Inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) for the analysis of fuels, biofuels and their feedstock using a high temperature total consumption sample introduction system operated under continuous sample aspiration mode

Abstract

Elemental analysis of (bio)fuels and their feedstock is performed for the first time through ICP-MS/MS using a high temperature torch integrated sample introduction system (hTISIS). The system has been operated in continuous sample aspiration mode at a 30 μL min⁻¹ liquid flow rate. An oxygen additional gas stream has been used in order to avoid soot deposit formation either in the torch or the ICP-MS/MS interface. Temperature and collision/reaction gas type and flow rate were varied in order to obtain the highest signal to background ratio. Compared with a conventional sample introduction system, the hTISIS operated at 300 °C yielded lower limits of detection. This parameter was included within the 0.005 (⁶⁰Ni) to 6 μg kg⁻¹ (²⁸Si and ⁶⁶Zn) range. An in-house method validation and uncertainty estimation were performed and it was verified that 80–90% of the uncertainty corresponded to the trueness assessment (i.e., bias, sample preparation and multielemental stock solution uncertainty). For most of the elements, the expanded uncertainty took values in between 7 and 24%. The hTISIS accounted for non-spectroscopic interferences, whereas ICP-MS/MS mitigated spectroscopic ones. This allowed the implementation of an accurate quantification method based on external calibration from a set of xylene-based standards. Thus, working with the hTISIS at 300 °C it was possible to perform the analysis of 36 samples including light petroleum cuts, diesel oil, kerosene, pyrolysis oils, vegetal oils and grease.