Post-functionalized Al-based metal-organic frameworks for fluorescent detection of total iron in food matrix

It is imperative to exploit simple and rapid methods for the detection of total iron in foods to ensure food quality and human health. Herein, we construct the MIL-53(Al)-NH 2 -MPA nanosensor synthesized by post-synthetic modification process for fluorescent detection of total iron in food matrix. The nanosensor emits intense blue fluorescence with excellent stability. The fluorescence can be efficiently quenched by Fe(III) due to the fact that Fe(III) can preferentially bind with O-quinone bands or –NH 2 of MIL-53(Al)-NH 2 -MPA to form strong coordination complex, and that the heteroatoms (N, O and S) in MIL-53(Al)-NH 2 -MPA can donate lone-pair electrons to Fe(III) to promote the electron transfer. Moreover, the competitive absorption of excitation energy of MIL-53(Al)-NH 2 -MPA by Fe(III) endows the nanosensor with superior sensitivity. The fluorescent sensor exhibits excellent anti-interference performances toward other metal ions, and reveals a LOD of 0.36 μM with the broad linear range of 0–110 μM for the detection of Fe(III). Satisfactory recoveries of 92.90–112.70% with RSDs of 0.54–2.48% have been achieved in water and food samples, which are well agreement with inductively coupled plasma mass spectrometry (ICP-MS) (P > 0.05), indicating that MIL-53(Al)-NH 2 -MPA is applicable for detecting total iron in food matrix.