Fluorescence-Enhanced Tb-MOF for Highly Sensitive and Selective Detection of Ammonia Nitrogen in Groundwater

The excessive presence of ammonia and ammonium in groundwater poses potential hazards to human health and ecosystems; thus, accurate measurement of the ammonia nitrogen concentration is very important. Herein, a stable and highly luminescent decorated Tb-MOF was prepared by a hydrothermal and substitution reaction. Under the optimized detection conditions, the decorated Tb-MOF can detect ammonia nitrogen with an exceptional fluorescence enhancement in a wide detection range. The detection limit was determined to be 1.5514 × 10^–2 μM in the lower concentration range from 0 to 0.0021 M. In addition, the as-prepared nanosensor also exhibited superior detection selectivity and anti-interference with respect to ammonia nitrogen, and the detection mechanism was investigated as the formation of an isoindole complex from dialdehyde with ammonia nitrogen to induce the energy transfer process. Furthermore, its practical ability was studied in groundwater with a decorated Tb-MOF. The detection in actual groundwater samples proves that this material can be used for practical applications. Our research provides a new method for visual, rapid, and in situ detection of ammonia nitrogen in groundwater.