shown below in table 7 enthalpy of fusion measurements were obtained on single sample analysis using a relatively small sample size of approximately 2 mg the thermal behavior of batch g was determined using differential scanning calorimetry and thermogravimetric analysis the dsc thermogram exhibited a sharp melting endotherm with an onset of 106 9 u00b0 c and an enthalpy of fusion of 118 9 j g microscopic evaluation of lot g showed birefringent acicular to columnar shaped particles ranging in size from approximately 5 to 100 microns fig1 shows the representative photomicrograph to perform the solvent based portion of the polymorph screen the 3 phenyl 5 thiophen 2 yl 1 2 4 oxadiazole test material was recrystallized using various solvents under approximately 240 different crystal growth conditions the scale of the recrystallization experiments was from approximately 0 5 ml to 15 ml the crystal growth conditions were changed by using binary gradient arrays of solvent mixtures and by changing the saturation temperature growth temperature and evaporation rate rate of supersaturation generation saturated solutions were prepared by agitating excess as possible test material in contact with the various solvent systems at the saturation temperature if solids did not completely dissolve in the solvent the mother liquor was separated from the residual solids by filtration the mother liquor was then heated above the saturation temperature overheated to dissolve any remaining solids the temperature of each solution was then adjusted to.