UiO-67 decorated on porous carbon derived from Ce-MOF for the enrichment and fluorescence determination of glyphosate.

A nanocomposite was prepared by loading UiO-67 nanoparticles onto porous carbon materials derived from Ce-MOF (Ce-PC) for fluorescence detection of glyphosate. The probe (UiO-67/Ce-PC) exhibits fluorescence emission at 414 nm as the response signal under excitation at 310 nm. The fluorescence enhancement mode of UiO-67 reduces the background interference, and the introduction of Ce-PC provide hierarchical nanostructure and large specific surface area that can increase the contact availability and improve the pre-enrichment effect, ensuring UiO-67/Ce-PC with superior sensitivity. The abundant metal hydroxyl group (M-O-H) of UiO-67/Ce-PC could recognize phosphoryl groups (-PO3H2) of glyphosate through ligand exchange, which synergizes with H-bonding interaction and electrostatic attraction to exhibit specificity toward glyphosate. The competitive coordination effects weaken the ligand-to-metal charge transfer (LMCT) and consequently induce the fluorescence recovery. The calibration plot of the fluorescence enhancement response of UiO-67/Ce-PC towards glyphosate was recorded in the range 0.02-30 μg mL-1 with a low limit of detection (LOD) of 0.0062 μg mL-1, which is superior to the pure UiO-67. In addition, the sensor exhibited high selectivity and satisfactory accuracy and precision with recoveries of 92.1-105.6% and RSDs below 3.4%. This work not only presents a feasible sensor for sensitive and selective determination of glyphosate from cereal samples, but also provides a promising strategy for the design of MOF-based nanocomposites to achieve trace detection of various pollutants.