Microwave induced plasma atomic emission spectroscopy (MP-AES) with nitrogen gas was employed for the determination. of trace elements in. petroleum fractions with a boiling point above 1000 degrees F, using direct dilution in an organic solvent. Nitrogen produces robust plasma for the analysis of fractions having an American Petroleum Institute (API) gravity range from -2 degrees up to 9.7 degrees and elemental. composition as follows: S (1.0-5.5 wt %) and N-(200-14 000 mg kg(-1)). A satisfactory limit of quantification and spike recoveries at low and high concentration levels were determined for Na, K, Ca, V, Fe, Ni, and Mo present in different residua samples. The recoveries obtained from. the analysis of three QC test materials were within +/- 10% of the actual and or certified values. It was found that V, Fe; and Ni are the most predominiant elements present-in these samples and the effect of the source of sustained plasma gas as well as sample preparation method was focused on the quantification of these three elements. Using a direct dilution method, V calculated recoveries-using NIST 8505-CRM (104% and 109%) are found independently of the plasma sustained gas source (argon vs nitrogen) Comparing sample preparation methods.(wet ashing vs direct dilution), recoveries of 99% and 109% were determined. Furthermore, for Ni, regardless of the fact that the NIST 8505 CRM reference value is not available, the calculations using our measured value of 51 mg kg(-1) indicate that that nickel quantification is not sensitive to either sample preparation or detection, methods, giving recovery of 100% in all cases. For Fe, the quantification is susceptible to a sample preparation method; microparticies, which are possible to,be present in such fractions, cannot be homogeneously dispersed into the organic media,. leading to bias to low measurements. in most cases. It seems that better results are obtained using, wet acid digestion. Finally, it was shown that, when using nitrogen-based plasma (MP-AES) versus argon-based plasma (ICP-OES), excellent agreement in all cases for vanadium and nickel was determined, indicating that MP-AES represents an alternative for analysis of these complex samples.