Efficient solid-phase extraction of quaternary ammonium alkaloids from traditional Chinese medicines on a novel sulfonic acid group functionalized microporous organic network coated SiO2 composite

In this work, a novel sulfonic acid-functionalized microporous organic network-coated SiO 2 composite (SiO 2 @MON-SO 3 H-2) was synthesized for efficient solid-phase extraction (SPE) of quaternary ammonium alkaloids (QAAs) from complex traditional Chinese medicine (TCM) samples. The material exhibits a high specific surface area (381.4 m 2 g −1 ), superhydrophilicity, and excellent stability. These properties, combined with synergistic interactions such as electrostatic attraction, hydrophobic effects, and π-π stacking, enabled the adsorbent to demonstrate outstanding extraction performance toward four typical QAAs. The developed method owns wide linear ranges (0.88–1000 μg L −1 ) with good linearity (R 2 > 0.999), high sensitivity (limits of detection: 0.26–1.02 μg L −1 ), satisfactory precision (intra- and inter-day RSDs < 6.3%), high enhancement factors (> 91), and insignificant matrix effects (86.6–115.3%). The material maintained excellent reusability, with recoveries remaining above 89% after 50 extraction-desorption cycles. When applied to spiked herbal matrices, the method provided recoveries of 92.7–112.0%. SiO 2 @MON-SO 3 H-2 also gave higher recovery than commercial C18, activated carbon, macroporous adsorption resin AB-8, and the cation-exchange resin Amberlite 732. The present work demonstrates the prospect of SiO 2 @MON-SO 3 H-2 for trace QAAs extraction from complex samples and provides a reliable approach for TCM analysis and quality control.