title: Separation of Gd-humic complexes and Gd-based magnetic resonance imaging contrast agent in river water with QAE-Sephadex A-25 for the fractionation analysis.
abstract: Gadolinium complexed with naturally occurring, negatively charged humic substances (humic and fulvic acids) was collected from 500 mL of sample solution onto a column packed with 150 mg of a strongly basic anion-exchanger (QAE-Sephadex A-25). A Gd-based magnetic resonance imaging contrast agent (diethylenetriamine-N,N,N',N″,N″-pentaacetato aquo gadolinium(III), Gd-DTPA(2-)) was simultaneously collected on the same column. The Gd-DTPA complex was desorbed by anion-exchange with 50mM tetramethylammonium sulfate, leaving the Gd-humic complexes on the column. The Gd-humic complexes were subsequently dissociated with 1M nitric acid to desorb the humic fraction of Gd. The two-step desorption with small volumes of the eluting agents allowed the 100-fold preconcentration for the fractionation analysis of Gd at low ng L(-1) levels by inductively coupled plasma-mass spectrometry (ICP-MS). On the other hand, Gd(III) neither complexed with humic substances nor DTPA, i.e., free species, was not sorbed on the column. The free Gd in the effluent was preconcentrated 100-fold by a conventional solid-phase extraction with an iminodiacetic acid-type chelating resin and determined by ICP-MS. The proposed analytical fractionation method was applied to river water samples.
authors: Division of Environmental Research, EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan. Electronic address: h-matsu@numse.nagoya-u.ac.jp.
authors: Hiroaki
authors: H
authors: Matsumiya
authors: Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
authors: Hiroto
authors: H
authors: Inoue
authors: Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
authors: Masataka
authors: M
authors: Hiraide
mesh_terms: D005591:Chemical Fractionation / Q000295:instrumentation / Q000379:methods*; D002852:Chromatography, Ion Exchange / Q000295:instrumentation / Q000379:methods; D003287:Contrast Media / Q000737:chemistry / Q000302:isolation & purification; D003911:Dextrans / Q000737:chemistry; D005682:Gadolinium / Q000737:chemistry*; D019786:Gadolinium DTPA / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification; D006812:Humic Substances; D007098:Imino Acids / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods; D017942:Nitric Acid / Q000737:chemistry; D009942:Organometallic Compounds / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D015203:Reproducibility of Results; D045483:Rivers / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D003287:Contrast Media; D003911:Dextrans; D006812:Humic Substances; D007098:Imino Acids; D009942:Organometallic Compounds; D014874:Water Pollutants, Chemical; D017942:Nitric Acid; C025614:sephadex; D005682:Gadolinium; D019786:Gadolinium DTPA; C008109:iminodiacetic acid
keywords: Fractionation analysis; Gd-based MRI contrast agent; Humic substance; Inductively coupled plasma-mass spectrometry; River water; Speciation analysis