(Equivalent Test Method: IP 369)
EXPLANATION
This test method provides a means of determining sulfonate content and of classifying and characterizing natural and synthetic petroleum sulfonate products by sulfonate content and average molecular weight. Purity of sodium sulfonate products is measured by basicity and inorganic salt contents and the reserve alkalinity of alkaline earth sulfonates by the total base number. This test method covers the analysis of refined and crude natural and synthetic oil-soluble sulfonate products. Resins, if present, are recovered with the oil phase and carboxylates are recovered as sulfonates. This test method covers the determination of mineral oil, sulfonate, water, total base number, average molecular weight, and specific gravity of calcium, barium, magnesium, sodium, and ammonium sulfonate products.
TEST SUMMARY
The sample, except a sodium sulfonate product, is dissolved in ethyl ether and converted to sulfonic acid, using dilute hydrochloric acid. The sulfonic acid after extraction is converted to sodium sulfonate and the isolated sodium sulfonate and mineral oil are dissolved in chloroform. An aliquot of the chloroform solution, or a sample of a sodium sulfonate product, dissolved in chloroform, is placed on a silica gel column. The oil is eluted with chloroform, the sulfonate with ethyl alcohol, and both are determined gravimetrically. Average molecular weight is calculated from the average equivalent weight of the sodium sulfonate, which is determined by ashing a portion of the isolated sodium sulfonate.
Water is determined by Test Method ASTM D95. Total base number is determined by Test Method ASTM D2896. Specific gravity is determined by pycnometer.
TEST PRECISION
