Spectrophotometric determination and FIA of aqueous ozone based on the ozone decoloration reaction of 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)aniline-Iron(II) complex

Abstract

The spectrophotometric and the flow injection determination of aqueous ozone based on the oxidation reaction of 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino) aniline-Fe(II) complex with ozone were examined. The results of the spectrophotometric technique are as follows. The apparent molar absorptivity for ozone added at λ_max 560 nm was 3604 dm³ mol ^-1 cm ^-1. The calibration curve showed good linearity (number of samples, 6; correlation coefficient, 0.999₈; significant level, 0.001), and rapid determinations of sub mg dm ^-3 mg dm^-3 levels of aqueous ozone were achieved. The detection limit of this method was about 30 μg dm^-3 O₃. The results of the FIA were as given below. The reproducibility of the FIA signal (O₃, 1.47 mg dm ^-3 ; number of samples, 5; RSD, 0.48%) was good, and determinations of sub mg dm ^-3mg dm^-3 levels of aqueous ozone were achieved at a sampling frequency of about 40 samples h^-1. Aqueous solutes in usual drinking water{Hardness(as CaCO₃) ≤50.83 mg dm^-3, Cl^-≤9.7 mg dm ^-3, NO₃≤4.1 mg dm ^-3, SO₄^2-≤25.6 mg dm^-3} were shown not to interfere with the ozone determinations by these methods.