This method is for determining maleic anhydride reactivity with a wide variety of oils, ranging from debutanized light hydrocarbon distillates to heavy drying oils, using titration.

The method gives a measure of the conjugated diolefin content of the sample. The determination is somewhat empirical since some conjugated diolefins may not react completely, while certain compounds other than conjugated diolefins also may be reactive. For example, anthracene, along with many of its homologs and corresponding alkylated compounds, as well as certain vinyl aromatics, react as dienes with maleic anhydride. Therefore, the results obtained by this method must be carefully interpreted in the light of these specified limitations.

The range of quantitation for diene value is from 1.2 to over 100. A modified procedure can be used to estimate diene values less than 1.2.

If the average molecular weight of the conjugated diolefins is known or can be estimated, the mass-% concentration of conjugated diolefins can be calculated.