In-capillary aptamer-functionalized dispersive solid-phase microextraction for dynamic transfer enrichment and miniature mass spectrometry analysis: A magnetically driven capture-and-release strategy

The rapid on-site mass spectrometry (MS) analysis of biofluids is of immense significance for point-of-care scenarios. In this study, an innovative magnetically driven capture-and-release strategy for in-capillary cyclical transfer enrichment of analytes of interest is reported. A dispersive magnetic solid-phase microextraction protocol is developed based on aptamer-functionalized polymer-modified magnetic nanoparticles, enabling specific recognition, fast transportation, and dynamic enrichment of target analytes within the capillary. Furthermore, a dicationic ionic liquid (DIL)-based charge inversion reaction is integrated with extraction nanoelectrospray ionization and miniature MS analysis to achieve significant signal amplification. The sensitivity of the analysis for typical per- and polyfluoroalkyl substances was enhanced by 6.3–28.9 times in the positive ion mode following the DIL-based charge inversion strategy, compared to that in the negative ion mode without any DILs used. The proposed method underwent validation, demonstrating good linearity with correlation coefficients exceeding 0.99, acceptable recoveries ranging from 89.6% to 111.1%, and satisfactory sensitivity with limits of detection and quantitation in the ranges of 0.05–0.2 and 0.2–2 ng/mL, respectively. This methodology demonstrates appealing analytical performance and environmental friendliness, which is of great importance for clinical and point-of-care applications.