Liquid-filled stick microextraction with in situ derivatization: An efficient tool for the quality control of herbal products targeting α-dicarbonyl compounds

A novel liquid-filled stick microextraction method with integrated in situ derivatization was developed. • Simultaneous derivatization and extraction were integrated into a single streamlined workflow. • The ready-to-use design minimizes manual reagent preparation and operational complexity. • Superior sensitivity was achieved with detection limits ranging from 0.04 to 0.29 ng/mL. • The platform successfully monitored α-dicarbonyl compounds in herbal oral liquids and granules. α-Dicarbonyl compounds (α-DCs) are critical indicators of quality and safety in herbal products, yet their analysis is challenging due to complex matrices and lacking fluorophores. This study developed a liquid-filled stick microextraction with in situ chemical derivatization (LFSME-ISD) method to streamline sample preparation. By pre-loading 50 μL of 2,3-diaminonaphthalene-saturated deep eutectic solvent (DES) into a hollow stick sealed with a polypropylene fabric tip, the ready-to-use device enables simultaneous derivatization and extraction upon activation and immersion. α-DCs are converted into fluorescent, hydrophobic derivatives, which partition into the DES phase. Under optimized conditions (60 min shaking at 60 °C followed by 1 min ultrasonic-assisted desorption), the method coupled with liquid chromatography-fluorescence detection demonstrated excellent linearity (R 2  ≥ 0.9927), low detection limits (0.04–0.29 ng/mL), satisfactory recoveries (91.1–104.0%), and high precisions (RSD ≤ 9.8%). Applied to herbal liquids and granules, LFSME-ISD provides a convenient and ready-to-use screening tool for monitoring quantifiable α-DCs in herbal matrices. Download: Download high-res image (132KB) Download: Download full-size image