CHEMICAL SENSING ELECTRODES

THE STUDY OF OCEAN PROCESSES SUCH AS MINERAL DISSOLUTION, ION SPECIATION AND REDOX EQUILIBRIA AS WELL AS EFFLUENT AND POLLUTION MONITORING REQUIRE ACCURATE AND PRECISE MEASUREMENTS OF BOTH MAJOR AND MINOR CHEMICAL CONSTITUENTS. ALTHOUGH SPECTROPHOTOMETRY AND FLAME PHOTOMETRY HAVE BEEN USED FOR SEA WATER ANALYSIS, POTENTIONMETRY WITH ION-SELECTIVE ELECTRODES IS THE MOST COMMON-METHODOLOGY, PARTICULARLY FOR PH MEASUREMENTS. THE USUAL PROCEDURES INVOLVE SAMPLE COLLECTION AT DEPTH FOLLOWED BY SUBSEQUENT ANALYSIS ON DECK. SEA WATER PH IS PRINCIPALLY DETERMINED BY THE OCEANIC CARBON DIOXIDE SYSTEM.CONSEQUENTLY MINIMIZATION OF TIME BETWEEN SAMPLING AND MEASUREMENT IS CRITICAL TO AVOID ERRORS WHICH MAY ARISE FROMATMOSPHERIC CO2 EXCHANGE, DEGASSING AS SAMPLE TEMPERATURE INCREASES AND BACTERIAL RESPIRATION.