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%.     

Bare polyprolylene hollow fiber as extractive phase for in‐tube solid‐phase microextraction to determine estrogens in water samples

Polypropylene hollow fibers as the adsorbent were directly filled into a polyetheretherketone tube for in‐tube solid‐phase microextraction. The surface properties of hollow fibers were characterized by a scanning electron microscope. Combined with high performance liquid chromatography, the extraction tube showed good extraction performance for five environmental estrogen hormones. To achieve high analytical sensitivity, four important factors containing sampling volume, sampling rate, content of organic solvent in sample, and desorption time were investigated. Under the optimum conditions, an online analysis method was established with wide linear range (0.03–20 µg/L), good correlation coefficients (≥0.9998), low limits of detection (0.01–0.05 µg/L), low limits of quantitation (0.03–0.16 µg/L), and high enrichment factors (1087–2738). Relative standard deviations (n = 3) for intraday (≤3.6%) and interday (≤5.1%) tests proved the stable extraction performance of the material. Durability and chemical stability of the extraction tube were also investigated, relative standard deviations of all analytes were less than 5.8% (n = 3), demonstrating the satisfactory stability. Finally, the method was successfully applied to detect estrogens in real samples.     

Triazine‐based organic polymers@SiO2 nanospheres for sensitive solid‐phase microextraction of polycyclic aromatic hydrocarbons

Triazine‐based organic polymers@SiO₂ nanospheres were prepared and applied as an extraction coating onto stainless steel wires and the wires were filled into polyetheretherketone tube for in‐tube solid‐phase microextraction. Taking polycyclic aromatic hydrocarbons as targets, main factors affecting extraction performance of the tube were investigated through coupling to high performance liquid chromatography. Under the optimum conditions, an online analytical method for polycyclic aromatic hydrocarbons was established with large linear ranges (0.010‐20 µg/L), low limits of detection (0.003‐0.010 µg/L), high enrichment factors (533‐2954), and good repeatability (relative standard deviations <1.7% for intraday test, <5.0% for interday test). The analysis method was successfully applied to the detection of trace targets in real water samples and the relative recoveries ranged from 82.9 to 119.9%, which demonstrated the applicability of extraction tube in sample preparation.     

Mesoporous titanium oxide with high‐specific surface area as a coating for in‐tube solid‐phase microextraction combined with high‐performance liquid chromatography for the analysis of polycyclic aromatic hydrocarbons

Stainless‐steel wires coated with mesoporous titanium oxide were placed into a polyether ether ketone tube for in‐tube solid‐phase microextraction, and the coating sorbent was characterized by X‐ray diffraction and scanning electron microscopy. It was combined with high‐performance liquid chromatography to build an online system. Using eight polycyclic aromatic hydrocarbons as the analytes, some conditions including sample flow rate, sample volume, organic solvent content, and desorption time were investigated. Under optimum conditions, an online analysis method was established and provided good linearity (0.03–30 μg/L), low detection limits (0.01–0.10 μg/L), and high enrichment factors (77.6–678). The method was applied to determine target analytes in river water and water sample of coal ash, and the recoveries are in the range of 80.6–106.6 and 80.9–103.5%, respectively. Compared with estrogens and plasticizers, extraction coating shows better extraction efficiency for polycyclic aromatic hydrocarbons.     

Basalt fibers functionalized with gold nanoparticles for in‐tube solid‐phase microextraction

Basalt fibers were functionalized with gold nanoparticles and characterized by scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. An in‐tube solid‐phase microextraction device was developed by packing the functionalized basalt fibers in a polyether ether ketone tube. The device was connected into high performance liquid chromatography equipment with a diode array detector to build online enrichment and analysis system. Eight polycyclic aromatic hydrocarbons were used as model analytes, important factors including sampling rate, sampling volume, organic solvent content in sample, and desorption time were investigated. Linear range (0.01–20 μg/L), detection limits (0.003–0.015 μg/L), and enrichment factors (130–1628) were given by the online analysis method. Relative standard deviations (n = 5) of extraction repeatability on one tube and tube‐to‐tube repeatability were less than 5.2 and 14.7%, respectively. The analysis method was applied to detect polycyclic aromatic hydrocarbons in environmental water samples, and relative recoveries ranged from 87 to 128%.     

Layer‐by‐layer self‐assembly of a novel covalent organic frameworks microextraction coating for analyzing polycyclic aromatic hydrocarbons from aqueous solutions via gas chromatography

In this study, a new covalent organic framework, consisting of tetra(4‐aminophenyl)porphyrin and tris(4‐formyl phenyl)amine, was layer‐by‐layer immobilized on stainless‐steel wire as a coating for microextraction. The fabrication process was easy and controllable under mild conditions. The as‐grown fiber was applied to extract polycyclic aromatic hydrocarbons in aqueous solution via head‐space solid‐phase microextraction. Furthermore, it was analyzed by gas chromatography with a flame ionization detector. A wide linear range (0.1–50 µg/L), low limits of detection (0.006–0.024 µg/L, signal‐to‐noise ratio = 3), good repeatability (intra‐fiber, n = 6, 3.1–8.50%), and reproducibility (fiber to fiber; n = 3, 5.79–9.98%), expressed as relative standard deviations, demonstrate the applicability of the newly developed coating. This new material was successfully utilized in real sample extraction with a satisfactory result. Potential parameters affecting the extraction efficiency, including extraction temperature and extraction time, salt concentration, agitation speed, sample volume, desorption temperature, and time, were also optimized and discussed.     

Spiral stir bar sorptive extraction with polyaniline‐polydimethylsiloxane sol‐gel packings for the analysis of trace estrogens in environmental water and animal‐derived food samples

A spiral stir bar was proposed by using stainless steel spring as the extraction phase carrier to avoid the extraction phase friction and increase the amount of extraction phase for improving extraction efficiency. The extraction phase is filled in the cavity of the spring, resulting in a larger amount of the extraction phase than that conventionally coated on glass stir bar or stainless steel wire. Polyaniline‐polydimethylsiloxane sol‐gel packed spiral stir bar was prepared and evaluated for the extraction of five estrogens. The prepared spiral stir bar presented good extraction efficiency/preparation reproducibility and long lifetime (more than 150 reused times) for target estrogens. Based on it, a method of spiral stir bar sorptive extraction combined with high performance liquid chromatography coupled with ultra‐violet detection was developed for the analysis of trace estrogens in environmental and food samples. The detection limit for five estrogens was 0.11–.31 µg/L, with the enrichment factors of 83.0–118‐fold (maximal enrichment factor: 200‐fold). The reproducibility evaluated with each estrogen of 5 µg/L (n = 5) was 5.8–8.9%. The method was successfully applied for the determination of estrogens in environmental water and animal‐derived food samples.     

Carbonized silk fibers for in‐tube solid‐phase microextraction to detect polycyclic aromatic hydrocarbons in water samples

Silk fibers were carbonized to develop a biomass carbon material as an adsorbent for solid‐phase microextraction. The surface structure of the carbonized silk fibers was characterized by scanning electron microscopy, and the graphitization degree was determined by Raman spectrometry. After carbonization under high temperature, the orderliness and structural regularity of carbon atoms on silk fibers were promoted. Extraction tube packed with carbonized silk fibers was prepared for in‐tube solid‐phase microextraction. Coupled with high performance liquid chromatography, it exhibited good extraction performance for hydrophobic polycyclic aromatic hydrocarbons. Main parameters including sampling volume, sampling rate, methanol content in sample, and desorption time were systematically investigated. Under the optimum conditions, the analysis method was established and it exhibited wide linear range (0.016–20 μg/L) with good linearity (correlation coefficient ≥ 0.9947), low limits of detection (0.005–0.050 μg/L), and high enrichment factors (1189–2775). Relative standard deviations (n = 3) for intraday (≤3.3%) and interday (≤9.6%) tests indicated that the extraction material had satisfactory repeatability. Finally, the analytical method was successfully applied to detect trace polycyclic aromatic hydrocarbons in real water samples, demonstrating its satisfactory practicability.     

Nano‐MoO3 for highly selective enrichment of polycyclic aromatic hydrocarbons in in‐tube solid‐phase microextraction

Nano‐molybdenum trioxide was prepared from nano‐molybdenum disulfide by simple firing in muffle furnace. Nano‐molybdenum trioxide was used as the extraction coating on the stainless steel wire. Four wires were filled in a polyetheretherketone tube to get an extraction tube. The tube was connected to the six‐port valve of a high performance liquid chromatograph, and the online analysis system was constructed. Extraction selectivity of the tube for different types of compounds, including polycyclic aromatic hydrocarbons, plasticizers, estrogens, anilines and neonicotinoids, was studied. Good enrichment ability for polycyclic aromatic hydrocarbons, but the extraction efficiency of others was not satisfactory. Using eight polycyclic aromatic hydrocarbons as the targets, an analytical method was established after optimizing main factors such as sampling volume, sampling rate, methanol content, and desorption time. The established method exhibited wide linear range to 0.016–20.00 μg/L and low limits of detection to 0.005 μg/L, and the enrichment factors can be up to 2443. The method was applied to the detection of trace polycyclic aromatic hydrocarbons in tap water and river water, and a good recovery was obtained. The tube showed good durability and chemical stability, and it still remained good extraction effect after more than 140 run.     

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%.     

An Ag2S@ZnS‐coated fiber for efficient,long‐life solid‐phase microextraction of polycyclic aromatic hydrocarbons in water

Although an efficient and stable fiber coating is essential for the development of solid‐phase microextraction technique, it remains a challenging prospect. Herein, an inorganic nanocomposite material Ag₂S@ZnS was prepared and used as a coating for fibers to detect polycyclic aromatic hydrocarbons in water samples in combination with a GC with flame ionization detector. Compared with a single ZnS material, the Ag₂S@ZnS composite shows many uneven nano‐protrusions on the surface of the microspheres. In conjunction with the relatively scattered microstructure of the coating and the effective anion‐π interaction formed between ZnS and the hydrocarbons, it has a large specific surface area, fast diffusion of the target molecule on its surface, and appropriate adsorption of the target molecules; therefore, it exhibits good extraction efficiency for the hydrocarbons. Under optimal conditions, the proposed analytical method exhibits superior performance with good linearity (0.01–500 µg/L) and low limits of detection (0.001–0.200 µg/L). Combined with high thermal, chemical, and mechanical stability, the service life of the coating was improved and could be used 200 times without a significant reduction in the extraction performance, and at least 2000 extraction–desorption cycles can be achieved. Satisfactory results were also obtained for the real samples.     

A green extraction material — natural cotton fiber for in‐tube solid‐phase microextraction

Natural cotton fiber was applied as a green extraction material for in‐tube solid‐phase microextraction. Cotton fibers were characterized by scanning electron microscope. A bundle of cotton fibers (685 mg, 20 cm) was directly packed into a polyetheretherketone tube (i.d. 0.75 mm) to get the extraction device. It was connected into high performance liquid chromatography, building an online extraction and dectection system. Through the online analysis system, several polycyclic aromatic hydrocarbons were used as the targets to evaluate the extraction performace of the device. In order to get high extraction efficiency and sensitivity, the extraction and desorption conditions were optimized. Under the optimum conditions, the sensitive analysis method was established, and provided low limits of detection of 0.02 and 0.05 μg/L, good linearity ranges of 0.06–15 and 0.16–15 μg/L, as well as high enrichment factors of 176–1868. The method was applied to the online determination of trace polycyclic aromatic hydrocarbons in snow water and river water, and the relative recoveries corresponding to 2 and 5 μg/L were in the range of 80–116%. The repeatability of extraction and preparation of the device was investigated and the relative standard deviations (n = 3) were less than 3.6 and 5.2%.     

Polydopamine‐coated cotton fibers as the adsorbent for in‐tube solid‐phase microextraction

Polydopamine was coated onto cotton fibers as the adsorbent to improve the extraction efficiency. Polydopamine‐coated cotton fibers were placed into a polyetheretherketone tube for in‐tube solid‐phase microextraction. To develop an online analysis system, the extraction tube was connected with high‐performance liquid chromatography. The tube was evaluated with five estrogenic analytes, and the extraction and desorption conditions were optimized to get high extraction efficiency. Under the optimum conditions, the enrichment factors of five analytes were 143–1745. An online analysis method was established, it had large linear ranges (0.10–40 and 0.16–40 μg/L), low limits of detection (0.03, 0.05 μg/L) and satisfactory repeatability (≤3.2%). The analysis method was applied to detect targets in the real samples like as hot water in new plastic cup and tap water. The relative recoveries spiked at 1 and 5 μg/L in these samples were investigated and the results were in the range of 83.7–109%.     

A novel method for the preconcentration and determination of ampicillin using electromembrane microextraction followed by high‐performance liquid chromatography

Electromembrane extraction was used with high‐performance liquid chromatography for preconcentration and determination of ampicillin residues in cow milk. Ampicillin is transferred from an aqueous solution through a thin layer containing octan‐1‐ol, silver nanoparticles, and reduced graphene oxide which serves as a supported liquid membrane. Inside the fiber impregnated with supported liquid membrane mixture was filled 10 µL of an acceptor phase. Experimental parameters were optimized for extraction efficiency of ampicillin. Under the optimized conditions, the proposed method provided acceptable linear range (2–100 µg/L), satisfactory repeatability (RSD% < 7.1), low limit of detection (0.6 µg/L), and a high enrichment factor (295) corresponding to extraction recovery of 37%. Consequently, the proposed method was successfully applied for the determination of ampicillin residues in different cow milks.     

Developing a novel packed in‐tube solid‐phase extraction method for determination ∆9‐tetrahydrocannabinol in biological samples and cannabis leaves

A novel plate‐like nano‐sorbent based on copper/cobalt/chromium layered double hydroxide was synthesized by a simple coprecipitation method. The synthesized nanoparticels were introduced into a stainless steel cartridge using a dry packing method. Then, the packed cartridge was introduced as a novel on‐line “packed in‐tube” configuration and followed by high performance liquid chromatography for the determination of trace amounts of ^?9‐tetrahydrocannabinol from biological samples and cannabis leaves. The as‐prepared sorbent exhibited long lifetime, good chemical stability, and high anion‐exchange capacity. Several important factors affecting the extraction efficiency, such as extraction and desorption times, pH of the sample solution and flow rates of the sample and eluent solutions, were investigated and optimized. Under optimized conditions, this method showed good linearity for ^?9‐tetrahydrocannabinol in the ranges of 0.09–500, 0.3–500, and 0.4–500 µg/L with coefficients of determination of 0.9999, 0.9991, and 0.9994 in water, serum and plasma samples, respectively. The inter‐ and intra‐assay precisions (n = 3) were respectively in the ranges of 1.8–4.6% and 1.9–4.0% at three concentration levels of 10, 50, and 100 µg/L. The limits of detection were also in the range of 0.02–0.1 µg/L.     

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.     

Carbon nanotubes functionalized mesoporous silica for in‐tube solid‐phase microextraction of polycyclic aromatic hydrocarbons

A mesoporous silica was functionalized by carbon nanotubes to enhance the extraction performance. The mesoporous material was coated on stainless steel wires, and three wires were inserted inside of a polyetheretherketone tube for in‐tube solid‐phase microextraction. The tube was coupled to high‐performance liquid chromatography with diode array detection to obtain online analytical system, then its extraction performance was evaluated using eight polycyclic aromatic hydrocarbons as the targets. In order to good sensitivity and accuracy, four conditions were optimized such as sampling volume, sampling rate, methanol content in the sample, and desorption time. Under the optimum conditions, an online analytical method was established and exhibited low limits of detection from 0.005 to 0.050 µg/L, wide linear range of 0.016‐20.00 µg/L with acceptable correlation coefficients in 0.9921‐0.9999, as well as large enrichment factors in the range of 311‐2412. The method was successfully applied to determine trace polycyclic aromatic hydrocarbons in some real water samples including, two kinds of bottled water, tap water, and river water, a few polycyclic aromatic hydrocarbons were detected but none quantified in these samples.     

Humic acid functionalized hyperbranched polytriazine based dispersive solid‐phase extraction for acaricides determination in tea matrix

Hyperbranched polytriazine functionalized with humic acid was prepared and developed as new sorbents for dispersive solid‐phase extraction of three acaricides (clofentezine, fenpyroximate, and pyridaben) in tea samples combined with high‐performance liquid chromatography detection. The sorbents were characterized by scanning electron microscopy, energy dispersive spectroscopy, Zeta‐potential, and Fourier transform infrared spectroscopy. The extraction parameters (extraction time, ionic strength, desorption conditions) were optimized. The adsorption mechanism was evaluated utilizing Fourier transform infrared spectra. Under optimum conditions, satisfactory analytical performances were achieved, which included high precision (1.33–9.62%), low limits of detection (0.19–3.54 µg/L), and wide linear range (2.5–500 µg/L) for the analysis of the acaricides. Moreover, the proposed method proved highly effective for the determination of acaricides in tea samples, with the relative recoveries in the range of 65.20–108.13% and relative standard deviations < 9.87%. The method has great application potential for the detection of acaricides in tea samples.     

Carbonized cotton fibers via a facile method for highly sensitive solid‐phase microextraction of polycyclic aromatic hydrocarbons

Cotton fiber is an environmentally friendly and natural material with a certain extraction capacity, while its enrichment ability is poor. In order to improve the extraction efficiency of cotton fibers, it was carbonized to form a layer of amorphous carbon as the sorbent by a simple carbonization method. Carbonized cotton fibers were filled into a polyetheretherketone tube for in‐tube solid‐phase microextraction. The carbonization time was investigated to obtain high extraction efficiency. Coupled to high‐performance liquid chromatography, the extraction tube was evaluated with polycyclic aromatic hydrocarbons, estrogens and phthalates, and it exhibited best extraction efficiency for polycyclic aromatic hydrocarbons. Under the optimum conditions, an online analysis method for several polycyclic aromatic hydrocarbons was established with large linear ranges (0.016–0.20 μg/L), low limits of detection (0.005–0.020 μg/L), and high enrichment factors (948–2874). Analysis method was successfully applied to the detection of targets in the real samples and shown satisfactory durability and chemical stability. Moreover, the relative recoveries ranged from 82 to 119.2%, which demonstrated the applicability of carbonized cotton fibers in sample preparation. Compared with other reported methods, the proposed method provided shorter extraction time, higher enrichment factors, comparable limits of detection, and recoveries.     

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.