3.3. Sol-Gel Analysis

A sol-gel fraction was performed for all formulations of SPSPAA hydrogels to know the sol and gel fraction of the developed system. Gel is the gelling, while sol is the soluble, unreacted part of hydrogels. A Soxhlet extraction process was carried out for analysis in such a way that a hydrogel disc (Z₁) of precise weight of each formulation was placed in distilled water at 85 °C for 12 h. After that, the extracted hydrogel disc (Z₂) was kept in an oven at 40 °C until the disc dried completely [40]. Equation (1) and (2) were used for analysis of the sol-gel fraction.

where, Z₁ = initial weight of hydrogels disc, and Z₂ = final weight of hydrogels disc.