Method of screening hydrocarbon compositions for low molecular weight naphthenic acids

摘要

A method for the quantitation of the naphthenic acid content of molecular weight less than 600 Daltons in a hydrocarbon composition (e.g. crude oil) comprising (i) separating naphthenic acids from the hydrocarbon composition (e.g. by dialysis) (ii) applying them to a macroreticular ion exchange resin additionally comprising complexes of transition metal ions co-ordinated with an amine or ammonia (said complexes being bound to the surface of the resin) (iii) washing the resin (iv) eluting the naphthenic acid-metal ion complexes from the resin (v) quantitating the number of naphthenic acid-metal ion complexes present (e.g. by UV absorbance). Alternatively step (i) may be omitted, whereby the crude sample is directly applied to the resin.