2.5 Drug Release Study
Four swatches of hydrogel (20mm × 20mm) were added into 50 ml artificial sweat solution with pH5.5. The solution was prepared by dissolving 1g lactic acid (Bendosen), 1g urea (Biofroxx) and 5g sodium chloride (Mallinckrodt) in 1L of distilled water. Then, 50 µL of the sample was withdrawn from each flask at 0, 2, 4, 6, 8, 12, 24, 48 and 72 hours. The sample was filtered using a 0.22 µm syringe filter. Then, the amount of phomopsidione released was analyzed using the High-Performance Liquid Chromatogram (Sahadan et al., 2019). The mobile phase used was chloroform/methanol at a ratio of 3:7 (v/v) with an HPLC (Perkin Elmer Series 200) coupled with Breeze software. The HPLC was set up with a wavelength of 245 mm, column (C18) particle size 5 µm, length 120 mm, and injection volume of 20 µL. The amount of phomopsidione was determined based on the calibration curve (0 to 1000 µg/ml phomopsidione).