What is the general procedure of cell dissociation?

The general procedure for cell dissociation is described in the steps below. 

1. Discard the used cell culture media
2. Wash the cells with a balanced salt solution or EDTA without calcium and magnesium. Then, pour the wash solution opposite the cells and gently rock the flask for 1-2 minutes and discard the wash solution.
3. Add the chosen dissociation solution (2-3 ml/25 cm2) opposite the cells, ensuring it covers the cell layer. Incubate at 37°C, gently rocking the flask. Cells are typically associated within 5-15 minutes, however, the time may vary for different cell lines. Watch carefully to prevent cell damage. For cells that are difficult to detach, gentle tapping may help.
4. Once the cells are fully detached, position the flask upright to permit the cells to settle at the bottom. Then add complete media to the flask and pipette across the monolayer surface to scatter the cells. Lastly, count and prepare the cells for subculture.