Activation of creatine kinase activity in lyophilized control materials

The activity of creatine kinase in lyophilized control materials has been studied. In most such samples the activity was highly dependent upon time of exposure to the reagent system including the thiol activator, increasing pre-incubation time gave rise to increasing activities of creatine kinase. The increase of the activity could be prevented by reconstitution in presence of a thiol activator. In this way stable control materials was obtained for use in several days.