Solvent crystallization with IPA noticeably improved DHSA
purity. Crude DHSA was 69.55% pure. Solvent crystallization
improved the purity to over 80%. A typical GC separation spectrum
for purified DHSA is shown in Fig. 3(b) with the major peak at Rt
13.779 min assigned to DHSA and smaller peaks for impurities. The
purity of the DHSA crystals at different final temperatures and IPA
concentrations is presented in Fig. 4(b).