الفهرس 
Development of a reference material from crude oil for sulfur and some trace elements
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Abstract
Crude oil quality and uses are largely affected by the presence of sulfur and some other elements in the oil. Controlling the risk associated with these elements in crude oil depends on their accurate determination which is crucially governed by the use of certified reference materials (CRMs). Therefore, the development of a natural-matrix reference material for quantification of sulfur, iron, nickel, vanadium and magnesium in crude oil has been a subject of our priorities and we have dealt with in this thesis. To start the work, the crude oil was homogenized and bottled to prepare the candidate reference material. Homogeneity and stability of the bottled reference material were investigated and characterization of sulfur content was carried out using wavelength-dispersive X-ray fluorescence (WD-XRF) spectrometry and gravimetric methods. Meanwhile, characterization of iron, nickel, vanadium and magnesium content was carried out using atomic absorption spectrometry (AAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) techniques. Statistical evaluation of the measurement results obtained showed good homogeneity and stability of the candidate reference material. The certified values were derived out of the different analytical methods at confidence level of approximately 95% and the certified uncertainty was calculated in terms of the SI units, which provided strong certification process