PH polymeric membrane microelectrodes based on neutral carriers and their application in aquatic environments

pH polymeric membrane microelectrodes based on neutral carriers have been d eveloped for sediment and bio-mat applications. The pH microelectrodes have a tip diameter of 10-40 mu m and contain poly(vinyl chloride) (PVC) or car boxylated PVC in its membrane phase. Compared to classic liquid membrane pH microelectrodes without polymers, the new pH microelectrodes have a much l onger lifetime (>1 month), a stronger tip, a lower resistance (1-4 x 10(9) Ohm) and a shorter response time (t(98) <4 s). Most pH microelectrodes have been developed for physiological application, but this new one has been de veloped for application in harsh environments, such as sediments and microb ial mats. Successful measurements of pH profiles in sediments and in microb ial mats have been made with the new pH microelectrodes. The pH microelectr odes may also be applicable for clinical measurements and they require only a very small volume of the sample. (C) 1999 Published by Elsevier Science B.V. All rights reserved.