title: Potassium Bromate Assay by Redox Titrimetry Using Arsenic Trioxide.
abstract: Bromate, a disinfectant, is one of the analytes of interest in wastewater analysis. Environmental laboratories have a regulatory need for their measurements to be traceable to NIST standards. Bromate is not currently certified as a NIST Standard Reference Material (SRM). Therefore, a traceable assay of potassium bromate (KBrO3) is needed. KBrO3 was dissolved in water and assayed by redox titrimetry using arsenic trioxide (As2O3). A nominal (0.1 g) sample of As2O3 was dissolved in 10 mL of 5 mol/L sodium hydroxide. The solution was acidified with hydrochloric acid and about 95 % of the KBrO3 titrant was added gravimetrically. The end point was determined by addition of dilute (1:3) titrant using an automated titrator. The KBrO3 assay was determined to be 99.76 % ± 0.20 %. The expanded uncertainty considered the titrations of three independently prepared KBrO3 solutions.
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899.
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Smeller
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899.
authors.forename: Stefan D
authors.initials: SD
authors.lastname: Leigh
keywords: arsenic trioxide; potassium bromate; redox titration