title: Field determination of trace iron in fresh water samples by visual and spectrophotometric methods.
abstract: Sensitive visual and micro spectrophotometric methods have been developed for field determination of trace iron in fresh water samples. For the visual method, a water sample (0.45-microm filtrate acidified to 0.1 M HCl) was placed in a glass vial and mixed with a reagent solution containing 1,10-phenanthroline, sodium thiocyanate and 0.1 M HCl. Iron was extracted as pink ferroin thiocyanate with 1 ml of 4-methy-2-pentanone. The sample up to 20 ml was added step-by-step, until the color of the extract was detected visually. Without any special instrument or color standard, iron down to 0.001 mg 1(-1) (0.025 microg) in a sample can be determined with an error of 20% in the field. For the micro spectrophotometric method, the extract for 20 ml of sample was separated by capillary suction in a column (micro pipette chip) with acrylic fibers. A part of the extract was pushed out into a micro cell for the absorbance measurement at 525 nm. The column was re-usable after washing with ethanol. This method had a detection limit of 0.001 mg 1(-1) and allowed determinations within an error of 5%. The proposed methods were applied to deionized-, tap-, river-, lake- and reservoir-water samples.
authors.affiliation: Department of Applied Chemistry and Biotechnology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Takeda, Kofu 400-8511, Japan. kawakubo@ab11.yamanashi.ac.jp
authors.forename: Susumu
authors.initials: S
authors.lastname: Kawakubo
authors.forename: Ayako
authors.initials: A
authors.lastname: Naito
authors.forename: Asuka
authors.initials: A
authors.lastname: Fujihara
authors.forename: Masaki
authors.initials: M
authors.lastname: Iwatsuki