Analytical Sciences

Improved Solid-phase Spectrophotometry for the Microdetermination of Chromium(VI) in Natural Water

Sulistyo SAPUTRO,*1 Kazuhisa YOSHIMURA,*2 Shiro MATSUOKA,*3 Kô TAKEHARA,*2 and Narsito*4

*1 Department of Mathematics and Natural Science Education, Faculty of Teacher Training and Education Sciences, Sebelas Maret University, Surakarta-57126, Indonesia
*2 Department of Chemistry, Faculty of Sciences, Kyushu University, Hakozaki, Higashi, Fukuoka 812-8581, Japan
*3 Department of Environmental Science, Faculty of Science, Niigata University, Ikarashi, Niigata 950-2181, Japan
*4 Department of Chemistry, Faculty of Mathematics and Natural Sciences, Gadjah Mada University, Yogyakarta-55281, Indonesia

A simple and sensitive solid-phase spectrophotometry procedure was improved for the microdetermination of Cr(VI). A 0.06 cm³ portion of a cation exchanger, Muromac AG 50W-X2, was used to concentrate the target Cr(VI) in a 20 cm³ water sample, and resin beads were introduced in a flow cell of 1.5 mm diameter and having a 10 mm light path length for measurements using a UV-visible spectrophotometer. Three lenses were used for focusing the incident light beam and for recovering light scattered by the solid phase in the cell. The sensitivity achieved was higher by a factor of 277 compared with that of the solution method, and the detection limit was 0.014 μg dm⁻³. The recovery on spiked real water samples by the standard addition method was 96 − 101%. Favorable working and performance characteristics made it possible to directly determine sub-μg dm⁻³ amounts of Cr(VI) in natural water samples.

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