Applicable to products in which the content of soluble aluminium, expressed as Al2 O3 , exceeds 100 mg/kg. The preparation of the test solution is carried out according to ISO 2217. The reaction proceeds with the formation of the complex between EDTA and aluminium in an aliquot part of solution. Decomposition of the complex using sodium fluoride. Titration of the amount of liberated EDTA against a zinc chloride solution of known concentration in the presence of xylenol orange as indicator.