The Establishments Of The Novel Microextraction Methods And Their Application In Complex Sample Analysis

Objective:In recent years, some microextraction technologies, mainly including liquid phase microextraction(LPME) and solid phase microextraction(SPME), are rapid development as new sample pretreatment method because they are simple operation, low cost, no need special equipment, less consumption of organic solvent or without organic solvent and high enrichment factor(EF). In this paper, based on the study of the extraction, separation and enrichment of complex samples for years, we proposed and established microporous membrane/solvent microextraction(MPMSME), microporous membrane/graphene/solvent synergistic microextraction(MPMGSSME) and hollow fiber/graphene bar portable sampler(HF/GBPS), and introduced them to separate, concentrate and enrich the trace levels of target analytes in complex samples.Methods:In part one of this paper, microporous membrane attached extraction solvent or graphene/extraction solvent dispersion solution was employed as a extraction platform,caffeic acid, ferulic acid and cinnamic acid were used as model compounds, we proposed and established the sample pretreatment technology of MPMSME and MPMGSSME.Through conditions optimization and methodology research, MPMSME or MPMGSSME coupled with high performance liquid chromatography(HPLC) was applied to simultaneous separation, enrichment and determination of caffeic acid, ferulic acid and cinnamic acid in traditional Chinese medicine Rhizoma Typhonii. Also, EF of target analytes were defined and derived, and extraction mechanisms of MPMSME and MPMGSSME were analyzed and discussed. In part two of this paper, hollow fiber/graphene bar(HF/GB) fixed in a handheld battery operated electric egg beater, which was composed of a portable field sampler HF/GBPS. It could be put directly into environmental water and conducted the field sampling and sample preparation. The several factors affecting performance, including types and content of graphene, extraction time and desorption time, were investigated and optimized in the laboratory. The ultrastructure ofHF/GB was characterized. The extraction mechanism of HF/GBPS was analyzed and illustrate. HF/GBPS coupled with HPLC was employed for on-site sampling, enrichment and determination of four trace levels of nitrobenzene compounds(nitrobenzene,o-nitrophenol, m-nitrophenol, and p-nitrophenol) in environmental water.Results:The experimental results show that:(1) MPMSME and MPMGSSME had advantages of the cheap material, simple operation, large extraction surface, less consumption of organic solvent;(2) microporous membrane not only was used as holder of extraction solvent or graphene/extraction solvent dispersion solution but also had a role of SPME to extracted and concentrated target analytes;(3) MPMGSSME had higher EF of target analyte than MPMSME because graphene was of large specific surface area and strong adsorption capacity;(4) Compared with other reported on-site techniques, HF/GBPS is excellent for simple preparation, convenient carrying, short sampling periods, and it can be conducted sampling and sample preparation anytime and anywhere.Conclusion:In a word, MPMSME, MPMGSSME and HF/GBPS are of simple operation, low cost,friendly environment, high EF, and they have been successful applied to extraction,concentration and determination of trace levels of target analytes in complex samples.Undoubtedly, the establishing and applying of MPMSME, MPMGSSME and HF/GBPS enriched and developed for modern sample pretreatment technology.