Accelerated stability studies of DTG PSIs. A) DTG concentration in PSIs before (day 0) and after storage at 40 °C and 75% RH for 14, 30, 90, and 180 days. B) Physical appearance of the DTG PSIs before (day 0) and after storage at 40 °C and 75% RH for 14, 30, 90, and 180 days. C) HPLC chromatograms of DTG extracted from PSIs before (day 0) and after storage at 40 °C and 75% RH for 14, 30, 90, and 180 days.