4851903 0024779 2 92-09EE NTERNATIONAL STANDARD Tso 3360 G--S2 Phosphoric acid and sodium phosphates for industrial use (including foodstuffs) - Determination of fluorine content - Alizarin complexone and lanthanum nitrate photometric method Acidephosphorique et phosphates de sodium a usage industriel(y compris les industries alimentaires) Dosagedufluor-Methodephotometriqueaucomplexoned'alizarineetnitratedelanthane First edition - 1976-08-15 W UDC 661.634/.635 :546.16 :543.42 Ref.No.ISO3360-1976(E) Descriptors:chemical compounds,food industry.phosphoric acids,sodium phosphates,chemical analysis,determination of content, spectrophotometricanalysis Price based on 5 pages COPYRIGHT 2OO0 Inte Standa Information Handling Services, 2000 48519030024780 3360-76 b FOREWORD Iso (the International Organization for Standardization) is a worldwide federation of national standards institutes (IsO Member Bodies). The work of developing Internationat 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. nternational organizations, governmental and non-governmental, in liaison with Iso, also take part in the work. Draft International Standards adopted by the Technical Committees are circulated to the Member Bodies for approval before their acceptance as International Standards by the ISo Council. International Standard ISO 3360 wasdrawnupbyTechnical Committee ISO/TC 47, Chemistry, and was circulated to the Member Bodies in January 1974. It has been approved by the Member Bodies of the following countries : Belgium Hungary Spain Bulgaria India Switzerland Chile Israel Thailand Czechoslovakia Italy Turkey Egypt, Arab Rep. of Netherlands United Kingdom Finland New Zealand U.S.S.R. France Poland Yugoslavia Germany South Africa, Rep. of No Member Body expressed disapproval of the document. International Organization for Standardization, 1976 : Printed in Switzerland CoPYRIGHT 2ooo International Organization For Standardization Information Handling Services, 2ooo ISO3360-1976 (E) INTERNATIONAL STANDARD 92-0EE T2h200 E06T59h 0 Phosphoric acid and sodium phosphates for industrial use (including foodstuffs) - Determination of fluorine content Alizarin complexone and lanthanum nitrate photometric method 1 SCOPEANDFIELDOFAPPLICATION approximately 300 mi of water and adjust the pH to 4,6 with 0,5 N sodium hydroxide solution, using a pH meter. This International Standard specifies an alizarin Dilute to 500 ml with water. complexone and lanthanum nitrate photometric method for the determination of the fluorine content of phosphoric 3.6.2 Alizarin complexone, 0,88 g/1 solution. acid and sodium phosphates for industriai use (including foodstuffs). Suspend 0,44 g of alizarin complexone in 200 ml of water The method is applicable to products of which the fluorine and add 0,5N sodiumhydroxide solution, in small portions, until the solid has just dissolved. Add 50 ml of the content, expressed as F, is equal to greaterthan buffer solution (3.6.1). Check the pH of the solution using 0,5 mg/kg. a pH meter and adjust, if necessary,to between 4,5 and 4,8 Dilute to 500 ml and store between 0 and 50 c. NOTE -This solution has a slightly higher equivalency than the 2 PRINCIPLE lanthanum nitrate solution (3.6.3)in order to ensure that the trivalent lanthanum ions are fully complexed in the test. Separation of fluorine from a test portion by steam distillation in a phosphoric acid medium. Formation of a 3.6.3 Lanthanum nitrate, 0,86 g/l solution. blue-coloured complex between the fluorine and the combined reagent alizarin complexone/lanthanum nitrate, Dissolve 0,43gof lanthanum(11l) nitrate hexahydrate at a controlled pH.Addition of acetone to increase the [(La(NO3)3.6H20)] in 500 ml of water. stability of the complex and the sensitivity of the method. Photometric measurement of the complex at a wavelength 3.6.4 Mix equal volume