Effect of various diluents on the activity of several enzymes present in serum.

We have evaluated the effect of diluting serum with water or NaCI solution (8.5 or 9.0 g/liter) before assayirlg by a manual method for creatine kinase (EC 2.7.3.2), alkaline phosphatase (EC 3.1.3.1), lactate dehydrogenase (EC 1.1.1.27), and aspartate aminotransferase (EC 2.6.1.1) activity. The t test and the F test show no significant difference in the accuracy and precision of the assays at the 95% confidence level when 100 different samples were compared for each enzyme activity after use of the three diluents.