1.1.2.4 3 - stable for short term exposure (30 s) 1.1.2.4 6.5 - very stable 1.1.2.4 7.25 - retains at least 25% activity down to pH 7.25, whereas it rapidly loses activity at lower pH values 1.1.2.4 7.5 - complete inactivation above pH 7.5 1.1.2.4 7.5 9.5 -