2, 4, 6-Trinitrophenyl—Amino acid derivatives as spectrophotometric reagents for sulfur dioxide

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 x 10-5M sulfite ions) were obtained at optimal reaction conditions of 7 x 10-5M 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 10-4M. The standard deviation of determining 3 x 10-5M sulfite solution (10 times) was 1.474 x 10-7M. © 1984, Taylor & Francis Group, LLC. All rights reserved.