ISO 2447 pdf download

ISO 2447 pdf download.Fruit and vegetable products — Determination of tin content 1 Scope This International Standard specifies a method for the determination of the tin content in fruit and vegetable products. The method is applicable to products which may contain, per kilogram, up to: – 1 ,25 g of copper; – 0,6 g of lead; – 6 g of zinc; – 40 g of phosphorus. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 551 5:1 979, Fruits, vegetables and derived products — Decomposition of organic matter prior to analysis — Wet method. 3 Principle After destruction of the organic matter by means of sulfuric and nitric acids, and conversion of the tin to the stannic form, a complex is formed in a buffered solution of pH 1 ,0 to pH 1 ,2 [the iron(III) being masked, if necessary, by reduction with ascorbic acid]. The complex is coloured orange with phenylfluorone and the colour compared with those obtained under the same conditions but starting from standard solutions of pure tin. 4 Reagents Use only reagents of recognized analytical grade, and distilled or demineralized water or water of equivalent purity. 4.1 Sulfuric acid, r 20 = 1 ,84 g/ml. 4.2 Dilute sulfuric acid, 1 ,25 mol/l. 4.3 Ascorbic acid, 50 g/l solution. 4.4 Nitric acid, r 20 = 1 ,42 g/ml. 4.5 Hydrochloric acid, r 20 = 1 ,1 9 g/ml. 4.6 Methanol. 4.7 Ethanol, 95 % (V/V). 4.8 Poly(vinyl alcohol), 1 6 g/l solution. Dissolve 1 ,6 g of poly(vinyl alcohol) in a little water with gentle warming and agitation. Dilute to 1 00 ml after cooling. 4.9 Buffer solution, containing 450 g of sodium acetate (CH 3 COONa) and 240 ml of acetic acid (CH 3 COOH) per litre. 4.10 Tin, standard volumetric solution I, containing 500 µg/ml in a sulfuric acid medium, approximately 3 mol/l. Dissolve, with heating, 0,5 g of pure tin in a mixture of 50 ml of sulfuric acid (4.1 ), 5 ml of nitric acid (4.4) and...