Determination of major heavy metals and species of vanadium bonded porphyrin in petroleum based fuels

Petroleum based metallic pollution in nature has, now, gradually increased as a consequence of the emission of burning products to atmosphere, occurred through the utilisation of petroleum based fuels and oils, such as gasoline, diesel fuel (diesel oil), jet fuel, fuel oil (heating oil), liquefied petroleum gas (LPG). The question, ?Why the determination of metal levels in petroleum based fuels is important? has become significant in the last years, since consumption of this type of fuels has considerably boosted. In the study, complete solubilisation of the samples was provided by optimising a microwave assisted mineralisation technique. Detection step was then performed by means of ?Inductively Coupled Plasma ? Optic Emission Spectroscopy (ICP/OES)? technique which gives quite precise results and allows also multiple analysis. Consequently, it was determined in the studied fuel samples, detectable minimum and maximum concentrations of Al, As, Co, Fe, K, Ni, Pb and V; 2.53±0.21?25.46±2.12, 5.08±0.76?6.71±1.04, 14.32±1.12?21.66±2.52, 2.89±0.33?19.42±1.97, 5.89±1.06-17.35±1.52, 11.02±1.13-32.08±3.10 (only in fuel-oil), 8.54±1.21?20.27±2.14, 47.62±2.21-87.34±5.01 (only in fuel-oil) mg/L, respectively. Among these elements, vanadium seems interesting, in view of the fact that it is the most common element found in petroleum composition that is a component absolutely found in the texture of petroleum. Vanadium is included to the petroleum structure as in the form of porphyrine complex during the formation of crude oil. Being excessive for vanadium in the petroleum fractions provides vanadium-porphyrine complex to play also a role as a marker for the amount of emission coming out during the burning. In the study executed, solid phase extraction process for vanadium-porphyrine complex in vanadium-rich fuel-oil samples was carried out using silica gel as adsorbent. Then, detection step was performed using UV/VIS Molecular Absorbance Spectrometry which has advantages of being easily applicable, giving quite precise results in quantitative determination of organic molecules with chromophore character and being achieved low detection limits. As a result, it was concluded that 41.2 % of total vanadium content of fuel-oil samples found as in the form of vanadium-porphyrine complex.Keywords: Fossil fuels, total element, vanadium, porphyrine, silica gel, SPE, ICP/OES, UV/VIS