National Geochemical Survey
Analysis of Tungsten by Visible Absorption Spectrophotometry (USGS laboratories)
Method
1 g of sample is heated at 100°C overnight with 5 ml conc nitric acid and 15 ml conc HF. Two 5-ml aliquots of 80% HCl are added. The sample is centrifuged, and 5 ml of the solution is heated with 5 ml of 30% stannous chloride. 1 ml of 1.5% zinc dithiol solution is added. After heating for 30 min, 4 ml heptane is added, and the sample is shaken. The absorption of the organic layer at 630 nm is then measured with a visible-light absorption spectrophotometer. Primary standards prepared from sodium tungstate are used for calibration. Details may be found in O'Leary (1990) and Welsch (1983).
Data analysis
| | Distribution maps |
| Element |
QA/QC |
Conter-
minous |
Alaska |
Hawai`i |
| W (ppm) |
In progress |
 |
no data |
no data |
(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/tungsten.htm
Maintained by Jeff Grossman
Last modified: 15:03:10 Tue 06 Jan 2004
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