Hasegawa, T.

Itano, A.

Moriya, T.

Tsuji, Y.

Okayama University Digital Information Repository

A New Micro-analytical Method for Iodine

Okayama University Scientific Achievement Repository

A New Micro司analyticalMethod for Iodine. By A. ltano， Y.Tsuji， T.Hasegawa and T. MOI匂a.[December 14， 1937.] In the detennination of iodine， itia e朗自ntial加 destroycom pletely the orga.nic component目 in0. sample without 100白ingiodine朗 pecia.llyw hen the Iomount of iodine present is very minute. Previously a.u electric clo日edcom・bustion method1) w朗 reportedfrom our labora.ωry， which wa.s lo.ter found tha.t them自thodis very expen白iveconsuming a. greo.t qua.ntity of electric current o.nd o.lso it is di血cult加 controlthe討目白 oftempera.ture looolly旬 de自troy0. lo.rge o.mount of orga.nic componen匂 fra.ctiona.llyI¥nd sa.tisfa.ctorily， I¥nd 0.180 it produces 自omuch black smoke in the course of combustion that necesRia.t朗 thesmoke screen， I\~ de咽cribedin the previou自 report，which should be trea.ted ca.refully la.ter for the extmctiol1 of iodine sustl¥ined by it. Furt，her it is di飴culもtoprevent the blo.ck soot remain a.ttached to the inside of the quartz combu日tiontube. In view of these di鐙巴ultie~ involved in t.he previous met，hod， the senior author devised a new method and developed by hi自 co-workers，制自，hownin Plate VIII， Fig. 1 o.nd 2， and which is applicable for the pla.nt and animal mo.teria.1B， rich with organic matter and conto.ining a minut，e amount of iodine. The deacription of method together with自omeanalytica.l results a.re presented朗 follows:1. Descn;企lion0/ A，鈴aralus.' A. - Ga~ combustion furnace，-The furnace is made of a piece of aぬωtUBcement chimney (9 cm. dia-meter a.nd 45 cm. long) of which the upper and lower sides o.re cuもopen1 cm. o.l1d 2 cm. wide longitudina.lly respectively田 tbatthe g嗣 flameburnB t.hrough the opening and heat the quo.rtz combustion tube (3 cm. X 50 cm. and 0.4 cm. thick) which is pl即 edinside of the chimney and held by means of t，he metal collars at both ends. B. - A sma.lI quartz tube (1 cm. x40 cm. and 0.15 cm. thick) t，hrough which a fi.ne platinum wire， consiBts of自everalfunnel like COil8， ispla.ced朗自howllin Plat.e VIII， Fig. 2. C. - A piece a smaU quartz tube飢 Bof 15 cm. long which ca.n be removed for wal'lhing. D. - Electric resisto.nce (15 !J o.djust.able). E &， F. - Nickel joints which connec旬A，B o.nrt C. G.一Ho.r<lglo.~B t.ube specia.ly mo.d白 toconnect the combustion tube with ab舶 rptionbottle句， a.nd t.he joint is sea.led with pl制 ter.9持 A. ITANo， Y. Tou.n， T.HASEO.""A nnd T. MORIVA: 1." 0.2 n.nc1 1.3 - The ab目orptionbottle自foriodine， ofwhich size is 1叩比一except且'3being 80 cc. a.nd placed there to ca.tch聞 ysmoke which ma.y e自ca.pebackwa.rd otherwise. H.・-A wa品hbottle with帥 tumtedK2003 to elimino.te iodine which might come from a.ir. 1. - A Buction 1l闘k加 whicha. wn.ter pump is connecもed.2. Procedure: 1.) Trea.tment of帥mple8，-the pla.nt ma.teria.l目 Ruch朗自tems，lea.ve自a.ndroots are dried n.nd powdered; t，he grn.ins a.nd Reecl日町esubjected to the a.l1n.lysiR directly; the a.nima.l mn.tもeris liquefied by men.ns of 80dium hydroxide， and a.cidified with閥 lfurica.cid to自lightn.cid under cooling. The saruple thus tren.t，ed i自placedin thre自porcelainboa.t自whi巴hn.r白tra.nsportedinto the combustion tube，朗inPlo.te VIII， Fig. 2. b.) Sixty cubic centimeter自 ofK2003 solution (切巴C.H20 + 3 c. of 10 % K~Û3 genera.ly) a.re pla.ced in旬0.1a.nd 1.2; 30巴c.of wa.tel' with 1.sma.1 qua.ntity of 10 % K2003 a.re pla.ce<l in a.s・The岡崎日orptionbottle日a.reconnected up respectively 朗自hownin Pla.te VIII， Fig. 1， n.nd 1.1 th白join旬 are自ea.ledup with Pla.ster of Pn.ris a.nd the sa.me with E a.nd F. c.) Next the suction by mea.ns of 1. wa.ter pump i日a.ppliedもoelimina.te the a.ir in the system; the electric current i日pa倒 edthru B ho.ving it red-hea.ted; light the burner a.t E in fu11 n.nd the combu前iontube is h伺 tedwit，h small g朗ln.me for the first 30 minutes 80 tha.t 0. la.rger port，ion of orga.nic ma.teria.ls is cn.rbonized， then gra.dua.lly more hen.t isa.pplied a.nd a.R 0. rule the combustion begins within ha.lf an hour. It is nec朗自aryto burn the随 mplegra.dua.ly since 旬ora.pid combu前ion圃endsthe black smoke over into出自a.bsorptionbottles which give自troublefor the del.ermina.tion; hea.ting:l.t E may be elimina.ted after t，h嗣combustionis completed in A b印刷seno smoke rema.in自白meo.redthere then ; a.lso the electric current p朗自ingthru B ma.y be reduced朗 thecombuRtion in A a.dve.nce白. The time for巴ombustionve.ries 8Omewha.t齢 cording加 thena.ture of se.mple but n.bout 30 minutes a.l'e閉館cientil most c嗣伺. After the combu前ioniR completed which co.n be judged looking a.t the sample thru G， the hea.ting is 日旬pped，gn.s e.nd electric， but the suction i目巴ontinuedfor five minutes longer. Then 0， 1.1， 0.2 a.nd 1.3 o.l'e ta.ken awayand the contents o.re w胞hedvery carefully into 5∞cc. volume bea.l{er with hot， wat，er， cvapora.ted over the hot water ba.th into 1.白ma.lvolume， 40 cc. 01'附;tl'anf'ferred to 50 c. pla.tinum dish and eva.po・l'ated旬 Rolidon n. steam ha.t，h; the pla.tinum dish is then pla.ced in 1. d1'yοven at 15000. for 20 to 30 millutes to n.Rsure compleぬdryn朗自;巴ovel'the ple.tinum dish with 0. wa.tch glass and iR subjected at 5∞。O.hen.ting for 2 minutes to burn up Bny tra.ce of organic mntter might he.ve日tilrema.ined; diS801ve the rema.ining ash in 1.自ma.lamount of hot wn.ter a.nd 2 cc. of 10 p白rcent白odiumbisulfite is e.dded， then 2 c. of 20 per cent sulfuric舵 idis slowly e.dded and heated on hot we.ter bath fo1' 1-2 minut倒. Then the acid i自neutra.lizedwith 20 per cent. po・te.回目iumcarbonate ndded， drop by drop， in 0. slight exce嶋 over the neutra.lit，y， AN自wMicro-analyもicalUethod {or Iodine. 99 evo.porate to dryne自国onthe hot wo.ter bo.lh o.nd moistened with 0.即0.1o.mount of distilled wo.ter. The p舗もethus obtained iR subjected for extro.ction of iodine with 95 per cent o.lcohol for 4-5 timeR by o.dding o.bout 2 c. alcohol o.t 0.time， o.nd 0.1 the extracts o.re p1o.ced in 0. p1o.tinum di8h of 10 c. vo1ume. To t.he extro.ct 0. 8mo.1 o.mount of 20 per cent pota.腿iumco.l'bono.te iR o.dded， evo.poraぬtodryne倒，heo.ted for 5 minuぬ8o.t 15000. o.nd then 1 minute， o.t民泊。0.;1-2 drops of di8-tilled wo.ter o.re a.dded o.nd stirred with 0. gla.品目 rodinto 0. p岨 te，o.ncl the p削除istr伺 tedwith a1coho1 for extraction of iodine as done previou81y. Ago.in the extra.ct i回 evo.poro.teddOWll旬 dryne8日o.fter0. smo.l o.mount of 20 per cent po・to.88ium co.rbonate is o.dded， and heo.ted o.t 15000. for 2・minutesto drive out 0.1 a1cohol. Then the re8idue is wa.shed repeo.ted1y 自由vel'o.1time8 in加 ERLENMEYER a幽 kof 25 c. vo1ume wit，h 0. sma11 o.mount of hoもwo.teru自edo.t 0.time so tho.t出efino.1 vo1ume rea.che8加o.bout10cc. Thus 0.1もheiodine contained in出e岨mp1eis transformed into a!1 inorgo.nic form which is determined quan“tative1y o.s fo11ows: The Volumetric Method U8ed. Reo.gents u8ed: (M回 OX'8.)1.) Sulfuric a.cid 801ution....…(20 %.) 2.) Metby1 oro.nge 801ution.…(0.01 %.) 3.) So.turated Brom wo.ter.…(Prepo.r自dfr倒 b1y.)4.) Pota.ssium iodine......・H ・.(5% solution， fresbly prepo.red ju凶heforeu自ed.)5.) Sodium bypo8ulfite....・H ・.(Nf1，0∞目to.ndard801ution which is prepo.red everytime from N/10白olutionby c1ilution o.ccord-ing加出etitro.tion va.lue determined o.t tbe time.) 6.) Sta.rcb卸 1uもion..・H ・...・ H ・(0.5%.)7.) Porcela.in ware. .・H ・.……(brokenpi自ces， boiled in dilute nitric acid， burned o.nd w制hedthorougb1y， o.nd dried.) A drop of metby1 Ol'8.nge i8 a.dded t.o the 801ution under tbe test o.nd ti甘乱tedwitb 20 % H2S04 to tbe neutra.l point， o.nd tben 0.0，5 cc. of tbe o.cid is a.dded in exce8s to mo.ke tbe 801ution acid; 3 drop8 of brom water are added and sbo.ken vigorou81y 80 tho.もbe801ution becomes do.rk oro.nge color to wbicb 0. piece of porcela.in is a.dded a.nd brougbt to boiling on出e8a.nd bo.tb witb oc倒的nalVigOI可)u吋円ha.kinguntilもheyellow color i8 l08t， a.nd白骨 boilingis continued for five minu同a.fterthat. Then 0.1 cc. of 5 % KI o.nd 3 drop自 of0.5 % 8ta.rcb 自olutiono.re a.dded， and ti凶 tedwith N/1刈)()No.28P3 through a burette which is gro.duo.もed加0.01c. until the b1ue co1or di飢 ppea.r自， o.nd the iodine conten旬Isco.1cu1叫ed副 usua.l3・AnalylicaJResulls : 0.) ln orderもodetermine出eo.ccuro.cy of the method，乱 knownvo.riou白amount of iodine mixed with filter po.per wo.s o.no.lY8ed， o.nd obta.inedもhefo11owing resu1旬制notedin Table 1. 100 A.ITANo， Y. TsuJI， T.HA8EGAWA and T. MORIYA: Tab1e 1. Determination of Accuracy cf the Method. 山 I情iinc副Ide-"tl. I伽linefOl1nrl. Difference. ( y ) (2Y.11 1珂・ 2.0 +0.1 2.18 +0.1~ 2.06 +0.06 " 5.0 5.07 +0.07 " 4.96 -0.04 " 5.14 +0.14 " 10.0 10.18 +0.18 " 10.04 十0.04" 10.∞ 0.00 AS Tab1e 1 indicat自由， the error becornes 1o.rg自ro.s the quo.ntity.of iodine decreases， for exo.mp1匂 wbere2 r ofiocline originally add自d，the error amounted 旬 3-10% while in other c倒 esthe eロorw制 a1mo凶 negligib1e. ln 0. majority of co.自es，more iodine w朗 foundthan it w朗 addedwhich may be due t.o the probab1e presence of iodine in K2C01 u自由dbut cbiefly the eηor in the t.it.r叫ionis r剖 ponsib1efor it. Consequently by more strict check on the manipulo.tion and the appa.ratus uRed， the error cou1d be reduced a.Uhough the method 0.8 des巴ribedserves the purpose v白rysati自fo.ctorilyin most cases. b.) Determination of iodine in meo.t:出edetermination of iodine in t.he anima1 ma.tter has been considered very di血cultowing to various factor目invo1vedespecia.lly i也 compleもecombu8tion， 80 that the beef W8S ana1ysed by this me出od旬朗cert.ainiωapp1icability， and the r白日u1tsobta.ined are shown in Tab1e 2. Table 2. E泌総rminationof lodine in Beef. Sample此Fresh heef， 5 g. Ibid. Ibid + 2 Kl. Fresh beef， 10g. Ibid. lodine fonnd. 日71.35 1.06 2.96 1.90 2.01 The above re白ult日泊dicatethat也egood comparab1e data. were obta.ined by this method. Many a.ttempts to determine出。 iodinecontent in the beef were made wi出outsuccess by tbe e1ectric combuRtion method1) owing to the following f加 tors: ( 1.) the iodine content in becf is veηminute， (2.) it w朗 verydi伍cu1t旬 bring about the comp1eもecombustion of beef without a.ny 10自由 of 出esmoke ANew Micr，争analyticalMethod for lodine. 101 produced beca.use the loca.l control of tempera.ture in the electric furna.ce wa.s not po倒iblea.nd ca.used a.n explosin in the furn郎自 whichma.y be contributed加 thepresence of gelatinous a.nd fi叫tysubsta.nce in the be自f. Aga.in 1. la.rge a.rnount of bla.ck 自ootpa.呂田edover to the smoke screen a.nd some rema.in 自rnea.red叫 va.riousjoin旬 ofthe a.ppa.ra.tu自whichcould not be removed e剖 ily. These di飽cultieswere removed in this new mel，hod which ena.bles the control of loca.l hea.ting 0.日well制11.1pa.rts of the a.ppa.ra.tus o.nd o.11ows no bl恥 ksmoke pa回 overbeyond the pla.tinum coil which bring自a.boutthe complete combustion nor a.ny回 otis a110wed加 remainin a.ny pal't of the o.ppo.ra.tu自・Summary. A new micro-analybical method for tll6determination of iodine which is. applicable to va.rioml帥 rnple白， pla.nt制 we11a.s a.nimal ma.tter a.nd others， is pr朗自nted. The merits of the method ma.y b白summarizedas follow自:1.) A miuute quantity of iodine in compara.tively日mall帥 mpleca.n be determined. 2.) The combustion 01 orgn.nic constituenta in出e白ampleis completed aud no bl邸 ksIDoke p副 sesover to the o.bsorption bottle nor o.ny soot rema.in 自mea.redin a.uy p町七oft.he appo.rat.us. 3.) By liquefying the anima.l ma.tter with ca.ustic自oda.and slighUy a.ciui・fying it under c∞ling j聞もbeloresubjected句 combu自tion，prevents any expl伺 ionmay occur in the course of combustion倒 wella.s va.pol'Ization of iodine a.t COO1-pa.ratively lower temperature is rnade pos.ible・4.) By this m自由odit wo.s found that the beef used in this investigation conta.ined a.bout 0.2 P.P.M.制 thedry matter. Literature. 1.) lTANo， A.， lel・ichw<1. dhara ln呂志.f. landw. :Forsch.， VI: 5トー 58.1933. PLATE VIII. Fig. 1. Complete Apparatus. Fig. 2. Cross Section of AppB.I叫us.110'1. .，ーー 5.0.'，1 州，L・ーー一ーー _Lo...~"".L _ ーー・・ーーιU U'院・m幻 I・同 1・・. ???????? ???????ι‘... (o.btI，t・肺開問.1・;..0・t

A New Micro-analytical Method for Iodine

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