ISO 13884:2003 specifies a method for the accurate determination of isolated trans bonds in natural or processed long-chain fatty acids, fatty acid esters and triglycerides with trans isomer levels greater than or equal to 5 %.

The method is not applicable, or is applicable only with specific precautions, to fats and oils containing high levels (over 5 %) of conjugated unsaturation (e.g. tung oil); materials containing functional groups which modify the intensity of the C-H deformation about the trans double bond [e.g. castor oil containing ricinoleic acid or its geometrical isomer, ricinelaidic acid (12-hydroxy-9-octadecenoic acid)]; mixed triglycerides having long- and short-chain moieties (such as diacetostearin); or in general, any materials containing constituents which have functional groups which give rise to specific absorption bands at or sufficiently close to interfere with the 966 cm-¹ band of the C-H deformation of the isolated trans double bond.