In-pipette-tip kapok fiber-supported liquid extraction/in-situ derivatization coupled with high-performance liquid chromatography for conveniently determining three furfurals

This study presents an in-pipette-tip kapok fiber-supported liquid extraction/in-situ derivatization (in-pipette-tip KF-SLE-ISD) method for simultaneous enrichment and derivatization of furfurals. Briefly, 3 mg of natural kapok fiber, which was loaded in an assembled pipette-tip, was used to support 12.5 μL of extractant (ethyl acetate/toluene, 75:25, v/v) containing 10 mM 2,4-dinitrophenylhydrazine. The in-pipette-tip KF-SLE-ISD procedure was conveniently conducted by aspirating/releasing 1 mL of sample solution 10 cycles, allowing simultaneous extraction and derivatization of furfurals. Then, 100 μL of acetonitrile was aspirated/released 5 cycles for elution, 10 μL of which was directly analyzed by high-performance liquid chromatography. The limits of quantitation were in ranges of 0.10-0.45 μg/mL. The method showed satisfied linearity (R² > 0.99), precision (RSD < 8.53%) and relative recovery (90.34-114.71%), which was successfully applied to determine furfurals in various samples (e.g., honeys, juices and glucose injections). The proposed method has the merits of effectiveness, simplicity, low cost, wide availability and ease of automation.