Extraction of Histidine, Proline, and Methionine and Their Mixtures Using Systems Based on N-VinylFormamide

Methods are proposed for the extraction of amino acids histidine, methionine, and proline from aqueous media with water-soluble polymers for their subsequent determination by capillary electrophoresis. Regularities of the interphase distribution of analytes in water–salt extraction systems based on poly-N-vinyl formamide and its copolymer with N-vinylimidazole are revealed and their efficiency is proved. The rate of formation of a two-phase system water-soluble polymer–aqueous salt solution of amino acid is substantially affected by the molecular weight and intrinsic viscosity of the extractant. The effect of the volume ratio of water and organic phases on the efficiency of extraction of histidine, methionine, and proline is studied, also on their simultaneous presence; quantitative characteristics of the process are calculated. Homo- and copolymers of N-vinylformamide are used for the efficient extraction and extraction separation of a histidine−methionine mixture. Partition coefficients and the recoveries of amino acids are specified in the systems containing poly-N-vinylformamide and its copolymer with N-vinylimidazole in the presence of an ammonium sulfate salting-out agent. The conditions for the electrophoretic determination of amino acids are optimized, i.e., the composition of the buffer solution and the type and concentration of the micelle-forming agent. The developed method for the electrophoretic separate determination of amino acids with the preliminary extraction of the target components with water-soluble polymers can be recommended for routine analyses in determining the safety of foodstuffs, energy drinks, and pharmaceuticals.