Comparison of Preparation Methods for the Determination of Metals in Petroleum Fractions (1000 °F+) by Microwave Plasma Atomic Emission Spectroscopy

Abstract

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 °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° up to 9.7° 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 predominant 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 d...