(ISO International Standard 3946 Starches and derived products - Determination of total phosphorus content - Spectrophotometric method Amidons, fecules et produits derives - Détermination de la teneur en phosphore total -- Methode spectrophotométrique First edition - 1982-12-01 SO 3946-1982 (E) UDC 664.2 : 543.847 Ref. No. ISO 3946-1982 (E) Descriptors:starches,chemicalanalysis,determinationofcontent,phosphorus,spectrophotometricanalysis. Price based on 3 pages Copyright Intern No reproduction or networking permited without license from IHS Not for Resale Foreword iso (the International Organization for Standardization) is a worldwide federation of national standards institutes (iso member bodies). The work of developing Inter- national Standards is carried out through ISO technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with Iso, also take part in the work. Draft International Standards adopted by the technicai committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISo Council. International Standard ISO 3946 was developed by Technical Committee ISO/TC 93 Starch (including derivatives and by-products), and was circulated to the member bodies in February 1982. It has been approved by the member bodies of the following countries : Austria Netherlands USA Egypt, Arab Rep. of Poland USSR France Portugal Germany, F.R. South Africa, Rep. of No member body expressed disapproval of the document. ? InternationalOrganizationforStandardization,1982 Printed in Switzerland No reproduction or networking permitted without license from IHS Not for Resale INTERNATIONAL STANDARD ISO 3946-1982 (E) Starches and derived products -- Determination of total phosphorus content -- Spectrophotometric method 1 Scope and field of application 4.4 Ammonium molybdate solution, prepared as follows. This International Standard specifies a spectrophotometric In a 11 flask, dissolve 10,6 g of ammonium molybdate method for the determination of the total phosphorus content tetrahydrate [(NH4)6Mo7024.4H20] in 500 ml of water. of starch,including derivatives and by-products,in which the expected content, calculated as phosphorus (P), does not Add 500 ml of 10 mol/1 sulphuric acid solution, mix and allow exceed5%(m/m). to cooltoambienttemperature. 4.5 Sodium hydroxide, 10 mol/I solution. 2 Definition 4.6 Phosphorus, standard solutions. totalphosphoruscontent:Thequantityofphosphorus determined in accordance with the conditions specified in this 4.6.1 Stock solution, corresponding to 100 mg of P per litre. International Standard and expressed as phosphorus (P) as a percentage by mass of the product as received. Weigh, to the nearest 0,5 mg, 0,439 3 g of anhydrous potassium dihydrogenorthophosphate and dissolve in water. Transfer quantitatively into a 1 000 ml one-mark volumetric 3Principle flask. Destruction of the organic substances by digestion with a Dilute to the mark with water and mix. sulpho-nitric mixtureand conversion of phosphates to ortho- 1 ml of this standard solution contains 100 μg of P. phosphates. Formation, by means of a reducing agent, of a phosphomolyb- NOTE -- The potassium dihydrogenorthophosphate shall be dried dateknow as molybdenumblue. before use for 1 h, in a drying oven controlled at 105 ± 2 C, and then allowed to cool in a desiccator. Spectrophotometric measurement of the intensity of the blue colour at a wavelength of825 nm. 4.6.2 Standard solution, corresponding to 4 mg of P per litre. Using a pipette, take 10 ml of the stock solution (4.6.1) and 4 Reagents place it in a250 ml one-mark volumetric flask. During the analysis, use only reagents of recognized analytical Dilute to the mark with water and mix. grade, and oniy distilied water of at ieast equivaient purity. 1 ml of this standard so