Crude DHSA was melted in an oven preset at 80 ◦C for 8 h. The
molten crude DHSA was mixed with IPA (at concentrations of 70%,
80% and 90%) in static 3.5 in 600 mL glass beakers. The mixtures
were allowed to cool in order for crystallization to occur. The crystallization
period was 720 min, the cooling rate was
−0.6 ◦C/min
and the final temperature varied between 20, 25 and 30 ◦C. The
real-time temperature profiles of the mixtures are shown in Fig. 2.
No significant temperature gradient was observed in the mixtures,
and DHSA crystals started to form at the bottom of the crystallization
vessels. Purified DHSA crystals were segregated from the
mother liquor through vacuum filtration. The entire mixture was
filtered. The segregated crystals were collected and dried in an oven
preset to 50 ◦C for 48 h