The following recipe and comments are from Lesley Barber, Melbourne, Australia. 

"I use citric saline to detach my cells as it is less harsh than EDTA or trypsin and the cells reattach well. I find I get excellent viability staining with this method."

For a 10X Stock Solution of Citric Saline

• 1.35M potassium chloride
• 0.15M sodium citrate
• Autoclave and store at 4° C
• Dilute 1:10 with sterile distilled water before use

Detaching Adherent Cells

1. Remove all media
2. Flood flask bottom with 1X citric saline (prewarmed to 37°C) 
3. Incubate at 37°C for a maximum of 5 minutes
4. Tap flask bottom to gently detach all cells
5. Decant cells
6. Mix well for single cell suspension
7. Add equal volumes PBS
8. Centrifuge and wash with fresh PBS