Determination of the solid liquid interfacial energy and thereby the critical nucleus size of paracetamol in different solvents

The effect of the type of solvent on the solid liquid interfacial energy was determined by performing induction time measurements of paracetamol in methanol, 1-propanol, acetone and water at a constant supersaturation temperature of 30 degrees C and different levels of supersaturation (a/a*) ranging from 1.03 to 1.24. At equal supersaturation level and temperature the induction time increases with decreasing solubility whereas the solid liquid interfacial energy decreases with increasing solubility. The interfacial energy has a minimum value of 1.45 mJ/m(2) in the solvent where paracetamol has a maximum solubility (methanol) whereas it has its maximum value of 2.91 mJ/m(2) in the solvent with minimum solubility. The interfacial energy is a function of the solubility has been established. The critical radius for homogeneous nucleation was found to be minimum in the solvent of highest solubility. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.