Selective extraction and analysis of phenolic acids in herbal plants using Fe₃O₄@MXene@PEI aerogel

A magnetic MXene aerogel (Fe₃O₄@MXene@PEI) was prepared by crosslinking amino modified MXene with polyethyleneimine using epichlorohydrin as a cross-linker. Adsorption properties of Fe₃O₄@MXene@PEI aerogel for phenolic acids were evaluated by adsorption kinetics and isotherms experiments, showing that the high adsorption affinity was governed by multilayer chemisorption process. An efficient MSPE/HPLC method was developed for the determination of phenolic acids with excellent selectivity, good linearity (0.025-5.0 μg mL^-1), low LODs (0.007-0.017 μg mL^-1), and satisfactory recoveries (80.0-120.0 %). Moreover, the antioxidant activity of the Fe₃O₄@MXene@PEI purified compounds was superior to that of the conventional method as demonstrated by the results of scavenging experiments on 2,2 -diphenyl-1-picrylhydrazyl radical scavenging assay. Finally, 65 organic acids were identified in the Fe₃O₄@MXene@PEI treated honeysuckle extracts by UHPLC-Q-Exactive Orbitrap MS/MS analysis. The proposed sorbent exhibits remarkable promise for the selective separation and purification of organic acids from herbal products.