Fast and Accurate Procedure for the Determination of Cr(VI) in Solid Samples by Isotope Dilution Mass Spectrometry

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• 作者：Neus Fabregat-Cabello ; Pablo Rodr铆guez-Gonz谩lez ; 脕ngel Castillo ; Julien Malherbe ; Antoni F. Roig-Navarro ; Stephen E. Long ; J. Ignacio Garc铆a Alonso
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：November 20, 2012
• 年：2012
• 卷：46
• 期：22
• 页码：12542-12549
• 全文大小：326K
• 年卷期：v.46,no.22(November 20, 2012)
• ISSN：1520-5851

文摘

We present here a new environmental measurement method for the rapid extraction and accurate quantification of Cr(VI) in solid samples. The quantitative extraction of Cr(VI) is achieved in 10 minutes by means of focused microwave assisted extraction using 50 mmol/L Ethylendiamintetraacetic acid (EDTA) at pH 10 as extractant. In addition, it enables the separation of Cr species by anion exchange chromatography using a mobile phase which is a 1:10 dilution of the extracting solution. Thus, neutralization or acidification steps which are prone to cause interconversion of Cr species are not needed. Another benefit of using EDTA is that it allows to measure Cr(III)-EDTA complex and Cr(VI) simultaneously in an alkaline extraction solution. The application of a 10 minutes focused microwave assisted extraction (5 min at 90 掳C plus 5 min at 110 掳C) has been shown to quantitatively extract all forms of hexavalent chromium from the standard reference materials (SRM) candidate NIST 2700 and NIST 2701. A double spike isotope dilution mass spectrometry (IDMS) procedure was employed to study chromium interconversion reactions. It was observed that the formation of a Cr(III)-EDTA complex avoided Cr(III) oxidation for these two reference materials. Thus, the use of a double spiking strategy for quantification is not required and a single spike IDMS procedure using isotopically enriched Cr(VI) provided accurate results.