D.O. samples are then subjected to Manganous Sulfate and Alkaline Potassium Iodine Azide and mixed. The reaction forms an insoluble precipitant which is allowed to stand until the yellow cloudy material begins to sink past the shoulder of the sample bottle. The samples then change to a bright dark yellow color. Cheryl Cutshall of Atlanta ISD is shaking these samples for two minutes. A titration to determine oxygen content is initiated.
Titration continues until the solution changes from a deep blue to a clear liquid.
D.O. is then read directly from the titration syringe and recorded on the data sheet. Phase II training was on the Texarkana College campus at Cowhorn Creek at the Tucker St. bridge. Billy Jackson, Hooks ISD, finishes the D.O. titration and records his data. Two trials are conducted and the values are averaged. This is important to get a better representation of the oxygen availability due to the variations encountered in sampling.