Adsorption mechanism of polycyclic aromatic hydrocarbons on polythiophene-graphene covalent complex and its analytical application in food contact materials

Physical contraction strategy for large-scale fabrication of reduced graphene oxide-coated solid phase microextraction fibers

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) pose severe ecological hazards and are widely distributed through both biological and anthropogenic processes, necessitating the development of a sensitive analytical method for their direct and quantitative monitoring in environmental samples. Due to the complexity of environmental water sample matrices and the trace concentrations of PAHs, a pre-concentration step is typically required before instrumental analysis. This study presents the development of a headspace-solid phase microextraction (HS-SPME) technique for the extraction and pre-concentration of seven common trace PAHs from environmental water samples.

RESULTS

A novel physical contraction method was applied for the first time to fabricate robust reduced graphene oxide (rGO)-coated fibers on a large scale. During the fabrication process, three-dimensional rGO was formed around a stainless steel wire (SSW) using ascorbic acid as a reducing agent in an aqueous medium. The coating was firmly fixed onto the SSW through the physical volume contraction of the wet rGO during the drying process. When coupled with capillary gas chromatography-mass spectrometry (GC/MS) in headspace mode, the as-fabricated fiber demonstrates exceptional extraction efficiencies for PAHs. This efficiency is attributed to the tree-bark-like structure and the π-electron conjugation systems present in rGO. Furthermore, the fiber exhibits remarkable stability, enduring over 150 extraction cycles without compromise, owing to the solvent and thermal resilience of rGO and the superior mechanical strength of SSW. For PAH analysis, the fiber provides a wide linear range of 1-100 ng/L, with detection limits between 0.1 and 0.3 ng/L. The method also achieves a relative standard deviation (RSD) below 6.4 % for a single fiber and 7.2 % across different fibers, along with recovery rates ranging from 85.2 % to 104.7 %.

SIGNIFICANCE

The proposed strategy introduces an innovative approach to fabricating SPME fibers, addressing many limitations of existing methods for producing rGO-coated fibers, such as chemical bonding, dipping, and physical adhesion. This method is compatible with commonly used support materials, including metal wires and silica fibers, and allows for convenient adjustment of the length and thickness of the rGO coating. By providing a robust foundation for commercial applications, this study offers a valuable tool tailored for industrial use.

Length-controlled hydrophobic CF3-COF as a highly efficient absorbent coating for dual-mode solid-phase microextraction of sixteen polycyclic aromatic hydrocarbons in water samples

Polycyclic aromatic hydrocarbons (PAHs), a group of seriously hazardous environmental contaminants, have attracted extensive attention due to their carcinogenicity, genotoxicity, mutagenicity, and ubiquity. In this work, the excellent hydrophobic trifluoromethyl-enriched covalent organic framework (CF3-COF) was designed and synthesized as coating of solid-phase microextraction (SPME). The CF3-COF offered a high adsorption selectivity for PAHs, which could be attributed to the multiple interactions between the CF3-COF and PAHs, including hydrophobicity interaction, π-π and H bond interactions. Furthermore, headspace (HS) and direct immersion (DI) dual-mode solid-phase microextraction (HS/DI-SPME) were innovatively integrated as a dual-mode extraction by varying the length of SPME coating on stainless-steel, which could simultaneously and efficiently extract 16 PAHs with different volatile. Amazingly, the proposed strategy achieved fast adsorption for PAHs and shortened the adsorption equilibrium time to 15 min. By further integrating with gas chromatography tandem mass spectrometry (GC-MS/MS), PAHs could be detected in the range of 0.008-0.16 ng mL-1 with a quantitative limit of 0.029-0.47 ng mL-1, respectively. The recoveries of PAHs in water samples ranged from 80.84 to 117.67 %. This work indicates that the dual-mode CF3-COF-SPME is a promising candidate for the enrichment of multiple hazardous substances in complicated samples.

Headspace Microextraction. A Comprehensive Review on Method Application to the Analysis of Real Samples (from 2018 till Present)

This work describes current trends in the development of headspace microextraction methods. The main trends in the selection of detection techniques used in combination with microextraction and preferences in the selection of headspace liquid-phase microextraction (HS-LPME) or headspace solid-phase microextraction (HS-SPME) methods, depending on the analytes and their quantity, are also briefly presented. In the main part of the work, on the basis of current journal literature, headspace microextraction analytical methods used for the determination of various inorganic and organic analytes are classified and compared over the last five years. The work also reflects the current modifications of techniques and approaches proposed for these microextraction methods.

Recent Advances in Non-Targeted Screening of Compounds in Plastic-Based/Paper-Based Food Contact Materials

Ensuring the safety of food contact materials has become a pressing concern in recent times. However, detecting hazardous compounds in such materials can be a complex task, and traditional screening methods may not be sufficient. Non-targeted screening technologies can provide comprehensive information on all detectable compounds, thereby supporting the identification, detection, and risk assessment of food contact materials. Nonetheless, the non-targeted screening of food contact materials remains a challenging issue. This paper presents a detailed review of non-targeted screening technologies relying on high-resolution mass spectrometry for plastic-based and paper-based food contact materials over the past five years. Methods of extracting, separating, concentrating, and enriching compounds, as well as migration experiments related to non-targeted screening, are examined in detail. Furthermore, instruments and devices of high-resolution mass spectrometry used in non-targeted screening technologies for food contact materials are discussed and summarized. The research findings aim to provide a theoretical basis and practical reference for the risk management of food contact materials and the development of relevant regulations and standards.

Application of Nanomaterials to Ensure Quality and Nutritional Safety of Food

Nanomaterials (NMs) are emerging novel tools for preserving quality, enhancing shelf life, and ensuring food safety. Owing to the distinctive physicochemical characters, engineered NMs under varying sizes and dimensions have great potentials for application in the manufacturing, packaging, processing, and safety of quality agrifood. The promise of various kinds of novel NMs that are useful for food industries has opened a possibility of a new revolution in agroprocessing industries in both the emerging and advanced nations. The rapid advancement of nanoscience has provided a great impact on material science that has allowed researchers to understand every aspect of molecular complexity and its functions in life sciences. The reduced size of NMs that increase the surface area is useful in the specific target of different organs, and biodegradable nanospheres are helpful in the transport of bioactive molecules across the cellular barriers. However, nanotechnology creates a great revolution in several sections including agriculture and food industry and also reduces environmental pollution, while the toxicity of some NMs in the food industry poses a great concern to researchers for their greater application. However, most of the developed countries have regulatory control acts but developing countries do not have them yet. Therefore, for the safe use of NMs and also to minimize the health and environmental risks in both the developed and developing countries, it is indispensable to recognize the toxicity-constructed, toxicodynamic, and toxicokinetic features of NMs, which should carefully be emphasized at the home and industrial levels. The current study highlights the updates of the NMs to safeguard the quality and nutritional safety of foods at home and also at the industrial level.