Triazine-based covalent porous organic polymer for the online in-tube solid-phase microextraction of polycyclic aromatic hydrocarbons prior to high-performance liquid chromatography-diode array detection

Supramolecular Materials as Solid-Phase Microextraction Coatings in Environmental Analysis

Solid-phase microextraction (SPME) has been widely proposed for the extraction, clean-up, and preconcentration of analytes of environmental concern. Enrichment capabilities, preconcentration efficiency, sample throughput, and selectivity in extracting target compounds greatly depend on the materials used as SPME coatings. Supramolecular materials have emerged as promising porous coatings to be used for the extraction of target compounds due to their unique selectivity, three-dimensional framework, flexible design, and possibility to promote the interaction between the analytes and the coating by means of multiple oriented functional groups. The present review will cover the state of the art of the last 5 years related to SPME coatings based on metal organic frameworks (MOFs), covalent organic frameworks (COFs), and supramolecular macrocycles used for environmental applications.

Construction of magnetic hydroxyl group-enriched hyper cross-linked polymers with functional triazine as the core for efficient enrichment of plant growth regulators

The determination of trace plant growth regulators (PGRs) residues in water and food samples make it crucial to develop novel sample pretreatment methods for the enrichment of PGRs. Herein, a novel magnetic hyper cross-linked polymer (M-CTT-9OH-HCP) was constructed and served as a magnetic adsorbent for the efficient extraction of some PGRs from water, watermelon, tomatoes, and milk samples for the first time. Combined with high performance liquid chromatography-fluorescence detection (HPLC-FLD), the established method presented a good linearity (0.03-60.0 ng g-1 (ng mL-1), (r) ≥ 0.9973), satisfactory accuracy with method recoveries (83.0%-119%) and acceptable precision with the intra-day and inter-day variations (expressed as the relative standard deviations (RSDs) ≤ 9.8%). The limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 0.01-1.50 and 0.03-5.00 ng g-1/ ng mL-1. The results show that the established method is sensitive and efficient for the determination of PGRs in real samples.

Determination of polycyclic aromatic hydrocarbons in surface waters by high performance liquid chromatography previous to preconcentration through solid-phase extraction by using polymeric monoliths

A simple, sensitive and reproducible solid-phase extraction method using plastic cartridges containing a monolithic sorbent (m-SPE), coupled to reverse phase liquid chromatography analysis, aiming to determine fifteen polycyclic aromatic hydrocarbons in surface water samples, was developed. The sorbent was easily prepared through a thermal polymerization reaction by using a mixture of n-butyl methacrylate as non-polar monomer and ethylene glycol dimethacrylate as crosslinker contained in a typical Polypropylene syringe cartridge. The effect of different parameters (type of hydrophobic monomer, elution solvent, sample volume, sorbent amount and sorbent load capacity) on the extraction efficiency was optimized. The optimal conditions were achieved by using n-butyl methacrylate as monomer, tetrahydrofurane (THF) as solvent for sorbent cleaning, THF:acetone (1:1) as elution solvent, 25.00 mL of sample volume, 600 µL of the polymerization mixture and 60 µg L^-1 as sample loading capacity. Finally, the sorbent charge capacity, the reusability of the cartridges and the extraction efficiency of the m-SPE monolith, as compared with a typical C8 cartridge, were evaluated. Under the optimized experimental conditions, enrichment factors were between 76 and 103, relative recovery factors from 78 to 103%, accuracy values in the range of 58 to 98%, and inter-batch reproducibility values from between 2 and 10%, were obtained. The limits of detection and quantification were obtained by two different procedures: the signal to noise (S/N) ratios (3 and 10, respectively) and the IUPAC convention. The lowest LOD and LOQ values, obtained with the S/N ratios, were between 0.02 and 1.00 µg L^-1, respectively whereas with the IUPAC convention the values were between 0.07 and 5 µg L^-1. Using this procedure, several PAHs could be detected in the surface water sample taken from a river stream located in La Plata city (Buenos Aires Province, Argentina).

Synthesis of the Magnetically Nanoporous Organic Polymer Fe3O4@SiO2-NH2-COP and Its Application in the Determination of Sulfonamide Residues in Surface Water Surrounding a Cattle Farm

Efficient extractions of trace antibiotic residues in the environment are a key factor for accurate quantification of the residues. A new nanoporous material, namely, magnetically covalent organic polymer (MCOP, Fe₃O₄@SiO₂-NH₂-COP) was synthesized in this work and was used for magnetic solid-phase extraction (MSPE). The combination of MSPE with high-performance liquid chromatography separation together with ultraviolet detection (HPLC-UV) was established as an effective method for the determination of four sulfonamide (SA) residues in surface water surrounding a cattle farm. The synthesized magnetic material was characterized by SEM, TEM, FT-IR, magnetic properties measurement system (MPMS), and nitrogen gas porosimetry. The material possessed many attractive features, such as a unique microporous structure, a larger specific surface area (137.93 m²·g⁻¹) than bare Fe₃O₄ (24.84 m²·g⁻¹), high saturation magnetization (50.5 emu·g⁻¹), open adsorption sites, and high stability. The influencing parameters, including pH, the used amount of MCOPs, the type of eluent, adsorption solution, and desorption time, were optimized. Under the optimized conditions, the method conferred good linearity ranges (R² ≥ 0.9990), low detection limits (S/N = 3, LOD, 0.10–0.25 μg·L⁻¹), and satisfactory recoveries (79.7% to 92.2%). The enrichment factor (EF) for the four SAs was 34.13–38.86. The relative standard deviations of intraday (n = 5) and of interday (n = 3) were less than 4.8% and 8.9%, respectively. The equilibria between extraction and desorption for SAs could be reached within 150 s. The proposed method was sensitive and convenient for detecting SA residues in complex environmental matrices, and the successful application of the new MCOPs as an adsorbent was demonstrated.

Nitrogen-rich carbon nitride as solid-phase microextraction fiber coating for high-efficient pretreatment of polychlorinated biphenyls from environmental samples

A two-dimensional nitrogen-rich carbon nitrogen (C₃N₅) material was prepared via a facile high temperature thermal polymerization. For the first time, the C₃N₅ was used as fiber coating of solid-phase microextraction (SPME) to extract and preconcentrate polychlorinated biphenyls (PCBs) before gas chromatography (GC) analysis. The X-ray diffraction, N₂ adsorption-desorption, Fourier transform-infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy were performed to investigate structure, functional groups, thermal stability, bonding type, element composition, and atomic ratio of C₃N₅. The two-dimensional planar stacking structure was further verified by scanning electron microscopy and transmission electron microscopy. Five PCBs including PCB-4, PCB-12, PCB-29, PCB-52 and PCB-101 were selected as targets to evaluate performance of SPME fiber. Under the optimal conditions, the method showed a good linear range from 0.01 to 1000 ng/mL with the correlation coefficients (R²) higher than 0.9990. Enrichment factors of the method were obtained from 2045 to 3080. The limits of detection (LODs, S/N = 3) and limits of quantification (LOQs, S/N = 10) were calculated as 0.0031-0.0111 ng/mL and 0.01-0.05 ng/mL, respectively. The precisions of intra-day and inter-day were obtained with the relative standard deviations (RSDs) at 1.5-6.6% and 0.8-6.9%, respectively. The fiber-to-fiber producibility was achieved with RSDs ranged from 3.5% to 11.4%. The method was applied to detect PCBs in river water and soil samples. The contents were calculated at 0.040-0.147 ng/mL in water and 0.520-3.218 ng/g in soil. The C₃N₅ as SPME fiber coating material may be applied to extract and preconcentrate other environmental pollutants which have similar chemical structures with PCBs.

Novel solid-phase microextraction fiber coatings: A review

The materials used for the fabrication of solid-phase microextraction fiber coatings in the past five years are summarized in the current review, including carbon, metal-organic frameworks, covalent organic frameworks, aerogel, polymer, ionic liquids/poly (ionic liquids), metal oxides, and natural materials. The preparation approaches of different coatings, such as sol-gel technique, in-situ growth, electrodeposition, and glue methods, are briefly reviewed together with the evolution of the supporting substrates. In addition, the limitations of the current coatings and the future development directions of solid-phase microextraction are presented.

Semi-continuous monitoring of HMWPAH in microalgae cultures by PT-SPE/HPLC/FD-UV: Estimation of the degradation constant

A degradation study has been performed with Selenastrum capricornutum incubated with benzo[a]anthracene and benzo[a]pyrene at 50, 100 and 266 ng mL^-1 in liquid cultures. After incubation, these high molecular weight polycyclic aromatic hydrocarbons (HMW PAH) were extracted from both, the medium and biomass in a single step, and then quantified by a sensitive and validated analytical methodology based on pipette-tip SPE and HPLC with fluorescence and UV detection (PT-SPE/HPLC/FD-UV). The methodology presented good linearity r² > 0.99, LOD of 0.9 and 0.7 ng mL^-1 for BaA and BaP, respectively. A fast and semi-continuous appreciation of the degradation behavior was achieved. The pollutants were monitored at different times (0.5-18 h) in the same culture flask, with sampling volume of 1 mL. Biodegradation percentages close to-90% were observed at 18 h. The degradation curves were fitted to the first order reaction (r² > 0.95) and the degradation rate constants were similar in all bioassays (0.1 h^-1) and independent of concentration and compound. The degradation pathways of HMW PAH by microalgae and their enzyme are poorly known but the hypothesis of the degrading enzyme proportionally activated according to the PAH concentration is supported by this result. The early emergence dihydrodiol-type metabolites were detected.

Recent developments in sample preparation techniques combined with high-performance liquid chromatography: A critical review

This review article compares and contrasts sample preparation techniques coupled with high-performance liquid chromatography (HPLC) and describes applications developed in biomedical, forensics, and environmental/industrial hygiene in the last two decades. The proper sample preparation technique can offer valued data for a targeted application when coupled to HPLC and a suitable detector. Improvements in sample preparation techniques in the last two decades have resulted in efficient extraction, cleanup, and preconcentration in a single step, thus providing a pathway to tackle complex matrix applications. Applications such as biological therapeutics, proteomics, lipidomics, metabolomics, environmental/industrial hygiene, forensics, glycan cleanup, etc., have been significantly enhanced due to improved sample preparation techniques. This review looks at the early sample preparation techniques. Further, it describes eight sample preparation technique coupled to HPLC that has gained prominence in the last two decades. They are (1) solid-phase extraction (SPE), (2) liquid-liquid extraction (LLE), (3) gel permeation chromatography (GPC), (4) Quick Easy Cheap Effective Rugged, Safe (QuEChERS), (5) solid-phase microextraction (SPME), (6) ultrasonic-assisted solvent extraction (UASE), and (7) microwave-assisted solvent extraction (MWASE). SPE, LLE, GPC, QuEChERS, and SPME can be used offline and online with HPLC. UASE and MWASE can be used offline with HPLC but have also been combined with the online automated techniques of SPE, LLE, GPC, or QuEChERS for targeted analysis. Three application areas of biomedical, forensics, and environmental/industrial hygiene are reviewed for the eight sample preparation techniques. Three hundred and twenty references on the eight sample preparation techniques published over the last two decades (2001-2021) are provided. Other older references were included to illustrate the historical development of sample preparation techniques.

[Recent advance of new sample preparation materials in the analysis and detection of environmental pollutants]

针对复杂样品的分析和痕量目标物的检测,样品前处理是必不可少的,高效的样品前处理技术不仅可以去除或减小样品基质干扰而且能够实现分析物的富集,提高分析检测的准确性和灵敏度。近年来,固相萃取、磁分散固相萃取、枪头固相萃取、搅拌棒萃取、固相微萃取等高效的样品前处理技术已在环境污染物分析检测中获得广泛关注,萃取效率主要取决于萃取材料,所以新型的高效萃取材料一直是样品前处理研究领域的重要发展方向。该文总结和讨论了近年来新型样品前处理材料在环境污染物分析检测中的研究进展,主要聚焦在石墨烯、氧化石墨烯、碳纳米管、无机气凝胶、有机气凝胶、三嗪基功能材料、三嗪基聚合物、分子印迹聚合物、共价有机框架材料、金属有机框架材料以及它们的功能化萃取材料等。这些材料已经被应用于环境样品中不同类别污染物的萃取富集,如重金属离子、多环芳烃、塑化剂、烷烃、苯酚、氯酚、氯苯、多溴联苯醚、全氟磺酸、全氟羧酸、雌激素、药物残留、农药残留等。这些样品前处理材料具有高的表面积、大量的吸附位点,并涉及多种萃取机理如π-π、静电、疏水、亲水、氢键、卤键等相互作用。基于这些萃取材料的多种样品前处理技术与各类检测方法如色谱、质谱、原子吸收光谱、荧光光谱、离子迁移谱等相结合,已广泛应用于环境污染物的高灵敏分析检测。最后,该文总结了样品前处理发展中存在的问题,并展望了其未来在环境分析中的发展趋势。