As conventional pH measurements are difficult and often give erratic results, special pH electrodes are used for viscous gels.
Determination of pH is therefore important to maintain consistent quality. They show highest viscosity at their gel point. PH:- Many gelling agents show pH – dependent gelling behavior. The lyophilized hydrogel is gold sputter coated and viewed under an electron microscope. It is assumed that the morphologies of the swollen samples are retained during this process.
Generally, the swollen gel is allowed to freeze in liquid nitrogen and then lyophilized by freeze drying. Homogeneity and Surface Morphology: – The homogeneity of gel formulations is usually assessed by visual inspection and the surface morphology by using scanning electron microscopy.
