Ultrasonic relaxation studies in some amino acids

Abstract

Ultrasonic relaxation studies have been carried out in aqueous solutions of some amino acids namely l-arginine, l-isoleucine and l-norvaline in the frequency range of 2 to 30 MHz and in the pH range 5.5 to 11.5. These studies have been carried out at a fixed amino acid concentration of 0.05 molar and at a fixed temperature of 303.15 K. The excess ultrasonic absorption obtained in aqueous solutions of amino acids has been explained in terms of proton-transfer reactions occurring in the amino acid solutions. The excess absorption observed around neutral pH has been attributed to ionic hydration. The rate constant for the forward and backward reactions occurring in these amino acid solutions and the volume change taking place due to these reactions have been estimated and reported in this article.