Analysis of Selenium by Hydride-generation Atomic Absorption Spectrometry (USGS and XRAL laboratories)
250-mg sample aliquots are weighed into test tubes. A mixture of nitric, hydrofluoric and perchloric acids is added, and the sample is heated. After the solution is cooled, hydrochloric and nitric acids are added, and the sample is heated again. The samples are diluted and analyzed for selenium 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 0.2 ppm to 4 ppm. See references 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%. For details, see Hageman
and others (1996, 2002).