title: Stopped-in-loop flow analysis system for successive determination of trace vanadium and iron in drinking water using their catalytic reactions.
abstract: An automated stopped-in-loop flow analysis (SILFA) system is proposed for the successive catalytic determination of vanadium and iron. The determination of vanadium was based on the p-anisidine oxidation by potassium bromate in the presence of Tiron as an activator to form a reddish dye, which has an absorption maximum at 510 nm. The selectivity of the vanadium determination was greatly improved by adding diphosphate as a masking agent of iron. For the iron determination, an iron-catalyzed oxidative reaction of p-anisidine by hydrogen peroxide with 1,10-phenanthroline as an activator to produce a reddish dye (510 nm) was employed. The SILFA system consisted of two peristaltic pumps, two six-port injection valves, a four-port selection valve, a heater device, a spectrophotometric detector and a data acquisition device. One six-port injection valve was used for the isolation of a mixed solution of standard/sample and reagent to promote each catalytic reaction, and another six-port injection valve was used for switching the reagent for vanadium or iron to achieve selective determination of each analyte. The above mentioned four-port selection valve was used to select standard solutions or sample. These three valves and the two peristaltic pumps were controlled by a built-in programmable logic controller in a touchscreen controller. The obtained results showed that the proposed SILFA monitoring system constituted an effective approach for the selective determination of vanadium and iron. The limits of detection, 0.052 and 0.55 µg L(-1), were obtained for vanadium and iron, respectively. The proposed system was successfully applied to drinking water samples without any preconcentration procedures.
authors.affiliation: Department of Applied Chemistry, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Ayala Quezada
authors.affiliation: Department of Applied Chemistry, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ohara
authors.affiliation: Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23 Road, Bangkok 10110, Thailand.
authors.forename: Nuanlaor
authors.initials: N
authors.lastname: Ratanawimarnwong
authors.affiliation: Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Rama 6 road, Bangkok 10400, Thailand.
authors.forename: Duangjai
authors.initials: D
authors.lastname: Nacapricha
authors.affiliation: Department of Applied Chemistry, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan.
authors.forename: Hiroya
authors.initials: H
authors.lastname: Murakami
authors.affiliation: Department of Applied Chemistry, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan. Electronic address: teshima@aitech.ac.jp.
authors.forename: Norio
authors.initials: N
authors.lastname: Teshima
authors.affiliation: Department of Applied Chemistry, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan.
authors.forename: Tadao
authors.initials: T
authors.lastname: Sakai
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry; D002384:Catalysis; D011756:Diphosphates / Q000737:chemistry; D060766:Drinking Water / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis* / Q000737:chemistry; D007700:Kinetics; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D013053:Spectrophotometry / Q000295:instrumentation / Q000379:methods*; D013696:Temperature; D014639:Vanadium / Q000032:analysis* / Q000737:chemistry
chemical_list: D000814:Aniline Compounds; D011756:Diphosphates; D060766:Drinking Water; D016877:Oxidants; D014639:Vanadium; C013813:4-anisidine; D006861:Hydrogen Peroxide; D007501:Iron
keywords: Catalytic reaction; Drinking water; Flow analysis; Iron; Spectrophotometry; Stopped-in-loop; Vanadium