基于功能材料的固相微萃取技术及其在法庭科学领域中的应用

Applications of functional materials-based solid phase microextraction technique in forensic science

样品的提取是法庭科学分析中至关重要的一步,尤其是在处理各种复杂基质(如土壤、生物样品、火灾残留物等)中痕量和超痕量的目标分析物时。传统样品前处理技术如索氏提取、液液萃取等,步骤繁琐,耗时耗力,过程中易造成样品的损失和二次污染,且萃取所需的大量溶剂还会对环境及研究人员的健康构成威胁。为此,无需或只需少量溶剂的固相微萃取技术(SPME)应运而生,其小巧便携,操作简单、快速,易于实现自动化等特点使之成为广泛应用的样品前处理技术。早期的研究大多采用商品化SPME装置,然而它的种类有限、价格昂贵、纤维易断、选择性不足,因此,近年来使用金属有机骨架化合物、共价有机骨架化合物、碳基材料、分子印迹聚合物、离子液体、导电聚合物等各种功能材料制备SPME涂层的技术越来越受到关注,在环境监测、食品分析及药物检测等方面应用广泛。然而这些SPME涂层材料在法庭科学领域的应用相对较少,考虑到SPME技术应用于犯罪现场样品原位高效提取的巨大潜力,该文对功能涂层材料进行了简要介绍,系统总结了基于功能材料的SPME技术在炸药、助燃剂、毒品、毒物、油漆、人体气味等分析中的应用,并指出了基于功能材料的SPME技术在法庭科学分析中存在的不足,对其未来可能的发展方向提供了建议,以期为从事相关研究的同行提供参考。

Sample extraction is a crucial step in forensic analysis,especially when dealing with trace and ultra-trace levels of target analytes present in various complex matrices(e.g.,soil,biological samples,and fire debris).Conventional sample preparation techniques include Soxhlet extraction and liquid-liquid extraction.However,these techniques are tedious,time-consuming,labor-intensive and require large amounts of solvents,which poses a threat to the environment and health of researchers.Moreover,sample loss and secondary pollution can easily occur during the preparation procedure.Conversely,the solid phase microextraction(SPME)technique either requires a small amount of solvent or no solvent at all.Its small and portable size,simple and fast operation,easy-to-realize automation,and other characteristics thus make it a widely used sample pretreatment technique.More attention was given to the preparation of SPME coatings by using various functional materials,as commercialized SPME devices used in early studies were expensive,fragile,and lacked selectivity.Examples of those functional materials include metal-organic frameworks,covalent organic frameworks,carbon-based materials,molecularly imprinted polymers,ionic liquids,and conducting polymers,all widely used in environmental monitoring,food analysis,and drug detection.However,these SPME coating materials have relatively few applications in forensics.Given the high potential of SPME technology for the in situ and efficient extraction of samples from crime scenes,this study briefly introduces functional coating materials and summarizes the applications of SPME coating materials for the analysis of explosives,ignitable liquids,illicit drugs,poisons,paints,and human odors.Compared to commercial coatings,functional material-based SPME coatings exhibit higher selectivity,sensitivity,and stability.These advantages are mainly achieved through the following approaches:First,the selectivity can be improved by increasing theπ-π,hydrogen bonds,and hydrophilic/hydrophobic interactions between the materials and analytes.Second,the sensitivity can be improved by using porous materials or by increasing their porosity.Third,thermal,chemical,and mechanical stability can be improved by using robust materials or fixing the chemical bonding between the coating and substrate.In addition,composite materials with multiple advantages are gradually replacing the single materials.In terms of the substrate,the silica support was gradually replaced by the metal support.This study also outlines the existing shortcomings in forensic science analysis of functional material-based SPME techniques.First,the application of functional material-based SPME techniques in forensic science remains limited.On one hand,the analytes are narrow in scope.As far as explosive analysis is concerned,functional material-based SPME coatings are mainly applied to nitrobenzene explosives,while other categories,such as nitroamine and peroxides,are rarely or never involved.Research and development of coatings is insufficient and the application of COFs in forensic science has not yet been reported.Second,functional material-based SPME coatings have not been commercialized as they don’t yet have inter-laboratory validation tests or established official standard analytical methods.Therefore,some suggestions are proposed for the future development of forensic science analyses of functional material-based SPME coatings.First,research and development of functional material-based SPME coatings,especially fiber coatings with broad-spectrum applicability and high sensitivity,or outstanding selectivity for some compounds,is still an important direction for SPME future research.Second,a theoretical calculation of the binding energy between the analyte and coating was introduced to guide the design of functional coatings and improve the screening efficiency of new coatings.Third,we expand its application in forensic science by expanding the number of analytes.Fourth,we focused on the promotion of functional material-based SPME coatings in conventional laboratories and established performance evaluation protocols for the commercialization of functional material-based SPME coatings.This study is expected to serve as a reference for peers engaged in related research.