Investigation on the nucleation kinetics, growth and thermal properties of γ-aminobutyric acid crystal

In this paper, the nucleation kinetics and thermal properties of γ-aminobutyric acid which is the chief inhibitory neurotransmitter in the mammalian central nervous system were investigated. The grown crystals have also been subjected to thermal studies. The DSC studies showed that the sample started to melt at 190.6°C with high melting enthalpy of -343.4 J/g. The solubility of γ-aminobutyric acid was estimated at different temperatures in water. The induction period was measured for the different supersaturation ratios. The study revealed that the induction period of γ-aminobutyric acid decreased as the supersaturation increasing. The metastable zone width of γ-aminobutyric acid was measured by polythermal method. Interfacial tension has been estimated by the experimentally determined induction period values. Nucleation parameters, such as the radius of critical nucleus and the Gibbs free energy barrier, have also been investigated based on classical nucleation theory. The relationship between high melting enthalpy of γ-aminobutyric acid and its structure was also explained.