Chlorine dioxide analysis

Water samples taken for chlorine dioxide analysis must be analyzed immediately after sampling. Most of the methods worked out for free chlorine measurements can be used for chlorine dioxide analysis if other oxidizing agents are not present. 

Other reactants that have been used to generate chemiluminescent reactions useful for chemical analysis include atomic sodium to detect halocarbons and chlorine dioxide to detect H2S and CH3SH. 

It was found that the concentration of total oxidants measured in the off-gas from the hypo unit varied with process conditions. Precise analysis of the off-gas showed that under certain conditions chlorine dioxide is formed in the reaction step where the hypochlorite concentration is approximately 160-180 g l-1. In the sections below formation of chlorine dioxide in the hypochlorite unit is discussed with regard to process conditions and peak load of the feed stream. In essence, the emission of chlorine dioxide can be reduced to nearly zero by using a scrubber in which the chlorine dioxide reacts with hydrogen peroxide. 

When the reaction temperature of step one increases, the total oxidant concentration in the off-gas is >6 mg m-3, but this depends on capacity and hypochlorite concentration. Careful analysis with infrared methods demonstrated that this total oxidant concentration was derived from chlorine dioxide. Measurements of the concentrations between steps one and two showed that concentrations were higher than in the off-gas and that hypochlorous acid (HOC1) was also found, which was totally absent in the off-gas. 

Thus taking into account the cohesion energy density allows essentially to improve upon results of correlation analysis on influence of medium properties on kinetics of oxidation of propanethiole by chlorine dioxide. At the same time a significance of this factor is indirect proof of radical stages in the process. 

The purpose of this chapter is to describe the analytical methods that are available for detecting, measuring, and/or monitoring chlorine dioxide and chlorite ion, and other biomarkers of exposure and effect to chlorine dioxide and chlorite ion. The intent is not to provide an exhaustive list of analytical methods. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used for environmental samples are the methods approved by federal agencies and organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by groups such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). Additionally, analytical methods are included that modify previously used methods to obtain lower detection limits and/or to improve accuracy and precision. 

APHA Method 4500-CL02-B, iodometric titration analysis, measures the concentration of chlorine dioxide in water by titration with iodide, which is reduced to form iodine. Iodine is then measured colorimetrically when a blue color forms from the production of a starch-iodine complex. The detection limit for this method is 20 pg/L (APHA 1998). 

Gas-diffusion flow injection analysis is capable of detecting very low concentrations of chlorine dioxide in water (i.e., detection limit is 5 ppb). A chemiluminescence flow-through detector cell is used to measure the concentration chlorine dioxide as a function of chemiluminescence intensity. A gas diffusion membrane separates the donor stream from the detecting stream and removes ionic interferences from iron and manganese compounds, as well as from other oxychlorinated compounds, such as chlorate and chlorite (Hollowell et al. 1986 Saksa and Smart 1985). 

Bjdrkholm E, Hultman A, Rudling J. 1988. Determination of chlorine and chlorine dioxide in workplace air by impinger collection and ion-chromatographic analysis. J Chromatogr 457 409-414. 

Hollowell DA, Gord JR, Gordon G, et al. 1986. Selective chlorine dioxide determination using gas-diffusion flow injection analysis with chemiluminescent detection. Anal Chem 58 1524-1527. 

Hollowell DA, Pacey GE, Gordon G. 1985. Selective determination of chlorine dioxide using gas diffusion flow injection analysis. Anal Chem 57 2851-2854. 

Saksa DJ, Smart RB. 1985. Chemiluminescent analysis of chlorine dioxide with a membrane flow cell. Environ Sci Technol 19 450-454. 

Tratnyek and Hoigne (1994) investigated 25 substituted phenoxide anions for QSARs that can be used to predict rate constants for the reaction of additional phenolic compounds oxidized by chlorine dioxide (OCIO). Correlating oxidation rates of phenols in aqueous solution is complicated by the dissociation of the phenolic hydroxyl group. The undissociated phenol and the phenoxide anion react as independent species and exhibit very different properties. The correlation analysis should be performed on the two sets of rate constants separately. 

It can be summarised that both chlorine dioxide and chlorite can be identified in many experiments at several time intervals. The C102 concentration depends on many influences but experiments with both rotating anode cells and parallel flow-through cells show proportional concentration values compared to the volume factor at constant current load on MIO anodes and using different analysis methods. 

This concentration is usually between 0.05 and 0.2 ppm. The large variety of possible C102 consuming reactions makes the analysis difficult. The consumption of chlorine dioxide could contribute to a certain extent to chlorate formation in drinking water (Fig. 7.11). 

Hong, C.C. and Rapson, W.H. (1968) Analysis of chlorine dioxide, chlorous acid, chlorite, chlorate, and chloride in composite mixtures. Can. J. Chem. 46, 2061-2064. 

As a result of the disinfection of drinking water by means of ozone, chlorine dioxide, chloramine, and chlorine, a variety of disinfection byproducts may occur in drinking water, including oxyhalides, haloacetic acids, and halogenated AEO and APEO metabolites (Ch. 8.4.2). The LC-MS analysis of disinfection byproducts in drinking water was recently reviewed by Zwiener and Richardson [65]. 

The CWM (1 g) is first depectinated by extraction with 0.05 M CDTA at 20°C for 6 h, twice. The insoluble residue is suspended in distilled water (75-100 ml) in a loosely stoppered flask and heated at 70°C. Glacial acetic acid (0.15 ml) and sodium chlorite (0.3 g) are added and the contents stirred for 15 min. The treatment is repeated and the mixture stirred for a further 15 min. To prevent accumulation of chlorine dioxide gas, the contents are continuously flushed with argon. After cooling, the contents are filtered and the residue washed with five bed volumes of distilled water. The filtrate is purged with argon to remove chlorine dioxide, dialyzed, and concentrated to yield the crude chlorite-soluble glycoprotein fraction, and an aliquot is freeze-dried for analysis (yield 80 mg from 1 g dry CWM of runner beans). 

D. A. Hollowell, G. E. Pacey, and G. Gordon, Selective Determination of Chlorine Dioxide Using Gas Diffusion Flow Injection Analysis. Anal. Chem., 57 (1985) 2851. 

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