Barium-polyethoxylate complexes as potentiometric sensors and their application to the determination of non-ionic surfactants

Abstract

Electrodes having PVC matrix membranes consisting of 2-nitrophenyl phenyl ether and sensors of the tetraphenylborate salts of barium complexes with Antarox CO-730, Antarox CO-430, Lutensol AO7 and Monflor 51 are compared with the corresponding electrodes of barium complexes with Antarox CO-880. Generally, they are inferior to the Antarox CO-880 electrodes for sensing barium ions. However, all of the electrodes respond to non-ionic surfactants in the manner described previously for the Antarox CO-880 system.

The electrode based on Antarox CO-430 is considered to be superior in its response to non-ionic surfactants and shows some selectivity towards these materials compared with its response towards cationic and anionic surfactants. The electrode has been evaluated for determining Dobanol 25-7, Synperonic 7 and Lutensol AO7 in detergent powders with good recoveries of the non-ionic surfactants and relative standard deviations ranging between 0.8 and 4.0%. The recommended procedure is based on known (standard) addition which, although taking up to 2 h to complete, is faster than analate addition.