Liu Yadi,Li Shu,Guo Xinyuan,Wang Tong,Yang Dawei,Zhan Jinhua,Chen Jing
A solid-phase microextraction-SERS (SPME-SERS) analysis system was enhanced by the synergistic integration of azo reaction and electroextraction (Azo/EEx/SPME-SERS) to directly determine aromatic amines in serum and urine. Azo reactions selectively converted aromatic amines (e.g., aniline) into positively charged derivatives, which were selectively absorbed onto a rough silver SERS substrate via charge-selective electroextraction (- 0.2 V), excluding anionic interferents. Electroextraction-accelerated mass transfer and real-time SERS detection enabled rapid preconcentration and spectral acquisition under 3 min. The azo reaction increased the Raman scattering cross-section of aniline, and electroextraction reduced the distance of azo aniline to the SERS hot spots. This enabled low detection limits (aniline, 0.005 µg·mL −1 ). The Azo/EEx/SPME-SERS method achieved dual-dimensional interference exclusion through chemical derivatization (azo reaction) and physical charge-selective electroextraction, granting aromatic amines competitive adsorption advantage over serum metabolites at SERS hotspots. This synergy allows for the direct detemination of aniline in urine/serum with only 5–10 fold dilutions. It avoids the need for tedious pretreatments, while maintaining recoveries of 92–107%, accuracy of 97.33% (urine) and 94.89% (serum), and method detection limits of 0.05 µg·mL −1 (urine) and 0.5 µg·mL −1 (serum). Graphical
The direct mass spectrometric analysis of complex biological samples is often hindered by matrix interference and the need for extensive sample preparation. In this study, an online electroextraction method based on nano-electrospray mass spectrometry (OEE–nESI–MS) was proposed for the high-sensitivity and rapid analysis of urine samples. Compared with other methods, OEE–nESI–MS requires only 5 μL of sample and 35 μL of extraction solvent to achieve the migration and simultaneous ionization of the target from the sample solution to the extraction solvent in the nano tip, and online extraction and simultaneous analysis can be achieved within 8 min, while maintaining comparable sensitivity to other detection methods. The OEE–nESI–MS showed good linearity (R2 > 0.995) in the range of 1–600 ng mL–1 for the five catecholamines (CAs) in urine, with detection limits as low as 0.39–0.89 ng mL–1 with recoveries of 91.9–104.9% (RSD ≤ 8.9%). Exploration of the OEE–nESI mechanism emphasized the electric field applied as a key factor facilitating online electroextraction. The OEE–nESI–MS was successfully applied to the analysis of five CAs in real urine samples. This advancement provides a very simplified solution for the online rapid, highly sensitive, and quantitative determination of complex samples.
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