Studies on the use of XeF2 as digestion reagent |
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Authors: | E Hoffmann C Lüdke J Kürner H Scholze E Ullrich and H Stephanowitz |
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Institution: | (1) Institut für Spektrochemie und angewandte Spektroskopie (ISAS), Institutsteil Berlin, Rudower Chaussee 5, D-12489 Berlin, Germany, DE;(2) Gesellschaft zur F?rderung der Optik, Optoelektronik, Quantenoptik und Spektroskopie e.V., Rudower Chaussee 5, D-12489 Berlin, Germany, DE |
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Abstract: | A digestion procedure was developed for the determination of selected elements (Al, Ba, Ca, Ce, Cd, Co, Cr, Cu, Fe, La, Mg,
Ni, Sr, Pb, Zn) in sediments using XeF2. The use of XeF2 has some interesting features but this reagent should be handled only under dry gas which is a severe limitation of the methodology.
In a first step the sediment sample (0.1 g) is dried (120 °C) and digested by XeF2 (1.5 g) in the vapor phase (190 °C; 9 × 106 Pa). Then the dry residue is dissolved in aqua regia and the solution digested at high pressure once again (aqua regia digestion).
Subsequently the digested solution is diluted with sub-boiling distilled water and is ready for the analysis by ICP-MS. The
sediment standard CRM 320 was analyzed to verify the procedure. A comparison of the results with those obtained by the normally
used fluoric acid digestion showed that the recovery rates of each investigated element agreed within a confidence interval
of 95%, except Cr. The recovery rate of Cr was lower for the XeF2 digestion than for the fluoric acid digestion by more than 5%. Further studies were focussed on the possible digestion of
SiC by XeF2 as first step for the trace element determination. In the gaseous reaction products Si could be detected by ICP-MS which
gives evidence to a decomposition of SiC. A digestion procedure for small Si samples (0.010 g) was developed. Detection limits
(DL) determined for selected elements of analytical interest (Al, Ca, Cd, Cr, Co, Cu, Fe, Mg, Ni, Pb) were between 1 to 12
ng/g. For most of the elements this is an improvement in comparison to the HF vapor phase digestion. The verification of the
method was carried out with GFAAS.
Received: 17 February 1999 / Revised: 15 June 1999 / Accepted: 17 June 1999 |
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