A host–guest complexation based fluorescent probe for the detection of paraquat and diquat herbicides in aqueous solutions

• Published in: RSC advances 2015, Vol.5 (121), p.100316-100321
• Main Authors: Song, Gui-Xian, Tang, Qing, Huang, Ying, Wang, Ruibing, Xi, Yun-Yun, Ni, Xin-Long, Tao, Zhu, Xue, Sai-Feng, Zhang, Jian-Xin
• Format: Article
• Language: English
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/C5RA18335A

The supramolecular interactions among thioflavin T (ThT), two herbicides paraquat (PQ) and diquat (DQ), and macrocyclic cucurbit[8]uril (Q[8]), were studied using spectrofluorimetry, ultraviolet-visible absorbance spectrometry, 1 H nuclear magnetic resonance spectroscopy, and isothermal titration calorimetry. A new method based on fluorescence quenching of the fluorescent host–guest complexes of Q[8]–ThT (the probe) upon cooperative binding with PQ or DQ to form a ternary complex, was proposed for the analytical determination of the two herbicides in aqueous solutions. Detection limits of 7.95 × 10 −9 mol L −1 and 8.07 × 10 −9 mol L −1 were obtained for PQ and DQ, respectively. Recoveries obtained by the proposed method in real-world examples such as river water and cabbage extracts were 104–108%. Interestingly, this method demonstrated high selectivity towards PQ and DQ in the presence of various metal ions and quaternary ammonium substances. Such a method provides a rapid, selective, sensitive and facile strategy for herbicides detection and quantification.