o-Dianisidine: a new reagent for selective spectrophotometric, flow injection determination of chlorine

Abstract

A flow injection analysis (FIA) procedure for the determination of free chlorine in industrial formulations and water samples is proposed. The manifold is provided with a gas-diffusion unit which permits the removal of interfering species and also the preconcentration of chlorine. The determination of chlorine is performed on the basis of the oxidation by o-dianisidine as a chromogenic reagent to a coloured product which can be monitored at 445 nm. The method (for a preconcentration step of 60 s) is linear over the range 0.04-1.00 mg l(-1) of chlorine, the limit of detection is 0.04 mg l(-1), the reproducibility of the procedure (as RSD of the slope) is 3.7% for a series of four independent calibrations, the precision (as RSD of a series of 30 continuous FIA peaks of 0.56 mg l(-1) of chlorine) is 1.4% and the sample throughput is 40 h(-1). A detailed comparative study of the analytical characteristics of a single mono-channel reverse FIA assembly and the same system but provided with a Fluoropore membrane filter of 0.5 microm pore size was performed to check the advantages of the new approach in terms of sensitivity, selectivity and limit of detection.

A new electro-generated o-dianisidine derivative stabilized MWCNT-modified GCE for low potential gallic acid detection

“…Since the discovery of o-dianisidine, it has been widely used as a substrate for the oxidation of horseradish peroxidase/ hydrogen peroxide and aromatic amines as well as dye intermediates and a colourimetric indicator of peroxidase activity. [10][11][12][13][14][15] Several studies reported that, o-dianisidine may produce the following oxidation products during potential cycling: (i) o-dianisidine quinonediimine, (ii) amine radical cation containing o-dianisidine and (iii) o-dianisidine dimer at a pH ranging from 1 to 11. 10,11,13 In addition, the voltammetry of the electro-oxidized o-dianisidine and its redox products is unstable, complicated and non-reproducible at pH > 3 due to the formation of multiple intermediate species.…”

Development of a personal passive air sampler for estimating exposure to effective chlorine while using chlorine‐based disinfectants

“…Among several dyes that change their colors via oxidation‐reduction reactions (eg, N,N′‐diphenyl‐1,4‐phenylenediamine (DPPD), N,N′‐diphenyl‐benzidine (DPB), and o ‐tolidine), 26,27 we chose o ‐dianisidine because (a) it changes color rapidly and vividly on exposure to oxidizing gases, (b) it is relatively environmentally friendly as compared to other oxidation dyes as a component in the passive sampler, 28 and (c) o ‐dianisidine doping within PDMS is stable over ten days under vacuum. The possible oxidation of o ‐dianisidine with oxidizing gases generated from bleach products (eg, HOCl and Cl 2 ) was previously suggested by Claiborne and Fridovich (1978), 29 shown in Figure 2.…”

Electrochemical detection of free chlorine at highly boron-doped diamond electrodes

“…The general detection methods for free chlorine include the colorimetric method, the amperometric titration method, and iodometry [5][6][7]. However, these methods are unsuitable for continuous on-line monitoring because they each have a number of disadvantages, such as the requirement for many types of reagent that may produce greater toxicity, a high detection limit, the difficulty of operation, etc.…”