Decoloring Spectrophotometric Method for the Determination of Sulfur Dioxide

The discharge of sulfur dioxide (SO₂) is one of the most important reasons of resulting in the environmental pollution. Current method for determination SO₂ is fuchsine-formaldehyde spectrophotometry. This paper describes a decoloring spectrophotometry, which is based on azo dye being reduced in the presence of manganese (Ⅱ) as inducer and in weak acidic medium. It is shown that the result has better selectivity and higher sensitivity. This method was used to measure the content of SO₂ in the air of northern china with satisfactory results.