>>> Not always. How far back do you mean 'always', 1 year, 5 years 25 years?
> I don't recall being able to buy a dilute solution years ago. Fluka
> sells both an NP 40 Substitute of 100% and an NP40 Substitute solution
> of 10% (v/v).
NP-40 has been discontinued I was told, supply limited to what has already
been manufactured. The chemical equivalent (?) we are using is Gepal CA-630
ICN cat. no. 198596. It is clear, viscous and works in western blots .
Don't know about cell lysis.