Various polarity chemicals exist in complex samples, such as plasma; nontargeted comprehensive analysis naturally requires multiple polar-extracted solvents; consequently, the polarity of the solvent plays a crucial role in the extraction efficiency of analytes from complex samples. In the present study, based on the diffusion behavior and nanoconfinement effect of solvents in the nanoconfined space, the polarity gradient solvent confinement liquid-phase nanoextraction (PGSC-NLPNE) protocol aimed to perform a one-step nontargeted analysis of a wide range of metabolites in plasma was established. The continuously wide range of extracted solvent polarities on carbon nanofibers/carbon fiber (CNFs/CF) membranes was achieved using a mixture of hexane, dichloromethane, methanol, and water as nanoconfined solvents. The polarities (Log P) of gradient solvents ranged from −1.38 to 3.94. Correlational analyses indicated that metabolites with Log P values ranging from −1.90 to 3.84 were closely related according to similarity-intermiscibility theory. Coupled with a homemade modified guard column device, CNFs/CF membrane cartridge (CCMC), a PGSC-NLPNE-UHPLC-MS online protocol was established and applied in plasma untargeted analysis. By comparing metabolome coverage, reproducibility, and extraction recovery with protein precipitation and two-step liquid–liquid extraction commonly used in untargeted analysis, the PGSC-NLPNE-CCMC protocol demonstrated higher reproducibility and recovery. This protocol has shown great potential for ultrafast analysis of plasma untargeted metabolomics with broader metabolome coverage. It could be a potential tool to rapidly screen out valuable biomarkers related to diseases in the clinic.

中文翻译：

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极性梯度溶剂限制膜小柱，可扩大血浆非靶向分析的代谢物覆盖范围


复杂样品中存在各种极性化学品，例如血浆;非靶向综合分析自然需要多种极性提取溶剂;因此，溶剂的极性对复杂样品中分析物的提取效率起着至关重要的作用。在本研究中，基于溶剂在纳米受限空间中的扩散行为和纳米约束效应，建立了极性梯度溶剂约束液相纳米萃取 （PGSC-NLPNE） 方案，旨在对血浆中的多种代谢物进行一步非靶向分析。使用己烷、二氯甲烷、甲醇和水的混合物作为纳米限制溶剂，在碳纳米纤维/碳纤维 （CNF/CF） 膜上实现了连续宽范围的萃取溶剂极性。梯度溶剂的极性 （Log P） 范围为 −1.38 至 3.94。相关分析表明，根据相似性-混溶性理论，Log P 值范围为 -1.90 至 3.84 的代谢物密切相关。结合自制的改进保护柱装置 CNFs/CF 膜柱 （CCMC），建立了 PGSC-NLPNE-UHPLC-MS 在线方案，并应用于血浆非靶向分析。通过将代谢组覆盖率、重现性和提取回收率与非靶向分析中常用的蛋白质沉淀和两步液-液萃取进行比较，PGSC-NLPNE-CCMC 方案表现出更高的重现性和回收率。该方案已显示出对血浆非靶向代谢组学进行超快速分析的巨大潜力，具有更广泛的代谢组覆盖面。它可能是一种潜在的工具，可以快速筛选出与临床疾病相关的有价值的生物标志物。