The method specified in ISO 25761:2008 measures the basic constituents in polyols that are soluble in glacial acetic acid and reactive with perchloric acid. Samples containing 0,3 % to 10 % of nitrogen have been evaluated by this method. The method is applicable to polyether polyols and polyether polyol blends that are used in polyurethane reactions. The results are measures of batch-to-batch uniformity and may be used to estimate reactivity in polyurethane reactions.