title: Speciation and preservation of Cr VI and Cr III in finished drinking water matrixes using collision cell ion chromatography-inductively coupled plasma-mass spectrometry.
abstract: The polyatomic background at the major isotope of Cr was evaluated as a function of collision cell gas flow rate using three different mobile phases. The stability of Cr VIwas evaluated as a function of solution pH by fortifying samples with enriched 53Cr VI. The 53Cr VI recovery was > or =95% at pH 7.8, but by pH 6.2 a significant amount of the enriched spike was recovered as 53Cr III-EDTA. The instability of Cr III at pHs above 7.8 required that Cr III be chelated prior to speciation. The concentration of EDTA was optimized by evaluating Cr III recoveries in six finished drinking waters, a U.S. Geological Survey reference water, and a challenge water fortified with competing matrix cations. If the Cr III was allowed to precipitate (characteristic of shipping a sample without field preservation), acceptable recoveries of Cr III required the sample to be heated to 70 degrees C in 10 mM EDTA to quantitatively produce the Cr III-EDTA complex. The overall preservation/speciation approach was evaluated using an enriched 53Cr VI and natural Cr III in seven drinking water matrixes over a 46 day period. A linear least squares analysis was performed on each water, and the corresponding P-values were estimated. The method detection limits for Cr III-EDTA and Cr VI were 0.06 and 0.1 pglL, respectively.
authors: Robert A
authors: RA
authors: Wilson
authors: Patricia A
authors: PA
authors: Creed
authors: Tatyana
authors: T
authors: Pinyayev
authors: Larry
authors: L
authors: Wymer
authors: John T
authors: JT
authors: Creed
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D002857:Chromium / Q000032:analysis*; D060766:Drinking Water / Q000032:analysis*; D004492:Edetic Acid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D013058:Mass Spectrometry / Q000379:methods*; D013054:Spectrophotometry, Atomic
chemical_list: D060766:Drinking Water; D002857:Chromium; D004492:Edetic Acid