The invention relates to a standard sample composition comprising a complexing agent and an alkali salt, mixed with a known amount of a foodstuff, the content of at least one component of which is accurately known. The mixture is dissolved in a solvent, e.g. water, and comminuted to form a dispersion. The solvent is removed e.g. by freeze-drying or other suitable method, such that the water content of said composition is < 5 % by weight, preferably < 1 % by weight, more preferably < 0,1 %, most preferably < 0,01 % by weight of the total composition.