How important is sample temperature when monitoring dissolved oxygen levels in boiler water?
A. Cooling the sample according to test kit instructions is of critical importance to accurate D.O. testing. High sample temperatures may cause test results to be biased high, especially in ppb-range testing applications. For optimal results, sample temperature should be no higher than 10deg. C above ambient temperature. CHEMets® ampoules have a high surface area to volume ratio. When sample temperature is too high, the sample cools quickly as it contacts the ampoule’s inner surface. This rapid sample cooling causes the small gas bubble in the ampoule to contract, drawing air into the ampoule. The atmospheric oxygen reacts with the oxygen sensitive reagent, causing positive interference. Q. How important is the color development time allotment listed in the test procedures? A. Timing is very important in colorimetric testing. Some reagents continue to develop color after the specified development time. The most accurate test results are obtained when the reading is taken in the prescri
