Preparation of branched polyethyleneimine‐assisted boronic acid‐functionalized magnetic MXene for the enrichment of catecholamines in urine samples

Herein, a magnetic borate‐functionalized MXene composite with multiple boronic affinity sites was fabricated by embedding Fe 3 O 4 nanoparticles with 4‐formylphenylboronic acid functionalized Ti 3 C 2 T x nanosheets and served as sorbent for the simultaneous extraction of catecholamines (CAs) in urine samples. The morphology and structure of the magnetic materials were investigated using scanning microscopy, vibrating sample magnetometer, X‐ray photoelectron spectrometer, and X‐ray diffraction. The introduction of polyethyleneimine can amplify the bonded boronic acid groups, thereby effectively improving the adsorption capacities for CAs based on the multiple interactions of boronic affinity, hydrogen bonding, and metal coordination. The adsorption performance was investigated using the kinetics and isotherms models, and the main parameters that influence the extraction efficiency were optimized. Under the most favorable magnetic solid‐phase extraction condition, a sensitive method for the analysis of CAs in urine samples was developed by combining magnetic solid‐phase extraction conditions with high‐performance liquid chromatography detection. The findings illustrated that the proposed approach possessed a wide linearity range of 0.05–250 ng/mL with an acceptable correlation coefficient (R 2 ≥ 0.9984) and detection limits of 0.010–0.015 ng/mL for the target CAs. The research not only provides a notable composite with multiple boronic affinity sites but also offers an effective and feasible measure for the detection of CAs in biological samples.