Cochin laboratory

ASPHALTENE CONTENT (D 6560, IP 143)

Percentage by mass of wax free material present in a sample which is insoluble in n-heptane but soluble in hot benzene is called Asphaltene content of the sample. The asphaltene fraction is the highest-molecular-weight, most complex fraction in petroleum. The asphaltene content gives an indication of the amount of coke that can be expected during exposure to thermal conditions. Asphaltenes in crude oils may give problems during storage and handling if the suspension of asphaltene molecules is disturbed through excess stress or incompatibility. They are also the last molecules in a product to combust completely, and thus may be one indicator of black smoke propensity. Their composition normally includes a disproportionately high quantity of the sulfur, nitrogen, and metals present in the crude petroleum or petroleum product.