Xiuqin Wang

Electrophoretic deposition of graphene oxide onto carbon fibers for in-tube solid-phase microextraction

Carbon fibers (CFs) were functionalized with graphene oxide (GO) by an electrophoretic deposition (EPD) method for in-tube solid-phase microextraction (SPME). GO-CFs were filled into a poly(ether ether ketone) (PEEK) tube to obtain a fibers-in-tube SPME device, which was connected with high performance liquid chromatography (HPLC) equipment to build online SPME-HPLC system. Compared with CFs, GO-CFs presented obviously better extraction performance, due to excellent adsorption property and large surface area of GO. Using ten polycyclic aromatic hydrocarbons (PAHs) as model analytes, the important extraction conditions were optimized, such as sample flow rate, extraction time, organic solvent content and desorption time. An online analysis method was established with wide linear range (0.01-50μgL-1) and low detection limits (0.001-0.004μgL-1). Good sensitivity resulted from high enrichment factors (1133-3840) of GO-CFs in-tube device towards PAHs. The analysis method was used to online determination of PAHs in wastewater samples. Some target analytes were detected and relative recoveries were in the range of 90.2-112%. It is obvious that the proposed GO-CFs in-tube device was an efficient extraction device, and EPD could be used to develop nanomaterials functionalized sorbents for sample preparation.

Silk fiber for in-tube solid-phase microextraction to detect aldehydes by chemical derivatization

Aldehydes are the potentially damaging pollutants in the environment, but it is difficult to be determined due to the low concentration level. Therefore, to accurate analysis of aldehydes, it is important for efficient sample preparation with selective enrichment and rapid separation. Environmentally friendly silk fiber as adsorbent material was directly applied to develop in-tube solid-phase microextraction for analyzing aqueous samples combined with high performance liquid chromatography. 2,4-Dinitrophenylhydrazine as a derivative reagent was used for chemical derivatization of aldehydes before extraction. Under optimum conditions, an online analysis method was built with the limits of detection in the range of 0.005-0.01μgL-1 and the linearity in the range of 0.03-10μgL-1. Three aldehydes were determined in two real samples, and the relative recoveries were in the range of 95-102%.

In situ hydrothermal growth of polyaniline coating for in-tube solid-phase microextraction towards ultraviolet filters in environmental water samples

A facile, low cost, sensitive and environmentally friendly polyaniline (PANI) coating was prepared onto the basalt fibers (BFs) by in situ hydrothermal growth method. PANI functionalized BFs were placed into a poly(ether ether ketone) (PEEK) tube as a fibers-in-tube solid-phase microextraction (SPME) device. The extraction and analysis processes were carried out by connecting it to high performance liquid chromatography (HPLC). Three ultraviolet filters including 2-hydroxy-4-methoxybenzophenone, phenyl salicylate and 2,4-dihydroxybenzophenone were employed as model analytes. Under the optimal extraction and desorption conditions, online in-tube SPME-HPLC analysis method was established and afforded satisfactory enrichment factors (1323-1555), wide linear ranges (0.06-100μgL-1) with correlation coefficients ranging from 0.9995 to 0.9999, low limits of detection (0.02-0.05μgL-1) and acceptable extraction repeatability (RSD<7.8%, n=6) and preparation repeatability (RSD<9.7%, n=3). The proposed method was successfully applied to the determination of the three ultraviolet filters in two environmental water samples.

An organically modified silica aerogel for online in-tube solid-phase microextraction

Aerogels have received considerable attentions because of its porous, high specific surface, unique properties and environmental friendliness. In this work, an organically modified silica aerogel was functionalized on the basalt fibers (BFs) and filled into a poly(ether ether ketone) (PEEK) tube, which was coupled with high performance liquid chromatography (HPLC) for in-tube solid-phase microextraction (IT-SPME). The aerogel was characterized by scanning electron microscopy (SEM) and fourier transform infrared spectrometry (FT-IR). The extraction efficiency of the tube was systematically investigated and shown enrichment factors from 2346 to 3132. An automated, sensitive and selective method was developed for the determination of five estrogens. The linear range was from 0.03 to 100μgL-1 with correlation coefficients (r) higher than 0.9989, and low detection limits (LODs) were 0.01-0.05μgL-1. The relative standard deviations (RSDs) for intra-day and inter-day were less than 4.5% and 6.7% (n=6), respectively. Finally, the analysis method was successfully applied to detect estrogens in sewage and emollient water samples.

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 (0.03-30xa0μg/L), low detection limits (0.01-0.10xa0μg/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 (nxa0=xa05) 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%.

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 0.03-20xa0μg/L, detection limits of 0.010-0.020xa0μg/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, 10xa0μg/L) in the range of 85.1-118.9%.

In-situ hydrothermal synthesis of titanium dioxide nanorods on titanium wire for solid-phase microextraction of polycyclic aromatic hydrocarbons

AbstractTitanium dioxide nanorods were prepared on the surface of titanium wire by hydrothermal synthesis for use as a solid-phase microextraction (SPME) fiber. The morphology of the SPME coating was observed by scanning electron microscopy (SEM). Employed in conjunction with gas chromatography (GC), the fiber was investigated with five polycyclic aromatic hydrocarbons (PAHs) and three terphenyls in direct-immersion extraction mode. Various parameters were optimized, such as the extraction time, the stirring rate, the extraction temperature, the ionic strength of the sample solution, and the desorption time. Under the optimized conditions, the SPME-GC analytical method achieved a low detection limit (0.003xa0μgxa0L−1) and wide linear ranges (0.01–100xa0μgxa0L−1 and 0.01–200xa0μgxa0L−1) along with good correlation coefficients (0.9892–0.9962). The established method was also used to analyze rainwater and an aqueous solution of coal ash. The results indicated that this fiber could be applied in real-world environmental monitoring. The proposed fiber also exhibited excellent durability.n Graphical AbstractThe schematic diagram of experimental process.

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 0.01-30xa0μg/L) with satisfactory correlation coefficients (0.9922-0.9966) and low detection limits (0.003-0.03xa0μg/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.

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 0.20-15xa0μg/L), low limits of detection (0.03-0.05xa0μg/L), and low limits of quantitation (0.10-0.20xa0μg/L) were achieved using a sample volume of 50xa0mL. 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%.