Interaction of amino acids with the herbicides diquat and paraquat studied by charge-transfer chromatography

Abstract

The interaction of the amino acids and some peptides with the herbicides diquat and paraquat was determined by reversed-phase charge-transfer chromatography. Only charged amino acids and gluthathion (both reduced and oxidized forms) influenced the mobility of diquat and paraquat. The strength of interaction increased in the order: aspartic acid > gluthathione oxidized > gluthathione reduced > ornithine > cysteine ≈ glutamic acid > lysine. No significant difference was found between the effects of D and L forms of aspartic acid. Except cysteine the strength of interaction was similar on cellulose and on reversed-phase layers. The strength of interaction nonlinearly decreased with growing concentration of Ca2+ ions in the eluent proving the hydrophilic character of interaction. Glutamic acid-ornithine and glutamic acid-lysine mixtures did not show lower interactive strength than the single amino acids although interactions of commensurable strength were also observed between these amino acids. This finding supports the possible formation of dibasic amino acid-dicarboxylic amino acid-herbicid complexes of unknown stoichiometry.