Abstract
Improvements were made on the West-Gaeke method on the basis of examination on the errors in the result of the conventional procedure.
The reproducibility of the conventional West-Gaeke method was 6.4% in coefficient of variation, but improvements in sampling and spectrophotometric processes reduced this value to 2.0%.
Results on a standard gas sample by using absorbing solution of 30°C indicated that values by the conventional method were approximately 9% lower than the calculated values. The collection efficiency of sulfur dioxide was 100%, and the difference was due to the oxidation of sulfur dioxide by aeration in the absorbing solution. Effect of nitrogen dioxide, chlorine, hydrogen chloride, iron or copper was removable.
Sulfur dioxide in atmosphere was determined by the improved field method with errors of 1.3%. Improvements in the procedure were:
( a ) elimination of bias with calibration using standard gas,
( b ) precise measurement of gas volume with a wet-type gas meter, and
( c ) precise control of temperature in the spectrophotometric analysis.
