Determination of Vanadium, Nickel, Copper and Iron as Complexes of Bis-Acetylpivalyl Methane (Ethylene Diamine) in Nigerian onshore and offshore Crude Oils Using HPLC

Abstract

Higher performance liquid chromatographic determination of vanadium, nickel, copper and iron was conducted from Nigerian Crude oil samples obtained from Nigerian Petroleum Development Company (NPDC). The procedure was based on complexation of the analytes with bis (acetyl pivalyl methane) ethylenediamine (H₂APM₂en) followed by solvent extraction and HPLC separation on a reverse phase, C18, 5µm column. The complexes were eluted with methanol : acetonitrile : water (60:20:20) at a flow rate of 1cm³/min. and uv detection at 260nm.The results show that nickel  had the highest concentration while copper had the least concentration. The concentration levels of these elements in the crude oil samples range from 210 – 1620 ppb for Ni, 975 – 1125ppb for Fe, 225 – 1060ppb for V, and 54  – 138ppb for Cu. The pattern of occurrence for each element agreed with earlier studies using Niger Delta oils. The results indicate that trace metal data compliment well with the organic geochemical data and trace metals are useful in oil classification. It was obvious from this study that Nigerian crude have low metal content. However, despite the low concentrations, they could still pose an intrinsic health hazard considering their cumulative effect in the environment.

Keywords: key words, Crude oil, Heavy metals, HPLC