title: Sequential injection lab-on-valve simultaneous spectrophotometric determination of trace amounts of copper and iron.
abstract: A sequential injection (SI) method in a lab-on-valve (LOV) format for simultaneous spectrophotometric determination of copper and iron has been devised. The detection chemistry is based on the complex formation of 2-(5-bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]aniline (5-Br-PSAA) with copper(II) and/or iron(II) at pH 4.6. Copper(II) reacts with 5-Br-PSAA to form the complex which has an absorption maximum at 580 nm but iron(III) does not react. In the presence of a reducing agent only iron(II)-5-Br-PSAA complex is formed and detected at 558 nm. Under the optimum experimental conditions, the determinable ranges are 0.1-2 mg l(-1) for copper and 0.1-5 mg l(-1) for iron, respectively, with a sampling rate of 18 h(-1). The limits of detection are 50 microg l(-1) for copper and 25 microg l(-1) for iron. The relative standard deviations (n=15) are 2% for 0.5 mg l(-1) copper and 1.8% for 0.5 mg l(-1) iron when determined in standard solutions. The recoveries range between 96 and 105% when determining 0.25-2 mg l(-1) of copper and 0.2-5 mg l(-1) of iron in artificial mixtures at copper/iron ratios of 1:10 to 5:1. The proposed SI-LOV method is successfully applied to the simultaneous determination of copper and iron in multi-element standard solution and in industrial wastewater samples.
authors.affiliation: Department of Applied Chemistry, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Ohno
authors.forename: Norio
authors.initials: N
authors.lastname: Teshima
authors.forename: Tadao
authors.initials: T
authors.lastname: Sakai
authors.forename: Kate
authors.initials: K
authors.lastname: Grudpan
authors.forename: Miroslav
authors.initials: M
authors.lastname: Polasek