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100-mg sample aliquots are weighed into zirconium crucibles. Approximately 0.75 g of sodium peroxide is added and mixed. The mixture is heated in a muffle furnace set at 750°C for four minutes. The sample is cooled, and 15 ml of water and 5 ml of concentrated HCl are added. The mixture is shaken and 0.25 ml of an ascorbic acid - potassium iodide solution is added, then diluted with 20% HCl and let to stand overnight. Arsenic is then measured using hydride generation atomic absorption spectrometry. Commercially available standards are used to calibrate the instrument. The optimum concentration range without sample dilution in various solid phase sample media is 0.6 ppm to 20 ppm. See Hageman and others (1996, 2002) for further details about this method. Analytical data for an experimental run are deemed acceptable based on results determined for two in-house quality-control standards: recovery for all elements present at >5 times the detection limit must be within 20% of the certified value, and the calculated relative standard deviation of duplicate samples is no greater than 20%.
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(Return to Analytical Methods Page)
U.S. Department of the Interior, U.S. Geological Survey
This page is part of U.S. Geological Survey Open-File Report 2004-1001
URL: http://www-tin.er.usgs.gov/geochem/doc/arsenic.htm
Maintained by Jeff Grossman
Last modified: 15:03:11 Tue 06 Jan 2004
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