of 255–294 were obtained. The calibration curves were investigated in the concentration range of 1–200 μg/L and good linearity was achieved with coefficient of determinations better than 0.997. Limits of detection of 0.1 and 0.3 μg/L and suitable precision with relative standard deviations better than 5.1% (n = 5) were attained. Finally, the proposed method was applied to determine the concentration of chlorobenzenes in different samples and acceptable recoveries were gained.     

Solid‐phase microextraction based on polyaniline doped with perfluorooctanesulfonic acid coupled to HPLC for the quantitative determination of chlorophenols in water samples

A porous and highly efficient polyaniline‐based solid‐phase microextraction (SPME) coating was successfully prepared by the electrochemical deposition method. A method based on headspace SPME followed by HPLC was established to rapidly determine trace chlorophenols in water samples. Influential parameters for the SPME, including extraction mode, extraction temperature and time, pH and ionic strength procedures, were investigated intensively. Under the optimized conditions, the proposed method was linear in the range of 0.5–200 μg/L for 4‐chlorophenol and 2,4,6‐trichlorophenol, 0.2–200 μg/L for 2,4‐dichlorophenol and 2–200 μg/L for 2,3,4,6‐tetrachlorophenol and pentachlorophenol, with satisfactory correlation coefficients (>0.99). RSDs were <15% (n = 5) and LODs were relatively low (0.10–0.50 μg/L). Compared to commercial 85 μm polyacrylate and 60 μm polydimethylsiloxane/divinylbenzene fibers, the homemade polyaniline fiber showed a higher extraction efficiency. The proposed method has been successfully applied to the determination of chlorophenols in water samples with satisfactory recoveries.     

Ultrapreconcentration and determination of organophosphorus pesticides in water by solid‐phase extraction combined with dispersive liquid–liquid microextraction and high‐performance liquid chromatography

Solid‐phase extraction coupled with dispersive liquid–liquid microextraction was developed as an ultra‐preconcentration method for the determination of four organophosphorus pesticides (isocarbophos, parathion‐methyl, triazophos and fenitrothion) in water samples. The analytes considered in this study were rapidly extracted and concentrated from large volumes of aqueous solutions (100 mL) by solid‐phase extraction coupled with dispersive liquid–liquid microextraction and then analyzed using high performance liquid chromatography. Experimental variables including type and volume of elution solvent, volume and flow rate of sample solution, salt concentration, type and volume of extraction solvent and sample solution pH were investigated for the solid‐phase extraction coupled with dispersive liquid–liquid microextraction with these analytes, and the best results were obtained using methanol as eluent and ethylene chloride as extraction solvent. Under the optimal conditions, an exhaustive extraction for four analytes (recoveries >86.9%) and high enrichment factors were attained. The limits of detection were between 0.021 and 0.15 μg/L. The relative standard deviations for 0.5 μg/L of the pesticides in water were in the range of 1.9–6.8% (n = 5). The proposed strategy offered the advantages of simple operation, high enrichment factor and sensitivity and was successfully applied to the determination of four organophosphorus pesticides in water samples.     

Polyaniline‐coated cigarette filters as a solid‐phase extraction sorbent for the extraction and enrichment of polycyclic aromatic hydrocarbon in water samples

Polyaniline coated cigarette filters were successfully synthesized and used as a solid‐phase extraction sorbent for the extraction and preconcentration of polycyclic aromatic hydrocarbons in water samples. The polyaniline helped to enhance the adsorption ability of polycyclic aromatic hydrocarbons on the sorbent through π–π interactions. The high porosity and large surface area of the cigarette filters helped to reduce backpressure and can be operated with high sample flow rate without loss of extraction efficiency. The developed sorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The parameters that affected the extraction efficiencies, i.e. polymerization time, type of desorption solvent and its volume, sample flow rate, sample volume, sample pH, ionic strength, and organic modifier were investigated. Under the optimal conditions, the method was linear over the range of 0.5–10 μg/L and a detection limit of 0.5 ng/L. This simple, rapid, and cost‐effective method was successfully applied to the preconcentration of polycyclic aromatic hydrocarbons from water samples. The developed method provided a high enrichment factor with good extraction efficiency (85–98%) and a relative standard deviation <10%.     

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.     

Extraction of phenolic compounds from water samples by dispersive micro‐solid‐phase extraction

In this article, the use of magnetically separable sorbent polyaniline/silica‐coated nickel nanoparticles is evaluated under a dispersive micro‐solid‐phase extraction approach for the extraction of phenolic compounds from water samples. The sorbent was prepared by in situ chemical polymerization of aniline on the surface of silica‐modified nickel nanoparticles and was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, X‐ray powder diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectrometry, and vibrating sample magnetometry. Effective variables such as amount of sorbent (milligrams), pH and ionic strength of sample solution, volume of eluent solvent (microliters), vortex, and ultrasonic times (minutes) were investigated by fractional factorial design. The significant variables optimized by a Box–Behnken design were combined by a desirability function. Under the optimized conditions, the calibration graphs of analytes were linear in a concentration range of 0.02–100 μg/mL, and with correlation coefficients more than 0.999. The limits of detection and quantification were in the ranges of 10–23 and 33–77 μg/L, respectively. This procedure was successfully employed in the determination of target analytes in spiked water samples; the relative mean recoveries ranged from 96 to 105%.     

Magnetic nanocomposite of self‐doped polyaniline–graphene as a novel sorbent for solid‐phase extraction

This work is the first study on the extraction efficiency of self‐doped polyaniline that is immobilized on the graphene‐modified magnetic nanoparticles. The new material was used as a sorbent for the magnetic solid‐phase extraction of methyl‐, propyl‐, and butylparabens. The use of graphene provides a high surface area and prevents aggregation of the nanoparticles. The self‐doped polyaniline also provides multifunctionality, high extraction capacity, and chemical stability even in the basic medium. The parabens were acetylated for determination by gas chromatography with flame ionization detection. The effects of monomer ratio, extraction solvent, sorbent amount, sample volume, desorption solvent volume, adsorption and desorption times, and sample ionic strength were optimized. Preconcentration factors obtained were from 190 to 310. The detection limits of the method were <2.8 μg/L. Linear ranges of the method were 5–2000 μg/L for propyl and butyl parabens, and 10–2000 μg/L for methyl paraben. The method was applied for the determination of the parabens in cosmetic products and extraction recoveries were 89–101% with RSDs ≤7.9%.     

Preparation of monolithic fibers for the solid‐phase microextraction of chlorophenols in water samples

Monolithic fibers were synthesized and applied for the solid‐phase microextraction and determination of chlorophenols in environmental water samples by coupling with HPLC. The fibers were prepared by copolymerization of vinylimidazole and ethylene dimethacrylate as functional monomer and cross‐linker, respectively. The effect of the preparation conditions of monolithic fibers on the extraction efficiencies was investigated in detail. Several characteristic techniques, such as elemental analysis, infrared spectroscopy, mercury‐intrusion porosimetry, and SEM were used to characterize the monolithic material. The effect of the extraction parameters, including desorption solvent, extraction and desorption time, pH values, and ionic strength in sample matrix on the extraction performance was investigated thoroughly. Under the improved extraction conditions, the linear ranges of 2‐chlorophenol, 2,4‐dichlorophenol and pentachlorophenol were 1.0–200 μg/L and 2.0–200 μg/L for 2,4,6‐trichlorophenol. The detection limits (S/N = 3) were in the range of 0.16–0.45 μg/L, the RSDs for intraday and interday precisions were <7.0%. Finally, the proposed method was successfully used to detect different environmental water samples. The recoveries of spiked water samples were ranged from 90.0 to 115%. At the same time, satisfactory repeatability was achieved with RSDs < 9.0%.     

Determination of three estrogens and bisphenol A by functional ionic liquid dispersive liquid‐phase microextraction coupled with ultra‐high performance liquid chromatography and ultraviolet detection

A hydroxyl‐functionalized ionic liquid, 1‐hydroxyethyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide, was employed in an improved dispersive liquid‐phase microextraction method coupled with ultra high performance liquid chromatography for the enrichment and determination of three estrogens and bisphenol A in environmental water samples. The introduced hydroxyl group acted as the H‐bond acceptor that dispersed the ionic liquid effectively in the aqueous phase without dispersive solvent or external force. Fourier transform infrared spectroscopy indicated that the hydroxyl group of the cation of the ionic liquid enhanced the combination of extractant and analytes through the formation of hydrogen bonds. The improvement of the extraction efficiency compared with that with the use of alkyl ionic liquid was proved by a comparison study. The main parameters including volume of extractant, temperature, pH, and extraction time were investigated. The calibration curves were linear in the range of 5.0–1000 μg/L for estrone, estradiol, and bisphenol A, and 10.0–1000 μg/L for estriol. The detection limits were in the range of 1.7–3.4 μg/L. The extraction efficiency was evaluated by enrichment factor that were between 85 and 129. The proposed method was proved to be simple, low cost, and environmentally friendly for the determination of the four endocrine disruptors in environmental water samples.     

Solid‐phase microextraction with a graphene‐composite‐coated fiber coupled with GC for the determination of some halogenated aromatic hydrocarbons in water samples

In this work, a graphene composite was coated onto etched stainless‐steel wire through a sol–gel technique and it was used as a solid‐phase microextraction (SPME) fiber. The prepared fiber was characterized by SEM, which revealed that the fiber had a highly porous structure. The application of the fiber was evaluated through the headspace SPME of five halogenated aromatic hydrocarbons (chlorobenzene, bromobenzene, 1,3‐dichlorobenzene, 1,2‐dichlorobenzene, and 1,2,4‐trichlorobenzene) in water samples followed by GC with flame ionization detection. The main factors influencing the extraction efficiency, including headspace volume, extraction time, extraction temperature, stirring rate, ionic strength of sample solution, and desorption conditions, were studied and optimized. Under the optimum conditions, the linearity of the method ranged from 2.5 to 800.0 μg/L for 1,2,4‐trichlorobenzene and from 2.5 to 500.0 μg/L for chlorobenzene, bromobenzene, 1,3‐dichlorobenzene, and 1,2‐dichlorobenzene, with the correlation coefficients (r) ranging from 0.9962 to 0.9980, respectively. The LODs (S/N = 3) of the method for the analytes were in the range between 0.5 and 1.0 μg/L. The recoveries of the method for the analytes obtained for the spiked water samples at 50.0 and 250.0 μg/L were from 76.0 to 104.0%.     

Preparation of novel ionic‐liquid‐modified magnetic nanoparticles by a microwave‐assisted method for sulfonylurea herbicides extraction

Ionic liquids immobilized on magnetic nanoparticles were prepared by an efficient microwave‐assisted synthesis method, and the properties of the ionic liquids were tuned based on the aromatic functional modification of its anion through a simple metathesis reaction. The novel as‐synthesized magnetic materials were characterized by various instrumental techniques. The magnetic nanoparticles have been utilized as adsorbents for the extraction of four sulfonylurea herbicides in tea samples, in combination with high‐performance liquid chromatography analysis. Significant extraction parameters, including type and volume of desorption solvent, extraction time, amount of adsorbent, and ionic strength were investigated. Under the optimum conditions, good linearity was obtained in the concentration range of 1–150 μg/L for metsulfuron‐methyl and bensulfuron‐methyl, and 3–150 μg/L for sulfometuron‐methyl and chlorimuron‐ethyl, with correlation coefficients R² > 0.9987. Low limits of detection were obtained ranging from 0.13 to 0.81 μg/L. The relative standard deviations were 1.8–3.9%. Comparisons of extraction efficiency with conventional solid‐phase extraction equipped with a commercial C₁₈ cartridge were performed. Results indicated that magnetic solid‐phase extraction is simple, time‐saving, efficient and inexpensive with the reusability of adsorbents. The proposed method has been successfully used to determine sulfonylurea herbicides from tea samples with satisfactory recoveries of 80.5–104.2%.     

Nanostructured copper‐coated solid‐phase microextraction fiber for gas chromatographic analysis of dibutyl phthalate and diethylhexyl phthalate environmental estrogens

A novel nanostructured copper‐based solid‐phase microextraction fiber was developed and applied for determining the two most common types of phthalate environmental estrogens (dibutyl phthalate and diethylhexyl phthalate) in aqueous samples, coupled to gas chromatography with flame ionization detection. The copper film was coated onto a stainless‐steel wire via an electroless plating process, which involved a surface activation process to improve the surface properties of the fiber. Several parameters affecting extraction efficiency such as extraction time, extraction temperature, ionic strength, desorption temperature, and desorption time were optimized by a factor‐by‐factor procedure to obtain the highest extraction efficiency. The as‐established method showed wide linear ranges (0.05–250 μg/L). Precision of single fiber repeatability was <7.0%, and fiber‐to‐fiber repeatability was <10%. Limits of detection were 0.01 μg/L. The proposed method exhibited better or comparable extraction performance compared with commercial and other lab‐made fibers, and excellent thermal stability and durability. The proposed method was applied successfully for the determination of model analytes in plastic soaking water.     

Multiple monolithic fiber solid‐phase microextraction based on a polymeric ionic liquid with high‐performance liquid chromatography for the determination of steroid sex hormones in water and urine

The development of a simple and sensitive analytical approach that combines multiple monolithic fiber solid‐phase microextraction with liquid desorption followed by high‐performance liquid chromatography with diode array detection is proposed for the determination of trace levels of seven steroid sex hormones (estriol, 17β‐estradiol, testosterone, ethinylestradiol, estrone, progesterone and mestranol) in water and urine matrices. To extract the target analytes effectively, multiple monolithic fiber solid‐phase microextraction based on a polymeric ionic liquid was used to concentrate hormones. Several key extraction parameters including desorption solvent, extraction and desorption time, pH value and ionic strength in sample matrix were investigated in detail. Under the optimal experimental conditions, the limits of detection were found to be in the range of 0.027–0.12 μg/L. The linear range was 0.10–200 μg/L for 17β‐estradiol, 0.25–200 μg/L estriol, ethinylestradiol and estrone, and 0.50–200 μg/L for the other hormones. Satisfactory linearities were achieved for analytes with the correlation coefficients above 0.99. Acceptable method reproducibility was achieved by evaluating the repeatability and intermediate precision with relative standard deviations of both less than 8%. The enrichment factors ranged from 54‐ to 74‐fold. Finally, the proposed method was successfully applied to the analysis of steroid sex hormones in environmental water samples and human urines with spiking recoveries ranged from 75.6 to 116%.     

Cyclodextrin‐functionalized reduced graphene oxide as a fiber coating material for the solid‐phase microextraction of some volatile aromatic compounds

A novel solid phase microextraction fiber was prepared for the first time by using a sol–gel technique with hydroxypropyl‐β‐cyclodextrin‐functionalized reduced graphene oxide as the fiber coating material. The results verified that the β‐cyclodextrin was successfully grafted onto the surface of reduced graphene oxide and the coating possessed a uniform folded and wrinkled structure. The performance of the solid phase microextraction fiber was evaluated by using it to extract nine volatile aromatic compounds from water samples before determination with gas chromatography and flame ionization detection. Some important experimental parameters that could affect the extraction efficiency such as the extraction time, extraction temperature, desorption temperature, desorption time, the volume of water sample solution, stirring rate, as well as ionic strength were optimized. The new method was validated to be effective for the trace analysis of some volatile aromatic compounds, with the limits of detection ranging from 2.0 to 8.0 ng/L. Single fiber repeatability and fiber‐to‐fiber reproducibility were in the range of 2.5–9.4 and 5.4–12.9%, respectively. The developed method was successfully applied to the analysis of three different water samples, and the recoveries of the method were in the range from 77.9 to 113.6% at spiking levels of 10, 100, and 1000 ng/L, respectively.     

Mesostructured cellular foam solid‐phase microextraction coating for the highly sensitive recognition of polychlorinated biphenyls in water samples

We herein presented a mesoporous cellular foam solid‐phase microextraction coating that showed highly sensitive recognition for weakly polarity polychlorinated biphenyls in water samples. The mesoporous cellular foam coater fiber was for the first time prepared by a simple sol‐gel method. The main experimental parameters including extraction temperature, extraction time, desorption time, stirring rate, and ionic strength were investigated by high‐efficiency orthogonal array design, a L₁₆ (4⁴) matrix was applied for the identification of optimized extraction parameters, and the optimized method was successfully applied to the analysis of environmental water sample. The novel mesoporous cellular foam coated fibers exhibited sensitive limits of detection (0.07–0.28 µg/L), wide linearity (5–3000 µg/L), and good reproducibility (3.5–8.3% for single fiber, and 4.9–8.7% for fiber‐to‐fiber) for polychlorinated biphenyls. The home‐made coating was successfully used in the analysis of polychlorinated biphenyls in real environmental water samples. These results indicate that the synthesized mesoporous cellular foams are promising materials for adsorption and separation applications in sample pretreatment.     

Effervescence‐assisted dispersive solid‐phase extraction using ionic‐liquid‐modified magnetic β‐cyclodextrin/attapulgite coupled with high‐performance liquid chromatography for fungicide detection in honey and juice

In this study, a simple effervescence‐assisted dispersive solid‐phase extraction method was developed to detect fungicides in honey and juice. Most significantly, an innovative ionic‐liquid‐modified magnetic β‐cyclodextrin/attapulgite sorbent was used because its large specific surface area enhanced the extraction capacity and also led to facile separation. A one‐factor‐at‐a‐time approach and orthogonal design were employed to optimize the experimental parameters. Under the optimized conditions, the entire extraction procedure was completed within 3 min. In addition, the calibration curves exhibited good linearity, and high enrichment factors were achieved for pure water and honey samples. For the honey samples, the extraction efficiencies for the target fungicides ranged from 77.0 to 94.3% with relative standard deviations of 2.3–5.44%. The detection and quantitation limits were in the ranges of 0.07–0.38 and 0.23–1.27 μg/L, respectively. Finally, the developed technique was successfully applied to real samples, and satisfactory results were achieved. This analytical technique is cost‐effective, environmentally friendly, and time‐saving.     

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%.     

Monodisperse silica nanoparticles coated with gold nanoparticles as a sorbent for the extraction of phenol and dihydroxybenzenes from water samples based on dispersive micro‐solid‐phase extraction: Response surface methodology

A selective and sensitive method was developed based on dispersive micro‐solid‐phase extraction for the extraction of hydroquinone, resorcinol, pyrocatechol and phenol from water samples prior to high‐performance liquid chromatography with UV detection. SiO₂, SiO₂@MPTES, and SiO₂@MPTES@Au nanoparticles (MPTES = 3‐mercaptopropyltriethoxysilane) were synthesized and characterized by scanning electronic microscopy, thermogravimetric analysis, differential thermogravimetric analysis, and infrared spectroscopy. Variables such as the amount of sorbent (mg), pH and ionic strength of sample the solution, the volume of eluent solvent (μL), vortex and ultrasonic times (min) were investigated by Plackett–Burman design. The significant variables optimized by a Box–Behnken design were combined by a desirability function. Under optimized conditions, the calibration graphs of phenol and dihydroxybenzenes were linear in a concentration range of 1–500 μg/L, and with correlation coefficients more than 0.995. The limits of detection for hydroquinone, resorcinol, pyrocatechol, and phenol were 0.54, 0.58, 0.46, and 1.24 μg/L, and the limits of quantification were 1.81, 1.93, 1.54, and 4.23 μg/L, respectively. This procedure was successfully employed to determine target analytes in spiked water samples; the relative mean recoveries ranged from 93.5 to 98.9%.     

Switchable‐hydrophilicity solvent‐based microextraction combined with gas chromatography for the determination of nitroaromatic compounds in water samples

A simple, fast, sensitive, and low‐cost method was developed for the quantification of nitroaromatic compounds in water samples based on CO₂‐assisted liquid‐phase microextraction using a switchable‐hydrophilicity solvent followed by gas chromatography detection. Dipropylamine was used as extraction solvent with switchable hydrophilicity that can be miscible or immiscible upon the addition or removal of CO₂ as a reagent. Experimental parameters affecting the extraction efficiency such as the volume of acceptor phase, the volume of donor phase, pH of donor phase, ionic strength, and extraction time were investigated. Under the optimal conditions, detection limits and preconcentration factors were obtained in the ranges of 0.9–1.8 μg/L and 132–138, respectively. Also, the extraction recoveries of water samples were above 88%. Finally, the developed method was successfully applied to the determination of nitroaromatic compounds in real water samples.