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

In-tube solid-phase microextraction of polycyclic aromatic hydrocarbons from refinery water samples using UiO-66/polyacrylonitrile electrospun nanofibers followed by high-performance liquid chromatography-ultraviolet detection

A simple and quick fiber-in-tube solid-phase microextraction (FIT-SPME) was introduced for the extraction and determination of nine polycyclic aromatic hydrocarbons followed by a high-performance liquid chromatography-ultraviolet detector in refinery water samples. For this purpose, a water-resistant metal-organic framework with a high surface area called UiO-66 has been applied in the form of an electrospun coating on stainless steel wires. After that, all the fibers were packed in the lumen of a stainless-steel tube to make the extraction phase. Both one variable at a time and experimental design methods have been used to optimize effective parameters on FIT-SPME. Under optimum conditions, the method demonstrated good linearity between 0.5 and 1000.0 µg/L with a coefficient of determination greater than 0.9906. Furthermore, the limits of detection values ranged from 0.2 to 1.5 µg/L. The intra-day and inter-day relative standard deviations were < 8.4% and < 9.7%, respectively. Lastly, the proposed method was applied to extract and determine analytes in four refinery water samples as well as surface water containing high total dissolved solids, and well waters where satisfactory results have been obtained.

Development of a novel porous cobalt, phosphorus and nitrogen co-doped carbonaceous coating by phosphiding ZIF-67 grown on nitinol fiber for selective solid-phase microextraction of polycyclic aromatic hydrocarbons from water samples

The nature and fabrication of the fiber coatings with good adsorption capacity and selectivity play a decisive role in solid-phase microextraction (SPME). In this work, a facile strategy was proposed to fabricate a cobalt, phosphorus and nitrogen co-doped carbonaceous (Co-P-NC) coating on superelastic nitinol (NiTi) substrate as a binder-free fiber for SPME. In particular, direct electrochemical in situ growth of ZIF-67 crystals served as the N-containing carbon precursor and sacrificial template for subsequent controllable conversion of ZIF-67 into a novel porous Co-P-NC coating on the NiTi wire substrate via a phosphiding process in a N₂ atmosphere. The obtained NiTi wire with the Co-P-NC coating (NiTi@Co-P-NC) was employed to investigate the adsorption of some representative aromatic analytes in water samples for the first time coupling with high-performance liquid chromatography with UV detection (HPLC/UV). The results proved that the resulting fiber showed superior adsorption selectivity for polycyclic aromatic hydrocarbons (PAHs). Therefore, the key parameters were further examined for the adsorption and preconcentration of PAHs. Under the obtained conditions, linear chromatographic responses were achieved over the concentration ranges of 0.03-100 μg L^-1 with the correlation coefficients ranging from 0.9980 to 0.9991. Limits of detection (LODs) were between 0.007 and 0.149 μg L^-1 (S/N = 3). The developed SPME-HPLC/UV method was applied to selective preconcentration and sensitive determination of PAHs in water. Moreover, this fiber had good fiber preparation reproducibility and presented 120 adsorption and desorption cycles at the same time in practical SPME application.

In-tube solid-phase microextraction: Current trends and future perspectives

In-tube solid-phase microextraction (IT-SPME) was developed about 24 years ago as an effective sample preparation technique using an open tubular capillary column as an extraction device. IT-SPME is useful for micro-concentration, automated sample cleanup, and rapid online analysis, and can be used to determine the analytes in complex matrices simple sample processing methods such as direct sample injection or filtration. IT-SPME is usually performed in combination with high-performance liquid chromatography using an online column switching technology, in which the entire process from sample preparation to separation to data analysis is automated using the autosampler. Furthermore, IT-SPME minimizes the use of harmful organic solvents and is simple and labor-saving, making it a sustainable and environmentally friendly green analytical technique. Various operating systems and new sorbent materials have been developed to improve its extraction efficiency by, for example, enhancing its sorption capacity and selectivity. In addition, IT-SPME methods have been widely applied in environmental analysis, food analysis and bioanalysis. This review describes the present state of IT-SPME technology and summarizes its current trends and future perspectives, including method development and strategies to improve extraction efficiency.

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.

Microextraction on a screw

For the first time, a rapid, efficient, simple, and inexpensive approach for solid phase microextraction on a screw (MES) was developed. MES is a miniaturized form of solid-phase extraction without any backpressure. In this system, analytes were adsorbed on the surface of micro channels of a screw that was coated by polypyrrole (PPy). Based on this procedure, the analytes are adsorbed on the solid phase and then eluted by a desorption solvent. The MES method followed by gas chromatography-mass spectrometry (MES-GC-MS) was applied for the rapid extraction and determination of six polycyclic aromatic hydrocarbons (PAHs) (as model analytes) in well water samples. Several parameters affecting the extraction procedure, including the sampling flow rate, the number of the loading/desorption cycles of the sample, and the volume of the desorption solvent, were evaluated and optimized. Under optimum conditions, the detection limits for the PAHs varied between 0.5 and 1 μg L^-1 and linear ranges varied between 2 and 600 μg L^-1. The results showed good correlation coefficients (R > 0.99) for all of the analytes in the studied calibration range. The relative recovery (RR%) of the desired MES-GC-MS method for the studied PAHs was between 83.0 and 104.0% and the interday and intraday precision (n = 5 days), expressed as relative standard deviation (RSD %), were between 3.9-6.2% and 6.2-8.9%, respectively. To evaluate the matrix effect, the developed method was also applied for preconcentration and determination of the selected PAHs in real water samples, and good results were obtained.

Durable molybdenum oxide coated solid-phase microextraction fiber for highly selective and efficient extraction of polycyclic aromatic hydrocarbons in water

A bonding method was developed for coating molybdenum oxides onto a steel wire substrate, which was used as a solid-phase microextraction fiber, was coupled with gas chromatography. Based on the characterization, it is found that the as-prepared molybdenum oxides material contained a nanobelt structure with a uniform size and good dispersibility. In addition, there were a large number of small protrusions on the surface of the nanobelts. These characteristics provided a large specific surface area for extraction. Molybdenum oxides exhibited a high extraction selectivity for polycyclic aromatic hydrocarbons owing to its moderate coordination. After the optimization of the factors, method detection limits of < 1.25 μg/L were achieved, and the calibration curves were linear within the range of 2-600 μg/L. In addition, repeatability was demonstrated, and the relative standard deviation < 6.4%. The molybdenum oxides coating had a high scratch resistance, which could effectively prevent coating wear and failure. Combined with the high thermal and chemical stability, the service life of the coating was improved and could be used 150 times without a significant reduction in the extraction performance. Finally, the as-prepared fiber had a comparable extraction capacity and higher partition coefficients that those of commercial polyacrylate fibers.

Coating of Polyetheretherketone Films with Silver Nanoparticles by a Simple Chemical Reduction Method and Their Antibacterial Activity

The coating of polymeric substrate polyetheretherketone (PEEK) with silver nanoparticles (AgNPs) was carried out by a wet chemical route at room temperature. The coating process was developed from the Tollens reagent and D-glucose as reducing agent. The resulting composite exhibited antimicrobial activity. The PEEK films were coated with a single layer and two layers of silver nanoparticles in various concentrations. The crystallographic properties of the polymer and the silver nanoparticles were analyzed by X-ray diffraction (XRD). Fourier transform infrared spectra (FTIR) show the interaction between the silver nanoparticles with the polymeric substrate. Transmission electron microscope (TEM) images confirmed the obtaining of metallic nanoparticles with average sizes of 25 nm. It was possible to estimate the amount of silver deposited on PEEK with the help of thermogravimetric analysis. The morphology and shape of the AgNPs uniformly deposited on the PEEK films was ascertained by the techniques of scanning electron microscopy (SEM) and atomic force microscopy (AFM), evidencing the increase in the amount of silver by increasing the concentration of the metal precursor. Finally, the antibacterial activity of the films coated with Ag in Escherichia coli, Serratia marcescens and Bacillus licheniformis was evaluated, evidencing that the concentration of silver is crucial in the cellular replication of the bacteria.

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.