Automated Method for Determination of Serum 5'-Nucleotidase Activity

Abstract

Abstract An automated method has been devised for determining 5'-nucleotidase activity in serum. A modified creatine phosphokinase cartridge (Technicon Instrument Corp., Tarrytown, N. Y.) is used to prepare a reaction mixture containing, per liter: barbital buffer (pH 7.5), 16.1 mmol; adenosine-5'-phosphate, 5.4 mmol; Mg2+, 20.2 mmol; phenyl phosphate, 7.8 mmol; adenosine deaminase, 0.78 mg; and sample, 0.21 ml/ml of reaction mixture. After incubation, the liberated ammonium ion is determined by use of the alkaline hypochlorite-phenol reaction. Nucleotidase activity as determined by the automated method correlated well with activities as determined manually by a Ni2+ inhibition—phosphate analysis procedure. Respective values obtained by the manual and by this procedure were: for sera with activities within the normal range, 7.9 ± 3.2 and 8.2 ± 3.3 U/liter; for activities between 16 and 50 U/liter, 26.3 ± 9.3 and 26.5 ± 8.8 U/liter; and for serum with activities greater than 50 U/liter, 79.1 ± 42.5 and 78.7 ± 41.3 U/liter.