Standards for petroleum analysis

It is vital that the standards used are as well characterised as possible, since the accuracy of any measurement is a function of the comparison made. Standard materials may be obtained in two forms, as solid organo-metallic compounds of known metal content or as ready made metal in oil-based standards of known concentration. 

Calibration standards in the chosen solvent may be prepared by subsequent dilution of the above standard. As an alternative to lubricating oil, solvents such as MIBK, xylene or white spirit may be used directly to prepare the master standard. It is not always necessary to follow rigidly the above procedure as many of the organometallics dissolve easily in a range of 

A range of single and blended organic sulphonate standards in oil bases is available. These appear to offer excellent stability and may be diluted with paraffinic and aromatic hydrocarbons as well as ketones. These may be obtained from Conostan Division, Continental Oil Company, P.O. Box 1267, Ponca City, Oklahoma 74601, U.S.A. 

Crude oil contains a number of metallic elements which are of interest either due to the undesirable effects they cause in the refining process or as an indication of the origin of the oil. The concentration levels encountered will vary with the type of crude oil. Crudes originating from different oil fields may vary markedly in trace-metal content. Also some crude oils will become contaminated in transport from the oil well to the refinery by, for example, pipeline material or seawater. The levels of such metals as Ni, V and Na must be carefully controlled in order to reduce production problems such as plant corrosion or catalyst poisoning. 

Two methods are given here for the determination of metals in crude and residual fuel oils the dilution—flame analysis method and an ashing procedure. Because of the nature of these oils simple dilution with solvent may leave undissolved solids in the solvent to be presented to the spectrometer. This could give rise to a decrease in the precision of the method. The ashing procedure overcomes this difficulty but is more time consuming. The method of choice will depend on whetiier the analytical emphasis is placed on speed of analysis or precision. Where very low levels of Ni or V are important it may be possible to modify the melhod given under fuel oils (Section IV.B.2.). 

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Derivation Propylene and hydrogen sulfide. Hazard Highly flammable, dangerous fire hazard. Use Standard for petroleum analysis, intermediate. 

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