I want the detailed procedure for SARA analysis, solvents required, apparatus and also detailed procedure on how to perform column chromatography with multiple solvents.
Analysis of the composition of crude oils can be endlessly complex, but the simple analysis scheme is to divide an oil into its saturate, aromatic, resin, and asphaltene (SARA ) fractions. Several methods can be used but the peferred methods are the high pressure liquid chromatographic ( HPLC ). The fastest separation method uses thin - layer chromatography ( TLC.) withquartz rods that are coated with sintered silica particles. A popular method is known as laroscan that combines TLC with flame ionization detection ( TLC-FID ) methods. For more details consult Evaluating Crude Oils by SARA Analysis. https://www.onepetro.org.SPE-75228
You can use SARA analysis to separate the crude oil into four major classes of compounds – saturates, aromatics, resins, and asphaltenes (SARA) – using a chromatographic column.
This method can be carried out by mixing 10 gram of crude oil with n- heptane to separate asphaltene; the asphaltene content can be measured from the weight of the precipitate.
The maltene (filtrate) freed from the solvent to the greatest possible extent, then weighed, and add 2 gm of it to the chromatographic column with activated silica (1000C) saturated with n-heptane and eluted sequentially with 100 ml of n-heptane (elution of saturates); 100 ml of toluene (elution of aromatics); 100 ml of toluene-methanol solution (50:50) (elution of polars/resins); 100 ml of methanol-chloroform solution (50:50) (elution of polars/resins); 100 ml of chloroform (elution of polars/resins); and 100 ml of acetonitrile (elution of polars/resins).
Collect elutes in separate containers and mix those from the last four elution sequences, stripped of their respective solvents under vacuum and weighed.
The saturate, aromatic and resin contents can be calculated from the weight percent of the residue in the whole crude.
ASTM D 4124-97 is one of the best and easiest method.However HPLC or ithroscan may be used.
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