The sample is titrated with bromide-bromate solution until a sudden change in potential due to free bromine signals the end point.  Bromine number is reported as grams of bromine that will react with 100 grams of sample.  It is useful as a measure of aliphatic unsaturation in petroleum samples and can be used in conjunction with Annex A2 of the method to calculate an estimate of olefin percentage in distillates boiling up to 315°C.  It is also an aid in establishing purity and identity of commercial aliphatic mono olefins. 

The method is not satisfactory for normal alpha-oleins.  ASTM D-2710 gives more accurate results for petroleum hydrocarbon mixtures with Bromine Number 0.5 to 1.0   for Bromine Numbers less than 0.5 ASTM D-2710 must be used.  Also, where Bromine number is less that 0.5, a comparable value, Bromine Index, can be obtained by ASTM Methods D-1492 and D-5776 for Aromatic hydrocarbons.