Phase Separation and Thermodynamic Behavior of Triton X-100 in the Occurrence of Levofloxacin Hemihydrates: Influence of Additives

Measurements of clouding phenomena in Triton X-100 (TX-100) were carried out in the aqueous system and the presence of the antibiotic drug levofloxacin hemihydrate (LFH)/(LFH + inorganic salts/alcohols) and were explained thoroughly. In the aqueous system, the observed values of cloud point (CP) of TX-100 increased continuously with the increasing concentration of TX-100. In the occurrence of LFH, the magnitudes of cloud point of a certain concentration of TX-100 were found to increase first, and after that, the CP value declined with increasing concentration of the drug. The magnitudes of CP for the LFH + TX-100 mixed system were found to be dwindled through the enrichment of salt concentration in the presence/absence of a drug (LFH). The CP values in the presence of salts follow the order K2SO4 < KNO3 < K3PO4. On the other hand, in the case of alcohol solvent, the CP values decreased from lower alcohol to higher alcohol and increased through the enrichment of alcohol concentration in the presence and absence of a drug (LFH). Various types of thermodynamics parameters, such as standard free energy (Delta G(c)(0)), standard enthalpy (Delta H-c(0)), and standard entropy (Delta S-c(0)) changes of phase separation, were also determined and explained in an extent on the basis of their nature. The values of free energy changes (Delta G(c)(0)) were positive, which indicated that the clouding processes were nonspontaneous in nature.