Ultra-trace level speciated isotope dilution measurement of Cr(VI) using ion chromatography tandem mass spectrometry in environmental waters

作者：Madler Stefanie; Todd Aaron; Kingston H M Skip; Pamuku Matt; Sun Fengrong; Tat Cindy; Tooley Robert J; Switzer Teresa A; Furdui Vasile I^*

来源：Talanta, 2016, 156: 104-111.

DOI：10.1016/j.talanta.2016.04.064

• Hexavalent chromium
• Ion chromatography
• Tandem mass spectrometry
• Chromium speciation
• Speciated isotope dilution

The reliable analysis of highly toxic hexavalent chromium, Cr(VI), at ultra-trace levels remains challenging, given its easy conversion to non-toxic trivalent chromium. This work demonstrates a novel analytical method to quantify Cr(VI) at low ng L-1 concentration levels in environmental water samples by using speciated isotope dilution (SID) analysis and double-spiking with Cr(III) and Cr(VI) enriched for different isotopes. Ion chromatography tandem mass spectrometry (IC-MS/MS) was used for the analysis of Cr(VI) as HCrO4- -> CrO3-. Whereas the classical linear multipoint calibration (MPC) curve approach obtained a method detection limit (MDL) of 7 ng L-1 Cr(VI), the modified SID-MS method adapted from U. S. EPA 6800 allowed for the quantification of Cr(VI) with an MDL of 2 ng L-1 and provided results corrected for Cr(VI) loss occurred after sample collection. The adapted SID-MS approach proved to yield more accurate and precise results than the MPC method, allowed for compensation of Cr(VI) reduction during sample transportation and storage while eliminating the need for frequent external calibration. The, developed method is a complementary tool to routinely used inductively-coupled plasma (ICP) MS and circumvents typically experienced interferences.

• 出版日期2016-8-15