Continuous Oxidant Recorder

Journal/Book: Reprinted from ANALYTICAL CHEMISTRY Vol. 25 NO. 10 Page 1480 October 1953. 1953;

Abstract: F. E. LITTMAN AND R. W. BENOLIEL1 Air Research Laboratory Stanford Research Institute Pasadena Calif. 1 Present address General Electric Co. Richland Wash. The unusually high concentration of an oxidant which appears to be ozone in smoggy Los Angeles air is one of the few distinguishing characteristics of the local atmosphere. In order to study the relationship between the occurrence of smog and the fluctuation of the oxidant concentration a continuous recorder was built which produces a direct reading record of oxidant concentration in terms of ozone equivalents. The instrument consists essentially of a continuous air-liquid contacting device and a recording colorimeter. It is based on the liberation of iodine from a buffered neutral potassium iodide solution by the oxidant. The light transmittance of the resulting yellow solution is measured by a double-cell colorimeter and continuously recorded on a strip chart. The contacting solution is regenerated by passing it through a bed of activated carbon and is re-used. By maintaining constant air and liquid flows it is possible to calibrate the instrument directly in terms of ozone equivalents in parts per hundred million by volume. Thus a continuous pen-drawn record of the fluctuation of the oxidant level can be obtained. Satisfactory performance for 18 months was achieved and an excellent positive correlation was established between the oxidant and smog as manifested by reduced visibility eye irritation and crop damage. schö

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