Chromium Speciation of Drinking Waters by IC-ICP-MS

Metals Analysis and Remediation
Oral Presentation

Prepared by H. Chen, J. Peters, H. Guo, R. Marfil-Vega
Shimadzu Scientific Instruments, 7102 Riverwood Drive, Columbia, MD, 21046, United States


Contact Information: [email protected]; 410-910-0899

ABSTRACT

The EPA has set a maximum contaminant level for total chromium in drinking water to be 100 ppb. Chromium in waters exist in two different oxidation states: trivalent [Cr(III)] and hexavalent [Cr(VI)]. While trivalent chromium is an essential human dietary element, hexavalent chromium is a carcinogen and a reproductive toxicant, and can cause other health issues. Despite the lack of Federal regulations specific for Cr(VI) in drinking water in the US, it is critical to develop robust and rapid methods speciating chromium due to the different toxicities of Cr(III) and Cr(VI).
In this study, through the combination of a Shimadzu Inductively Coupled Plasma Mass Spectrometer (ICPMS-2030) and a Shimadzu Prominence Ion Chromatography (IC), a sensitive, robust and reliable method for the determination of chromium species in drinking waters has been developed. An IC column to separate both cations and anions was used to avoid sample pretreatment with complexing agents like 2,6‐pyridinedicarboxylic acid (PDCA) or ethylenediaminetetraacetic acid (EDTA) that are used in the ISO CD24384 method, eliminate possible risks of contamination, and maximize sample throughput. This IC-ICPMS method for analysis of hexavalent chromium has superior detection limits to the EPA 7196 colorimetric method and EPA 218.7 IC method, and is not affected by interferences from mercury, molybdenum, and vanadium. The Shimadzu ICPMS-2030 equipped with a newly developed collision cell effectively eliminates polyatomic interferences to achieve high-sensitivity and specificity. We will share the results from the performance assessment of the IC-ICP-MS based method for the simultaneous analysis of Cr(III) and Cr(VI) in three types of environmental waters. Linearity, matrix spike recoveries and detection limits will be also reported.