Photoelectric Colorimeter for Rapid Reactions

Abstract

A differential photoelectric colorimeter has been built for the high speed measurement of small absorption changes in enzyme substrate reactions. Under the conditions of the experiments, the total differential change of light intensity was approximately 0.2 percent and a photoelectric resolution of approximately 1.7×10⁴ was achieved, giving an accuracy of 3 percent. The time resolution of the system was at least 0.01 second and a complete kinetic curve was obtained with as little as 0.5 cc of peroxidase solution of 1×10⁻⁶ molar hematin iron.