Detection of Trace Metals in Asphaltenes Using an Advanced Laser-induced Breakdown Spectroscopy (LIBS) Technique

The significance of trace elements in the petroleum industry has increased because of the role of non-hydrocarbon components in the elucidation of the mechanisms of migration and origin of crudes. Determining the amounts of trace elements is also very important in the petroleum industry for refining and processing of crudes and even exploration. In the development of different instrumental analytical techniques for trace elemental analysis of crudes and its products, little attention has been devoted to the broad variation in data because of poor sampling and the proper nature of the matrix. Accurate detection of trace metals in asphaltene samples using conventional methods is not a trivial task. In this work, the determination of 13 trace elements in asphaltenes including Co, Fe, V, Ni, Pb, P, Mo, Ca, Si, Ti, Mn, Cd, and Cu are reported for the first time using an advanced laser-based analytical technique. For this purpose, laser-induced breakdown spectroscopy (LIBS) using a Nd:YAG laser at 1064 nm was employed to determine the concentration of these trace elements present in four asphaltene samples derived from the marketable Saudi Arabian crude oils. The concentration determined with our LIBS setup of different trace metals present in the same samples was also measured using a standard technique, Such as inductively Coupled plasma (ICP), and results achieved with LIBS are in close agreement with ICP results. The limit of detection for these elements was also determined and reported. This is the first time. to the best of our knowledge, the LIBS technique has been applied for the determination of trace metals in asphaltenes. The unique features of LIBS are no or little sample preparation requirements, fast and rapid analysis, and in situ detection, which are lacking in the conventional analytical techniques.