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pH‐Selective Fluorescent Enhancement with Glyphosate in Aqueous Media
Author(s) -
Luo MengHan,
Dou HongXi,
Wang Kui,
Feng YuXin,
Xing SiYang,
Zhu BoLin,
Wu Yue
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201901038
Subject(s) - glyphosate , titration , chemistry , fluorescence , aqueous solution , binding constant , phosphate , aqueous medium , nuclear chemistry , binding site , inorganic chemistry , organic chemistry , biochemistry , biology , physics , quantum mechanics , agronomy
In this work the host–guest interactions between calixpyridinium and glyphosate were studied in aqueous media at pH 2.0 and 6.0 by using a calixpyridinium–dye complex. A pH‐selective fluorescent enhancement with glyphosate at pH 6.0 was found. The results of competitive binding titration experiments showed that calixpyridinium formed 1:1 host–guest complexes with glyphosate at pH 6.0. The association constant of calixpyridinium with glyphosate, extracted from the competitive binding titration, was (4.83±1.42)×10 2 M −1 . The binding mode between calixpyridinium and glyphosate in D 2 O at pD 6.0 was further deduced by using 1 H NMR spectroscopy. The result showed that the anionic carboxyl group, rather than the anionic phosphate group, was the main binding site of glyphosate to calixpyridinium accompanied by electrostatic interaction. pH 6.0 is in the pH range suitable for plant growth. Therefore, it is anticipated that these results are extremely important in the detection of glyphosate. These studies were further performed in some real aqueous samples, and the results were similar to those obtained in simple pure water. More importantly, this method indeed could be applied in the detection of glyphosate in the different real soil samples, and some potential background interferences could not affect the detection. All these studies in the real samples can greatly increase the usefulness of this work.