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

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 (R² ≥ 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.