Measurement of nitrate gradients with an ion-selective microelectrode

Abstract

Nitrate-selective microelectrodes (1-μm tip diameter) with a liquid membrane ion exchanger were prepared. The response of the electrode is linear from 10-1 to 10-5 M nitrate and the response time is 30 s. Selectivity coefficients are of the same order as specified for macroelectrodes. Measurements in sediments of a mesotrophic lake and measurements in spherical agar gels with immobilized denitrifying bacteria are presented. © 1989.