Speciation and Preservation of CrVI and CrIII 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.

Preparation of polymethacrylate monolith modified with cysteine for the determination of Cr(iii) ions

“…Numerous analytical techniques including inductively coupled plasma-atomic emission spectrometry (ICP-AES), 4,[6][7][8] ame atomic absorption spectrometry (FAAS), 1,9,10 inductively coupled plasma-mass spectrometry (ICP-MS), 11,12 ultraviolet visible absorption spectrometry (UV-vis), 13 high performance liquid phase chromatography (HPLC), 14 gas chromatography (GC), 15,16 inductively coupled plasma optical emission spectrometry (ICP-OES), 17 spectrouorimetry spectrophotometry, 18 and total reection X-ray spectrometry (TXRF) 19 have been reported for Cr determination. In spite of the advancement in modern analytical instruments, complications exist with direct determination of analytes at trace and ultra-trace levels.…”