Flow-injection potentiometric determination of triiodide by plasticized poly(vinyl chloride) membrane electrodes and its application to the determination of chlorine-containing disinfectants

摘要

Plasticized poly(vinyl chloride) (PVC) membrane,, of different compositions were tested for use in the construction of potentiometric flow detectors for triiodide. A membrane with a 2:1 (w/w) 2-nitrophenyl octyl ether to PVC ratio was selected. The influence of thiosulphate in the carrier solution composition and of the flow-injection variables on the determination of triiodide was studied. In the selected conditions, a linear relationship between peak height and log[l(3-)] was obtained between 5 x 10(-6) and 1 x 10(-4) Mol l(-1) triiodide. Peak height relative standard deviations for 2 x 10(-5) and 1 x 10(-4) Mol l(-1) triiodide were +/- 0.4 and +/- 1.8%, respectively, and sampling frequency was 80 samples per hour. The method proposed was applied satisfactorily to the iodometric determination of different chlorine-containing disinfectants, among them trichloroisocyanuric acid and dichloroisocyanurate in several types of commercial sample. (c) 2004 Elsevier B.V. All rights reserved.