Analytical Sciences

A Robust Method for the Determination of Cr(VI) and Cr(III) in Industrial Wastewaters by Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry Combined with a Chelating Pretreatment with 2,6-Pyridinedicarboxylic Acid

Kaori SHIGETA,* Ai FUJITA,* Tetsuya NAKAZATO,* and Hiroaki TAO**

*Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
**AIST Shikoku, National Institute of Advanced Industrial Science and Technology (AIST), 2217-14 Hayashi-cho, Takamatsu, Kagawa 761-0395, Japan

We have developed a method for the determination of Cr(VI) and Cr(III) in industrial wastewater by liquid chromatography–inductively coupled plasma mass spectrometry (LC-ICP-MS) combined with a chelating pretreatment with 2,6-pyridinedicarboxylic acid (PDCA). The PDCA unified the chemical forms of the Cr(III) species in water samples by the formation of a stable Cr(III)-PDCA complex, which was then separated by a LC column. The chromatographic mobile phase at neutral pH and the column of a mixed-bed of anion and cation exchangers successfully separated not only the chromium species without any redox conversion, but also chloride, which interfered with ICP-MS detection. The method detection limits measured at m/z 53 were 0.66 μg of Cr L⁻¹ for Cr(III) and 0.74 μg L⁻¹ for Cr(VI) with a sample injection volume of 20 μL under a no gas mode. The recoveries of spiked Cr(VI) at 50 and 500 g L⁻¹ into the fifteen kinds of industrial wastewater samples were satisfactory (>90%). The proposed method for the determination of Cr(VI) was also validated by comparing with a colorimetric method using 1,5-diphenylcarbazide prescribed by the ISO 11083 and the JIS K0102.

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