0.45 m nylon filter

Concentrations of Hed and Het during solubility, dissolution rate, and permeability studies were measured by high-performance liquid chromatography with the DAD detector (HPLC-DAD). In this study, a Shimadzu Nexera (Shimadzu Corp., Kyoto, Japan) equipped with SCL-40 system controller; DGU-403 degassing unit; LC-40B XR solvent delivery module; SIL-40C XR auto sampler; CTO-40C column oven; SPD-M40 photo diode array detector, was used. For the stationary phase, a Dr. Maisch ReproSil-Pur Basic-C18 100 Å column, 5 µm particle size, 250 × 4.60 mm (Dr. Maisch, Ammerbuch-Entringen, Germany), was used. The mobile phase was methanol/0.1% acetic acid (65:35 v/v). The mobile phase was vacuum-filtered through a 0.45 µm nylon filter (Phenomenex, CA, USA). The experimental conditions were as follows: 0.9 mL·min⁻¹ flow rate, wavelength 280 nm for Hed and 288 nm for Het, and the column temperature at 30 °C. The injection volume differed depending on the assay. For the solubility study, it was 1 µL, whereas for the dissolution rate and permeability assays, it was 10 µL. The method duration time was 10 min. The retention time was 4.17 min for Hed and 5.83 min for Het.

Concentrations of Hes during apparent solubility studies of the pure compound and its amorphous solid dispersions with carriers were measured by high-performance liquid chromatography with the DAD detector (HPLC-DAD). In this study, Shimadzu Nexera (Shimadzu Corp., Kyoto, Japan) equipped with an SCL-40 system controller; DGU-403 degassing unit; LC-40B XR solvent delivery module; SIL-40C XR autosampler; CTO-40C column oven; and SPD-M40 photodiode array detector were used. For the stationary phase, a Dr. Maisch ReproSil-Pur Basic-C18 100 Å column, 5 µm particle size, 250 × 4.60 mm (Dr. Maisch, Ammerbuch-Entringen, Germany), was used. The mobile phase was methanol/0.1% acetic acid (70:30 v/v). The mobile phase was vacuum filtered through a 0.45 µm nylon filter (Phenomenex, CA, USA). The experimental conditions were as follows: 1.0 mL·min⁻¹ flow rate, wavelength 284 nm, and the column temperature was set at 30 °C. The injection volume was 10 µL for both solubility and dissolution rate studies. The retention time of Hes was 3.2 min.