Determination of low-ppt levels of acetate, propionate, and formate in semiconductor-grade deionized water via ion chromatography.
The goals of this research were the development of a method to determine acetate, propionate, and formate at low part-per-trillion (ppt; w/w) levels in deionized water, and the assessment of sources of variability and contamination associated with the method; both objectives were met. A calibration study involving six replicates of each of four standards (blank, 20, 50, and 80 ppt) resulted in straight-line (with ordinary-least-squares fitting) curves for all analytes. At 95% confidence, the half-widths of the prediction intervals were +/- 30, 14, and 14 ppt for the three analytes, respectively. Much of the acetate and formate seen in blanks was found to originate in the deionized water system itself. For formate, peak heights increased with water temperature.
Vanatta
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Air Liquide-Balazs, Dallas, TX, USA. Lynn.Vanatta@airliquide.com