Abstract
A spectrophotometric method for sulfur dioxide determination was explored on the basis of its complexation with TNP-amino acid derivatives forming an orange colored 1:1 complex with an increase in absorbance at 420 nm. TNP-glycine, TNP-threonine, TNP-serine and TNP-histidine were investigated. The color development was instantaneous and the absorbance remained unchanged even after 24 hrs of mixing when kept in the dark. Linear calibration graphs (0-5 × 10
−5
M sulfite ions) were obtained at optimal reaction conditions of 7 × 10
−5
M TNP-amino acid and pH 8.0 phosphate buffer (0.05 M). The investigation of the effect of several diverse ions revealed an interference by sulphide and mercury (II) ions at concentration levels of 10
−4
M. The standard deviation of determining 3 × 10
−5
M sulfite solution (10 times) was 1.474 × 10
−7
M.