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%.     

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.     

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.     

Mesoporous silica hybridized by ordered mesoporous carbon for in‐tube solid‐phase microextraction

To enhance the extraction performance, a mesoporous silica was modified with ordered mesoporous carbon for solid‐phase microextraction. Three stainless‐steel wires coated with the mesoporous material were placed in a polyetheretherketone tube for getting an extraction tube. The tube was coupled to high‐performance liquid chromatography with diode array detector, and the online analysis system was constructed. Then its extraction performance was evaluated using hydrophobic polycyclic aromatic hydrocarbons, phthalates, and hydrophilic neonicotinoids. The best selectivity was presented for polycyclic aromatic hydrocarbons. Several main conditions were optimized such as sampling volume, sampling rate, methanol concentration in the sample, and desorption time, a rapid and sensitive analytical method was established toward polycyclic aromatic hydrocarbons. The analytical method exhibited wide linear range from 0.017 to 15 µg/L with acceptable correlation coefficients more than 0.9990, limits of detection in 0.005‐0.020 µg/L, limits of quantification ranging from 0.017 to 0.066 µg/L as well as large enrichment factors of 377‐2314. It was successfully applied to detect trace polycyclic aromatic hydrocarbons in some real water samples including tap water, snow water, and domestic sewage.     

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%.     

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%.     

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 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%.     

Nanostructured‐silver‐coated polyetheretherketone tube for online in‐tube solid‐phase microextraction coupled with high‐performance liquid chromatography

Polyetheretherketone tube is a better substrate for in‐tube solid‐phase microextraction than fused‐silica capillary and metal tube because of its resistance to high pressure and good flexibility. It was modified with a nanostructured silver coating, and characterized by scanning electron microscopy and energy dispersive X‐ray spectroscopy. It was connected into high‐performance liquid chromatography equipment to build the online analysis system by replacing the sample loop of a six‐port injection valve. To get the highest extraction capacity, the preparation conditions of the coating was investigated. Important extraction conditions including length of tube, sample volume, and desorption time were optimized using eight polycyclic aromatic hydrocarbons as model analytes. The tube exhibits excellent extraction efficiency toward them, with enrichment factors from 52 to 363. The online analysis method provides good linearity (0.5–100 or 1.0–100 μg/L) and low detection limits (0.15–0.30 μg/L). It has been used to determine polycyclic aromatic hydrocarbons in water samples, with relative recoveries in the range of 92.3–120%. The tube showed highest extraction ability for polycyclic aromatic hydrocarbons, higher extraction ability for hydrophobic phthalates and anilines, and almost no extraction ability for low hydrophobic phenols, due to the possible extraction mechanism including hydrophobic and electron‐rich element‐metal interactions.     

Resorcinol–formaldehyde aerogel coating for in‐tube solid‐phase microextraction of estrogens

Resorcinol–formaldehyde aerogel coating was in situ prepared on the surface of basalt fibers. The aerogel coating is uniformly modified onto basalt fibers, and it is very porous according to the characterization by using scanning electron microscopy. An extraction tube was prepared for in‐tube solid‐phase microextraction by placing the aerogel‐coated basalt fibers into a polyetheretherketone tube. To evaluate the extraction performance toward five estrogenic compounds, the tube was connected with high performance liquid chromatography, the important extraction and desorption conditions were investigated. An online analytical method for detection of estrogens was developed and presented low limits of detection (0.005–0.030 µg/L), wide linear ranges (0.017–20, 0.033–20, and 0.099–20 µg/L), good linearity (r > 0.9990), and satisfactory repeatability (relative standard deviation < 2.7%). The method was successfully applied to detect trace estrogens in real water samples (bottled pure water and bottled mineral water), satisfactory recoveries were ranged from 80 to 125% with two spiking levels of 2 and 6 µg/L.     

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.     

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.     

An in‐needle solid‐phase microextraction device packed with etched steel wires for polycyclic aromatic hydrocarbons enrichment in water samples

A novel, low‐cost and effective in‐needle solid‐phase microextraction device was developed for the enrichment of trace polycyclic aromatic hydrocarbons in water samples. The in‐needle solid‐phase microextraction device could be easily assembled by inserting hydrofluoric acid‐etched wires, which were used as adsorbent, into a 22‐gauge needle tube within spring supporters. Compared with the commercial solid‐phase microextraction fiber, the developed device has higher efficiency for the extraction of polycyclic aromatic hydrocarbons with four to six rings from water samples using the optimized extraction conditions. With gas chromatography equipped with a flame ionization detector, the limits of detection for the polycyclic aromatic hydrocarbons with four to six rings ranged from 0.0020 to 0.0067 ng/mL. The relative standard deviations for one needle and needle‐to‐needle extractions were in the range of 5.2–9.9% (n = 5) and 3.4–12.3% (n = 5), respectively. The spiked recoveries of the polycyclic aromatic hydrocarbons in tap water samples ranged from 73.2 to 95.4%. This in‐needle solid‐phase microextraction device could be a good field sampler because of the low sample loss over a long storage time.     

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%.     

Silicon carbide nanomaterial as a coating for solid‐phase microextraction

Silicon carbide has excellent properties, such as corrosion resistance, high strength, oxidation resistance, high temperature, and so on. Based on these properties, silicon carbide was coated on stainless‐steel wire and used as a solid‐phase microextraction coating, and polycyclic aromatic hydrocarbons were employed as model analytes. Using gas chromatography, some important factors that affect the extraction efficiency were optimized one by one, and an analytical method was established. The analytical method showed wide linear ranges (0.1–30, 0.03–30, and 0.01–30 μg/L) with satisfactory correlation coefficients (0.9922–0.9966) and low detection limits (0.003–0.03 μg/L). To investigate the practical application of the method, rainwater and cigarette ash aqueous solution were collected as real samples for extraction and detection. The results indicate that silicon carbide has excellent application in the field of solid‐phase microextraction.     

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.     

Cadmium sulfide nanoparticles as a novel coating for solid‐phase microextraction

CdS nanoparticles coated on a stainless‐steel wire for solid‐phase microextraction was prepared. Scanning electron microscopy showed that the CdS nanoparticles clustered together to form a porous structure and X‐ray diffraction confirmed that the CdS nanoparticles were the wurtzite phase. Coupled to gas chromatography with flame ionization detection, the extraction abilities of the fiber for polycyclic aromatic hydrocarbons were examined by the headspace method. The parameters of adsorption time, adsorption temperature, salt concentration, desorption time, and desorption temperature were investigated and optimized. For the method, wide linearity and low limits of detection from 5 to 15 ng/L were obtained. The relative standard deviations for single‐fiber repeatability and fiber‐to‐fiber reproducibility were less than 10.2 and 12.6%, respectively. The enrichment factors were from 1155.6 to 3905.4, showing the fiber has good extraction capacity for polycyclic aromatic hydrocarbons. Moreover, the fiber can be used more than 50 times, exhibiting good stability. The established method was also used to analyze the polycyclic aromatic hydrocarbons in two real samples, and the recoveries from 82.7 to 114.2% further proved the reliability of the method.     

Carbon nanospheres as solid‐phase microextraction coating for the extraction of polycyclic aromatic hydrocarbons from water and soil samples

A solid‐phase microextraction with carbon nanospheres coated fiber coupled with gas chromatographic detection was established for the determination of eight polycyclic aromatic hydrocarbons (naphthalene, biphenyl, acenaphthene, fluorine, phenanthrene, anthracene, fluoranthene, and pyrene) in water and soil samples. The experimental parameters (extraction temperature, extraction time, stirring rate, headspace volume, salt content, and desorption temperature) which affect the extraction efficiency were studied. Under the optimized conditions, good linearity between the peak areas and the concentrations of the analytes was achieved in the concentration range of 0.5‐300 ng/mL for water samples, and in the concentration range of 6.0‐2700 ng/g for soil samples. The detection limits for the analytes were in the range of 0.12‐0.45 ng/mL for water samples, and in the range of 1.53‐2.70 ng/g for soil samples. The method recoveries of the polycyclic aromatic hydrocarbons for spiked water samples were 80.10‐120.1% with relative standard deviations less than 13.9%. The method recoveries of the analytes for spiked soil samples were 80.40‐119.6% with relative standard deviations less than 14.4%. The fiber was reused over 100 times without a significant loss of extraction efficiency.     

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.     

Improvement of solid‐phase microextraction efficiency by the application of a carbon‐nanotubes‐based ternary microextraction fiber composite

In this study, a novel technique is proposed for preparation of an efficient and unbreakable metal‐wire‐supported solid‐phase microextraction fiber. A sol–gel film was deposited on electrophoretically deposited carbon nanotubes on a stainless‐steel wire. The applicability of the fiber was evaluated through the extraction of some aromatic pollutants as model compounds from the headspace of aqueous samples in combination with gas chromatography and mass spectrometry. The parameters affecting the structure and extraction efficiency of the fiber (including the type of solvent, time, and potential for electrophoretic deposition) and the parameters affecting the extraction efficiency (such as coating type, salt content, extraction temperature, and time) were investigated. The results showed that the film thickness will be increased by increasing the potential and time duration. Finally, the characterization of the deposited film was accomplished by scanning electron microscopy and thermogravimetric analysis. After the optimization of the extraction parameters, the limit of detection of less than 20 pg/mL was achieved, and the calibration curves were all linear (r ² ≥ 0.9737), in the range from 50 to 500 pg/mL. The solid‐phase microextraction fiber has a high mechanical strength; good stability and long service life, making it potentially applicable in the extraction of trace polycyclic aromatic hydrocarbons from aqueous samples.