Metal-organic framework-based magnetic dispersive micro-solid-phase extraction for the gas chromatography–mass spectrometry determination of polycyclic aromatic compounds in water samples

High enrichment and measurement of heterocyclic aromatic hydrocarbons from environmental waters with magnetic resorcinol-formaldehyde nanocomposites coupled with high performance liquid chromatography

Heterocyclic aromatic hydrocarbons are concerned pollutants with carcinogenic toxicity, which exist universally in various environmental matrices and have great harm to environmental and human health. In present work, magnetic resorcinol-formaldehyde composites (Fe3O4@SiO2@R-F) were fabricated via aldol condensation reaction under alkaline condition. The prepared magnetic materials were examined and analyzed with Fourier transform infrared spectroscopy and other related instruments. The Fe3O4@SiO2@R-F composites were utilized to develop an efficient magnetic solid phase extraction (MSPE) method for extracting six heteropolyclic aromatic hydrocarbons from environmental water samples including carbazole (CB), 7-methylquinoline (7-MQL), 9-methylcarbazole (9-MCB), dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The analytes were analyzed by high performance liquid chromatography-ultraviolet variable wavelength detector (HPLC-VWD). The main factors affecting MSPE were optimized. With the optimal parameters, 9-MCB and 4-MDBT have good linearity over the concentration range of 0.1-300 μg L-1, and 7-MQL, CB, DBT and 4,6-DMDBT have good linearity over the concentration range of 0.5-300 μg L-1. The limits of detection were over the concentration range of 0.012-0.031 μg L-1. This method was successfully employed to measure real waters, and the spiked recoveries ranged from 89.4% to 99.9%. The results confirmed that the developed method was reliable, robust and could be employed as a usefully alternate way for analyzing such pollutants in waters.

An ex vivo headspace gas chromatography-mass spectrometry method for the determination of short-chain siloxanes in silicon oil tamponades used in ophthalmic surgery

Being able to facilitate retinal reattachment by preventing water migration into the subretinal space, silicone oils are widely used as long-term intraocular tamponade to treat cases of retinal detachment. Various commercial tamponades constituted by linear polydimethylsiloxane polymers with different molecular weights and cyclic impurities are available. In this study, for the first time, an untargeted headspace-gas-chromatography-mass spectrometry (HS-GC-MS) method was developed to identify low-molecular weight contaminants in three different types of silicone oil tamponades, namely Siluron 2000, RS-OIL ECS5000 and Densiron Xtra. Both commercial and post-operative tamponades were analysed to screen for the different classes of compounds present in the samples. The most abundant classes were short-chain siloxanes, fluorinated compounds, and hydrocarbons. To quantify the siloxanes present in the samples, a targeted HS-GS-MS was optimized using a central composite design and validated according to guidelines for bioanalytical methods. Lower limits of quantification in the low μg/L range, good precision with RSD% < 12% and accuracy with recovery rates in the 81 ( ± 7) - 96 ( ± 4) % range were achieved. Short-chain siloxanes were quantified in both commercial and post-operative tamponades, being the RS-OIL ECS5000 characterized by the highest concentration levels of the investigated analytes. By contrast, Densiron Xtra tamponades showed the lowest amount of short-chain siloxanes, observing a general decrease in their concentration levels according to the residence time in the eyes.

An overview on human exposure, toxicity, solid-phase microextraction and adsorptive removal of perfluoroalkyl carboxylic acids (PFCAs) from water matrices

Perfluoroalkyl carboxylic acids (PFCAs) are sub-class of perfluoroalkyl substances commonly detected in water matrices. They are persistent in the environment, hence highly toxic to living organisms. Their occurrence at trace amount, complex nature and prone to matrix interference make their extraction and detection a challenge. This study consolidates current advancements in solid-phase extraction (SPE) techniques for the trace-level analysis of PFCAs from water matrices. The advantages of the methods in terms of ease of applications, low-cost, robustness, low solvents consumption, high pre-concentration factors, better extraction efficiency, good selectivity and recovery of the analytes have been emphasized. The article also demonstrated effectiveness of some porous materials for the adsorptive removal of the PFCAs from the water matrices. Mechanisms of the SPE/adsorption techniques have been discussed. The success and limitations of the processes have been elucidated.

Analytical perspective and environmental remediation potentials of magnetic composite nanosorbents

The synthesis and application of magnetic nanosorbents to remove emerging pollutants have been considered the best environmental remediation and sustainability option. Incorporating magnetism shortens the treatment time and allows the sorbent to be recovered quickly using external magnetic with many cycles. The implementation of magnetic solid-phase extraction (MSPE) using magnetic materials of different shapes, sizes, and surface morphology can be a valuable tool in applying materials to prepare analytical samples. In MSPE applications, materials with strong magnetic domain can be used as precursors for constructing magnetic composite as a promising sorbent. This article focuses on the most recent and exceptional applications of magnetic adsorbents for preconcentration and removal purposes. Magnetic adsorbents, such as nanoparticles (NPs), foam, sponges, nanocomposites, hydrogels, and beads with multifunctional attributes have been comprehensively studied in terms of preparation procedures, limitations, advantages, and interactions between pollutants and magnetic composites. The role of magnetic sorbents in sample preparation methods, such as simple solid-phase extraction and microextraction, as well as sorptive extraction using a stir bar, was also examined. The use of magnetic adsorbents with analytical techniques, such as solid-phase extraction and solid-phase microextraction improves the method for preparing samples concerning the influential role of magnetic adsorbents. Towards the end, promising features and future outlook are also directed.