ANsr Inlara Doc Sect (ISo 6866 International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEKAYHAPOAHAR OPTAHM3ALMR NIO CTAHAAPTM3AUMW·ORGANISATION INTERNATIONALE DE NORMALISATION Animal feeding stuffs - Determination of free and total gossypol Aliments des animaux -- Dosage du gossypol libre et du gossypol total First edition - 1985-11-15 3861& 330 UDC 636.085.19 : 543.8 Ref. No. ISO 6866-1985 (E) ISO 6866-1985 ( Descriptors : agricultural products, animal feeding products, chemical analysis, determination of content, gossypol. Price based on 3 pages Copyright International Organization for Standardization Not for Resale Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through Iso technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by least 75 % approvai by the member bodies voting. International Standard iSO 6866 was prepared by Technical Committee ISO/TC 34, Agricultural food products. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other international Standard implies its latest edition, unless otherwise stated. International Organization for Standardization, 1985 Printed in Switzerland Copyright International Organization for Standardization Not for Resale ISO 6866-1985 (E) INTERNATIONAL STANDARD Animal feeding stuffs - Determination of free and total gossypol 5.3 Solvent B. 1 Scope This International Standard specifies a method for the deter- Place in a 100 ml volumetric flask 2 ml of 3-aminopropan-1-ol mination of the . content of free and total gossypol and and 10 ml of glacial acetic acid. Cool to room temperature and chemically related substances in animal feeding stuffs. make up to volume with N,N-dimethylformamide. 2 Field of application This reagent is stable for one week only. The method is applicable to cottonseed and cottonseed meals and cakes, and to compound feeding stuffs containing these 5.4 Aniline. substances. If the absorbance determined in the blank test exceeds 0,022, total gossypot is 50 mg/kg. distil the aniline over zinc dust, discarding the first and last 10 % fractions of distillate. Store in a stoppered brown glass 3 References bottle in a refrigerator (0 to 4 oC). ISO 6497, Animal feeding stuffs -- Sampling. 1) The reagent is stable for several months. ISO 6498, Animal feeding stuffs - Preparation of test samples. 4Principle Apparatus Extraction of the gossypol in the presence of 3-aminopropan-1. ol, either with a mixture of 2-propanol and hexane for the deter- Usual laboratory apparatus and in particular mination of free gossypol or with dimethylformamide for the determination of total gossypol. Conversion of the gossypol in to gossypol-dianiline using aniline. Measurement of the absorb- 6.1 Tumbler mixer, having a rotational frequency of ance at the wavelength of maximum absorbance (between 435 approximately 35 min -1, or other shaker. and 445 nm). 6.2 Spectrometer, suitable for making measurements at Reagents 5 wavelengths between 435 and 445 nm, with cells of optical path length 10 mm. All reagents shall be of recognized analytical grade. The water used shail be distilled water or water of at least equivalent purity 6.3 Volumetric flasks, of capacities 25 and 50 ml. 5.1 2-Propanol/n-hexane, 60 + 40 mixture by volume. 5.2 Solvent A. 6.4 Conical flasks, of capacities 50, 100 and 250 ml. Place in a 1 000 ml volumetric flask approximately 500 mi of the 2-propanol/hexane mixture (5.1), 2 ml of 3-aminopropan-1-ol, 8 ml of glacial ac