Carbonaceous nanomaterials immobilised mixed matrix membrane microextraction for the determination of polycyclic aromatic hydrocarbons in sewage pond water samples

Polycyclic aromatic hydrocarbons in water environments: Impact, legislation, depollution processes and challenges, and magnetic iron oxide/graphene-based nanocomposites as promising adsorbent solutions

Environmental pollution is a big challenge of today's world, as population continues to grow, and industrialisation and urbanisation increase. Out of the different micropollutants in the atmosphere and aquatic environments, polycyclic aromatic hydrocarbons are of particular importance because they have known severe associated health risks to human life and they have high stability, leading to their persistence in the environment. They are generally present in the environment in low concentrations, but, even at these levels, they pose threats. This review thus focuses on this family of pollutants, on their occurrence and consequences, as well as the current methodologies employed to remove them from water environments and the challenges that remain. This work then focuses on the potential of magnetic iron oxide/graphene nanocomposites for the adsorption of PAHs, extensively discussing past and undergoing works, as well as the interactions between these adsorbents and PAHs.

New Materials for Thin-Film Solid-Phase Microextraction (TF-SPME) and Their Use for Isolation and Preconcentration of Selected Compounds from Aqueous, Biological and Food Matrices

Determination of a broad spectrum of analytes, carried out with analytical instruments in samples with complex matrices, including environmental, biological, and food samples, involves the development of new and selective sorption phases used in microextraction techniques that allow their isolation from the matrix. SPME solid-phase microextraction is compatible with green analytical chemistry among the sample preparation techniques, as it reduces the use of toxic organic solvents to the minimum necessary. Over the past two decades, it has undergone impressive progress, resulting in the development of the thin-film solid-phase microextraction technique, TF-SPME (the thin-film solid-phase microextraction), which is characterized by a much larger surface area of the sorption phase compared to that of the SPME fiber. TF-SPME devices, in the form of a mostly rectangular metal or polymer substrate onto which a thin film of sorption phase is applied, are characterized, among others, by a higher sorption capacity. In comparison with microextraction carried out on SPME fiber, they enable faster microextraction of analytes. The active phase on which analyte sorption occurs can be applied to the substrate through techniques such as dip coating, spin coating, electrospinning, rod coating, and spray coating. The dynamic development of materials chemistry makes it possible to use increasingly advanced materials as selective sorption phases in the TF-SPME technique: polymers, conducting polymers, molecularly imprinted polymers, organometallic frameworks, carbon nanomaterials, aptamers, polymeric ionic liquids, and deep eutectic solvents. Therefore, TF-SPME has been successfully used to prepare analytical samples to determine a broad spectrum of analytes in sample matrices: environmental, biological, and food. The work will be a review of the above-mentioned issues.

Carbon nanomaterial-based membranes in solid-phase extraction

Carbon nanomaterials (CNMs) have some excellent properties that make them ideal candidates as sorbents for solid-phase extraction (SPE). However, practical difficulties related to their handling (dispersion in the atmosphere, bundling phenomena, reduced adsorption capability, sorbent loss in cartridge/column format, etc.) have hindered their direct use for conventional SPE modes. Therefore, researchers working in the field of extraction science have looked for new solutions to avoid the above-mentioned problems. One of these is the design of CNM-based membranes. These devices can be of two different types: membranes that are exclusively composed of CNMs (i.e. buckypaper and graphene oxide paper) and polysaccharide membranes containing dispersed CNMs. A membrane can be used either as a filter, operating under flow-through mode, or as a rotating device, operating under the action of magnetic stirring. In both cases, the main advantages arising from the use of membranes are excellent results in terms of transport rates, adsorption capability, high throughput, and ease of employment. This review covers the preparation/synthesis procedures of such membranes and their potential in SPE applications, highlighting benefits and shortcomings in comparison with conventional SPE materials (especially, microparticles carbonaceous sorbents) and devices. Further challenges and expected improvements are addressed too.

Functional catalytic membrane development: A review of catalyst coating techniques

Catalytic membranes combine catalytic activity with conventional filtration membranes, thus enabling diverse attractive benefits into the conventional membrane filtration processes, such as easy catalyst reuse, antifouling, anti-microbial, and enhancing process efficiency. Up to date, tremendous progresses have been made on functional catalytic membrane preparation and applications, which significantly advances the competitiveness of membrane technologies in process industries. The present article provides a critical and holistic overview of the current state of knowledge on existing catalyst coating techniques for functional catalytic membrane development. Based on coating mechanisms, the techniques are generally categorized into physical and chemical surface coating routes. For each technique, we first introduce fundamental principle, followed by a critical discussion of their applications with representative case studies. Advantages and drawbacks are also emphasized for different surface coating technologies. Finally, future perspectives are highlighted to provide deep insights into their future developments.

Mixed Matrix Membrane Tip Extraction Coupled with UPLC–MS/MS for the Monitoring of Nonsteroidal Anti-Inflammatory Drugs in Water Samples

An ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method, in combination with a mixed matrix membrane microextraction method for the quantification of nonsteroidal anti-inflammatory drugs (NSAIDs) in environmental water samples, is reported. The extraction device was prepared by casting well-dispersed polymeric bonded octadecyl (C18) particles in a cellulose triacetate matrix solution onto commercially available 200 μL micropipette tips. The membrane formed contains 25% of the adsorbent loading amount and was firmly attached to the inner wall of the membrane tip. The dynamic extraction was performed by withdrawing and dispensing the sample solution through the tip device for effective analyte adsorption, followed by the analyte desorption process into 40 μL of methanol and acetonitrile (1:1) prior to UPLC–MS/MS analysis. NSAIDs—namely diclofenac, ibuprofen, indoprofen, naproxen and sulindac—were chosen as targeted analytes. Several extraction parameters were comprehensively optimized, including sample pH value, ionic strength, dynamic extraction cycle, desorption solvent and desorption time. The optimized conditions demonstrated a linear range from 0.25 to 500 ng L−1, with correlation coefficients (r2) from 0.9988 to 0.9992 and detection limits ranging from 0.08 to 0.40 ng L−1. The recoveries of the spiked water samples were between 92% and 99% and exhibited excellent precision relative to standard deviations (RSDs ≤ 4.9%), and enrichment factors (EFs) were at 201–249 for the developed approach.

Membrane-Protected Molecularly Imprinted Polymer for the Microextraction of Indole-3-butyric Acid in Mung Bean Sprouts

Based on the hollow fiber protected molecularly imprinted polymer, a micro-solid-phase extraction (μ-SPE) method was developed and applied for the analysis of indole-3-butyric acid in mung bean sprouts by high-performance liquid chromatography. The extraction conditions of the μ-SPE method were optimized using L⁹(3⁴) orthogonal, and optimum conditions were found as follows: pH of sample solution was 2.0, chloroform was the organic solvent for embedding the μ-SPE bars, and acetonitrile was the desorption solvent. In addition, the extraction time was 80 min, desorption time was 5 min, stirring speed was 800 rpm, and concentration of NaCl was 10%. Under the optimum conditions, a standard curve was established for IBA, with a correlation coefficient of 0.9999. After extraction with phosphate buffer solution (pH = 9.0), successful pretreatment of mung bean sprouts was achieved by the μ-SPE method. The limit of detection was 0.075 mg/kg, and the recoveries were found to be in the range of 88.9-106.4%. This method is simple, environmentally friendly, and can be used for the determination of indole auxin contents in green bean sprouts quickly and accurately.

Development, Optimization and Applications of Thin Film Solid Phase Microextraction (TF-SPME) Devices for Thermal Desorption: A Comprehensive Review

Through the development of solid phase microextraction (SPME) technologies, thin film solid phase microextraction (TF-SPME) has been repeatedly validated as a novel sampling device well suited for various applications. These applications, encompassing a wide range of sampling methods such as onsite, in vivo and routine analysis, benefit greatly from the convenience and sensitivity TF-SPME offers. TF-SPME, having both an increased extraction phase volume and surface area to volume ratio compared to conventional microextraction techniques, allows high extraction rates and enhanced capacity, making it a convenient and ideal sampling tool for ultra-trace level analysis. This review provides a comprehensive discussion on the development of TF-SPME and the applications it has provided thus far. Emphasis is given on its application to thermal desorption, with method development and optimization for this desorption method discussed in detail. Moreover, a detailed outlook on the current progress of TF-SPME development and its future is also discussed with emphasis on its applications to environmental, food and fragrance analysis.