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1、International Standard $ 1271 0 N 4 d!igib INTERNATIONAL ORGANIZATION FOR STANDARDIZATION.MEXYHAPOLHAR OPTAHMBAt I) The method for the potentiometric titration of essential oils will form the subject of IS0 4726. 2 Copyright International Organization for Standardization Provided by IHS under licens
2、e with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 22:06:05 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 1271-1983 (E) m is the mass, in grams, of the test portion (8.2); k c is the volume, in millilitres, of hydrochloric acid solu-
3、tion (5.1) used in the blank test (8.3); V, is the volume, in millilitres, of hydrochloric acid solu- tion (5.1) used in the determination (8.4). The carbonyl compounds content, expressed as a specified aldehyde or ketone as a percentage by mass, is given by the formula M,(V(y v, 10m Xc where c, m,
4、Vc and VI have the same meanings as above; Mr is the relative molecular mass of the aldehyde or ketone specified in the International Standard specification for the essential oil concerned. Express the result to two significant figures. 10 Test report The test report shall state the method used and
5、the result ob- tained. It shall also mention any operating conditions not specified in this International Standard, or regarded as op- tional, as well as any circumstances that might have influenced the results. The test report shall include all details required for the complete identification of th
6、e sample. 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 22:06:05 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 1271-1993 (El Annex Modified pr
7、ocedure to be used for strongly coloured essentials oils when the potentiometric method cannot be applied (This annex forms an integral part of the Standard.) Transfer, by means of a pipette (6.1.2), 20 ml of the hydrox- ylammonium chloride solution (5.4) into a flask (6.1 .I 1. Add 15 ml of the pot
8、assium hydroxide solution (5.2) from a pipette or a burette and mix. Transfer the mixture into the flask containing the test portion and retain the emptied conical flask without washing it. Allow the flask containing the mixture to stand, or boil under reflux, for the time specified in the Internati
9、onal Standard specification for the essential oil concerned. If boiling is carried out, cool rapidly before removing the reflux condenser. Titrate with the hydrochloric acid solution (5.1) until the greenish-yellow end-point is observed. Transfer about half of the content to the original flask, neut
10、ralize until the solution takes on a lemon-yellow colour, transfer to the other flask, mix, and again return one half of the solution to the original flask. Repeat this operation until the addition of two drops of the hydrochloric acid solution (5. I) to the solution contained in one of the two flas
11、ks causes no further change of colour when compared with the solution contained in the other flask. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 22:06:05 MDTNo reproduction or networking permitted without license from IHS -,-,-