title: Flow-injection simultaneous determination of selenium(IV) and selenium(IV + VI) using photooxidative coupling of p-hydrazinobensenesulfonic acid with N-(1-naphthyl)ethylenediamine.
abstract: A flow-injection spectrophotometric method has been developed for the simultaneous determination of selenium(IV) and (IV + VI) at nanogram per milliliter levels. It is based on the catalytic effect of selenium(IV) on the photooxidative coupling of p-hydrazinobenzenesulfonic acid (HBS) with N-(1-naphthyl)ethylenediamine (NED) to form an azo dye (lambda(max) = 538nm). In this reaction, bromide acted as an activator for the catalysis of selenium(IV) and an reducer for selenium(VI) to selenium(IV) in an acidic medium which allowed the determination of selenium(IV + VI). A sample solution, being split by Y-piece into two portions, passed through the low-temperature coil (4m, 25 degrees C) and the high-temperature coil (20m, 100 degrees C). By monitoring the absorbance of the dye produced in the two portions, selenium(IV) and (IV + VI) in the range of 0.2-6ngml(-1) were determined simultaneously. The relative standard deviations for 3ngml(-1) selenium(IV) and (VI) (n = 10) were 1.2 and 1.3%, respectively. There were few interfering ions in the selenium determination. The proposed method was applied to the determination of selenium(IV) and (VI) in natural water samples.
authors.affiliation: Department of Environmental Sciences, Faculty of Education and Regional Sciences, Tottori University, Koyama-cho, Tottori 680-8551, Japan.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Nakano
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yoshii
authors.forename: Takuji
authors.initials: T
authors.lastname: Kawashima