Determination of selenium in soils by slurry-sampling graphite-furnace atomic-absorption spectrometry with polytetrafluoroethylene as silica modifier |
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Authors: | Ryszard Dobrowolski |
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Institution: | (1) Maria Curie-Sklodowska University, Faculty of Chemistry, Maria Curie-Sklodowska Sq.3, 20-031 Lublin, Poland e-mail: rdobrow@hermes.umcs.lublin.pl, PL |
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Abstract: | A 6% slurry of polytetrafluoroethylene (PTFE) in 4% hydrofluoric acid and 1% nickel nitrate were used as modifiers for determination
of selenium in soils by GF AAS. PTFE was used to remove silica from the soil sample, because this resulted in severe matrix
effects. The temperature of fluorination, determined thermogravimetrically, was 600 °C. The yield of fluorination depends
on the molar ratio of PTFE/silica, particle size, and the time and temperature of fluorination. The soil samples were pretreated
with a small amount of concentrated hydrofluoric acid placed directly in the cup of autosampler. The results for the determination
of selenium in the reference soil materials by means of the slurry-sampling technique and use of aqueous standards are in
good agreement with the certified values.
Received: 20 December 2000 / Revised: 3 April 2001 / Accepted: 5 April 2001 |
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