Patent ID: 8114678

Claim:
A method for the chromatographic analysis of hydrocarbon oil comprising: Step 1: passing a mixture of the hydrocarbon oil and a first solvent sequentially through a 2,4-dinitro-anilinopropyl-silica gel (DNAP) and a silver ion strong cation ion exchange column (Ag + /SCX − ) to elute pure ‘saturate’ fraction of said oil and sending it to an evaporative light scattering detector (ELSD), Step 2: passing a solvent through Ag + /SCX − to elute a fraction of said hydrocarbon oil, repeating steps 1 and 2 only with solvents chosen to elute different fractions of said hydrocarbon oil, back-flushing DNAP and Ag + /SCX − to elute different fractions, sending said eluting fractions to an evaporative light scattering detector (ELSD), Step 3: detecting light scattered by said eluting fractions; and Step 4: determining the composition of said hydrocarbon oil from said detected scattered light.