Reproducible digestion method for ion-chromatographic analysis of anions in 30% hydrogen peroxide.
Semiconductor-grade hydrogen peroxide (30%) is analyzed for anion contamination to be certain the levels of each analyte do not exceed 30 ppb (w/w). This paper presents a reproducible, platinum-decomposition approach that uses ion chromatography to quantify the various analytes (fluoride, chloride, sulfate, bromide, nitrate, and phosphate). Important to the success of the method are: (1) use of disposable HDPE bottles for the digestion, (2) immersion of the bottles in a water bath, (3) careful re-mixing of the digesting peroxide after two (of six total) hours, and (4) careful clean-up and sample-handling procedures (to avoid contamination). Except for fluoride and nitrate, all analytes exhibited recoveries from 89.6 to 98.3%, with +/- prediction intervals (at the 95% confidence level) from 1.5 to 3.0 ppb. Fluoride's recovery was low (74.9%), but reproducible (+/- prediction interval at 95% confidence=2.0 ppb). Nitrate reeovery was 99.1%, but noisy (+/- prediction interval at 95% confidence=8.7 ppb); this imprecision was thought to be due to contamination from atmospheric nitrite. A Dionex DX 500 microbore ion chromatograph with AS15 column and 1-ml sample loop were used for all determinations; detection was by conductivity. Statistical analyses were performed using JMP software.
Vanatta
L E
LE
Air Liquide America, Dallas, TX 75265, USA. lynn.vanatta@airliquide.com
Coleman
D E
DE
D000838:Anions / Q000032:analysis*; D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000838:Anions; D006861:Hydrogen Peroxide