Why doesn’t PromoCell specify a fixed trypsinization time for primary cells?

The time required to detach primary cells by trypsinization varies and depends on multiple factors, including cell type, cell density, cell lot, trypsin concentration, efficiency of the washing step before adding trypsin, and trypsinization temperature.
Because of this variability, a single fixed trypsinization time would not be reliable or safe for all situations.
 
PromoCell recommendation
For most primary cell types, PromoCell recommends:

• Trypsinization at room temperature
• Continuous microscopic monitoring of cell detachment

This approach allows you to determine the optimal trypsinization time for your specific culture and to keep the contact time between cells and trypsin as short as possible, minimizing cell damage. In practice, most cells detach within approximately 2-8 minutes.
 
Cell‑type‑specific exceptions
For certain cell types:

• Trypsinization at 37°C, or
• the use of Accutase or another dedicated Detachment Solution

may be recommended. Please refer to the Instruction Manual of the respective cell type for detailed guidance.