2.7. Determination of solubility
Powder solubility was determined by following the method of Shittu and Lawal (2007) with some modifications. The powder (1.0 g) was dissolved in 10 mL of distilled water and continuously stirred for 30 min. The suspension was then transferred to a tube and centrifuged at 6000 rpm (Magafuge 1.0R, Heraeus, Germany) for 20 min. The supernatant was transferred completely to an aluminum can and dried at 105 °C for 24 h. After drying, the dried weight of soluble solid was measured and used to calculate the solubility as a percentage.