TITLE

Isotope dilution ICP-MS with laser-assisted sample introduction for direct determination of sulfur in petroleum products

AUTHOR(S)
Boulyga, Sergei F.; Heilmann, Jens; Heumann, Klaus G.
PUB. DATE
August 2005
SOURCE
Analytical & Bioanalytical Chemistry;Aug2005, Vol. 382 Issue 8, p1808
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) with direct laser-assisted introduction of isotope-diluted samples into the plasma, using a laser ablation system with high ablation rates, was developed for accurate sulfur determinations in different petroleum products such as ‘sulfur-free’ premium gasoline, diesel fuel, and heating oil. Two certified gas oil reference materials were analyzed for method validation. Two different 34S-enriched spike compounds, namely, elementary sulfur dissolved in xylene and dibenzothiophene in hexane, were synthesized and tested for their usefulness in this isotope dilution technique. The isotope-diluted sample was adsorbed on a filter-paper-like material, which was fixed in a special holder for irradiation by the laser beam. Under these conditions no time-dependent spike/analyte fractionation was only observed for the dibenzothiophene spike during the laser ablation process, which means that the measured 34S/32S isotope ratio of the isotope-diluted sample remained constant—a necessary precondition for accurate results with the isotope dilution technique. A comparison of LA-ICP-IDMS results with the certified values of the gas oil reference materials and with results obtained from ICP-IDMS analyses with wet sample digestion demonstrated the accuracy of the new LA-ICP-IDMS method in the concentration range of 9.2 μg g−1 (‘sulfur-free’ premium gasoline) to 10.4 mg g−1 (gas oil reference material BCR 107). The detection limit for sulfur by LA-ICP-IDMS is 0.04 μg g−1 and the analysis time is only about 10 min, which therefore also qualifies this method for accurate determinations of low sulfur contents in petroleum products on a routine level.
ACCESSION #
19148602

 

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