Final answer:
Before pouring the liquid gel solution into the gel casting tray, it is critical that the solution is cooled to room temperature to ensure proper gel polymerization and to mitigate safety risks.
Step-by-step explanation:
Before pouring the liquid gel solution into the gel casting tray, it is essential to ensure that the solution has cooled down to room temperature. This is crucial because the polymerization of the gel, which is necessary for creating the matrix through which samples can migrate during electrophoresis, occurs as the agarose cools. Proceeding with pouring the gel solution into the casting tray while it is still hot can prevent proper gel formation and may cause irregularities in the wells.
As an example, in the procedure of casting an agarose gel, only after the solution has cooled to around 55-60°C (which is above room temperature but below the point where it would solidify quickly), the comb is introduced to form the wells. If the solution is too hot when poured, it can warp the tray or impair the formation of clean, well-defined wells. Once the gel has polymerized, the gel gasket can be assembled, and further preparations, such as washing the wells and adding buffer, can be completed.
Moreover, if the solution is not allowed to cool adequately, it can also pose a safety risk due to the high temperature. Therefore, cooling the gel solution to room temperature is a safety measure and a critical step for successful gel electrophoresis.