This European Standard specifies a method for the determination of the mass fraction of d-biotin by high performance liquid chromatography (HPLC). The method has been validated in an inter-laboratory test on fortified and non-fortifed samples such as cereal breakfast powder, infant milk powder, lyophilized green peas with ham, lyophilized chicken soup and on nutritive orange juice, at levels from 16 μg/100 g to 200 μg/100 g. For further information on the validation data, see Annex B. NOTE 1 d-biocytin can also be estimated by this method. But none of the samples used for the validation step contained d-biocytin. Nonetheless the recovery rate is more than 90 % for d-biotin and d-biocytin, see [2] and [3]. NOTE 2 The method underestimates the real biotin content when used for samples containing egg.