In order to improve the accuracy, precision and broaden numbers of trace elements measured in crude or fuel oils using a single sample preparation method, the following conditions generally must be satisfied: 1) complete digestion of organic matter in the samples, 2) completed recovery of the analyte abundances during sample preparation, 3) low procedural blanks, 4) elimination of the deleterious effects of organic matter on analytical MS instruments used, 5) the elimination of polyatomics (e.g., oxides and hydrides) and influence of any direct isobaric or doubly charged interferences on the mass of the analytes of interests and 6) use of higher sensitivity instruments appropriate to detect and quantify a wide range of trace element abundances. The principal analytical instruments that have been employed most commonly for routine analyses of trace elements in crude oils and refined products have historically been the XRF, AAS and ICP-OES because of their ease of use and limited sample preparation necessary using, for example, direct simple dilution techniques. More recently the usefulness of Q (Quadrupole)-ICP-MS have been demonstrated for multi-element analyses of increasing numbers of lower abundances trace and ultra-trace elements. Here we present a new methods that could be adapted for more routine multi-element measurements that utilize strong acid digestion or mineralization in a single reaction chamber (SRC) temperature and pressure controlled microwave system and analyses with a newly developed instrument, the QQQ (triple Quadrupole)-ICP-MS, in tandem with an ICP-OES for higher abundance elements. These methods achieve expansion of measured trace elements within oils of up to 50-57 elements. These methods allow analyses of elements in crude oil at low dilution factors that range in concentration over 10 orders of magnitude and include both low abundance elements such as the rare earths and typical high abundance elements such as S, V, and Ni with a single sample digestion. The method streamlines multi-element analysis for a more complete fingerprinting of oils by using one sample preparation method and one sample introduction system. Results to date using this approach have shown that complete elemental recovery and removal of organic matrices for SRMs and natural crude oils can be achieved safely.

Single reaction chamber microwave-assisted mineralization and analysis of > 50 high to low-abundance minor, trace and ultra-trace elements in crude oils by ICP-OES and QQQ-ICP-MS: New methods of geochemical fingerprinting

253rd National Meeting (2017)

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