IODINE NUMBER: ASTM D2078
EXPLANATION
Iodine value is a measure of the unsaturation of the alkyl group or groups expressed in terms of percent iodine absorbed. This test method measures the unsaturation as iodine value in fatty quaternary ammonium chlorides by addition of an iodine/chlorine reagent. The amount of reagent absorbed is determined by back titrating the excess reagent and comparing it to a blank determination. This determination is an indication of the source of the fatty component or, if the source is known, the number of the fatty components (for example, 1, 2, 3, or 4), in the quaternary ammonium chloride. This test method is essentially equivalent to Test Methods ASTM D1959 and ASTM D2075.
TEST SUMMARY
A sample is dissolved in chloroform and reacted with Wijs solution for 30 min in the dark at 25° C. At the end, the solution is mixed with potassium iodide (KI) and titrated with sodium thiosulfate using starch indicator.
TEST PRECISION
The precision or bias data have not been obtained; however, this test method has been in use for many years, and its usefulness has been well established.
