S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn I HC THI NGUYN TRNG I HC S PHM -------------------------- PHM TH HNG THI NGHIN CU PHNG PHPPHN TCH VI LNG IOT TRONG CC I TNG MI TRNG Chuyn ngnh: Ho Phn tch M s: 60.44.29 L LU U N N V V N N T TH H C C S S H HO O H H C C THI NGUYN - 2009 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn I HC THI NGUYN TRNG I HC S PHM -------------------------- PHM TH HNG THI NGHIN CU PHNG PHPPHN TCH VI LNG IOT TRONG CC I TNG MI TRNG Chuyn ngnh: Ho Phn tch M s: 60.44.29 L LU U N N V V N N T TH H C C S S H HO O H H C C Ngi hng dn khoa hc: GS. TS TRN T HIU THI NGUYN - 2009 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn LI CM N Ti xin by t lng bit n su sc n GS.TS. Trn T Hiu Trng i hc khoa hc t nhin i hc quc gia H Ni, tn tnh hng dn, gip ti trong sut qu trnh lm lun vn Ti xin chn thnh cm n ThS Trn Thu Qunh khoa Ho trng i hc bch khoa H Ni nhit tnh gip ti trong qu trnh lm thnghimvcnhngkinnggpqubugiptihonthnh lun vn. Ti xin gi li cm n chn thnh ti cc thy c gio trong khoa HohctrngihcSPhmThiNguyncngccbnng nghip gip ti hon thnh bn lun vn ny. Thi nguyn ngy 25 thng 9 nm 2009 Hc vin Phm Th Hng Thi S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn MC LC M U ...................................................................................................... 1 Chng I. TNG QUAN ............................................................................. 3 1.1. Gii thiu v nguyn t iot ...................................................................... 3 1.1.1. Trng thi t nhin ca nguyn t Iot [ 1],[1] ................................. 3 1.1.2. Mt s tnh cht vt l v ha hc ca Iot [1] .................................. 4 1.1.3. Vai tr ca Iot i vi sinh ha ngi [1],[2] .................................. 6 1.1.4. Tnh trng thiu Iot trn th gii v vit nam ............................... 8 1.2. Cc phng php tch v lm giu (sc k-chit) ................................. 10 1.2.1. Cc phng php sc k ................................................................ 10 1.2.1.1. Sc k bn mng ..................................................................... 11 1.2.1.2. Sc k kh ............................................................................... 12 1.2.1.3. Sc k lng hiu nng cao (HPLC) ......................................... 13 1.2.2. Phng php chit ......................................................................... 14 1.3. Mt s phng php nh lng iot ...................................................... 18 1.3.1. Phng php chun [16] ........................................................... 18 13.2. Phng php o ph hp th phn t (Phng php UV-VIS) ...... 18 1.3.3. Phng php quang ph pht x nguyn t plasma (ICP - AES) v ph khi plasma (ICP - MS) ...................................................... 20 1.3.4. Phng php in ho ................................................................... 20 1.3.4.1. Phng php in cc chn lc ion [24] ................................. 20 1.3.4.3. Phng php cc ph dng xoay chiu (AC) .......................... 21 1.3.4.4. Phng php Von - ampe ho tan [25] .................................... 21 1.3.5. Phng php kch hot ntron (NAA) [26] ................................... 22 1.4. Mt s k thut v c ho mu xc nh iot ..................................... 22 1.4.1. K thut v c ho t .................................................................. 22 1.4.2. K thut v c ho bng l vi sng [28] ........................................ 23 1.4.3. K thut v c ho kh [28] .......................................................... 23 1.5. Kt lun phn tng quan........................................................................ 24 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn Chng 2. THC NGHIM ..................................................................... 25 2.1. Dng c v thit b ................................................................................ 25 2.3. Qu trnh thc nghim .......................................................................... 27 2.3.1. Gii thiu v Fucsin baz .............................................................. 27 2.3.2. C ch tng tc gia I2 vi cc cht mu baz hu c. ............... 27 2.3.3. Cc thc nghim kho st .............................................................. 28 2.3.3.1.nhhngcapHnschitcaFucsinbazbng cc dung mi hu c. ............................................................ 28 2.3.3.2.nhhngpHcamitrngnshnhthnhhp cht lin hp ion gia fucsin baz v iot. .............................. 28 2.3.3.3. Kho st ph hp th ca hp cht fucsin baz - iot ............... 29 2.3.3.4.KhostsphthuchpthquangAvolng dung dch HCl 2M ................................................................. 29 2.3.3.5. Kho st s ph thuc lng dung dch NaNO2 0,1M ............ 30 2.3.3.6. nh hng ca lng thuc th fucsin baz. ......................... 30 2.3.3.7.Khostsphthuchpthquangcahpcht mu theo thi gian. ................................................................ 31 Chng 3. KT QU TH NGHIM V BN LUN ........................... 32 3.1.Khostnhhngcaphnschitthucthfucsinbaz bng cc dung mi .......................................................................... 32 3.2.Khostnhhngphcamitrngncnshnhthnh hp cht mu lin hp gia fucsin baz vi iot ............................... 34 3.3. Ph hp th ca hp cht mu fucsin baz - iot .................................... 35 3.4. Kho st nh hng ca lng axit hcl ln phn ng ............................ 36 3.5. Kho st s ph thuc ca lng cht oxi ho NaNO2 0,1M ...................... 37 3.6. nh hng ca lng thuc th ............................................................ 38 3.7. Kho st s ph thuc hp th quang ca hp cht mu theo thi gian ....... 38 3.9. Lp ng chun .................................................................................. 39 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 3.10. Kho st nh hng ca mt s nguyn t. ......................................... 43 3.11.pdngnhngktqunghincucphntchmts mu mi trng: t, nc, trng. ................................................. 45 3.11.1. Phn tch iot trong t. .................................................................. 45 3.11.2. Phn tch iot trong nc................................................................ 48 3.11.3. Phn tch iot trong trng ............................................................... 49 3.12. Cc quy trnh phn tch iot trong cc mu mi trng t, nc, trng. ...... 50 3.12.1. Quy trnh phn tch iot trong mu t ........................................... 50 3.12.2. Quy trnh phn tch iot trong nc ................................................ 51 3.12.3.Quy trnh phn tch iot trong trng ................................................ 51 KT LUN ................................................................................................ 60 TI LIU THAM KHO ......................................................................... 62 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn DANH MC CC BNG Bng 1.1: c im v cc hng s vt l ca Iot ....................................... 5 Bng 1.2: Sphnbhmlngiottrongmitrngtncv khng kh [7] .............................................................................. 8 Bng 1.3: Phn loi mc ri lon thiu Iot ........................................... 10 Bng 3.1: Gi tr A ca dch chit Fucsin Baz bng CHCl3 cc pH khc nhau ca dung dch nc .................................................. 32 Bng 3.2: Gi tr A ca dch chit fucsin baz bng CH2Cl2 cc pH khc nhau ca dung dch nc .................................................. 33 Bng 3.3: GitrAcadchchitfucsinbazbng1,2-dicloetan(C2H4Cl2) cc gi tr pH khc nhau ca dung dch nc......... 33 Bng 3.4: GitrAcadchchithpchtmuFucsinbaz-Iottrong Clorofom cc pH khc nhau trong mi trng nc ..... 34 Bng 3.5: Gi tr A ca dch chit hp cht mu lin hp Fucsin baz - IottrongdiclometantmitrngncccgitrpH khc nhau .................................................................................. 35 Bng 3.6: GitrAcadchchithpchtmulinhpFucsin baz-iottrong1,2-dicloetanccpHkhcnhauca mi trng nc ...................................................................... 35 Bng 3.7: S ph thuc hp th quang (A) vo nng HCl ............... 37 Bng 3.8: Gi tr A ca dch chit hp cht mu Fucsin baz - iot bng 1,2 - dicloetan ph thuc vo lng cht oxi ho NaNO2 .......... 37 Bng 3.9: KtqukhostnhhngcalngthucthFucsin baz .......................................................................................... 38 Bng 3.10:S ph thuc gi tr A vo nng iot ...................................... 40 Bng 3.11:S ph thuc gi tr A vo nng iot ...................................... 41 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn Bng 3.12:Kt qu kho st nh hng ca Br- .......................................... 44 Bng 3.13:Kt qu kho st nh hng ca 3ClO....................................... 44 Bng 3.14: Kt qu kho st nh hng ca Cl- ........................................... 45 Bng 3.15:Kt qu kho st nh hng ca CN- ........................................ 45 Bng 3.16:Kt qu kho st nh hng ca S2- .......................................... 45 Bng 3.17:Kt qu kho st nh hng ca Fe3+ ........................................ 45 Bng 3.18:Kt qu xc nh iot khi x l mu bng phng phpkim chy, phng php ha tan bng Axit ....................................... 47 Bng 3.19:Kt qu xc nh iot trong mu nc khi c cn muv khi x l bng HNO3 37% .............................................................. 48 Bng 3.20:Kt qu phn tch iot di ng trong mu t.............................. 51 Bng 3.21:Kt qu phn tch iot trong mu nc ....................................... 52 Bng 3.22:Kt qu phn tch iot trong mu trng vt .................................. 52 Bng 3.23: Kt qu phn tch iot trong cc mu t i Thi Nguyn ....... 53 Bng 3.24:Kt quphntchiot trongccmutvnvt rung H Ni v Thi Nguyn ......................................................... 54 Bng 3.25:Ktquphntchiottrongmtsmunckhuvc Thi Nguyn v H Ni ............................................................ 55 Bng 3.26:Kt qu phn tch iot trong mt s mu trng H Ni ............ 57 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn DANH MC CC HNH Hnh 3.1: Phhp th cahp cht muFucsin baz - iot ccnng iot khc nhau c chit bng diclometan. ........................... 36 Hnh 3.2: nh hng ca thi gian n bn mu ca hp cht mu lin hp Fucsin -baz -iot (dung mi chit l CHCl3) ................ 39 Hnh 3.3: ng chun xc nh iot bng thuc th fucsin baz ............... 40 Hnh 3.4: ng chun xc nh iot bng thuc th fucsin baz ............... 41 Hnh 3.5: ng chun xc nh iot bng phng php thm ................... 43 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 1 M U Ccnguyntvilngcvaitrquantrngivisckhecon ngi, chng c trong thnh phn ca cc enzym, iu khin s hot ng ca cc c th sng, cho nn cc nguyn t vi lng khng nhng duy tr s sng m cn m bo cho s pht trin ca con ngi c v th cht ln tr tu. Iotlnguyntvilngrt cnchospht trincacthnhqu trnhtnghphocmontuyngip,duytrthnnhit,phttrinxng,qu trnh bit ha v pht trin ca no cng nh h thn kinh ca bo thai. Thiuiotsgyhintngtuyngipkhnglnghocmoncn thit, dn n nng hocmon trongmu thp gy tn thng no v cc c quan khc trong c th. Hin tng ny c gi l ri lon Thiu iot. Theo thng k ca t chc y t th gii (WHO). Hin ti trn ton cu c khong1,5tngisngtrongccvngthiuiotvcnguycmccc chng bnh thiu iot, trong c hn 20 triu ngi mc chng bnh n n. Vit Nam cng nm trong vng thiu iot. theo s liu iu tra quc gia v tnh trng thiuIot nm 1992 cho thyc ti 84% dn s Vit Nam trong tnhtrngthiuiot:trong16%thiunng,45%thiuvav23%thiu nh, khong 10% tr em nc ta b bnh bu c. Mitrng(khquyn,thyquyn,aquyn)vlngthc,thc phm l ngun cung cp Iot cho con ngi.Hng ngy khu phn iot a vo c th di 100g th s xy ra hin tng thiu iot. Bu c v cc bnh ri lon do thiu iot l nhng bnh nan gii. Gii php phng chng hin tng ri lon thiu iot l trn ln iot vo mui n chonhn dn dnghngngy. ivinhng bnhnhnnng dng mui iot khng t c kt qu mong mun, ngi ta phi iu tr bng bin phptchcchnnhtimhaychoungduthcvt cgniot(Lipiodol) hoc cc vin nn c hm lng iot cao theo ch nh ca bc s iu tr. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 2 Khiphntchmitrnghayccngunnc,lngthcvthc phmcamtvngal,ngitathyhmlngcaiottrongcci tng ny c lin quan n t l nhng ngi mc bnh bu c. Bnhbucsinhrakhngphichdohmlngiottrongcci tngkhngkh,ncung,lngthcvthcphmthpmcndocc yu t vi lng khcna. Chnghnhm lng canxitrong t, trongnc qucao,dotpqunsinhhotnungcaccdntc,docacatng ngiv.vVthchonnmtsnimcdhmlngiottronglng thc,thcphmcaonh:HiPhng,ThiBnhvnctlngimc bnh bu c ng k. nhgivilngiottrongt,nc,lngthcvthcphmcn phinghincutmcphngphpphntchcnhy,lpliv chnhxccao,nhccphngphpphntchquanghchini(AAS, AES,) phng php ng hc xc tc, phng php in ha hin i (Von -ampehatan,hp ph,) phng php sc k lnghiunng cao(HPLC), phng php phng x, phng php kch hot Ntron. Songccphngphpnyihiphicthitbchuyndng,t tin, cha ph hp vi a s cc phng th nghim hin c nc ta. Xutphttnhngldotrn,tronglunvnnychngtitcho mnh nhim v nghin cu tm mt phng php phn tch iot n gin c thpdngchoccphngthnghimcs,lphngphptrcquang UV-VISdatrnphnngtophcmucaiotvimt thucthhuc. tng nhy ca phng php chng ti s kt hp vi phng php chit tch v lm giu iot ng thi loi tr nh hng ca lng thuc th d. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 3 Chng I TNG QUAN 1.1. GII THIU V NGUYN T IOT1.1.1. Trng thi t nhin ca nguyn t Iot [1], [1] Nguynnhn conngimcbnh thiuht iotl domi trngthiu iot. Qu trnh chuynhoiot tmi trngvongil qua ng thc n, nc ung. Chu trnh c m t bng s sau: Con ng- i Vt nuiCy trng tN- c S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 4 Nhvycthkhngnhmtiultvngnogiuiotth ncvngcngchmlngiotcao,cytrngvtnuinhng vng cng cha hm lng iot cao. Cui cng con ngi s dng ngun nc,lngthc,thcphmchmlngiotcaothstrnhcs thiu ht iot.Iot tn Hy Lp Iodes, ngha l tm, sau ny hip hi quc t v ha l thuytv ng dnggi lIodine,lnguyn t hahc, khiulI,nguyn t s l 53. Iot l nguyn t vi lng rt cn cho s sng ca cc sinh vt. Iotlnguyntthotngnht,cminthpnhttrongcc halogen. Ging nh cc nguyn t nhm VIIA (h halogen), iot t do thng dng phn t c cng thc I2. Iot cththucdngtinhkhitbngcchunnnghnhpKI vi CuSO4. Iot c th iu ch tngun to b, rong bin vmt s loi cy khc, do chng c kh nng hp th v tch t iot trong c th. iu ch iot tngunnguynliuny,ngitalyrongbinkh,tthnhtroriha tan tro vo nc. sau lc ly dung dch, c dung dch n khi mui kt tinh lngxung(muikttinhlccmuiclorua,sunfat).Gnlyphnnc trong (c mui ca iot). Dng kh clo hay MnO2 v H2SO4 oxi ha I- trong dungdchthnhI2.ChoI2thnghoatasthuciot.Ngunnguynliu chnh iu ch I2 l nc ging khoan du m. Hi iot gy kh chu chomt vmng nhy, khi tip xc vi thi gian ko di = 8 gi trong bu khng kh c nng I2 1mg/m3. Khi thao tc nu dy iot vo da c th gy bng. 1.1.2. Mt s tnh cht vt l v ha hc ca Iot [1] Iot tinh khit c mu tm xm. iot c tnh thng hoa, hi iot c mu tm, mi kh chu v gp lnh s kt tinh li (khng qua th lng). S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 5 Bng 1.1. Trnh by mt s c im v cc hng s vt l ca Iot. Bng 1.1: c im v cc hng s vt l ca Iot Tinh th IotCu to trc giaoTnh cht vt lTrng thi Rnim nng chy 113,7 K (236,660F) im si184,3 K (363,70F) Th tch phn t1.10- 6m3/mol Nhit bay hi (I2)41,57 kJ/mol Nhit nng chy (I2)15,52 kJ/mol m in2,66 (thang Pauling) Nhit dung ring54,41J/ kgK ( 250C) dn in1,3107 O/mk dn nhit449W/mk (3000K) I2 khng cT tnh Nng lng ion ho1. 1008,4 kJ/mol 2. 1845,9 kJ/mol 3. 3180 kJ/mol Cc ng v n nh nht ca iot ISOThi gian bn r DMDE (Mev)DP 127 I~ 100%Rt n nh 129 ITng hp1,57.107 nm | -0,194 129Xe 131 ITng hp8,0207 ngy| - 0,194 131Xe 128 ITng hp25 pht S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 6 IotcnggingnhCl2,Br2ncthtonhiuhpchtvicc nguynthahc,nhngnthotnghnsoviccnguyntkhc trong nhm VIIA v iot c tnh cht hi ging vi kim loi. Iottantrongccdungmihuc:Nudungmihuclcchp chtkhngchaoxinhCHCl3,CCl4,CS2,C6H6,etxng...tothnhdung dchmu tm; nu dung mi hu c trong phn t c cha oxi nh ru, te, xton... to thnh dung dch mu nu. Iot ha tan t trong nc ( 25oC tan ca I2 trong nc l 0,34 g I2/l) toradungdchmuvng.Iot tannhiutrongdungdchnccchaI-v c phn ng I2 +I- = I3-, dung dch I3- c mu nu v c tnh cht ca mt hn hp gm I2 v I-. Iot c phnngvi dung dch tinh bt longto dungdchmuxanh, muxanh s binmt khiunnng dungdch,nhngngui muxanh s xut hin tr li. dung dch tinh bt long c dng lm ch th nhn bit v chun iotHpchtcaiotthnggplccmuinatrivkali:NaI,KI, NaIO3, KIO3,... 1.1.3. Vai tr ca Iot i vi sinh ha ngi [1],[2] ivi conngiiotlnguyn tvilng cck quan trng.Trong c thngi,iot ch chim4.10-5%trnglng c th (15-23mg),nhngn ng vai tr quan trng cho s pht trin ca c th c v th cht ln tr tu.Trn 75%iot trong c th tp trung tuyngip, phn cnlic phn b trong cc m tuyn v, dch tiu ha, thn, nc bt. Iot tn ti dng I- hoc gn vi protein vn chuyn lu thng trong c th. Chc nng quan trng nht ca iot l tham gia to hocmon T3 (triiotothyronin) v T4 (thyroxin). Hocmon tuyn gip ng vai tr quan trng trong vic iu haphttrincth,hotngcahocmontuyngiprtcnchospht S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 7 trin bnh thng ca no, lm tng qu trnh bit ha ca t bo no v tham gia vo chc nng ca no b. Chnh v vy cc hocmon tuyn gip T3 v T4 rt cn cho s pht trin chc nng ca no v h thng thn kinh. Khng iot to hocmon tuyn gip s gy ra ri lon ni tit, cc ri lon ny c biu hin thnh cc chng bnh n n, thiu nng tuyn gip v bnh bu c [3], [4], [5], [6]. Bnhnnxyratrongqutrnhphttrincabothai,thiuiot gyrahintngsythailintip,thaichtluhocatrsinhrabn ndonobtnthngvnhvin,thnkinh,trtuvthcht chmpht trin, c th gy ra cm, ic, ln, kh nng t duy hc tp km v.v... Thiu nng tuyn gip do c th khng nhn hocmon tuyn gip do lnghocmontuyngiptrongmuthp,sinhrabnhvinhngbiuhin chm chp, l , bun ng, da kh v to bn. Bnhbuclhintngtuyngiptohnbnhthng,lng hocmontuyngiptrongmuthp,sinhranhiuhocmonkchthchtuyn gip lm cho tuyn gip phnh to thnh bu. Theokhuynnghcatchcytmingyngitrngthnhcn 150giot,phncthai175g,phnchoconb200g.Liulngln ti 1000 g iot/ ngy c th coi l an ton.Iot c trong thc phm tn ti nhiu dng khc nhau nh: I-, dng iot v c t do, dng hu c... Iot c dng lm thuc kh trng, dung dch iot trong cn c nng 3% dng kh trng vt thng. Ccngvcaiotcsdngnhiutronghahuc,ngnhy. ngv 128Idngtrongyttonhvxtnghimhotngcatuyn gip, ng v 131I c dng iu tr ung th tuyn gip. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 8 1.1.4. Tnh trng thiu Iot trn th gii v Vit NamTrongmitrngiotphnbkhngngu.Hmlnggnng ca iot trong cc thnh phn mi trng c trnh by trong bng 1.2. Bng 1.2: S phn b hm lng iot trong mi trng t ncv khng kh [7] Mi trngNng (ppm)%I Khng kh 0,002 2.10-8 - 2.10-7 Nc sng0,00110- 7 Nc bin0,0110 -6 - 10 -5 Than bn3,43,4.10 -4 t1,81,8. 10-4 Khong0,33.10-5 Nhng khu vc t lin cng xa i dng cng c nguy c thiu ht iot ln. S thiuht iot nghimtrngxyra trnminni cao, cng c khixy ra vng hay b l lt hoc ng bng c cc sng ln. Vng tun hon ca iot trong mi trng c th m t nh sau: iot d b ra tri t t i vo cc ngun nc ri ra bin. T nc bin iot theo nc bchiivokhngkh.Mtphniotctrlit,nctheoma, lng iot c b sung theo ma khng , v vy t v nc nhiu vng lunthiuiot,cbitlccvngnicao.Ccsnphmnngnghipnh lngthc,thcphm,ccgiascchnnui...ccvngnycngmang dunthiuiot.Conngisinhsngbngccloisnphmcngchu hu qu thiu iot, mc chng bnh chung l bu c. *Trnthgii,theonhgicaWHOvUNICEFckhong29% dn s th gii (1570 triu ngi) c nguy c thiu iot, trong t nht c 655 triu ngi b tn thng no; 11,2 triu ngi b n n [8], [9]. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 9 Hinnayc110nccvnthiuiotccvngMLatinh, Chu u, vng Andit v Himalaya ni m iot b si mn bi ma v bng. TiTrung Qucnm1978 clng ti 80%ngi dnmcbnh bu c, 11% b n n. Ti vng ni Jawa (indonexia) lng iot trung bnh thp, c ti 70% ngi b mc bnh bu c (1972). S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 10 * Vit Nam s thiu ht iot mc trm trng. Nm 1993, UNICEF vbnhvinnitittrungngtinhnhkhosttimtsimngu nhintrntonqucbngcchkhmbucvxcnhlngiotniu, ktquchothy94%dnsbthiuiot[10].Cngtheosliuca UNICEF [11] nm 1993 v t l bu c v lng iot niu c thng k trn bn . A = T l bu c (%) BIot niu (g/dl) Da theo kt qu kho st cho thy, cc tnh Lao Cai, Sn La, Cao Bng, Yn Bi, Ngh An l nhng tnh c s ngi mc bnh bu c cao. nh gi mc thiu iot theo iot niu c trnh by trong bng 1.3. Bng 1.3: Phn loi mc ri lon thiu Iot Iot niu (g / dl) Mc ri lon thiu iot < 2Nng 2 - 4,9Trung bnh 5 - 9,9Nh > 10 1.2. CC PHNG PHP TCH V LM GIU (SC K - CHIT) 1.2.1. Cc phng php sc kNguyn tc ca phng php sc k [12] l qu trnh tch lin tc tng phn hn hp cc cht do s phn b khng ng u ca chng gia pha tnh v pha ng khi cho pha ng i xuyn qua pha tnh. ChtlngvhiuqutchcbiudinbngphngtrnhVan-Demter, chiu cao a l thuyt ca mt ct H ph thuc vo tc pha ng. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 11 CUUBA H + + = Trong :A: H s khuych tn xoy ca cc phn t cht B: H s khuych tn phn t C: Tc trao i gia 2 pha U: Tc tuyn tnh ca pha ngChiu cao H cng nh th hiu qu tch cng ln. Tng s a l thuyt ca mt ct tch n c tnh bng chiu di l ca ct (c nh) chia cho chiu cao a l thuyt H.=lnH Phng php sc k c phn chia nh sau: - Theo c ch tch (hp ph, phn b, trao i ion) - Theo s phn loi cc pha trong sc k (lng - lng, lng - kh, lng - rn). - Theo cng c s dng tin hnh (sc k bn mng, sc k kh, sc k lng hiu nng cao).1.2.1.1. Sc k bn mngQu trnh tch hp cht bng sc k bn mng xy ra khi cho pha ng di chuyn qua pha tnh. Cht hp ph trong pha tnh sc k bn mng c rithnhmtlpmngtrntmknhhoctmkimloi.Cccutc dchchuyntrnlpmngtheohngphangvitckhcnhau.Kt qu thu c mt sc trn lp mng [12].Cc i lng c trng cho sc k lp mng l:*HsdichuynRf:ltscakhongcchttuynxutphtti tm vt sc k (I) v khong cch t tuyn xut pht ti tuyn dung mi (Io): 0=fIRIOsRs 1 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 12 GitrRfctrngchostngtcgiahotcht-dungmi- chthp th. nhgi khnng tchccvt trn sc ta dng2i lng sau:+ ARf l hiu gi tr Rf ca 2 cu t ln cn nhau.+Klhstchctnhbngtshsphnbca2cutA (KA) v B (KB): ABKKK= *Chthpph(phatnh)csdngtrongsckbnmnggm silicagen, oxit nhm, xenlul, tinh bt, nha trao i ion.* Dung mi (pha ng) dng chy sc k bn mng, thng l dung mihuchayhnhpdungmihuc,chnghnnhheptan;CHCl3 hoc hn hp heptan - clorofom, propanol - CHCl3 - benzylamin [13], [14]. nctasckbnmngcpdngnhiutrongphntchmi trng, nhng cha c cng trnh no p dng cho vic tch iot [13]. Trnthgii,phngphpscklpmngcpdngtrong nhiu lnh vc nghin cu, v cng c s dng trong phn tch iot [13]. 1.2.1.2. Sc k khLqutrnhtchccchttrongcttchtrngthikh,chtmang mu l cht kh. V vy ch c th tch c hn hp cc kh, nu l hn hp cht lng hay cht rn th phi ho kh . Thng ch tch c cc cht rn dho kh ( = 2500C) [12]. Trong sc k kh, phatnh l cht rn, cnpha nglmt cht khhayhnhpkh.Cht khnymangkhcnphntch voctthchinqutrnhtch,nchuynnglintctrongsutqu trnh tchvi tc xc nh. Pha tnh ngvai tr chnhtrongvic tonn tng tc cn thit tch cc cu t khi nhau. S thay ipha tnhv cc S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 13 thng s lmvic s nhhng n tng tc gia khmang, cht mang rn vcutcntch.KhmangdngtrongsckthnglN2,H2,He phn tch lng vt, kh mang phi tinh khit (99,99%). Vt liu lm ct trong sc k kh c th lm bng kim loi hay thu tinh.Phngphpsckkhlmttrongnhngphngphphinnay csdngnhiutrongphntchmitrng,ncthigianphntch nhanh, nhy cao, hiu qu tt. Bonner v cc cng s dng mui grafit c din tch bmt ring 100m2/glm cht nhi ct. Dng ct ny pht hin c cc kh c c cha lu hunh nh: SO2, H2S, (CH3)2Svi hm lng ch my chc ppb. Phngphpsckkhcngcdngxcnhthnhphndu m v cc sn phm ca chng. Ngoi ra cng c dng phn tch lng thc, thc phm, cc loi dc phm.v.v...1.2.1.3. Sc k lng hiu nng cao (HPLC) Phng php ny dng cc cht nhi ct nh mn, ct cng c kch c nhnnthchinqutrnhtch,phidngpxut caoychtlng quact.Chnhnhngiukinlmchophngphpnycnhiuu im hn so vi sc k lng c in l tc nhanh, tch tt, nhy cao (v d dng detector UV - VIS th nhy t 10-9g, dng detector hunh quang,inhot10-12g)cttchdngcnhiuln,muthulidv khng b ph hu [12], [15].HPLCcsdngrtrngriphntchnhiuitngkhc nhau. HPLC c kh nng tch c c cc hp cht.+ Cc hp cht cao phn t, ion thuc cc i tng sinh hc, y hc + Cc hp cht khng bn+ Cc hp cht d n, km bn nhit, v.v S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 14 Phng php HPLC l mt trong nhng phng php tch, xc nh iot vccnguynthalogenttnhttrongccphngphpphntchhini, t nhy, chnh xc cao, c th xc nh nhiu cht trong cng mt mu.1.2.2. Phng php chitHmlngiottrongt,nc,lngthc,thcphmnichungrt thpcppb-ppm,vvyngitathngdngphngphpchitlm giu, tng nhy, chn lc v chnh xc ca php xc nh.Nguyn tc ca phng php chit da trn s tch cht bng cc dung mihuc,dotancachttrongccdungmikhcnhau.Nuhotan cht A vo 2 dung mi khng trn ln (thng l nc - nc v dungmi hu c - hc), khi cn bng nng cht A trong 2 dung mi s tun theo nh lut phnbNerst:mtpxutvnhitnhtnh,nuchttanAkhng phn li hoc lin hp trong 2 dung mi th t s nng cht tan trong 2 dung mi l mt hng s (gi l hng s phn b D0). | || |hconcADA=Trong [A] nc, [A] hcl nng cn bng ca cht A trongpha nc v phahu c. D0 cngln th cht chuynvo phahu c cngnhiu.Mt cch chnh xc.nchcAAoaaD = aAhc, aAnc l hot ca cht A trong tng hu c v tng nc.Ngoi hng s phn b D0, ngi ta cn dng khi nim chit R. chit R c xc nh bng t s gia khi lng G ca cht chit A so vi khi lng ban u G ca n. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 15 'ooG D%R 100% 100%G D r= = + Trong :nchcVrV= ; Vnc v Vhc l th tch pha nc v pha hu c (ml)Ngi ta chia cht chit A ra lm cc loi sau:* Cht chit A khng in ly, khi s phn b A vo 2 tng:AncAhc trng thi cn bng,hng s phn bv chit c tnh theo cc cng thc n gin trn.* Cht chit A l cht in li Khi cht chit A l cht in ly v d A l mt axit yu, qu trnh phn b tr nn phc tp v phng trnh cn bng gia 2 pha: HAncHAhcH+ + A- | |+ (( =ncH AKaHA (hng s phn ly ca axit)| || |0 =hcncHADHA; +01001r[H ]D=+aRK Hsphnbtrongtrnghpnyltsnngttcccdng trong pha hu c v tt c cc dng trong pha nc.hc 0nc+[HA][HA] [A]1[H ]= =++aDDK Nu [H+ ] >> ka th Ka/[H+] = 0 khi D = D0 Tng t nh vy khi A l mt baz yu ta cng tnh c D v R ca dung dch kim. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 16 * Chit cht lng tnhHngsphnbvchitcachtinlylngtnhphthuc vo pH kh phc tp v cht in li lng tnh s tn ti nhiu dng trong c 2 pha.Khi trng thi cn bng, khi lng G ca cht in ly lng tnh A l: G = E [Ayx ] hc. Vhc + E [Ayx ] nc. Vnc

yx hc hc(A ) .VRG= Hng s phn b D s c tnh theo phnliv tnti c th tng cht gia 2 pha.* Chit tp hp lin hp ionVic chit linhpion chxy ra pHxc nhv tphpion ch c khnngthchinpHmticcthnhphn(tcaxithaybaz)ng thi tn ti. m bo chit tt, cht b chit phi b solvat ho yu bi cc phn t H2O v tan tt trong dung mi chit.Cht b chit l lin hp ion th n b chit cng tt nu nhng cation v anion trong thnh phn cng k nc.Nhnglinhpion to bi mt cationvmt anionv c bit lion mt in tch lun b chit tt hn nhng lin hp ion c thnh phn khc.Bng tnh ton ngi ta thy c th chit cc ion v c mt cch thun libngcchchonlinktviccphi thuctothnhnhngtp hpionmtrnminvintchckhong10-15nguyntcabon. Ngi ta chia chit lin hp ion thnh my loi sau: S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 17

(((((N N Co 2+ SCN- 2 SbCl6 _

(((((+ N(C2H5)2(C2H5)2N+

(((((Nguyn t c mu Phit Anionv c khng mu (1) Nguyn t khng mu Phit Anionhu c c mu (2) Nguyn t

Thuc th hu cc gc SO3- Cation hu c (3) Anion phc caKim loi

Cationhu c (4) Co 2 SO3OO=NSO3_ _ + N ( ( ( ( (

(((((_ N O I I Er 4 + ( ( ( ( ( COOC2H5HN NHO S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 18 Phnngtolinhpionlcscaccphngphptrcquang, chittrcquang,hunhquangxcnhnhiukimloi.Nichungcclin hpionthngchshpthmoltngilnnnrtnhyvvycho php xc nh lng rt nh cc cht.1.3. MT S PHNG PHP NH LNG IOT1.3.1. Phng php chun [16] Nguyn tc chung caphng phpnyl chuyn tt c cc dng ca iot c trong mu phn tch v dng I-, sau dng iodat IO-3 oxi ho I- v dng I2, chun lng I2 gii phng bng dung dch chun Na2S2O3 vi ch th h tinh bt.5KI + KIO3 + 3H2SO4 = 3I2 + 3K2SO4 + 3H2O I2 + 2Na2S2O3 = 2NaI + Na2S4O6 Phngphpnycnhythp,chdngphntchiotvihm lng ln 5 - 50mg.uim ca phngphpnyl dthaotc, khng cnmymct tin, nhanh. Zhao Guiging v cng s [17] lp h thng chun t ng; ghpnivimy tnh, tm cch chun Cl-, Br -, I- trongnc t nhy v lp li cao.1.3.2. Phng php o ph hp th phn t (Phng php UV-VIS) Nguyn tc ca phng phpnyl chuyn cc dngiot c trongmu phntchvdngI-,saudngNaNO2oxihoI-thnhI2,chit I2sinhra bngCCl4,toluen,sauohpthquangcadungdchmax= 657nm. Bng phng php chit ny lm tng nhy ln n 10-6mol/l. [18]BulinskiRvcngs[19]dngN-Ndi(|-Hidroxipropyl)-o- phenylene diamin xc nh iot trong sa v trong kh, phng php ny c nhycppmvhngchcppb.SalinaoFvcngs[20]dng2- S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 19 oximiodimedonevdithiosemicacbazonlmthucthxcnhIO-3v BrO3-;obcsng400nm, phng php xc nh c 0,24 - 5g IO3-/ml v 0,16 - 3,6g BrO-3/ml. CcbovmitrngvhiphibovsckhoHoaKxc nh I- bng cch dng KHSO5 oxi ho chn lc thnh I2, I2 sinh ra cho phn ngvi4,4,4-metyliclynetris(N-N-dimetylanilin)(thnggilthuc thLeueoCrystalViolet-khngmu)tothnhhpchtmutmm. Phng php ny c dng lm phng php tiu chun xc nh iot. Phchpthcci=592nmvkhongtuntheonhlutLambert-beer l 50 - 600 g/l xc nh vi lng iot ngi ta thng dng phng php trc quang nghcxctcdatrnphnngoxihokhgiaCe(IV)vAs(III) trong mi trng axit. [21] Ce (IV) + As (III) 2 4IH SO Ce (III) + As (V) (mu da cam)(khng mu) (khng mu) (khng mu) Hm lng iot trong mu c xc nh bng s gim hp th quang.(=370nm)AAcadungdchtrcvsauphnngvithigianc nh, khi c mt cht xc tc l iot, AA t l vi nng ca iot trong dung dch. NgitacngdavophnnggiaclopromazinviH2O2[22].Khi c mt iot to ra sn phm trung gian c mu , bn trong mi trng axit v hpthcciti=525nm.TcphnngtlvinngI-trong dung dch.Phng php ny c u im l xc nh c ring r cc dngI-, IO-3vcsdngrngriphntchiottrongmunc. Phng phpnyt c s dng phn tchiot trong cc i tnglng thc v thc phm bi v trong cc i tng ny rt phc tp, lm gim hiu ng xc tc ca iot. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 20 1.3.3. Phng php quang ph pht x nguyn t plasma(ICP - AES) v ph khi plasma (ICP - MS) ViphngphpICP-AES,musaukhichuynthnhdungdch, cbmtrctipvongunkchthchplasma(ICP)cnhitkhong 60000C,nhitmubnguynthohontonvbkchthchri pht ra bc x c bc sng xc nh. o cng bc x (Ipx) ti bc sng c trng cho nguyn t cn xc nh (l iot), t suy ra hm lng ca iot c trong mu.ViphngphpICP-MS,mucngcbmtrctipvongun plasma ICP, nguyn t b ion ho, cc dng ion c a vo h phn tch khi lng tch cc ion da vo t s mZ (m, z l khi lng v in tchion).Dngionsaukhitchcavodetectorchuynthnhtn hiu nh lng.Tcgi[23]dngphngphpICP-MSnhlngiottrong nc tiu vi khong tuyn tnh 0,1 - 10g I-/dl. Phng php ICP - MS cng nh phng php kchhot ntron(NAA) c xeml phng php chun vng nh lng vt v siu vt iot1.3.4. Phng php in ho1.3.4.1. Phng php in cc chn lc ion [24] in cc chn lc ion dng trong phng php o th nh lng iot linccmngrn,cchtotAgI/Ag2S,ccutrcnhsau:Ag/ AgCl/KI 0,1M/ mng rn AgI + Ag2S / dung dch phn tch / KCl/AgCl/Ag.Th o c ph thuc vo lg [I-]. Phng php ny b Cl- v SO32- cn tr v vy phi tch cc ion ny khi dung dch trc khi o. Trong qu trnh oiot,inccthngbmtmngbaophnnphilmschmngph trn in cc. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 21 Phng phpny c dng xc nhiot trongH2O. Cmt s tc gi dng xc nh iot trong nc tiu, sa nhng kt qu km chnh xc.1.3.4.2. Phng php cc ph dng mt chiu (DC) Trongphng phpny, ngi ta chuyniot trongmuthnh IO-3 sau ghi cc ph DC ca ion IO3- trong nn NaCl hay KCl. IO3- b kh trn cc git thu ngn theo phn ng.IO3- + 6H+ + 6e = I- + 3H2O Qutrnhphnnginhocsthamgiaca6ennphngphp nycchnhxckhcao.Phngphpnychophpxcnhnhng nng iot c 10-6 M.1.3.4.3. Phng php cc ph dng xoay chiu (AC) PhngphpnydavotnhthunnghchcaqutrnhoxihoI- thnh I2. 2I- + 2eI2 Chiu cao pic t l vi nng I-. Dng phng php ng chun v phng php thm nh lng I-.1.3.4.4. Phng php Von - ampe ho tan [25] Trong phng php ny, I- c tch lu trn b mt in cc git thu ngn tnh dng Hg2I2 bng mt th in phn trong mt thi gian nht nh. Sau Hg2I2 tch lu c ho tan bng qut th catot. Qu trnh ho tan in ho s to pic th - 0,33v (vi in cc so snh l in cc calomen). Chiu cao ca dng pichotanHg2I2 tlvinng I- trong dung dch. Phng php ny xc nh c I- trong khong 0,13 - 10,2g I-/l. AnionS2-cntrphpxcnh,loitrS2-bngcchaxitdungdch S2- to thnh H2S, ri sc khng kh ui ht H2S, sau chnh pH dung dch v 8 ri mi tin hnh phn tch. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 22 PhngphpVon-ampehotancthxcnhlngnhiot,cho kt qu nhanh, chnh xc, lp li cao. Song phng php ny khng c dngphntchccmulngthcvthcphmv nhhngcann qu ln, kt qu phn tch khng chnh xc. Ch yu l dng phn tch I- trong nc.1.3.5. Phng php kch hot ntron (NAA) [26] Trongphngphpny,ngitathngdngngvphngxca iot 128I c thi gian bn hu ngn (25 pht) phn tch iot.Nguyntccaphngphpnyldngmtchmntronkchhot vo mu phn tch v o bc x gama c gii phng bi 128I. Gii hn pht hincaphngphpnykhong91ppb.Mcdphngphpkchhot ntron c nhy cao, nhng nh hng ca cc nguyn t i km l rt ln nh 56Mn, 27Mg, 24Na, 28Al v 43K.Cc nguyn t phng x ny cng pht ra mc nng lng nh 128I. loi tr nhhng ca ccnguyn t phngx trn,ngi ta thngnghin cu s dng cc ngun kch hot v thi gian kch hot khc nhau.1.4. MT S K THUT V C HO MU XC NH IOT 1.4.1. K thut v c ho t Nguyn tc chung ca k thut nyl dng cc axitmnh, cc axit c tnhoxihomnh,hnhpccaxithochnhpaxitcvmtchtoxi ho phn hu mu.xcnhiot trongthcphm,tcgiTakashi[27]sdnghn hpHNO313M+HClO49M+H2SO418Munnhit 2300Cvc homu.Sauiotcxcnhdatrnhiungxctccaphnng gia Clopromazin vi H2O2 trong mi trng H2SO4 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 23 Phngphpvchotkhngphhpchophntchhnglot mu v thi gian x l ko di, phi s dng mt lng ln axit nn c nguy c b nhim bn.1.4.2. K thut v c ho bng l vi sng [28] C ch ca s phn humu bng l vi sng l s dng nng lng vi sng un nng dung mi v mu c ng trong bnh kn.Phnhumubnglvisng,lngaxitdngthn,thigianphn hungnhn,mbocht phntchkhngbmtvkhngbnhimbn do mi trng bn ngoi.1.4.3. K thut v c ho kh [28] K thut v c ho kh l k thut nung mu trong l nung nhit 4500- 7500 (tu thuc vo bn cht v lin kt tng loi mu m chn nhit thch hp). Khi nung cc cht hu c c trong mu s b t chy thnh CO2 v hi H2O.Saukhinung,cnhotancnli cxl tipbngdungdchaxit haymuiphhpchuynhtchtphntchtrongcnhotanvodung dch, sau xc nh cht phn tch theo phng php chn.- K thut v c ho kh gm 2 loi:* V c ho kh khng dng tc nhn v c ho mu L qu trnh x l s b mu bng cch nung mu mt nhit thch hptrongmt thigiannht nhphvcutrcdngbanucamu phn tch, t chy cc cht hu c chuyn n sang mt hp cht khc n gin, d tan bng cc dungmi thch hp (dung dch axit, kim) a hon tonchtcnphntchvodungdch,sauxcnhchtphntchtheo phng php chn.Phngphpny khng dng c i vinhng cht d bayhi khi nung, lm mt mt lng cht phn tch, kt qu s sai. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 24 * V c ho kh c dng tc nhn v c ho mul qu trnh xl munhtc dng canhit(500 -7000C)v c thm cc tc nhn v c gim nhit nung, hn ch smt mt camt s nguyn t. xc nhiot trong ccmu sinhhc,ngi ta thng dng phng php v c ho kh bng cch nung mu nhit ~ 6000C vi cc tc nhn vchonh:KOH,K2CO3,Na2CO3+ZnO4,Na2CO3+KNO3,KClO3+ Glycin + Na2CO3 Saukhinung,hotanmubngdungdchaxit,lclydungdch nhlngiot.ChkhilcdungdchkhngdnggiylcWhatmanv giy lc ny c th hp ph iot.1.5. KT LUN PHN TNG QUANIotlmtnguyntvilngquantrngtrongdinhdngngiv ngvtnichung.Trongcthngiiotcphnbnhiutchc khc nhau nh mu, sa, nc bt, nc tiu, tcThiuiot sgy rilon c th, biuhinquamt s chng bnhnh bu c, n n, thn kinhMi ngy mi ngi cn 200g iotNgun cung cp iot cho ngi l nc sinh hot, lng thc, thc phm.nhgivilngiottrongnc,t,lngthcthcphm.Cn phiphntchthngxuyn.Phngphpphntchkhngnhngc chnh xc, nhy cao m cn phi ph hp vi c s vt cht hin c trong nhiu phng th nghim.Vildotrnchngtichnphngphptophcmucaiotvi thuc th Fucsin baz ri o bng cc my o mu thng thng m hu ht ccphngthnghimcsuc.Theochngtinghhnggiiquyt ny c thc thnmc d nhy ca phng phpny c kmhn so vi ccphngphpphntchhininhAAS,AES,inho,kchhot ntron, ng hc xc tc.. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 25 Chng 2 THC NGHIM nhgimcthiuhtiotiviconngi,cnphntch nh gi hm lng iot c trong t, nc v trong lng thc, thc phm.Vi mc ch , ng thi xy dng c phng php phn tch c th s dng rng ri, trong lun vn ny chng ti t ra nhim v sau:1- Nghin cu phng php o quang phn tch hm lng iot bng phn ng n gin d thc hin.2- Nghin cu xy dng quy trnh phn tch iot trong mt s i tng mi trng: t, nc, thc phm.3- Dng phng php thm v phng php thng k xc sut nh gi cc kt qu phn tch thu c.2.1. DNG C V THIT B- Phu chit dung tch 125ml- Cc loi bnh ng mc 25ml, 1000ml. - Pipet cc loi- Cc dng c thu tinh khc.- Cn phn tch chnh xc n 0,02mg- My o pH - My o hp th quang JASCO V - 530 UV - VIS Spectrophotometer ca Nht. My thit k o c gii ph hp th t 200 -1100nm. Ngun n deterium khi o ph t ngoi (200 - 400nm), nu o vng ph kh kin (400 - 1100nm) th dng n halogen.nh sng ca ngun c hi t v i vo b phn to n sc bi cch tv hi t khe ra. Ngun sngny c chia thnh hai tia,mt tia i qua dung dch phn tch, mt tia i qua dung dch so snh. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 26 nhsngitidetetorchuyntnhiuthnhtnhiuin,saukhi c chnh ng b, chuyn thnh tn hiu s i vo b vi x l. Tn hiu sau khi c x l bng b vi x l v hin th d kin di dng s hng ph.2.2. CC VN NGHIN CU- Bn cht ca phng php m chng ti nghin cu l IottrongmitrngphnlnnmdngI-,dngNaNO2oxiho chuyn v dng I2. Di tc dng ca cc baz hu c c mu nh mtyl tm, malachitxanh,brilliantxanh,Fucsinbazphntiotbphncc,slin kt tnh in vi phn t Fucsin baz to thnh lin hp ion, mu ca lin hp ionnygingvimucathucthFucsinbaznhngFucsinbazlhp cht phn cc, cn lin hp ion l hp cht khng phn cc.Vytacthdngphngphpchittchlinhpionravo mu, t tnh c hm lng iot c trong mu phn tch.Trncslplun,qutrnhnghincucachngticthc hin theo cc bc sau:- Kho st nh hng pH ca mi trng n qu trnh chit thuc th v cc dung mi hu c.-Sdngphngphpcnhmtthnhphn[29]khostnh hngpHcamitrngncnstothnhhpchtlinhpionv kho st lng thuc th ti u.- Kho st ph hp th ca hp cht lin hp ion- Kho st kh nng chit hp cht lin hp ion- Kho st cc yu t nh hng n s to thnh hp cht lin hp ion.- Kho st khong tuyn tnh ca hp th quang A v nng iot. -Sdngphngphpthmvphngphpthngkxcsut kim tra ng v chnh xc, xc nh LOD, LOQ. - Xy dng quy trnh phn tch. - Xc nh hm lng iot trong mu gi v mt s mu t, nc, thc phm S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 27 2.3. QU TRNH THC NGHIM C TIN HNH NH SAU 2.3.1. Gii thiu v Fucsin baz 2.3.1.1. Tnh chtFucsin baz l nhng tinh th xanh l cy sm, sng nh ho tan trong 100g dung mi: nc 0,26g (260C), ru 5,9g (250C). Tantthntrongncnngchodungdchmuhng,dungdchnyc hp th quang cc i = 487,1nm v 543,9nm. Kt tinh t dung dch nc c ngm 4 H2O. 2.3.1.2. ng dngDung dch sunfua Fucsin (thuc th anhit) dng xc nh brm v cc cht oxi ho bng phng php o quang. Ngi ta nghin cu phn ng mu ca fucsin baz vi SO2[30].SdngFucsinbazxcnhAuCl-4,TaF5-[31]bngphng php chit trc quang.2.3.2. C ch tng tc gia I2 vi cc cht mu baz hu c Tngtcgiaiotvccchtmubazhucnhtmtinhth, malachitxanh,brilliantlc,rodanin,fucsinbazkhngphilphnng traoi,axitbazhayoxihokhv.vmlphnngtolinhpion. Cc chtmu bazhu cl cc cht phn ccmnh[32], khi chng tng tc vi I2, lm cho phn t I2 phn cc I+o - I -o do s chuyn di ca cc in t trong phn t. Hai phn t cht mu baz hu c v iot u phn cc, cc cc tri du s ht nhau do lc ht tnh in to thnh hp cht lin hp. Cc dng ca phn t iot phn cc tng tc vi cc m ca phn t cht mu baz hu c v cc m ca phn t iot ny s tc dng vi cc dng kia ca phntthuc th, bivkhong cchgia hai u cc ca phn tiotngn hngiahaiucccaphntthucth.Phntiotnmgntrongl hng ca cc phn t thuc th gn nh theo c ch hp ph ca lc ht tnh S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 28 into thnh thp cht mubaz-iot.Thplinhpmuny ddng bchitbiccdungminhbenzen,toluen,diclometan,dicloetan, tetracloruacacbonTrongkhiccphntthucthliphnccnn chng khng b chit bi cc dungminy.Li dng tnh cht ny ta c th dngccdungmikhngphnccchittchhpchtlinhpiongia iot vi chtmu bazhu c khi thuc th d. Chnhv vyphnngny c chn lc tt.2.3.3. Cc thc nghim kho st2.3.3.1. nh hng ca pH n s chit ca Fucsin baz bng cc dung mi hu c Ly3mldungdchfucsinbazvodyphuchit,sauthmvo mi phu 5ml dung dch m c pH = 1, 2, 3, 4, 5, 6. Thm nc ct n th tch25ml.Thmcnthn5mldungmihuc,yphuchitbngnt nhm, lc k trong mt pht.yntchpha.Tchphahucvobnhnhmc25ml.Tin hnh chit li 2 ln na, mi ln bng 5ml dungmi hu c. Thm dung mi huctivch,lcvtrnu.ohpthquang(A)cadchchit Fucsin baz ti bc sng hp th cc i ca hp cht fucsin baz - iot. Ghi cc kt qu thu c v bin lun trong mc bn lun kt qu thc nghim.2.3.3.2.nhhngpHcamitrngnshnhthnhhpchtlin hp ion gia fucsin baz v iot Chun b mt dy dung dch c pH thay i, cn tt c cc cu t khc u nh nhau. Ly 5ml dung dch KI 1mg/l, 1ml dung dch NaNO2 0,1M. 1ml dung dch HCl 2M v 3ml dung dch Fucsin baz. Thm tip 1ml NaOH 2M trunghovi 5mldungdchmcpH=1,2,3,4,5,6vophuchit c nh s t 1, 2, 3, 4, 5, 6. Thmnc ct ti thtch 25ml vlc trn. Tinhnhchithpchtlinhpfucsinbaz-iot3ln,milnbng5ml S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 29 dungmihuc.Dchchitcthuvobnhnhmc25ml.nhmc dch chit bng dungmihu c, lc trnu. o hp th quang(A) ca dung dch thu c ti bc sng hp th cc i ca hp cht lin hp fucsin baz v iot.2.3.3.3. Kho st ph hp th ca hp cht fucsin baz - iotChunbmtdydungdchchunbngcchlyvodyphuchit nhng lng dung dch nh sau: S dung dch 123456 Th tch dung dch KI 1mg/l012345 Thmvomi phu chit 1ml dung dchNaNO2 0,1M, 1ml dung dch HCl 2Mlc trn, thm tip 3ml fucsin baz, thmtip 1ml dungdch NaOH 2M trung ho, 5ml dung dch m pH = 4, pha long bng nc ct n th tch 25ml.Tin hnh chit hp cht lin hp fucsin- baz- iot 3 ln, mi ln bng 5mldungmihuc.Dchchitcgomvobnhnhmc25ml.nh mctivchbngdungmihuc,lctrnu.ohpthquang(A) ca tng dung dch trong khong bc sng t 450 - 600nm. Biu din s ph thuc(A)=f()tacphhpthcadchchit.Txcnhc max ca hp cht lin hp fucsin -baz - iot.2.3.3.4.KhostsphthuchpthquangAvolngdungdch HCl 2M Chun b mt dy phu chit, ly vo lng HCl 2M t 0; 0,5; 0,8; 1; 1,5;2ml,thmvomiphu5mldungdchKI1mg/l,1mldungdch NaNO20,1Mlcu,thm tipvomiphu3mldungdchfucsinbaz, dng dung dch NaOH 2M va trung ho lng axit d ri thm vo mi phu5mldungdchmcpH=4,phalongbngncctnth S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 30 tch25ml.Tinhnhchit3ln,milnbng5ml1,2-icloetan.Dch chitcthuvobnhnhmc25ml.nhmcbngdungmihuc ri o A ca dy dung dch bc sngmax va tm c trn. Kt qu thu c s cho thy lng axit ti u cn dng.2.3.3.5. Kho st s ph thuc lng dung dch NaNO2 0,1M NaNO2 dng oxi ho I- thnh I2 vy lng NaNO2 dng bao nhiu l v khi th c nh hng g khng. Chng ti thit lp th nghim sau:Ly 5ml dung dch KI 1mg/l cho vo 6 phu chit sch c nh s th t.ThmlngNaNO2 0,1Mlnltvoccphuchitnhnglngnh sau: 0; 0,2; 0,4; 0,8; 1,2; 1,6 ml. Thm vo mi phu 1ml dung dch HCl 2M lcu,thmvomiphu3mldungdchfucsinbaz,1mldungdch NaOH 2M trung ha, 5ml dung dch m c pH=4. Thm nc ti 25ml. Tinhnhchithpchtmu3ln,milnbng5mldungmihuc. Dch chit c 3lncgomvo bnh nhmc25ml.nhmcti vch bng dung mi, lc trn, em o A ca dy dung dch max va tm c th nghim trn.2.3.3.6. nh hng ca lng thuc th fucsin baz. I2 to hp cht lin hp ion hon ton cn dng d thuc th fucsin baz. Lng fucsin baz d khng b chit (th nghim 3.1). Tuy nhin kho st lng thuc th bao nhiu th va, chng ti tin hnh th nghim sau: Ly 5ml dung dch KI 1mg/l, 1ml dung dch NaNO2 0,1M v 1ml dung dch HCl 2M cho vo 6 phu chit sch c nh s th t thm vo cc phu theo th tlng dung dchfucsin baznhnglng khcnhau: 0,5; 1; 1,5; 2; 2,5; 3ml,trunghodungdchbngdungdchNaOH2M,thm5ml dung dchmcpH=4.Tinhnhchithpchtmu3ln,milnbng5ml dung mi hu c. Gp dch chit c li vo bnh nh mc 25ml, ri nh mc bng dung mi. Tin hnh o A ca dy dung dch. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 31 2.3.3.7.Khostsphthuchpthquangcahpchtmutheo thi gian Ly5mldungdchKI1mg/l,1mldungdchNaNO20,1M,1mldung dchHCl2M,3mldungdchfucsinbaz,lcudungdch,hodungdch thucbngdungdchNaOH2M.Thm5mldungdchmcpH=4. Tin hnh chit hp cht mu 3 ln, mi ln bng 5ml dung mi hu c. Dch chitthucnhmcthnh25mlrioAcadungdchtheothigian (tnh t sau khi chit xong): 5, 6, 7, 8, 9, 10, 15, 20, 30, 40 pht.2.3.3.8. Lp ng chunTng hp tt c cc iu kin ti u m chng ti kho st c, chng ti tin hnh xy dng ng chun biu din s ph thuc A vo lng iot.2.3.3.9. Kho st nh hng ca mt s cation v anion n phn ng S dng cc kt qu kho st c trong cc th nghim trn, chng ti tin hnh kho st nh hng ca mt s cation v anion n phn ng.Phng php nghin cu ca chng ti da vo nguyn tc c nh cc iu kin ti u ca phn ng, thm dn cc yu t gy nh hng vo ri tm s ph thuc hp th quang ca dung dch theo hm lng yu t gy nh hng thm vo A = f (yu t nh hng). Tbinluntmctlnothyutlgynhhngcho phn ng v tm bin php loi tr. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 32 Chng 3 KT QU TH NGHIM V BN LUN Cc kt qu ghi trong cc bng l kt qu trung bnh ca 3 ln o3.1.KHOSTNHHNGCApHNSCHITTHUCTHFUCSIN BAZ BNG CC DUNG MIFucsinbazlphntphnccnnnkhngbchitbiccdung mihuckhngphnccnhBenzen,Tetracloruacacbonkhichit Fucsinbazbngtetracloruacacbon(CCl4),phahuchontonkhngc mu tt c cc gi tr pH kho st, chng t Fucsin baz khng b chit bi CCl4.KhidungmihuclClorofom(CHCl3),phahucchitc khng c mu cc pH tr gi tr pH = 2, dch chit c mu hng nht. i vi dungmi chitldiclometanv1,2-icloetan,dchchitcmuhng m pH s 2, cc pH kho st cn li, dch chit c mu hng rt nht. Khi chit bng hn hp dung mi diclometan: clorofom vi cc t l theo th tch l 1:4; 1:3; 1:2; 1:1; 2:1; 3:1; 4:1 th cng ch pH = 2 lp chit mi c mu hng cn trong mi trng pH t 3 n 6 lp chit hu nh khng c mu. S chit fucsin baz bng cc dung mi hu c phn cc ph thuc vo pH dung dch nc c ghi trn cc bng t 3.1 n3.3.Bng 3.1: Gi tr A ca dch chit Fucsin Baz bng CHCl3

cc pH khc nhau ca dung dch nc pH123456 A551nm0,0190,0400,0180,0160,0180,020 Cc s liu ghi trong bng 3.1 cho thy, trong khong pH kho st (t 1 n 6) thuc thfucsin baz hunh khng b chit bi CHCl3 v cc gi tr hp th quang A u nh (tr pH = 2 dung dch cmu hi hng nht). Vi kt quny cho thynu chit bngCHCl3 th thuc thfucsin baz d khngbchit,nhvythucthdkhngnhhngnqutrnhphn tch khi chit hp cht mu. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 33 Bng 3.2: Gi tr A ca dch chit fucsin baz bng CH2Cl2

cc pH khc nhau ca dung dch nc pH123456 A537nm0,1020,1960,0220,0390,0450,036 Ccsliughitrongbng3.2chothy,trongkhongpHt3n6 thuc th hu nh khng b chit nn nu tin hnh th nghim trong khong pHny,thucthdkhnggynhhng,cnpHt1n2thfucsin baz c b chit v vy khng nn tin hnh th nghim cc gi tr pH ny.Bng 3.3: Gi tr A ca dch chit fucsin baz bng 1,2 - dicloetan(C2H4Cl2) cc gi tr pH khc nhau ca dung dch nc pH123456 A539nm0,0560,1590,0440,0470,0480,046 Ccsliughitrongbng3.3.chothyfucsinbazbchit bidung mi 1,2- dicloetan pH = 2 v khong pH 3-6 thuc th gn nh khng b chit.TachnnthchinccthnghimtrongkhongpH3-6thlng thuc th d khng gy nh hng cho qu trnh phn tch. Chng ti dng dung mi chit l hn hp CH2Cl2: CHCl3 theo cc t lv th tchl 1: 4; 1: 3; 1: 2; 1:1; 2:1; 3: 1v 4:1. Kt qu cng cho thy chpH=2lpchitmicmuhihng,cnccgitrpHkhclp chit hu nh khng mu.Vi kt qu thnghim trn khi chit hpcht linhpFucsin- baz - iot c th dng cc dung mi trn nhng tin hnh pH trong khong 3 - 6 th lng thuc th d khng gy nh hng g cho qu trnh phn tch.Chng ti chn pH th nghim bng 4; dng dung dch m. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 34 3.2.KHOSTNHHNGpHCAMITRNGNCNSHNH THNH HP CHT MU LIN HP GIA FUCSIN BAZ VI IOT Thnghimctinhnhnhtrnhbymc3.2chng2vthu c cc kt qu nh sau:*DngdungmichitlClorofom,hpthquangcadungdch chit c o bc sng 551nm, kt qu o c ghi trong bng 3.4.Bng 3.4: Gi tr A ca dch chit hp cht mu Fucsin baz - Iottrong Clorofom cc pH khc nhau trong mi trng nc pH123456 A551nm0,1590,2180,2460,2460,2460,246 Cc sliughi trongbng3.4 chothy,gi tr pH1- 2hpth quangcadchchitnh,iunycthgiithchnhsau:trongkhong pHnydungdchcaxitcaonnthucthFucsinbazdngcation cn t, tc ng phn cc ca n i vi phn t iot t nn hp cht mu lin hptothnhcnt.pH3-6gitrhpthquangAocgn bng nhau, chng t cc gi tr pH ny Fucsin baz nm dng cation ht, chng phn cc ton b cc phntiot tothnhhp chtmulinhp Fucsin baz -iot. KthpviktqukhikhostnhhngcapHnschitca thucthtrn,chngtithypHt3-6iot tohpchtmulinhp htviFucsinbaz,hpchtnybchitbiCHCl3,nhngthucthd khng b chit. iu ny rt thun li cho qu trnh phn tch, chng ti chn pH = 4 kho st cc yu t tip theo. bo m gi tr pH ny trong cc th nghim chng ti dng dung dch m.* Nu chit bng dung mi diclometan, hp th quang ca dch chit o ti bc sng cc i 537nm, cn nu dng dung mi l 1,2 -dicloetan th o ti 539nm. Kt qu c ghi trong bng 3.5 v 3.6. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 35 Bng 3.5: Gi tr A ca dch chit hp cht mu lin hp Fucsin baz - Iot trong diclometan t mi trng nc cc gi tr pH khc nhau pH123456 A537nm0,1740,2380,2710,2710,2690,270 Bng 3.6: Gi tr A ca dch chit hp cht mu lin hp Fucsin baz - iot trong 1, 2 - dicloetan cc pH khc nhau ca mi trng nc pH123456 A539nm0,1500,2050,2340,2350,2340,235 Ccgitrghi trongbng3.5v3.6chothydngdungmi chitl diclometanv1-2dicloetantrongmitrngcpH3-6iot cngtohp chtmulinhphtviFucsinbaz.Tacthdngccdungminy chit tch hp cht mu ra khi dung dch v loi tr cc nh hng khc.3.3. PH HP TH CA HP CHT MU FUCSIN BAZ - IOT Cc th nghim c chun b nh trong mc 3.3 ca chng 2 Chngtitinhnhghiphhpthcahpchtmulinhp Fucsin baz - iot trong dch chit bng cc dung mi nh Clofom, diclometan, 1 - 2 dicloetan.CcngbiudinphhpthcahpchtmulinhpFucsin baz-iotchittrongccdungmi thcccihpthkhcnhau(chit bngCHCl3thmax=551nm,chitbngCH2Cl2thmax=537nm,cn bng C2H4Cl2th max =539nm)nhngtngloidungmi vi ccnng iot khcnhauuccngmtccihpth.iuchngthpcht mu cthnhphnkhngi v c bnmu tt, iunyrt cli cho php phn tch. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 36 Di y chng ti trnh by 1 ph hp th ca hp cht mu lin hp giaFucsin bazviiot khichit bngdiclometan.Khidngccdungdch iot c nng khc nhau. Mc d nng iot bng bao nhiu cc ph hp th u c 1 dng v c cc i hp th max = 537nm. Hnh 3.1: Ph hp th ca hp cht mu Fucsin baz - iot cc nng iot khc nhau c chit bng diclometan. 3.4. KHO ST NH HNG CA LNG AXIT HCl LN PHN NGPhn ng oxi ho I- thnh I2 bng NO2- thc hin trong mi trng axit.NO2- + 2H+ + 2I- NO + H2O + I2 V vy cn kho st tm lng axt ti u cn cho s oxi ho.Qu trnh th nghim c trnh by trong mc 3.4 chng 2.Diychngtichtrnhbyktquthnghimthucv bin lun.KtqukhostsphthuchpthquangAvonngaxit HCltrongdungdchctrnhbybng3.7(chitbngdungmi1,2-dicloetan). S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 37 Bng 3.7: S ph thuc hp th quang (A) vo nng HCl VHCl 2M (ml)00,50,81,01,52,0 A539nm0,0200,1300,2100,2150,2100,205 Ccgitrghitrongbng3.7chothyhpthquangcadung dch tng. khi tng lng HCl 2M t 0 n 0,8 (ml). T gi tr 0,8- 2,0ml thhpthquangcadungdchhunhkhngi.iucth gii thch nh sau, nng axt thp cha thc hin phn ng oxi hohtiodua thnhI2tdo.Khitnglng axtln 0,8mlHCl 2Mlc ny lng axit oxi ho ton b iodua thnh I2 nn lng hp cht mutrongdungdchn nh. Chngti chnlngaxt cndngl 1ml HCl 2M.Sau khi thc hin phn ng xong, phi to pH ca dung dch nc ti u(pH=4)thchinphnngtohpchtmulinhp.Munvy phitrungholngaxtdbngdungdchNaOH2Msaumidng dung dch m pH = 4 gi gi tr pH ca dung dch.3.5. KHO ST S PH THUC CA LNG CHT OXI HO NaNO2 0,1M Qutrnhthnghimctinhnhnhtrnhbytrongmc3.5 chng 2.Kt qu kho st trnh by trong bng 3.8.Bng 3.8: Gi tr A ca dch chit hp cht mu Fucsin baz - iotbng 1,2 - dicloetan ph thuc vo lng cht oxi ho NaNO2 VNaNO2 0,1M(ml)00,20,40,81,21,6 A539nm0,0250,060,110,1900,1900,20 S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 38 Ccktqughitrongbng3.8chngttrongiukinthnghim (5ml dung dchKI 1mg/l) th cn dnglngcht oxi ho NaNO2 0,1M l 0,8ml l oxi ho ht I- thnh I2, lng d NaNO2 khng nh hng n qu trnh phn tch. Chng ti dng1ml dung dch NaNO2 cho cc th nghim kho st.3.6. NH HNG CA LNG THUC THTh nghim c pha ch nh trong mc 3.6 chng 2. Ktquthnghimkhichithpchtmubngdungmi1,2- dicloetan c ghi trong bng 3.9.Bng 3.9: Kt qu kho st nh hng ca lng thuc th Fucsin baz V thuc th(ml)0,511,522,53 A359nm0,1020,1150,2130,2150,2140,215 Tccktqubng3.9chothytrongiukinthnghim(5ml dung dch KI 1mg/l) ti u th khi lng Fucsin baz 1,5ml dung dch c hp th quang ln nht v khng i. iu ny rt hp l bi v iot to hp cht mu hon ton vi thuc th cn phi dng d thuc th, mt khc lng thucthdlikhngbchitcngvihpchtmu.mbolng thuc th dng d nhng khng cn d qu nhiu, s tn km, trong iu kin thnghimchngtidng3mldungdchFucsinbaz.Ttnhintuthuc vohmlngI-ctrongdungdchmtadnglngthucththchhp nhng phi m bo d nhiu so vi lng iot.3.7. KHO ST S PH THUC HP TH QUANG CA HP CHT MU THEO THI GIAN Cchphachdungdchvquytrnhthnghimcthchinnh trong mc 3.7 chng 2. S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 39 Cc kt qu th nghim c trnh by trn hnh 3.2. Hnh 3.2: nh hng ca thi gian n bn mu ca hp cht mu lin hp Fucsin -baz -iot (dung mi chit l CHCl3) Kt qu kho st cho thy kh nng hp th ca hp cht mu lin hp to bi Fucsin bazviot gnnhkhng i trongkhong30 pht saukhi chit,sauAgimdn.Vvyphitinhnhotrongvng30phtsau khichithpchtmu.Khostkhichitbngdungmikhcnh diclometan, 1, 2 - dicloetan cng cho kt qu tng t.3.8. NH HNG CA NHIT Nh trn trnh by, phn ng gia Fucsin baz vi iot l phn ng hpphtngtnhphnnggiah tinhbt viiot.Vvynhit c nh hng ln ti phn ng. Nhit thp th phn ng xy ra chm, nhng nhit cao th hp cht mu b phn hu. m bo cho phn ng xy rattvphhpviiukinphngthnghim,chngtitinhnhth nghim trong phng iu ho nhit c nhit khong ~ 200C.3.9. LP NG CHUNSaukhi khost ttcccyut nhhngnphnng,chngti rt ra cc iukin tiu khi thchin phn ng. Davo cc iu kin tiu,chngtitinhnhlpngchun.kimtrangca S ha bi Trung tm Hc liu i hc Thi Nguynhttp://www.Lrc-tnu.edu.vn 40 ngchun,chngtixydngngchuntheophngphpthmtin hnh song song vi th nghim xy dng ng chun.Chngtixydngngchunvitngloidungmichit.xy dng ng chun, chng ti lp th nghim iu kin ti u, nhng lng dung dchiotchuntngdn.Saukhichithpchtmu,tinhnhohpth quang ca dy dung dch bc sng max i vi tng loi dung mi, dung dch so snh l dung dch khng c iot. ng chun l ng biu din A = f (CI-). lp ng chun, chng ti tin hnh nh sau:Dng dung mi chit l Clorofom. Chng ti xy dng ng chun hai khong nng I-: 0,001 - 0,1 mg/l v t 1 n 9mg/l. * ng chun 1: Dng dung dch KI 1mg/l. Bng 3.10: S ph thuc gi tr A vo nng iot CI- (mg/l) 00,040,080,120,160,20,240,280,320,36 A551nmDD so snh0,040,0810,130,170,210,250,290,340,38 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.400.000.050.100.150.200.250.300.350.40Y = A + B * XParameter Value Error------------------------------------------------------------A -0.00131 0.00227B 1.05708 0.01006------------------------------------------------------------R SD N P------------------------------------------------------------0.99968 0.00312 9