2.6. Swelling capacity
0.2 g of microcapsules was weighted. To simulate gastric liquid,a pH 2.2 solution was prepared (HCl/KCl). To simulate the intestinalliquid, a pH 6.8 phosphate-buffered saline (PBS) solution was pre-pared. Microcapsules were added into the solutions, and were leftfor 48 h in the pH 6.8 solution and 2 h in the pH 2.2 solution. Swollensamples were put into a centrifuge tube together with some filterpaper at the bottom centrifuged at 500 rpm for 3 min and weighed.To determine the swelling percentage (SP), the formula given belowwas used.