title: Fast detection of lead dioxide (PbO2) in chlorinated drinking water by a two-stage iodometric method.
abstract: Lead dioxide (PbO(2)) is an important corrosion product associated with lead contamination in drinking water. Quantification of PbO(2) in water samples has been proven challenging due to the incomplete dissolution of PbO(2) in sample preservation and digestion. In this study, we present a simple iodometric method for fast detection of PbO(2) in chlorinated drinking water. PbO(2) can oxidize iodide to form triiodide (I(3)(-)), a yellow-colored anion that can be detected by the UV-vis spectrometry. Complete reduction of up to 20 mg/L PbO(2) can be achieved within 10 min at pH 2.0 and KI = 4 g/L. Free chlorine can oxidize iodide and cause interference. However, this interference can be accounted by a two-stage pH adjustment, allowing free chlorine to completely react with iodide at ambient pH followed by sample acidification to pH 2.0 to accelerate the iodide oxidation by PbO(2). This method showed good recoveries of PbO(2) (90-111%) in chlorinated water samples with a concentration ranging from 0.01 to 20 mg/L. In chloraminated water, this method is limited due to incomplete quenching of monochloramine by iodide in neutral to slightly alkaline pH values. The interference of other particles that may be present in the distribution system was also investigated.
authors.affiliation: Division of Environmental Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117576.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yi-Pin
authors.initials: YP
authors.lastname: Lin
mesh_terms: D002700:Chloramines / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007454:Iodides / Q000737:chemistry; D007854:Lead / Q000032:analysis*; D010087:Oxides / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002700:Chloramines; D007454:Iodides; D010087:Oxides; D014874:Water Pollutants, Chemical; D007854:Lead; C047365:lead oxide; C030816:chloramine