Potentiometric monitoring of proteins. Part 3.—Direct potentiometry with a copper electrode

Abstract

Results are presented for the direct potentiometric determination of L-cysteine, L-histidine and a number of proteins with copper electrodes which are cathodically treated before measurement. Comparisons are made with untreated and chemically treated electrodes. It is shown that provided the cathodic pretreatment technique is used the electrode response is fast and reproducible enough for the method to form the basis of a simple, reliable and inexpensive procedure for the monitoring of proteins. The Nernstian responses and equilibration times, together with the improved behaviour of the electrochemically pretreated electrodes, are discussed in terms of various models for the complexation of copper with amino acids and proteins.