Interaction of L-Phenylalanine with Nicotinic Acid in Buffer Solution by Volumetric Measurements at Various Temperatures

摘要

The interaction between l-phenylalanine (Phe) and nicotinic acid (NA) was studied in aqueous phosphate buffer solutions (pH 7.35) by a volumetric method. Densities of l-phenylalanine-buffer, NA-buffer and l-phenylalanine-NA-buffer mixtures were determined at T = (288.15, 298.15, 303.15, 308.15 and 313.15) K using a DSA 5000 M (Anton Paar) density meter. The apparent molar volumes of NA () in buffer solution and in buffer-amino acid solutions were evaluated. The concentration of NA was varied from (0.0023 to 0.0364) mol center dot kg(-1). The interaction of Phe with NA is accompanied by complex formation. The partial molar volumes of transfer of NA from buffer to buffer-amino acid solutions are positive. The results are discussed in terms of various interactions operating in this system.