Green Solvents for Microextraction

Scientists from the Chinese Academy of Inspection and Quarantine in Beijing, China recently published a review on how green solvents and green analytical chemistry (GAC) techniques could be used to further the evolution of microextraction techniques. Their findings were later published in TrAC Trends in Analytical Chemistry (1).

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Analytical procedures usually consist of three main parts: sampling, sample preparation, and analysis. Regarding matrix interferences, sample preparation that relies on solvent extractions is vital for most analytical processes to return accurate and reliable analysis results. The most well-known conventional extraction techniques are solid-phase extraction (SPE) and liquid-liquid extraction (LLE), though these processes can be tedious, time-consuming, and consume large amounts of volatile and toxic organic solvents. If one were to implement green analytical chemistry (GAC) concepts, which encourage the minimization of extraction procedures and replacing hazardous solvents with environmentally friendly alternatives, then these processes could function more effectively.

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GAC has been a popular topic at industry conferences over the last year, and using greener solvents is just one part of the conversation. At Analytica in Munich, Germany, earlier this month, scientists focused their presentations on the future of sustainability in chemistry. At Pittcon in February, the Wallace H. Coulter lecture was delivered by Omowunmi Sadik of the New Jersey Institute of Technology (NJIT) spoke about the 12 principles of green analytical chemistry.

In this study, the scientists sought to implement more sustainable green solvents into microextraction techniques, like solid-phase microextraction (SPME), liquid-phase microextraction (LPME), or their modifications, can help establish efficient and environmentally friendly sample preparation procedures prior to instrumental analysis. Taking advantage of solvation properties and greenness merits can help sustainable green solvents be tailored as promising extractants for specific microextraction tasks. In this article, the scientists summarize recent advancements made in prominent sustainable green solvents (including ionic liquids, natural deep eutectic solvents, and switchable solvents) that are used in microextraction techniques. The team also reviewed their applications and how they can be coupled with various mass spectrometric approaches for highly selective and sensitive analysis are discussed, as well as potential future outlooks in this field.

GAC has enabled analytical scientists to create new sustainable green solvents, improve microextraction techniques, and innovate advanced instruments to increase sustainability and greenness of analysis processes and improve performance. Sustainable green solvents have proven useful alternatives to conventional organic solvents, due to their eco-friendliness, superior extraction efficiency, excellent chemical and thermal stability, and adjustable physicochemical properties. Task-specific and highly efficient microextraction techniques that employ sustainable green solvents in sample preparation are typically characterized by high extraction recoveries and enrichment factors, along with enhanced greenness and sustainability.

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When combined with advanced mass spectrometric analytical instruments, such as gas chromatography–mass spectrometry (GC–MS), liquid chromatography–mass spectrometry (LC–MS), and capillary electrophoresis (CE)–mass spectrometry (CE­–MS), these techniques can selectively and sensitively analyze trace compounds with diverse properties within short time spans. GAC will continue to grow rapidly in the future, but how it will grow will depend on how much green solvent use is expanded, how efficient green extraction techniques become, and how the community chooses to advance the application of green analytical methodologies.

Reference

(1) Zhang, Y.; Chen, M.; Li, L.; Lv, Y.; Ma, Q. Recent Advances in Microextraction Techniques Using Sustainable Green Solvents for Mass Spectrometry Analysis. TrAC Trends Analyt. Chem. 2024, 170, 117412. DOI: 10.1016/j.trac.2023.117412