Alternative spectrophotometric method for standardization of chlorite aqueous solutions.
The chlorite ion is the principal by-product of the treatment of drinking water by chlorine dioxide. In function of the chlorite salt instability, standard solutions of this ion need standardization by iodometric titration, which is a reliable method although labor intensive and time consuming. An alternative method to standardization of aqueous chlorite solutions, based on its direct UV absorption measurement, was presented. Besides the maximum absorption (260 nm) generally used in other studies, the minimum (239 nm) and isosbestic (248 nm) wavelengths were proposed as supplementary points to chlorite quantification and their molar absorptivity coefficients were estimated (155.2+/-0.6, 104.5+/-1.0 and 69.0+/-1.2 L cm(-1) mol(-1), respectively). The direct spectrophotometric determination of chlorite could be made selectively even in the presence of high concentration of major contaminants (chorine dioxide, chloride and chlorate), being a simple and rapid method, consuming very low volume of sample and generating low quantities of laboratory wastes.
Philippi
Marilia
M
Faculty of Chemistry, Pontifical Catholic University of Rio Grande do Sul, Av. Ipiranga 6681, 90619-900 Porto Alegre, Brazil.
dos Santos
Heldiane S
HS
Martins
Aline O
AO
Azevedo
Carla M N
CM
Pires
Marçal
M
D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002704:Chlorates / Q000737:chemistry; D002712:Chlorides / Q000032:analysis* / Q000737:chemistry; D017606:Chlorine Compounds / Q000737:chemistry; D002852:Chromatography, Ion Exchange / Q000379:methods; D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry; D015203:Reproducibility of Results; D013053:Spectrophotometry / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D013997:Time Factors; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply
D002704:Chlorates; D002712:Chlorides; D017606:Chlorine Compounds; D010087:Oxides; D014874:Water Pollutants, Chemical; C025109:chlorine dioxide; C001599:chlorite