DESIGN AND RESPONSE CHARACTERISTICS OF AN ENZYME ELECTRODE FOR MEASUREMENT OF PENICILLIN IN FERMENTATION BROTH

A principle for the construction of an autoclavable enzyme electrode is presented. Some characteristics of a penicillin electrode constructed according to this principle are given. The response time is ~1 min. The response to increasing concentrations of penicillin is linear in buffered samples but logarithmic in unbuffered samples. The reason for the linearity is discussed. A local pH decrease in the enzyme, which is a is a consequence of the enzymatic reaction, reduces the buffering capacity within the electrode and thus increases the sensitivity. It is suggested that this increased sensitivity eliminates the logarithmic response predicted by the Nernst equation for a pH-based enzyme electrode. © 1979.