Ultra-trace level speciated isotope dilution measurement of Cr(VI) using ion chromatography tandem mass spectrometry in environmental waters.
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 ngL(-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 7ngL(-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 2ngL(-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.
Ontario Ministry of the Environment and Climate Change, 125 Resources Road, Etobicoke, Ontario M9P 3V6, Canada.
Stefanie
S
Mädler
Ontario Ministry of the Environment and Climate Change, 125 Resources Road, Etobicoke, Ontario M9P 3V6, Canada.
Aaron
A
Todd
Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282, USA.
H M
HM
Skip Kingston
Applied Isotope Technologies, 2403 Sidney Street, Suite 280, Pittsburgh, PA 15203, USA.
Matt
M
Pamuku
Ontario Ministry of the Environment and Climate Change, 125 Resources Road, Etobicoke, Ontario M9P 3V6, Canada.
Fengrong
F
Sun
Ontario Ministry of the Environment and Climate Change, 125 Resources Road, Etobicoke, Ontario M9P 3V6, Canada.
Cindy
C
Tat
Ontario Ministry of the Environment and Climate Change, 125 Resources Road, Etobicoke, Ontario M9P 3V6, Canada.
Robert J
RJ
Tooley
Ontario Ministry of the Environment and Climate Change, 125 Resources Road, Etobicoke, Ontario M9P 3V6, Canada.
Teresa A
TA
Switzer
Ontario Ministry of the Environment and Climate Change, 125 Resources Road, Etobicoke, Ontario M9P 3V6, Canada. Electronic address: vasile.furdui@ontario.ca.
Vasile I
VI
Furdui
Chromium speciation; Hexavalent chromium; Ion chromatography; Speciated isotope dilution; Tandem mass spectrometry