Direct Trace and Ultra-Trace Metals Determination in Crude Oil and Fractions by Inductively Coupled Plasma Mass Spectrometry

    Volume 2, Issue 9 (October 2005)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Page Count: 8


    Dreyfus, S
    LCABIE/CNRS UMR 5034, Pau Cedex 9,

    Institut Français du Pétrole, Rueil Malmaison Cedex,

    Pécheyran, C
    LCABIE/CNRS UMR 5034, Pau Cedex 9,

    Magnier, C
    Institut Français du Pétrole, Rueil Malmaison Cedex,

    Prinzhofer, A
    Institut Français du Pétrole, Rueil Malmaison Cedex,

    Lienemann, CP
    Institut Français du Pétrole, Rueil Malmaison Cedex,

    Donard, OFX
    LCABIE/CNRS UMR 5034, Pau Cedex 9,

    (Received 8 October 2004; accepted 22 March 2005)

    Abstract

    A method was developed to analyze direct trace and ultra-trace metal elements in crude oil and its fractions (maltenes-asphaltenes) by ICP-MS after sample dilution in xylene. Efficient introduction of organic compounds requires addition of O2 for complete combustion of the sample, carbon deposit on cones (interface) and extraction lenses was minimized by optimization of argon to oxygen ratio in the plasma. A PFA-100 (100 μl.mn−1) MicroFlow Nebulizer and a Scott “double pass” chilled spray chamber were associated for an optimal introduction of petroleum products. The Q-ICP/MS was equipped with platinum cones to limit drifts caused by cone corrosion during an organic analysis. A standard addition method was realized for the calibration procedure in order to control the matrix effects. Method validation was completed by analyzing three certified reference materials from the National Institute for Standards and Technology (NIST). NIST 1085b, NIST 1084a, and NIST 1634c accuracies were approximately 10 %. Detection limit of ultra trace elements in xylene were at pg.g−1 level. A clean PFA filter system was developed to separate the oil fractions (maltenes and asphaltenes) by precipitation of asphaltenes (heavy fraction) in n-heptane. For optimal detection conditions, the samples were diluted in xylene according to their pre-estimated element concentration range. Total mass balance shows a recovery close to 100 % for Ni, V, Cu, Mo, Ag, Sn, Ba, and Pb. These results show that elements analyzed are highly concentrated in the asphaltenic fraction.


    Paper ID: JAI12969

    DOI: 10.1520/JAI12969

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    Author
    Title Direct Trace and Ultra-Trace Metals Determination in Crude Oil and Fractions by Inductively Coupled Plasma Mass Spectrometry
    Symposium Elemental Analysis of Fuels and Lubricants: Recent Advances and Future Prospects, 2004-12-08
    Committee D02