[Determination of sulfur dioxide in air by sequential injection spectrophotometry].

A sequential injection spectophotometric method for the determination of sulfur dioxide by decolorizing malachite green in an alkali medium is studied; the decreasing in color is proportional to the amount of sulfur dioxide. The loading sequence, the concentration of reagents, the amount of sample and the flow of reagent rate are optimized by univariate method. With sequential injection sample introducing, the volumes of sample and reagent are reduced greatly and the speed of determination is increased apparently, a throughput of 60 samples/h can be achieved. A liner calibration curve was obtained in range of 0.5-4.0 microg x mL(-1). The determination limit is 0.15 microg x mL(-1), the RSD and the recovery are 1.5% and 94%-108% respectively.