The invention relates to method for quantification of the absolute amount of allergen in an allergen sample comprising:a) providing a known amount of one or more allergen calibration standard peptide(s) having a sequence of amino acids which is identical with, and optionally unique for, a sequence to be found in the allergen to be quantified and optionally labelling said allergen calibration standard peptide(s),b) degrading the allergen sample to obtain a mixture of peptides, and optionally labelling said peptides with one or more labelling agent(s),wherein at least the peptides in the degraded allergen sample or the calibration standard peptides are labelled, and if both the peptides in the degraded allergen sample and the allergen calibration standard peptide(s) are labelled, the labelling agent(s) used for labelling the allergen calibration standard peptide(s) are different from the labelling agent(s) used for labelling the peptides of the degraded allergen sample,c) quantifying the absolute amount of allergen by correlating the amount of the allergen calibration standard peptide(s) with the amount of the corresponding peptide(s) of the degraded allergen sample by mass analysis.
