Abstract: The present invention relates to an electrode for measuring the nitrate concentration in aqueous solutions. The electrode consists of a container with an internal reference system and a membrane which is a combination of an organic nitrate sensor phase of a quaternary ammonium salt as electroactive material, an organophilic, hydrophobic solvent for the quaternary ammonium salt with substantial viscosity and polyvinyl chloride or polyurethane as non-porous material. The quaternary ammonium salt is chosen from the group consisting of: tetraoctyl ammonium nitrate, tetranonyl ammonium nitrate, tetradecyl ammonium nitrate, tetraundecyl ammonium nitrate, tetradodecyl ammonium nitrate, tetratridecyl ammonium nitrate and tetratetradecyl ammonium nitrate; and the solvent consists of dialkylphthalate or a dialkyladipate of a solubility parameter of 9 .+-. 2 (cal/cm.sup.3).sup.1/2.

Abstract: A continuous flow analytical system in which there is provided a continuous unobstructed carrier stream into which discrete volumes of sample solutions to be observed for reaction with the carrier stream are injected successively. A detector for measuring the results of any reaction between the carrier stream and sample solutions is positioned downstream from the point of injection.

Abstract: An electrochemical cell for measuring the gas content in a solution, said electrochemical cell having a potentiometric ion sensitive electrode and a reference electrode, said electrodes being in electrochemical contact through an electrolyte solution, said electrolyte solution forming a thin, continuous, stabilized, stationary layer covering the surface of said ion sensitive electrode so that said thin electrolyte layer is in direct physical contact with a gaseous phase.