Intelligent Cellulose-Based Sorbent for Light-Driven Solid-Phase Extraction of Amphetamine

An intelligent cellulose-based sorbent (Cell-Azo) was developed by grafting azobenzene onto cellulose via atom-transfer radical polymerization, enabling the light-driven solid-phase extraction of amphetamine (AMP). Successful grafting was verified by FT-IR and XPS, with UV-vis spectroscopy demonstrating the rapid and reversible <i>trans</i>-<i>cis</i> isomerization upon alternating UV/visible light irradiation. Batch adsorption studies revealed a maximum capacity of 19.86 mg·g^-1 at pH 9.0, governed by synergistic electrostatic, π-π stacking, and hydrogen-bonding interactions. The core functionality of the switch was demonstrated by triggering AMP release with UV light, achieving a high desorption efficiency of 90.54%, significantly surpassing the <35% observed in the dark. This light-controlled release is attributed to conformational change in azobenzene units, which disrupts the binding sites. A dispersive solid-phase extraction protocol coupled with HPLC-UV was developed, demonstrating wide linearity (0.05-2.00 mg·L^-1), low LOD (7 μg·L^-1) and LOQ (23.33 μg·L^-1), and satisfactory precision (RSD < 5.1%). When applied to spiked urine samples, the method achieved recoveries of 69.53-75.68%, demonstrating the potential application of Cell-Azo as an efficient, green, and controllable alternative for trace AMP analysis in complex matrices.