title: Redox speciation analysis of dissolved iron in estuarine and coastal waters with on-line solid phase extraction and graphite furnace atomic absorption spectrometry detection.
abstract: An automatic on-line solid phase extraction (SPE) system employing the flow injection (FI) technique directly coupled to a graphite furnace atomic absorption spectrometer (GFAAS) was established for speciation and determination of dissolved iron in estuarine and coastal waters. Fe(II) was mixed with ferrozine solution in a sample stream to form the Fe(II)-ferrozine complex which was extracted onto a C18 SPE cartridge, eluted with eluent and detected with GFAAS. In a parallel flow channel, Fe(III) was reduced to Fe(II) with ascorbic acid and then detected in the same way as Fe(II). The home-made interface between FI-SPE and GFAAS efficiently realized the sample introduction to the furnace in a semi-automated way. Parameters of the FI-SPE system and graphite furnace program were optimized based on a univariate experimental design and an orthogonal array design. The salinity effect on the method sensitivity was investigated. The proposed method provided a detection limit of 1.38 nmol L(-1) for Fe(II) and 1.87 nmol L(-1) for Fe(II+III). With variation of the sample loading volume, a broadened determination range of 2.5-200 nmol L(-1) iron could be obtained. The proposed method was successfully applied to analyze iron species in samples collected from the Jiulongjiang Estuary, Fujian, China. With the 2-cartridge FI-SPE system developed, on-line simultaneous determination of Fe species with GFAAS was achieved for the first time.
authors.affiliation: State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiang׳an Campus, Xiamen 361102, Fujian, China.
authors.forename: Yaojin
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiang׳an Campus, Xiamen 361102, Fujian, China.
authors.forename: Sichao
authors.initials: S
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiang׳an Campus, Xiamen 361102, Fujian, China.
authors.forename: Yongming
authors.initials: Y
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiang׳an Campus, Xiamen 361102, Fujian, China. Electronic address: yuandx@xmu.edu.cn.
authors.forename: Dongxing
authors.initials: D
authors.lastname: Yuan
keywords: Dissolved iron redox speciation; Estuarine and coastal waters; Flow injection analysis; Graphite furnace atomic absorption spectrometry; Solid phase extraction