1. Student, Dept. of Chemistry, Tertiary Techn. Coll., Hengelo, spent 6 months at Sprenger Inst. for practical training
2. To whom correspondence should be addressed
3. Beaucamp, K., Bergmeyer, H. U. and Beutler, H. O. 1974.Methods of Enzymatic Analysis, 2nd Engl., Edited by: Bergmeyer, H. U. Vol. 1, 546–547. New York: Academic Press.
4. Dawson, R. M.C., Elliott, D. C., Elliott, W. H. and Jones, K. M. 1969.Data for Biochemical Research, 2nd ed., 486Oxford: Clarondon Press.