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Research Article
ScienceAsia 25 (1999) : 099-106 |doi: 10.2306/scienceasia1513-1874.1999.25.099
Flow injection spectr ophotometry for speciation of
Cr(VI) and Cr(III) using diphenylcarbazide and
solid phase extraction with C18 in-valve mini-column
Kate Grudpana,*, Ngarmnet Worakijcharoenchaia,1, Orawan Tue-Ngeuna,2, Ponlayuth
Sooksamitib and Jaroon Jakmuneea
ABSTRACT: Flow injection (FI) spectrophotometric sequential determination of Cr(VI) and Cr(III) has
been proposed by using flow systems assembled with inexpensive and easily available components. It is
based on the reaction of Cr(VI) with 1,5-dipenylcarbazide(DPC) to form a colored complex for the
determination of Cr(VI). Cr(III) is oxidized in-line to Cr(VI) by Ce(IV) yielding the total Cr concentration.
From the difference, Cr(III) concentration can be evaluated. Solid phase extraction with C18 in-valve
mini-column provides on-line preseparation and preconcentration. Single standard calibration is possible.
Optimization for the conditions was investigated. The FI procedure developed has been applied for
speciation of Cr(VI) and Cr(III) in waste water samples taken from industry in Thailand. The results
obtained agree well with those obtained by ICP-AES.
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a Department of Chemistry, Faculty of Science, and Institute for Science and Technology Research and Development, Chiang Mai University, Chiang Mai 50200, Thailand.
b Office of the Mineral Resource Region III (Chiang Mai ) Chiang Mai, 50200 Thailand.
1 Permanent address : Department of Industrial Works, Ministry of Industry, Bangkok 10400, Thailand.
2 Permanent address : Department of Chemistry, Faculty of Science, Naresuan University, Phitsanulok 65000, Thailand.
* Corresponding author: Tel: + 66-53-943345 ext 157, Fax: + 66-53-222268,
E-mail: kate@chiangmai.ac.th
Received 8 Mar 1999
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