Simple Colorimetric Analysis for Determining Hexavalent Chromium with High Sensitivity via Homogeneous Liquid-Liquid Extraction

Colorimetric analysis with diphenylcarbazide has been used as a simple method to determine hexavalent chromium (Cr(VI)). However, the low sensitivity of this technique makes it difficult to determine concentrations close to the environmental standard value (0.05 mg/L). We found that the phase separa...

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Bibliographic Details
Published in:Bulletin of the Chemical Society of Japan 2019-04, Vol.92 (4), p.807-810
Main Authors: Yokota, Yuki, Manaka, Atsushi, Tafu, Masamoto, Kato, Takeshi, Tomita, Keiichi, Akazawa, Toshiyuki
Format: Article
Language:English
Subjects:
Chromium
Colorimetry
Diphenylcarbazide
Ethylenediaminetetraacetic acids
Groundwater
Hexavalent chromium
Liquid-liquid extraction
Masking
Phase separation
Sensitivity analysis
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Summary:Colorimetric analysis with diphenylcarbazide has been used as a simple method to determine hexavalent chromium (Cr(VI)). However, the low sensitivity of this technique makes it difficult to determine concentrations close to the environmental standard value (0.05 mg/L). We found that the phase separation phenomenon produced a small amount of the extraction phase when a mixture of 2-propanol and a small amount of dimethyl phthalate were added to a water sample, and that the Cr(VI)-diphenylcarbazide complex was extracted into this phase with high efficiency. Based on these findings, we report a simple method for colorimetric analysis for determining Cr(VI) with high sensitivity via homogeneous liquid-liquid extraction using water, 2-propanol, and dimethyl phthalate. As a result, the extraction percentage for Cr(VI) was 88% and the concentration factor improved up to 121-fold (27.4 mL → 226 µL). Using the proposed extraction method, determination limit (10σ) and detection limit (3σ) were 0.11 ppb and 0.03 ppb, respectively. This method can be employed for the determination of hexavalent chromium in groundwater systems by the use of EDTA as masking agent.
ISSN:0009-2673
1348-0634
DOI:10.1246/bcsj.20180351