Research on visual detection of the residues of amide herbicides in water using lanthanide metal-organic framework

Convenient detection of amide herbicides in water is essential for assessing the herbicide pollution and proposing the corresponding countermeasures. In this work, Eu³⁺ and Tb³⁺ co-doped lanthanide metal-organic frameworks (Ln-MOF) were prepared using hydrothermal and microwave methods respectively. Their structure and optical properties were also characterized. Then the synthesized material was applied to the analysis of five amide herbicides (acetochlor, propisochlor, pretilachlor, napropamide and metolachlor) in water qualitatively and quantitatively. Results showed that the Ln-MOF prepared by microwave synthesis method was fluffy clusters with good crystallinity and high luminous efficiency. Therefore, the microwave synthesis method was selected. Test results show that diverse herbicides quench the fluorescence of Tb³⁺ and Eu³⁺ differently, which can change the color of emission light, then realizing the visual detection of amide herbicides in water. Further, when the concentration of pretilachlor is between 0.1 to 1 mmoL/L, the emission intensity ratio of I (Tb³⁺)/I (Eu³⁺) increased with increase of the concentration of pretilachlor, with a correlation coefficient of R² = 0.998. The limit of detection is 0.08 mmoL/L. Moreover, Ln-MOF can also be used for the qualitative analysis of the herbicide in lake water. These results indicated potential application of Ln-MOF for the qualitative and quantitative analysis of amide herbicides in water.