Automated oxygen titration and salinity determination

Abstract

This report describes a newly developed automated Winkler titration system for dissolved oxygen in seawater which is presently in use at the Woods Hole Oceanographic Institution. This amperometric, calculated endpoint system was compared with two different automated and one manual Winkler method during a recent cruise. The four different methods agreed to within about 0.04 ml/l. The system described here measures the titrant needed to reach the endpoint with a resolution better than 0.001 ml. The standard deviation of replicate samples is 0.005 ml/l and the accuracy is about 0.02 ml/l. A technique to automatically acquire conductivity ratio measurements and calculate salinity using a Guildline Autosal Salinometer is also describe.