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I n tern ati on al I N TE RN ATI ON AL ORG AN I ZATI ON Essen t i al Free H u i l es essen ti el l es - edi t i on Corrected U DC oi l s S TAN D ARD I ZATI ON M E X~ YH AP OL\H AR - an d D&t ermi n ati on - repri n ted OP TAH M B At &l R Det ermi n at i on h yd roxyl ami n e Se co n d i FOR St an d ard fl @$ 271 N 4i b d! i g CTAH /J AP TM A~ I I M ~ ORG AN l SATl ON of carbon yl I N TE RN ATI ON ALE val u e DE N ORM ALI S ATI ON - met h od de l ’ i n di ce de carbon yl e - M&h o d e B l ’ h yd roxyl ami n e l i bre 983- 2- 01 - 985- 08- 01 Ref 668 : 547 28 : 543 86 No I S0 71 - ( E) : Descri pt ors : essen ti al oi l s, ch emi cal an al ysi s, d etermi n ati on of ten t, carbon yl compou n d s Pri ce based on pag es Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies) The work of preparing International Standards is normally carried out through IS0 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, 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 IS0 Council They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting International Standard IS0 271 was prepared by Technical Committee ISO/TC 54 Essential oils International Standard IS0 271 was first published in 1972 This second edition cancels and replaces the first edition, of which it constitutes a technical revision International Organization for Standardization, Printed in Switzerland 993 INTERNATIONAL IS0 271 -1 983 (El STANDARD Essential oils - Determination Free hydroxylamine method Scope and field of application This International Standard specifies a method for the determination of the carbonyl value of essential oils It is applicable to essential oils which contain carbonyl compounds (especially ketones, excluding methylketones) which are difficult to convert to oximes by the method specified in IS0 1279 The method is not applicable to essential oils which contain substantial amounts of esters or other alkali-sensitive constituents International Standards specifying requirements for individual essential oils will specify whether this method or the hydroxylammonium chloride method specified in IS0 2791 ) is applicable References IS0 356, Essential oils - Preparation of test sample Definition Standard, the following carbonyl value (of an essential oil) : The number of milligrams of potassium hydroxide, per gram of essential oil, required to neutralize the hydrochloric acid liberated in the oximation reaction with hydroxylammonium chloride NOTE - Oximes are the result of the reaction of carbonyl compounds with hydroxylamine Principle Conversion of the carbonyl compounds to oximes by reaction with free hydroxylamine liberated in a mixture of hydroxylammonium chloride and potassium hydroxide 1) IS0 279, Essential oils - Determination Titration of the excess alkali with hydrochloric acid solution, either calorimetrically or potentiometrically Reagents All reagents shall be of recognized analytical grade and the water used shall be distilled water or water of at least equivalent purity 5.1 Hydrochloric acid, standard volumetric solution, c(HCI) = 0,5 mol/l 5.2 Potassium hydroxide in 95 % ( V/ VI ethanol 5.3 IS0 212, Essential oils - Sampling For the purpose of this International definition applies of carbonyl value - Bromophenol solution, c(KOH) = 0,5 mol/l, blue, ethanolic solution Dissolve, by heating, 0,2 g of bromophenol blue in ml of ethanolic potassium hydroxide solution, c(KOH) = 0,l mol/l, and ml of 95 % ( Vl VI ethanol After cooling, dilute to 00 ml with the same ethanol 5.4 Hydroxylammonium chloride, ethanolic solution Dissolve 50 g of hydroxylammonium chloride in approximately 00 ml of water, add about 800 ml of 95 % ( V/VI ethanol, then IO ml of the ethanolic bromophenol blue solution (5.3) and dilute to 000 ml with 95 % ( V///v) ethanol Add the ethanolic potassium hydroxide solution (5.2) until the solution is green, if the liquid is observed in a thin layer, or until red, if the layer is thick A lemon-yellow colour shall be obtained when 0,05 ml of the hydrochloric acid solution (5.1) is added to 20 ml of the solution, and a red colour shall be obtained when 0,05 ml of the potassium hydroxide solution (5.2) is added to another 20 ml of the solution The solution is stable for one week of carbonyl value - Hydroxylammonium chloride method I S0 271 - 983 (El Apparatu s Usu al l aboratory For an d equ i pment, the two and in parti cu l ar techni qu es potenti ometri c Determi n ati on (cal ori metri c Cal ori metri c Transfer, ti trati on by tai ni ng Gl ass wi th ground wi th g l ass di ameter fl asks, al kal i - resi stant, n ecks, tu bes to fi tted at l east serve wi th ei ther m l ong as refl u x of capaci ty and 00 to 200 ground g l ass at l east mm and ml , stoppers Pi pettes, of capaci ti es 20 and 50 ml wi th Bu rettes, of capaci ty 25 ml , the graduated in 0, l ml out the rapi dl y greeni sh- yel l ow carri ed for speci fi ed before in a in the oi l is the or to con- potassi u m a burette stand, or boi l I nternati onal the The If refl u x sol u ti on wel l hydrox- (6 I ) concerned aci d that the a pi pette i s observed l ocati on of mi xtu re removi n g hydrochl ori c end-poi nt of fl ask ml the essenti al ml the from contai ni ng ti me 20 i nto Add measu red fl ask the cool (6 2) , (5 4) (8 2) (5 2) the for out, Ti trate a pi pette sol u ti on porti on speci fi cati on carri ed condensers Al l ow refl u x, dard i n i nternal test sol u ti on mi x under or of chl ori de the hydroxi de mean s yl ammon i u m ti trati on) ti trati on Stan boi l i ng is condenser (5 ) unti l ti trati on the shou l d i l l u mi nated by be natural dayl i ght di vi - si on s NOTE - Thi s strongl y Anal yti cal in bal ance or, descri bed For the potenti ometri c Potenti ometer wi th combi n ed ti trati on (preferabl y g l ass Mag n eti c by sti rrer test porti on sol uti on (5 2) Sampl i n g of by essen ti al avai l abl e, oi l s meth od th e For speci fi ed modi fi ed procedu re u sed a pi pette (6 21 , sol u ti on (8 2) 25 Cl ose wel l be col ou red poten ti ometri c ti trati on chl ori de pi pette, l i gh tl y th e i s n ot sh ou l d mean s another contents an n ex yl ammon i u m the 2 th e to oi l s, Potenti ometri c Transfer, potenti ometer) , el ectrodes i s appl i cabl e essen ti al i f a poten ti ometer in recordi ng meth od col ou red and of the the fl ask swi rl i ng or boi l I nternati onal Standard the wi th refl u x, the speci fi cati on for to ti me the hydrox- contai ni ng by mean s of hydroxi de stopper mi xtu re for the potassi u m i ts g l ass the of fl ask add, ethanol i c Al l ow under 50 ml i nto i mmedi atel y ml temperature, (5 4) and stand mi x the at room speci fi ed essen ti al i n the oi l con- cerned See I S0 21 Ti trate potenti ometri cal l y (5 1 , Procedu re I S0 of the test Cal cu l ate sampl e 356 Test Wei g h , test change the essenti al to the nearest as speci fi cati on for mg , i nto speci fi ed the in essenti al oi l a fl ask the (6 I) Bl ank Standard the omi tti ng the the reagents test oi l the bei ng so wi l l sti rrer greatl y hydrochl ori c the I t shou l d same carbon yl h ydroxi de wi th same pH Expressi on 56, u si ng in of from h ydrochl ori c ti trati on si mpl i fy aci d cu rve the that ti trati on pH at to thi s sol u ti on The u sed or readi ngs the from that, at the accordi ng end-poi nt a fi xed pH u se operati on sol u ti on be emph asi zed tested, aci d (6 21 ) wi l l val u e of to not i s ex- determi nati on, and of resu l ts concerned test Si mu l tan eou sl y vol u me the mag n eti c m of the a mass I nternati onal The be the cl u ded porti on sampl e, the the wi th wi th potenti ometer equ i val ence- poi nt al ways sti rri ng of a recordi ng Preparati on See whi l e fol l owi ng carry the out same a bl ank procedu re, per x val u e, g ram ( Vo- test essenti al in oi l , mi l l i g rams i s gi ven of by the potassi u m formu l a Vl ) m but expressed of xc porti on where I f the techni qu e i s i mportant mi nati on, I) Th e that by potenti ometri c the i n order meth od for bl ank to th e test operate ti trati on i mmed i atel y at the poten ti ometri c same ti trati on i s u sed (see precedes 2) the it deter- c temperatu re of essenti al is the h ydrochl ori c oi l s wi l l form th e su bj ect of I S0 exact aci d 4726 concentrati on, sol u ti on (5 ) ; in mol es per l i tre, of the I S0 m i s the mass, k’ c i s the ti on (5 ) V, i s the in grams, vol u me, used in i n the of the mi l l i l i tres, bl ank test test of porti on (8 2) ; hydrochl ori c Mr aci d sol u- aci d sol u- is ti on The (5 ) carbonyl al dehyde or used in i n the for essenti al the as of determi nati on content, a percentage mol ecu l ar i n the oi l mass I nternati onal of the Standard (E) al dehyde or speci fi cati on concerned (8 3) ; mi l l i l i tres, compou n ds ketone rel ati ve speci fi ed Express vol u me, the ketone 271 - 983 hydrochl ori c the resul t to two si gni fi cant fi gures (8 4) expressed by mass, as a speci fi ed i s gi ven by the 10 Test report formul a The M, (V(y v, , test tai ned report It speci fi ed 0m Xc ti onal , in resul ts The test al so thi s as wel l the shal l shal l state the menti on I nternati onal as any method any used Standard, ci rcu mstances and operati ng that or mi ght the resul t condi ti ons regarded have obnot as op- i nfl uenced where c, m, Vc and VI have the same meani ngs as above; report i denti fi cati on shal l of the i ncl ude al l detai l s requi red for the compl ete sampl e I S0 271 - 993 (El An n ex Modi fi ed procedure to the be Transfer, by mean s ml or of of chl ori de the a pi pette and (6 2) , sol u ti on potassi u m a burette for potenti ometri c (Th i s yl ammon i u m u sed (5 4) hydroxi de 20 i nto sol u ti on annex ml of a fl ask (5 2) strongl y method forms the an hydrox- (6 I Add from i ntegral col oured cannot part of the Ti trate Transfer and the for for retai n fl ask the the rapi dl y the empti ed contai ni ng ti me essen ti al oi l the fl ask i cal the speci fi ed before i nto mi xtu re i n the fl ask to the wi thout stand, I nternati onal concerned removi n g contai ni ng refl u x If the boi l Standard boi l i ng test washi n g or porti on i t under appl i ed the hydrochl ori c end-poi nt aci d sol u ti on (5 ) unti l the i s observed about out, unti l to the sol u ti on to the Repeat thi s hal f the of the content sol u ti on other fl ask, ori gi nal takes mi x, to on and a agai n the ori gi nal l emon - yel l ow return one fl ask, col our, hal f of the fl ask Al l ow refl u x, speci fi cati on i s carri ed condenser wh en a pi pette mi x mi xtu re oi l s Standard ) wi th transfer the be greeni sh- yel l ow neu tral i ze Transfer essenti al s cool h ydrochl ori c of the two compared operati on aci d fl asks wi th unti l sol u ti on the cau ses sol u ti on the (5 I ) no addi ti on to the further contai ned of sol u ti on change in the two drops contai ned of other col ou r fl ask of the i n one wh en