Nghiên cứu xác định lượng vết iốt trong cơ thể người và môi trường : Luận án TS. Hoá học : 1 04 03

Danh gia tinh trang dinh dudng idt trong ca the, ngudi la su dung nhung chi lieu sinh hgc nhu ham lugng idl trong huyet thanh, idt trong sua, va dac biel la idl trong nude tieu con ggi l

Dp/ii^ hoc xuc tac

Bien i^io'i tin cay

Ccic rdi loan thieu hut idt

Gic/i han dinh hi'ang

Gio'i han phdt hien

Hoi dong kiem scat cac rdi

loan thieii hut idt

Ilocnion Tj

Idt i>dn protein

Khocing tin cay

Kich gidp td

Phcin ticJi ddng chdy

Phd/i ffch kich Jioat no'tron

QuT nhi dong Lien hiep qudc

To chu'c Y te'The gioi

Thu'ngJiiem mien dich phong xci

Thyroxin

Standard Deviation Catalytic kinetic Confidence Limits Iodine Deficiency Disorders Determination limit

Detection limit International Council for the Control of Iodine Deficiency Disorders

Triiodothyronine Protein Bound Iodine Confidence Interval Thyroid Stimulating Hormone Flow Injection Analysis Neutron Activation Analysis United Nations Children 'sFund World Health Organization Radio Immuno Assay

Tetraiodothyronine

SD DHXT

CL CRLTHI GHDL GHPH ICCIDD

Tj

PBI

CI TSII FIA NAA UNICEF WHO RIA

r,

Hinh i 2 Do tin xdc dinh nong do chat xiic tac theo plni'ong phdp tga

Hinh L3 Do tin xdc dinh nong do chat xiic tdc theo phu'o'ng phdp

CO dinh thdi gian

Hinh L4 Do tlii xdc dinh nong do chat xuc tdc theo phu'o'ng phdp

CO dinh tin hieu do A^

Hinh L5 So' do bieu dien thuc nghiem tim dieu kien tdi u'u theo

phu'o'ng phdp du'dng doc nhd't

Llinh 3.L Do tin bieu dien do hap thu cua dung dich Ce(IV) theo

ndng do

Llinh 3.2 Gid tri chudn Student ciia cdc he so hoi c/uy

Llinh 3.3 Sitphu thuoc cua tdc do phdn li'ng theo nhiet do (L > 15

ng/ml)

Hinh 3.4 Sii'phu thuoc cua tdc do phdn li'ng theo nhiet do (L < 15

ng/ml)

Hinh 3.5 Suplui thuoc cua tdc do phdn ii'ng theo thdi gian

Hinh 3.6 Suphu thuoc cua tdc do phdn ung vdo nong dp chdt xuc

tdc (pinto'ng phdp dn dinh thdi gian)

Hinh 3.7 Sit phu thuoc cua tdc do phdn itng vdo ndng dp chdt xuc

tdc (phu'o'ng phdp tga)

Hinh 3.8 Plid hap thu dung dich clopromazin sau khi hi oxi hoa

hang I-I2O2

Hinh 3.9 Gid tri chudn Student cua cdc he sdhoi quy

Hinh 3.10 Do tlii chudn bieu dien sit phu thuoc ndng dp idt vdo tga

Hinh 3.1 L Gid tri chudn Student ciia cdc he sdhoi quy

Hinh 3.12 So' do bieu dien qui trinh phdn ticli litc/ng vet idt trong

nitdc tieu

llinh 3.13 Sit phu thuoc ciia tdc dp phdn I'tng theo ndng dp chdt

xuc tdc

Hinh 3.14 So' do bieu diin qui trinh phdn tich lu'p'ng vet idt trong

su'a vd toe ngitdi

Hinh 3.15 Sa do bieu dien qui trinh phdn tich lu'p'ng vet idt trong

hiiyet thanh

Llinh 3.16 So'do qui trifih phdn tich litpng vet idt trong nu'dc sinh hoa!

Llinh 4.L Do tin bieu dien ham lu'p'ng idt-nien trung vi cua hai nliom

phu nn'imang thai vd ddi chu'ng) phdn bdtheo viing sinh thdi

Hitih 4.2 Ham lu'p'ng idt nieu (nliom cliii citu: A vd nlidni chu'ng:

B) vd idt trong su'a me dcdc viing sinh thdi cdc nliau

BciiiM 1.1 Mot sotinli chdt li hoc cua idt

Bang 1.2 Nhu can idt hang ngdy theo tiidi

Bdng L3 Phdn loai mi'tc dp thieu hut idt dita vdo nong dp idt nieu

Bang 1.4 Dieu kien thi nghiem cua cdc yen to'dnh hitdng

Bdng 1.5 Gid tri cdnh tay don d vd tham sd (p trong ma trdn tlutc

nghiem bdc hai tdm xoay

Bdng 1.6 Quy hoach hod thuc nghiem theo phu'o'ng phdp du'dng

ddc nhd't

Bdng 1.7 Nhu'ng cong trinh nghien citu xdc dinh lu'png vet idt bdng

phito-ng phdp DHXT klwng sit dung he [Ce'^-As^^f tit 1985'2()()()

Bdng 3.1 Cdc mi'tc gid tri vd khodng bien thieu cua cdc yen td

Bdng 3.2 Ma trdn tlutc nghiem vd ket qua

Bdng 3.3 Anh hitdng dinh lu'p'ng cua cdc yen tdden hdm muc tieu

Bdng 3.4 Cdc gid tri ddc tritng cua phu'o'ng sai thi nghiem

Bdng 3.5 Gid tri cdc he sdhoi quy trong phu'o'ng trinh hoi quy

Bdng 3.6 Anh hitdng dinh lu'p'ng cua cdc he sd hoi quy sau khi da

loai bo cdc he sd klwng co y ngliTa

Bdng 3.7 Cdc gid tri cua phdn tich phu'o'ng sai

Bdng 3.8 He sd hoi quy sau khi loai bo cdc yen td anh hitdng

klwng ddng ke

Bdng 3.9 Ket qua sai klidc giu'a li thiiyet vd tlutc nghiem

Bdng 3.10 Quy hoqch hod tlutc nghiem theo pinto'ng phdp du'dng

ddc nhd't

Bdng 3.11 Ket qua khdo sdt anh hitdng cua mot sdchdt gay can

Bdng 3.12 Ket qua xdc dinh ndng do idt trong mdu gid

Bdng 3.13 Ket qua xdc dinh hdm lu'p'ng idt trong nude mdy thdnh

phd I Iiie

Bdng 3.14 Ma trdn tlutc nghiem bdc hai tdm xoay 4 yen td

Bdng 3.15 Khodng bien thien vd cdc mi'tc thi nghiem

Bdng 3.16 Anh hitdng dinh litpng cua cdc yen ttJ'de'n hdm muc tieu

Bdng 3.17 Phdn tich phu'o'ng sai cdc he sdhoi quy

Bdng 3.18.Cdc he sdhoi quy trong phu'o'ng trinh hoi quy

Bang 3.19 Anh hitong dinh lu'p'ng cua cdc yen to sau khi loai bo

cdc he sdkhong c6 y ngliTa

Bdng 3.20 Cdc gid tri phdn tich plntang sai

Bdng 3.21 Cdc he sdhdi quy trong phu'o'ng trinh hoi quy

Bdng 3.22 Dieu kien tdi itu ciia phdn ting chi thi

Bdng 3.24 Ket qua khdo sdt sicdiing EDTA deche Fe^* va Fe^*

Bdng 3.25 Ket qiid khdo sdt khodng tuye'n tinli

Bdng 3.26 Ket qiid xdc dinh ham lu'p'ng iot trong niio'c sinh hoat bdng phu'o'ng phdp trdc quang DHXT he [Clopromazin-H2O2I vd lie ice-" As^y

Bdng 3.27 Cdc mii'c thi nghiem

Bdng 3.28 Ma trdn thuc nghiem vd ket qud tin nghiem

Bang 3.29 Anh hu'ong dinh litpng cua cdc yen to den hdm muc tieu

Bdng 3.30 Ket qud phdn tich phu'o'ng sai

Bdng 3.31 Cdc he sdhoi quy trong phu'o'ng trinh hoi quy

Bdng 3.32 Anh hitdng dinh litpng cua cdc he sdhoi quy co y nglua

Bdng 3.33 Cdc gid tri ciia phdn tich pinto'ng sai

Bdng 3.34 Cdc he sdhoi quy da hieu chinli

Bdng 3.35 Dieu kien tdi u'u de phdn huy mdu nude tieu

Bdng 3.36 Ket qud do dp phong xa tru'dc vd sau khi phdn huy mdu

bdng (NHdiSjO,

Bdng 3.37 Ket qud khdo sdt klid ndng tieu khit SCN' bdng (NHdS20,

Bdng 3.38 Ket qud khdo sdt khd ndng tieu khitF' bdng (NLI^SjO^^

Bdng 3.39 Ket qud khdo sdt khd ndng tieu khit axit ascorbic bdng (NHdS^O,

Bdng 3.40 Ket qud khdo sdt khd ndng tieu kliii protein bdng (NHJS20,

Bang 3.41 Ket qud khdo sdt dp lap Igi npi nghiem

Bdng 3.42 Ket qud khdo sdt dp lap Igi lien nghiem

Bdng 3.43 Ket qud khdo sdt dp thu hoi

Bdng 3.44 Ket qud xdc dinh nong dp iot trong 22 mdu nu'dc tieii

being hai kT thuat phdn Inly mdu: axit cloric vd amonipesunfat

Bdng 3.45 Hdm lu'p'ng iot-nieu ciia phu nit khong mang thai vd

khong CO con < 5 tuoi dThi(a Thien Hue

Bdng 3.46 Ket qud khdo sdt dp lap led trong mdu sua vd toe ngu'di

Bdng 3.47 Ket qud khdo sdt dp thu hoi khi them 1'^' vdo mdu

nghien cii'u

Bdng 3.48 Dp thu hoi khi them KIOj vdo mdu nghien cii'u

Bdng 3.49 Ket qud phdn tich hdm lu'p'ng iot trong mdu toe chudn

Bdng 3.50 Ket qud xdc dinh hdm lii'png iot trong toe theo hai

phu'o'ng phdp: phdn tich kich hoat no'tron vd dong hpc xiic tdc

Bdng 3.51 Ket qud xdc dinh hdm lu'p'ng iot trong sua me

Bdng 3.52 Ket qud xdc dinh hdm lu'p'ng iot trong toe

Bdng 3.53 Ket qud khdo sdt dp hoi pliuc (iot trong huyet thanh)

Bdng 3.54 Ket qud xdc dinh hdm liipng iot trong mdu huyet thanh

Bdng 3.56 Ket qud xdc duih ham litang PBI vd tdng nong dp

L trong mot sd mdu huyet thanh cudn rdn tre so' sinh

Bdng 3.57 Ket qua khdo sdt dp lap led

Bdng 4.1 Hdm litpng idt-nien cua hpc sinh tieu hoc df cdc xa

vd phit&ng thuoc tinh Thita Thien Hue

Bdng 4.2 Ket qud xdc dinh hdm lu'p'ng iot-nieu (/ugl'/di) dphu nil' mang thai vd nliom phu ml ddi chu'ng

Bdng 4.3 Hdm lu'p'ng iot-nieu phdn bdtheo thai ki

Bdng 4.4 Hdm lu'p'ng idt trong su'a me

Bdng 4.5 Hdm lu'p'ng idt-nieu (/ugL/dl) cua cdc bd me dang

cho con bii (nliom A) vd nliom chu'ng (nlwm B)

Bdng 4.6 Hdm lu'p'ng idt trong mot so'loai sua hop vd su'a bpt

d'Thita Thien Hue

Bdng 4.7 Ket qud xdc dinh hdm litpng PBI vd idt vd co' (L)

trong huyet thanh dcudng rdn tre so'sinh tai thita Thien Hue

Bdng 4.8 Ket qud xdc dinh hdm litpng idt-nieu d mdu ngdu

nhien vd mdu 24 gid

Bdng 4.9 LIdm lu'p'ng idt trong tdc

Bdng 4.10 Ket qud xdc dinh hdm lu'p'ng idt trong nu'dc sinh

hoat d cdc vung sinh thdi

MUC LUC

Trang DAT VAN DE i Chuong 1 TONG QUAN 4

1.1 Gioi thieu phuang phap dong hoc xiic tac 4

1.1.1 Nguyen tac 4

1.1.2 Cac phuang phap xac dinh nong do chat xiic tac bang phuang

phap dong hoc 5

1.1.2.1 Phuang phap do toe do ban &lu 5

1.1.2.2 Phuang phap a'n dinh lh5i gian 6

1.1.2.3 Phuang phap codinh tin hieu do (Ao) 6

1.1.3 NhQiig yeu to anli huong chu ycu den phuang phap phan tich DHXT 7

1.1.3.1 Anh huang ciia nhiet do den toe do phan ling 7

1.1.3.2 Anil huang cua hang so dien moi dung dichden toe do phan ung 7

1.1.3.3 Anh huang cua luc ion trong dung dich den toe do phan ung 8

1.1.3.4 Do nhay CLia phuang phap phan tich DHXT 9

1.2 Nhung diem can chu y khi phan tich lugng vet 12

1.3 Cac dac trung h' hoa sinh cua iot 13

1.3.1 Dai cuang ve idt 13

1.3.2 Nhu Cctu va vai tio iot Iroiig sinh li nguai 15

1.3.3 Hap thu va chuyen hoa iot 16

1.3.4 Subaitiet iot 17

1.3.5 Nguy ca thieu va thija iot 17

1.3.5.1 Nguy ca thieu idt 17

1.3.5.2 Cac rdi loan thieu hut idt tren the giai 18

1.3.5.3 Nguy cathiia idt 18

1.3.6 Nhung chi thi sinh hoc thuang duac su" dung de danh gia dinh

duong idt 6 ngudi 18

1.3.7 Phan loai va danh gia muc do tliieu dii idt dua vao idl-nieu 19

1.4 Mot sd phuoiig phap phan huy niSu nghiem de phan ticli luoiig vet idt 20

1.4.1 Phuang phap udt 20

1.4.2 Phuang phap kho 21

1.4.3 Phuang phap thiiy nhiet phan 21

1.4.4 Cac phuang phap khac 21

1.5 Tdng quan cac phuang phap xac dinh luang vet idt 22

1.5.1 Cac phuang phap xac dinh lugng vet idt 22

1.5.1.1 Phuang phap phan tich quang phd 22

15.1.2 Phuang phap s^c ki 23

1.5.1.3 Phuang phap dien ho 24

1.5.1.4 Phuang phap phan tich kich hoat natron 25

1.5.1.5 Phuang phap miSn dich phong xa 27

1.5.1.6 Cac Phuang phap khac 28

1.5.2 Phuang phap xac dinh idt dua vao cac phan ii'ng xuc tac 28

1.5.2.1 Phuang phap phan tich DHXT dong chay 28

1.5.2.2 Phuang phap DHXT khong sir dung phan ling chi thj

[Ce(lV>As(III)] 29

1.6 Phuong phap ke hoach hoa thuc nghiem 29

1.7 Tinli llinh nghien cuu xac dinh ham lugng idt trong : nude tieu, sua,

toe, huyet thanh nguoi va nuoc sinh hoat 34

1.7.1 Idt trong nude tieu 35

1.7.2 Idt trong sua 37 1.7.3 Idt trong huyet thanh 38

1.7.4 Idt trong tdc 38 1.7.5 Idt trong nude sinh hoat 39

1.8 Ket luan phan fong quan 39

2.1.1 Khao sat cac dieu kien de xac djnh lugng vet idt

bang phuang phap trdc quang DHXT, phan ling chi thi [Ce(IV)-A s(III)]

va [clorpromazin-H202] 41

2.1.2 Nghien cuu dieu ki6n phan hiiy mSu 66 xAy dung qui trinh phan lich

de Xiic dinh lugng vet idt trong nude tieu, sua, tdc, huyet thanh ngudi

va nude sinh hoat 41 2.1.3 Xac dinli mdi tuang quan ciia ham lugng idt trong cac ddi tugng: nude

lieu,sua me, tdc, huyet thanh d cudng rdn tre sa sinh, nude sinli hoat 42

2.2 Vat hcu va phuang phap nghien ciiu 42

2.2.1.Thietbi 42 2.2.2 Dung cu va hoa chat 43

2.2.3 Phuang phap nghien ciiu 45

2.2.3.1 Lay miu 45 2.2.3.2 Nghien ciiu ap dung mo hinh toan hoc de qui hoach hoa thuc

nghiem nh^m thn dieu kien thi nghiem tdi uu ciia cac yeu td anh hudng

den phiin ling chi thi [Ce(IV)-As(III)]va [clopromazin-H202] va dieu kien

de phan hiiy mSu nude tieu 47

2.2.3.3 Phuang phap xac dinh idt 47

2.2.3.4 Phuang phap danh gia do tin cay ciia qui trinh phan tich 47

2.2.3.5 XLI' ir sd heu phan tich bang phuang phap thdng ke 48

Chuong 3 KET QUA VA THAO LUAN 49

3.1 Phuong phap trac quang DHXT xac dinh lugng vet idt, dung phan ling

chi thi [Ce(IV)-As(III)] 49

3.1.1 C a s d c i i a phuang phap 49

3.1.2 Khao sat cac dieu kien thuc nghiem 51

3.1.2.1 Chon budc sdng de do do hap thu ciia dung dich Ce(IV) 51

3.1.2.2 Khoang tuye'n tinh cua ndng do Ce(IV) 51

3.1.2.3 Tim dieu kien tdi uu cua nong do dau cac tcxc nhan tham gia

phcin li'ng chi thi [Ce(IV)-As(III)] theo phuang phap dudng ddc nhat 52

3.1.1.4 Anh hudng ciia cac yeu tdkhac 59

3.1.2.5 Xac dinh ndng do idt trong mSu thuc tc 64

3.1.3 Ket luan 64

3.2 Phuong phap trdc quang DHXT xac dinh lugng vet idt, dijng phan ling

chi thi [clopromazin-HjOa] 65

3.2.1 Ban chat phuang phap 66

3.2.2 Khao sat nhQng didu kien thuc nghiem 68

3.2.2.1 Phd hap thu ciia CPH sau khi oxi hoa 68

3.2.2.2 Tim di6u kien tdi uu ciia cac tac nhan tham gia phan ling chi

thi r[CPH- H2O2] theo phuang phap dao ham rieng 68

3.2.2.3 Anh hudng ciia nhung yeu id khac 74

3.2.2.4 Phuang tiinh dudng chuan, khoang tuye'n tinh va GHPH 76

3.2.2.5 Xac dinh ham lugng idt tren mau thuc te 77

• Ket luan 80

3.3 Xay dung qui trinh phan tich lugng vet idt trong nude tieu, sua, tdc

huyet thanh ngudi va nude sinh hoat 80

3.3.1 xay dung qui trinh phan tich lugng vet idt trong nude tieu 80

3.3 i.l Phan huy mau nude tieu bang amoni pesunfat 80

• Su dung phuang phap dao ham rieng nham tim dieu kien tdi uu de plu'in

hiiy mau nude lieu bang ki thuat amoni pesunfat 81

3.3.1.2 Qui trinh phan ifch lugng vet idt trong nude lieu 90

3.3.1.3 Danh gia do tin cay cua qui trinh phan tich 90

3.3.1.4 Xac dinh ham lugng idt tren mSu thuc te 94

3.3.2 x a y dung qui trinh phan tich lugng vet idt trong sua va tdc ngudi 95

3.3.2.1 Danh gia do tin cay ciia qui liinh phan tich trong sua va tdc 97

3.3.2.2 Ket qua phan tich tren mau thuc te 100

3.3.3 x a y dung qui trinh phan tich lugng vet idt trong huyet thanh 102

tluieic 106 3.3.4 xay dung qui tiinh phan lich lugng vet trong nude sinh hoat 107

VA NU'CC SINH HOAT 111

4.1 Ham lugng idt-nieu trong cac ddi tugng nhay cam 111

4.1.1 Hoc sinh tieu hoc (8-12 tudi) d c a c viing sinh thai khac nhau 111

4.1.2 Ham lugng idt-nieu ciia phu nirmang thai d c a c vCmg sinh ihai 114

4.2 Mdi tuong quan giua ham lugng idt-neu va idt trong sua me 117

4.3.Ham lugng idt trong huyet thanh dcudng rdn tre sasinh 120

4.4 Ham lugng idt trong nude tieu va trong tdc cua ngudi trudng thanh 122

4.5 Ham lugng idt trong nude sinh hoat 123

KET LUAN 126 TAI LIEU THAM KHAO

P H U L U C (Gdm 37 bang sd lieu tho, trinh bay cac kdt qua phan tfch ham lugng

idt trong 2079 miiu sinh hgc lay tii' ca the ngudi va moi trudng)

Trong nhieu nam qua d nude la, cung nhu cac nude khac lien the gidi, ngudi la da va dang quan lam nhieu den va'n de dinh duang idt trong ca the ngudi

va idt trong moi trudng Dinh duang idt la van de loan cau Mac du idl cd trong ca the vdi mot lugng khong Idn (khoang 15mg); nhung no lai dugc xem la mot Irong nhimg nguyen td vi lugng tdi can Ihidt cho su phat tri^n ciia ca the ngudi Ngudi la

ndi: "idt \l\ nguyen td can thiet cho phat tiien tri tue" [22],

Co" the con ngudi thieu hay thiia idt ddu gay ra nhieu tac hai va thudng gpi

la "cac rdi loan thieu hut idt" (Iodine Deficiency Disorders: IDD) Cac rdi loan thieu hill idl (CRLTHI) gay ra can benh xa hoi, anh hudng den siic khde cong ddng va su phat trien xa hoi tren loan the gidi [14], [17]

Danh gia tinh trang dinh dudng idt trong ca the, ngudi la su dung nhung chi lieu sinh hgc nhu ham lugng idl trong huyet thanh, idt trong sua, va dac biel la idl trong nude tieu (con ggi la idt-nieu) [133], De xac dinh lugng vet idt trong cac dich sinh hgc, ngudi la thudng sii" dung nhQng phuang phap phan tich cong cu

nhu: srlc ki khi (GC), sdc ki long hieu suat cao (HPLC), kich hoat nalion, do the

dung dien cue chgn Igc ion, trac quang dong hgc xiic Uic (DHXT) [44], [57], [77], [79], [92] Trong dd, phuang phap trdc quang DHXT dang dugc nhieu phong Ihi nghiem tren the gidi sii' dung, do cd nhieu uu diem nhu: phan lich nhanh, do lap lai cao, gioi han phat hien (GHPH) thap, thiet bi re Tuy vay, cd nhieu ycu id anh hudng den dong hgc phan ung nhu; chat can trd ciia n6n, nhiet do va thdi gian phan ung Vi the can phai nghien ciiu khau phan hiiy mSu de xay dung qui trinh phan tich va tdi uu hda cac dieu kien thi nghiem Cac van de nay cho den nay vfm chua dugc cac tac gia cong bd thdng nhat [65], [92], [121], [131], [142]

Tu nam 1995, Thii ludng Chinh phii nude la da ban hanh nghi dinh ve vice

"Van dong loan dan an mudi Iron idt" de phong chdng CRLTHI [9] Danh gia hieu qua ciia Chuang trinh nay, Benh vien Ngi liel Ha Ngi, cung nhu cac nude

tren the gidi, dang sii' dung chi tieu idt trong nude lieu d liia tudi: 8-12 va xem do

la thong sd dai dien de danh gia tinh trang dinh dudng idt d cong ddng [4], [39] Tuy nhien, ham lugng idl trong sua me, trong huyet thanh cudng rdn Ire sa sinh cung la nhung chi tieu sinh hgc giiip giam sat hieu qua ciia chuang trinh can Ihicp idt

Ben canh idt-nieu d liia tuoi 8-12, thi ham lugng idt-nieu d nhung ddi lugng khac nhu: phu nu mang thai, cac ba me dang cho con bii, la nhung ddi lugng cung cap true liep idt cho thai nhi va tie sa sinh, vi the de phong ngiia nhung hau qua ciia CRLTHI cd the xay ra ddi vdi tre sa sinh, can theo doi idt-nieu d nhung ddi tugng nay

Mai khac, mot sd tac gia cho rang idt trong ca the cung dugc bai liel qua

tdc Nhu ihc, idl trong tdc cd mdi tuang quan w6i idt-nieu hay khong? Cd the su

dung idt trong tdc lam cha't chi thi de theo doi tinh trang dinh duang idt d ngudi dugc khong?

Nhu vay, de giai quyet nhiing van de tren day, Irudc lien can nghien ciiu khau phan hiiy mSu de xay dung qui trinh phan tich xac dinh lugng vet idl trong Ccic ddi tugng sinh hgc, tiep den la danh gia tuong quan giua ham lugng idl trong cac mau sinh hoc, cung nhu tuang quan giij'a ham lugng idt trong ca the ngudi dan sdng d Ccic viing sinh thai khac nhau Mdi tuang quan ciia ham lugng idt vdi cac yeu td tren day cd y nghia rat Idn, se giiip cac nha quan li y te cd nhung dinh hudng dung cho vice bd sung idt trong lu'ng giai doan The nhung, cho den nay d nude la chua cd Uic gia nao de cap den nhung van de tren day mot cacii lie thdng

Xual phat lu nhu'ng van de tren, trong luan an nay chiing toi nghien ciiu ap dung phan ling DHXT xac dinh lugng vet idt trong cac ddi tugng sinh hgc va moi trudng, nhiim lam sang td mot sd qui luat tuang quan tren De thuc hien dugc muc dich dd, luan an can thuc hien nhung nhiem vu sau:

1 Nghien ciiu ap dung mo hinh loan hgc de qui hoach hda thuc nghiem nham lim cac dieu kien Ihi nghiem tdi uu thuc hien phan ling DHXT sii' dung he [Ce(IV)]-As(III)] va [clopromazin-H202] de xac dinh lugng vet idl

me mang Ihai, ba me cho con bii dang sdng d cac viing sinh thai khac nhau va tuong quan ciia idt-nieu vdi idl trong sua ciia cac ba me dang sdng d mien niii, ddng bang va ven bien

4 Xac dinh idt trong tdc va khang dinh idt trong tdc cd the dQng lam chat chi thi de danh gia tinh trang dinh dudng idt trong ca the ngudi dugc khong?

5 Xiic dinh mdi tuang quan giua ham lugng idt d dang PBI trong huyet thanh d cudng rdn Ire sa sinh vdi trgng lugng cua tie

Cac kel qua thu dugc se gdp phan danh gia hieu qua ciia chuang trinh phong chdng CRLTHI d tinh Thiia Thien Hue

1.1 G l 6 l TlllfiU PHUONG PHAP PHAN TICH DONG HOC XUC TAC 1.1.1 Nguyen tdc [37], [51], [91], [139]

Ca sd ciia phuang phap phan tich dong hgc xiic lac (DHXT) la xac dinh

ndng do chat xiic lac dua vao Uic dung ciia chat xiic lac Icn phan liiig chi thj Vi tdc do ciia phan ling chi thi ly le vdi ndng do cha't xiic tac, do dd bang each do tdc

do phan ling chi thi cd the suy ra ndng do cha't xiic tac

Vdi dieu kien phan ling gia bac 1, phuang trinh bieu diln tdc do phan ling

cd dang:

d[A]

V =

dt = k[A][C] + kJA] (1.1)

Trong do: k : Hang sd tdc d6 phan ii'ng xiic tac

k, : Hang sd tdc do phan ling khong xiic tac

C : Ndng do chat xiic tac

A : Chat chi thi

Trong phan ling xiic tac, chat xiic tac dong vai tro tao thanh phiic chat trung gian (hoac phiic hoat hoa) lam giam nang lugng boat hoa ciia phan ling [21], do dd tdc do phan ling tang len Su bien ddi nang lugng

trong lien trinh phan ling dugc bieu didn theo sa dd b hinh 1.1

Toa do phan ling

Hinh I.L Gian dd bien doi nang lugng phan ling trong lien trinh phan ling

(Trong do A va B la hai chat phan ii'ng; K la chat xiic tac)

Di xac dinh ndng do cha't xiic lac, ngudi la six dung hai phuang phap vi

phan va lich phan, trong dd phuang phap vi phan thuc hien dan gian han, do dd hi^n nay da sd cac cong trinh nghien ciiu ve phan tich DHXT, ngudi la thudng diing phuang phap vi phan Khi sii" dung phuang phap nay, ngudi la do cac dai lugng hda ly nhu do hap thu, chi6u cao pic ciia ddng dien phan, chieu cao sdng cue phd la ham ciia ndng dd chat xiic tac Neu tat ca cac tac nhan tham gia phan ling xiic uic deu cd dinh Ihi ndng d6 cha't xiic tac se chi phu thuoc vao ndng do

cha't chi ihi Su phu thu5c nay chi gidi han trong m6l khoang ndng d6 nao do Sir

dung phuong phap vi phan de xac djnh ndng d6 cha't xiic tac, ngudi la thudng diing ba phuang phap sau

1.1.2.1 Phuong phap tdc do ban dau (cun ggi la phuang phap tga)

Tdc do phan ling dugc do theo thdi gian phan ling

C3

A

c,

tga' tgtti tgttz tgai Q) tgao

t C, C2 c , c

Llinh 1.2 Dd thi xac dinh ndng do chat xiic tac theo phuang phap tga

Qua trinh thuc hien phuang phap nay nhu sau: ngudi la do ndng do chat chi thi thong qua tin hieu phan ling theo thdi gian, ling vdi cac ndng do chat xiic tac khac nhau, xay dung cac dudng dong hgc, sau dd xac dinh tga ciia cac dudng bieu didn, va dung dd thi bieu di6n su phu thuoc tga vao ndng do chat xiic tac (hinli 1.2) Dd tlii nay dugc xem nliudd tlii chuan de xac dinli ndng do chat xiic lac Xcic dinh ndng do chat xac tac bang phuang phap nay can phai lien hanh nhieu thi nghiem, vi the cd do chinh xac cao U'u diem ciia phuang phap nay la han chc dugc

Phuang phap nay dua vao viec do tdc do phan ung chi thj ling vai nhung ndng do chat xuc tac khac nhau khi cd dinh thdi gian I; nghla la lai mot thdi diem nao dd ciia phan ling, ngudi la do (do hap thu, chidu cao pic, ) ciia siin pham tao thanh ciia cac gia tri ndng do chat xiic tac khac nhau va bieu diSn su phu thuoc ciia (do hap thu, chieu cao pic, ) theo ndng do chat xiic tac

Phuang phap nay dan gian va cd do lap lai cao, nen thudng dugc six dung

khi phan tfch hang loat mSu nghiem

Hinh 1.3 Dd tlii xac dinh ndng do chat xiic lac theo phuang phap an dinh thdi gian

1.1.2.3 Phuang phap cd djnh tm hieu do (Ay)

Phuang phap nay dua vao nguyen tac: do thdi gian (I) ling vdi do hap thu

d Ccic ndng do chat xiic tac khac nhau (C^j ) dat den gia tri A(, nao dd va dung

dudng bieu dien su phu thuoc 1/t - C^^

i/t' l/t3 1/t 1/t

Nhiet do phan ling la mot trong nhung yeu td anh hudng manh nhat den tdc

d6 phcin ling Theo thuy^'t va cham, khi tang nhi6t d6, su chuyen dong nhiet cua

cac phan lu trong binh phan ling tang do dd lam tang sd va cham cd hieu qua

(nhung va chain cd nang lugng vugt qua hang rao the nang de xay ra phan ling), vi

the tdc do phan ling tang Cd the bieu didn su phu thuoc nay theo phuang trinh

Arenius nhu sau:

d(lnk)

dT

RT E/RT hay K ^ A e - ' ^ ' " ' (1.2)

:z^InK = l n A - — Hoac logK = logA (1.3)

RT • 2,303RT Trong dd

K : hfing sd tdc do phan ling

T : nhiet do tuyet ddi

E : nang lugng hoat hda

R : hang sd khf

A : hang sd (thiia sd tan sd)

Phuang trinh (1.3) chiing td hang sd tdc do gia tang theo nhiet do Thong

thudng khi nhiet do tang 10"C thi tdc do phan ling tang iix 2-3 Ian Phuang irinh

(1.3) cung thudng dugc diing de tinh nang lugng hoat hda, neu hang sd tdc do

dugc do nhi^u Ian

1.1.3.2 Anh huong ciia h£ing sddien moi dung djch den tdc do phan ling [85]

Vi phan ling xiic tac ddng the xay ra trong dung dich, do dd, dung moi

ddng vai trd quan trgng ddi vdi cac phan ling xay ra theo ca che ion; nghla la tdc

do phan ling xay ra trong dung dich phu thuoc mot phan vao hang sd dien moi

(dielectric constant) ciia dung dich

Gia sii" phan ling giua hai cha't A va B xay ra theo phuang trinh:

A + B —> AB* (dang phiic hoat hda)

I-IA ' I^B > M-AB*- momen ludng cue ciia A, B, AB*

ZA , ZB : dien lich ciia A va B

^A ' HJ ' I'AB*- ban kinh ion ciia A, B, AB*

T : nhiet do tuyet ddi

K : hang sd Bollzman

e : dien tfch cua proton (l,602xlO"'^C)

Phuang trinh (1.4) cho thay, neu A va B la cac ion trai dau (Z^-Zg < 0), thi

khi e giiim, tdc do phan ling se tang len va ngugc lai, neu A va B la ion ciing dau

(ZA-ZB > 0), thi khi 8 giam, tdc do phan ling se giam Dua vao tinh chat nay, la cd

the khong che phan liiig nen, neu ca die phan ling n6n va phan ling xiic xay ra

khac nhau d giai doan quyet dinh tdc do phan ling

1.1.3.3 Anh hudiig cua luc ion trong dung djch den tdc do phan ling [85], [139]

Trudng hgp trong dung dich cd hai chat A va B phan ling vdi nhau theo

phuang trinh:

A + B -> AB^ (phuc hoat hda)

Vdi su cd mat ciia nhCing mudi hay nhung nguyen id khac se anh hudng

den can bang tao phiic ciia phuang trinh tren.Va ngudi la thudng ggi anh hudng

nay la hieu ii'ng mudi De giai thich anh hudng nay trong dung dich, ngudi la sii"

dung phuang trinh :

logk = logko + ZAZBVM +(bA + bs + b * ) p (1.5)

mudi hay nguyen id ngoai lai

ZA, ZQ : dien tich ciia A va B

[X :lucion(ia = i X * ^ i ^ ' ^

bA, bs, b* : hang sd kinh nghi6m ciia A, B, va phiic hoat hda AB**

Phuong llinh (1.5) chiing id rang: vdi su cd mat ciia mudi ngoai lai cd the

dan den mot su gia tang tdc do phan liiig hda hgc ( neu dien tich ciia A va B gidng

nhau) hoac ngugc lai, tdc do phan ling se giam (neu dien tich ciia A va b trai dau)

1.1.3.4 Do nhay ciia phuang phap phan tich DHXT [139]

Khi sii" dung cac phuong i^hap hda ly de xac dinh ndng do chat phan tich,

do nhay ciia phuang phap dugc dinh nghla la gia tri cue tieu ciia li sd P/e :

Trong dd

P

Qnin= - (1.6)

s

Cniin : do nhay ciia phuang phap phan tich

P : tin hieu do

£ : hang sd ti le

Phuang trinh (1.6) cho thay C^^^ phu thuoc vao P va £ Trong phuang phap

phan tfch DHXT, bang each theo ddi tdc do pluin ling chi Ihi, ta cd the suy ra ndng

do chat xiic Uic Neu idc do phiin ling xiic Uic dugc tinh ILT phuang trinh:

^ = Xn,Cl=N,Cl (1.7)

dt

Trong dd

X : ndng do san pham tao thanh tai thdi diem t

X : hang sd tdc do phan ling

KQ : lich ndng do ta't ca cac cha't con lai

CK : ndng do cha't xiic tac

T u ( 1 7 ) , t a c d : C°^=~~ —

dt x T i c

Nhu the vdi mot lugng cue tieu ciia ndng do chat xiic tac cd the xem

^ ^ ^ x _ ^ _ A > ^ (1.8) AtxTic AtN,

dday : NK = X-T^C

Trong dd AtN^ biSu diSn sd chu trinh ma mot phan tir xiic uic tham gia

trong khoang thdi gian At; AlA^ con dugc ggi la he sd khuyech dai Vi mdi chu

trinh ciia phan lilig se tao ra mot san pham phan ling, do vay neu sd chu trinh cang

Idn thi san pham phiin ling cang tang ngliTa la do nhay phiin ling tang cao

Phuang trinh (1.8) cung cho thay, do nhay ciia phan ling xiic Uic sc gia tang

CLing \'6\ su gia Uuig cua khoiing thdi gian phan ling At

Mat khcic, iCi' phuang trinh (1.3) thay rang khi tang nhiet do phan ling thi do

nhay ciia phuang phap xac dinh tang theo

Tu nhOng di6u vua trinh bay d tren, va qua phuang trinh (1.8), cd the ndi

rang do nhay ciia phuang phap phan tfch DHXT la rat cao

Neu sii" dung phuang phap trac quang de do tdc do phan ling xiic tac

(phuang phap irac quang DHXT); thi do nhay ciia phep xac djnh phu thuoc vao

khii nang do cudng do mau ciia chat hap thu (A) va he sd hap thu moi phan tu ciia

/\

cha'l dd (e), nghla la phu thuoc vao ti sd — Ddi vdi phuang phap trac quang, cd

e

the Xiic dinh ndng do cha't edn phan tich cd lO'^mol/L, va neu thdi gian phan ling

la 10 phiil; ndng do chat phan ling bang 1 mol/L, va he sd xiic lac bang 10^ thi do

nhay ciia phep xac dinh nhu sau:

moi hay 60.000 phan tii" cha't xiic tac

Neu trong lugng phan tii' ciia cau tii edn phan tich la 100, thi do nhay ciia

phuang phcip la :

CKm.n=10"''g/nil hay IQ-'Vg/ml

Nhu vay, bang each sii' dung phuang phap tide quang DHXT, cd Ihe xac

dinh ndng do chat phan tich ca ng/ml ma khong can phai lam giau

Tuy nhien, trong qua trinh thuc hien phuang phap phan tfch DHXT, cd mgl

sd yeu id han che do nhay ciia phuang phap phan tfch, trong dd quan trgng nhat la

su iham gia cua phan ling khong xiic tac (plum ling nen)

Nhu da trinh bay d tren, ddi vdi phan ling xiic tac, tdc do phan ling do dugc

(v) thudng bao gdm tdc do chung ciia phiin ling cd xiic lac (vjva phan ling khong

xiic Uic (V(,);

V = V;, + V(, (1.9)

dx

dt Vdi K : hang sd phan ling khong xiic lac

va : V(, = K.Tic

Tu(1.9), tacd : Vk = V - v,,

Khi su khcic bict giua v - v„ la Idn so vdi v,„ trudng hgp nay sai sd ciia phep

xac dinh luang ddi nhd, nhung khi sir khac biel nay giam se gay sai sd Ian, do su

bien ddi ciia V(,; va ngudi ta bieu Ihi su khac biet ciia v - V(, bang he sd a, vdi :

v^ > aV() (1-11)

Neu tdc do phan ling xiic tac Idn han rat nhieu so vdi phan liiig khong xiic tac, thi:

C,, = - ^ Tu-phuang trinh (1.8) va (1.11), ta duac:

Q = - ^ ^ ^ ^ ^ = - - ^ ^ ^ - ^ a ^ (1.12)

Kei hgp phuang trinh (1.2) va (1.12), do nhay ciia phuang phap xac dinh sc

K phu thuoc vao li sd — , va duac bi6u diSn theo phuang trinh:

Phuong trinh (1.13) chi ra rang mudn cd do nhay cue dai, can phai su dung loai phcin ung chi thi cd su khac biel cue dai giua hang sd tdc do ciia phan ling xiic lac va phan ling nen (nghla la E„ va E}^ khac biel cue dai) Neu su khac biel nay la Idn, thi li sd K/x Irong phuang trinh (1.12) cd the bd qua va liic dd cd ihe sii" dung phuang tiinh (1.8) de linh do nhay

Do nhay ciia phan ling xiic tac cang cao khi nen 6n dinh(tuc la giam he sd

a Irong phuang trinh (1.11)) Sau day la nhung nguyen nhan quan trgng gay su bieii ddi ciia nen :

- Su dao dong nhiet do ciia binh phan ung

- Su khcic nhau ve thanh phan ciia dung dich nen va dung dich sii dung de

ve dudng cong chuan (dac biel la: pH, thanh phan mudi, luc ion, va cac tap cha'l lii"

hda chat va nvioc cat),

- Su khac nhau ve be mat binh pluin ling, su cd mat ciia chat hap phu, bui

va hai hda chat trong phong Ihi nghiem

1.2 NHUNG DIEM CAN CHU Y K i l l PHAN TICH LUONG VE I I O T

•^ Su n h i l m ban va mat chaft phan tich [6], [43], [52], [65], [82], [133] Trong qua trinh phan tfch lugng vet idt, can phai quan tarn deii mot sd yeu

td se cinh hudng manh den kel qua phan tfch, trong dd quan trgng nhat la: moi trudng khong khf ciia phdng thi nghiem, do tinh khiet ciia hda cha't va nude cat, do sach ciia dung cu thiiy tinh, tinh on dinh ciia thiet bi do Ra't khd de loai Iru nhung yeu id neu tren, vi the, cac kel qua phan tfch lugng vet idt tren cting mot ddi tugng

cd khi dao dong kha Idn, tiiy thuge vao ky thuat phan tfch ciia liing phdng ihf nghiem cung nhu tay nglie thao Uic ciia kl thuat vien phan tfch

Mai khac, su nhiSm ban hoac mat chat phan tfch cung cd the xay ra trong qua trinh lay mfiu va chuan bi mau de phan tfch; chang han nhu khi phan hiiy mfiu bang phuong phap udt (hdn hgp axit manh) hoac phuang phap kho (tro hda d nhiet

do cao) cd the lam mat hoac nhi6m ban chat phan tfch De han che tdi da vice gay sai lech kel qua phan tich can phai luan thii mot sd dieu kien can thiet sau:

Tiiudng xuyen kiem tra he thdng phan tfch (nude cat, hda cliat, dung cu va

Ihiel bi do, quy trinh chuan bi mJu, moi trudng khong khf phdng thf nghiem) Ngoai ra, hang ngay can phai lien hanh Ihf nghiem tren mSu trang, de hieu chinh

ket qua phan tfch (ket qua phan tfch bang ket qua do d mau phan tfch ivix ket qua

do tren mAu trilng)

1.3 CAC DAC TRUNG LY-HOA-SINH CUA IOT

1.3.1 Dai cu'ong ve idt [3], [19], [22], [26], [30], [40], [119], [137], [146], [147]

Idt la nguyen id thuoc nhdm VIIA trong bang phan hang luan hoan Mendeleev Nam 1812, B Courlois Ian dau lien phai hien ra idt, khi ong ta dot rong bien say kho lay tro de san xual diem lieu va tinh cd tim thay idl trong rong bien Nam I8I5 J.L Gay-Lussac va Humphry Davy da nghien ciiu Ifnh chat hda hgc cua idt va xac dinh idt la mot nguyen id hda hgc mdi

Idl ran cd ap suat hai rat Idn nen d nhiCl do thudng idl bay hai va khi dun ndng nhanh no Ihang hoa ma khong ndng chay Hai idt cd mau tfm sfun, (vi liie dugc dai ten la idt (lir chQ: Hy lap lODES cd nghla la tfm]), va hda rfin khi dugc lam lanh

Trong cac dung mdi khong phan cue (vi du CS2, CCI4) idt tan va cho dung dich mau ifm; ddi vdi cac dung moi hiiu ca ma phan tir chiia oxi (nhu rugu, etc va axelon) idl tan va cho dung dich mau nau Trong dung dich mau tfm, idl d dang phan lii' I2 gidng nhu trong trang thai hai, con trong dung dich mau nau, idl tao nen vdi dung moi nhung sonval khong ben Dua vao nhung dac diem nay, ngudi ta

da sii' dung phuang phap chiet trac quang de xac dinh idt

Idt cd the tan nhieu trong nude cd cliiia iodua niid tao nen phan ling ket hgp:

I2 + r = Dung dich chiia ion I^ cd mau nau va cd Ifnh chat ciia mot hdn hgp phan tir I2 va ion 1*

I.,-Idl tao thanh hgp cha't mau xanh vdi hd tinh bgt, trong dd nguyen tii" idl dugc sap xep trong cac ranh cCia polisacarit amilaza Giua idt va hd tinh bgt khong

cd phan ling hda hgc xay ra ; khi dun ndng mau xanh bien mat, day la Ifnh chat dac biel de' nhan biel idt

Trong thien nhien chi xual hien mot ddng vj ben '^^I Ddng vi phdng xa nguy hiem nha't la '^^I cd thdi gian ban ra 1,57.10^ nam (dugc tao ra trong moi trudng do qua trinh thtr vu khf hat nhan) Hien nay ngudi ta da dieu che dugc tren

22 ddng vi phdng xa nhan tao, trong dd, hai ddng vi phdng xa '"*'! (thdi gian ban

hiiy 8 ngay) va '^'^I (thdi gian ban hiiy 60 ngay), dugc ling dung rong rai trong y hgc Mot sd Ifnh chat If hgc ciia idl dugc neu d bang 1.1

Bdng 1.1 Mot so Ifnh cha't li hgc ciia idt

kJImol

150

Do dai lien kel/4 2,67

Nang lugng hidrat hda

AHb tlhnol

297

The dien cup chuan

E\V

0,54

Vdi cau hinh dien tii" [Kr]4d'"4s^5p^, idt cd the idn lai d 6 miic oxi hda khac nhau; - 1 , +1, +3, +5, +6, +7; trong dd hgp cha't lO'^ va IO4 ben vung han ca Trang thai hda tri bdn vung nhal ciia idl la I(VII), chfing han nhu mudi pciodat la chat cd Ifnh oxi manh, cac phan ling oxi hda thudng xay ra manh liel va nhanh

chdng ntn hay dugc ling dung trong phan tich

Trong moi trudng baza hoac axit ra't manh, idt ton lai d dang 10'^ ; con trong moi Irudng axil idt ton lai d dang I", T day la nhung dang kcm ben ciia idt

Vi the, trong khi lua chgn phuang phap de xac dinh idt trong dung dich can phai luu y deii dac diem nay

Cac the oxi hda-khii' lieu chuan ciia cac cap oxi hda-khii" ciia cac nguyen td trong phan nhdm VII A nhu sau:

F ° = 0,54V < F ° = 1,07V < F ° = 1,36V < F ° = 2 87V

Do the oxi hda-khii' lieu chuan ciia idt nhd, nen idt viia cd tinh oxi hda lai vLia cd Ifnh khii'

Khii nang oxi hda-khii' ciia idl dugc trinh bay tdm tat trong sa 66 the dien

cue cua cac hgp chat cua idt trong moi Irudng axit va moi trudng baza

4-0,7 +1,14 +1,45 +0,53

H5IOQ — IO3 — H I O — I2 — I (moi trudng axit)

K20 + 0,7 +0,14 +0.45 +0.53

H 3 l O g — IO3 — 1 0 — I2 — I (moi trudng baza)

+0,29 Tfnh oxi hda ciia idt the hien khi nd tac dung vdi chat khii* manh, vf du:

I2 + Na2S203 = 21" + Na2S406

Phcin ling nay thudng dung trong phuang phap chuan do oxi hda-khii

Tfnh khii" ciia idt the hien khi nd tac dung vdi mot chat oxi hda manh, vf du:

CI2 + 2KI = 2KC1 + I2 Mgl dac diem quan trgng cQa nguyen id idt la nd cd kha nang xiic Uic cho nhi6u phan ling hda hgc [30]; dua vao dac diem nay cd the dinh lugng idt bang phuang phap dong hgc xiic tac, va den nay ngudi ta da tim dugc rat nhieu he phan ling dugc xiic tac bdi idt [51] Tuy nhien khi sir dung phuang phap dong hgc xiic

tac de xac dinh idt trong cac ddi tugng sinh hgc va moi irudng, can phai luu y 6cn

nhung di6m sau: Trong cac ddi tugng sinh hgc va moi trudng idt thudng idn lai d

trang thai hda tri - 1 , +1 la nhung dang kem ben, nen ra't di bi mat idl trong qua

trinh bao quan va che hda mau phan tfch; vi the, de loai trii" nhuge diem nay, khi chgn kl thuat phan hiiy mSu, can phai sii' dung cac tac nhan oxi hda manh de chuyen idl deii trang thai hda tri +5 (dang rat ben ciia idt) va sau dd lai dua idl vd dang r bang nhung tac nhan khir ihfch ling

1.3.2 Nhu cau va vai trd idt trong sinh ly ngudi [38], [40], [133], [137]

Idl \h mot trong nhiing nguyen td vi lugng tdi quan trgng cho ca the ngudi

Ca the ngudi trudng thanh chiia khoang 15 - 20 mg idt, trong dd khoang 70-80% dugc du Iru" d tuyen giap Ngoai tuye'n giap la ca quan thu nhan lugng Idn idt, mot

sd td chiic khac ciing thu nhan idt nhu tuyen vii, mang dem (chorion), luycn nude bgt, da day, budng triing, tinh hoan, lach, tuyen thugng than vdi mot lugng nhd

Idl la nguyen td ca ban de long hgp hooc-mon giap (Thyroxin-T4 va Triiodothyronine -T3), cac hooc-mon giap nay ddng vai trd quan trgng ciia su

chuyen hda tat ca cac te bao trong ca the trong lien trinh tang irudng va phai trien phan Idn cac ca quan, dac biel la nao bg

"= Nhu cau idt ciia ca the ngudi

Theo tai lieu [22], [62], nhu cau idt ddi vdi ngudi irudng thanh la l^ig idl/

kg the lrgng/24 gid; nhung vi trong Ihiic an cd the idn lai mgl sd chat sinii budu (goilrogen), vi the, ngudi la de nghi miic thu nhap idt ddi vdi ihieu nien va ngudi trudng thanh la 150 pg/24 gid ; ddi vdi phu nu cd thai va cho con bii phai tang them 25-50 pg/24 gid

Theo Hoi ddng qudc le \6 kiem soat cac thieu hut idl (International

Council for the Control of Iodine Deficiency Disorders - ICCIDD)/ Quy Nhi ddng Lien hiep qudc (United Nations Children's Fund-UN1CEF)/T6 chiic Y te the gidi (World Health Organization - WHO) nhu cau idt hang ngay dua theo tudi dugc neu d bang 1.2

Bdngl.2 Nhu cau idt hang ngay (theo tudi) [133], [135]

Cho con bii

Nhu cau (|ug/ngay)

cd Irong hai san, Ihil, cii, triing Mudi an tuy san xual ILT nude bien nhung cd rat ft idl VI KI trong nude bien khong cd ciing do ket tinh vdi NaCl; va khi thu hoach mudi, ngudi ta da bd lai idl trong nude chat Rau cd va thii ca san xual d vung dai thieu idl, cung bi thieu idt Nguyen nhan sau xa lam cho con ngudi thieu idt la do moi Irudng, nhat la trong dat thieu idl Ngoai ra, idt edn bi ma't di mgl phan trong qua Irinh che bieii thii'c an, vf du: ham lugng idl trong ca se mat 20% khi ran, 23% khi nudng va 50 % khi luge Ngudn bo sung idl quan trgng nhat cho ca the la sii' dung mudi an da idt hda

1.3.3 Hap thu va chuyen hda idt [22], [38], [133], [137]

Idl lii" thuc pham va nude udng (dang I") nhanh chdng hap thu qua rugl vao mau III" miiu, phan Idn idt dugc tap Irung d tuyen giap Trong tuyen giap, I bi oxi hda thanh I2 rdi kel hgp vdi nhanh lyrosin ciia thyroglobulin de lao ra monoiodotyrosin (MIT) va diiodotyrosin (DIT), sau dd MIT va DIT dugc ghep doi de tao ihanh hooc-mon giiip la T3 (Iriiodothyronin) va T4 (letraiodolhyronin, thyroxin)

1.3.4 Su bai tict idt [22], [38], [40]

Nhu tren da trinh bay, sau khi idt vao ca the ngudi, phan Idn idt dugc lap trung d tuyen giiip Kho du iru nay luon luon dugc bd sung va ddi mdi Vf du, hang ngay mot ngudi thudng ha'p thu khoang 500 pg idt tCr thuc pham vao tuyen giiip; trong thdi gian dd tuyen giap san xual va liel vao mau khoiing 500 fig idt dudi dcing hooc-mon giap hoac d the tu do hoac lien ket vdi TBG Sau khi hoan thiinh nhiem vu chuyen hda d cac td chiic ngoai vi, idt lien ket huu ca bi ihoiii giang (bi khii" idt) phat sinh khoang 500|ag idt vo ca (I") Nhu vay idt huyet thanh gdm hai thanh phan: ngoai lai va ngi sinh ggi chung la idt ngoai tuyen giap Tu huyet ihanh idl phai dugc cung cap dii cho tuye'n giap khoiing 500^g/ngay, va ngudi la ggi day la hien tugng "do tap trung idt tuyet ddi" ciia tuyen giiip Lugng idl con liii Irong huyet thanh dugc thai ra ngoai qua nude tieu (khoiing 500|-tg)

Vi phan Idn idt thu nhan vao ca the deu dugc thiii qua nude lieu (lugng idt bai liei qua phan khong dang ke, < 5|j.g/ ngay), do dd ngudi ta xem ham lugng idt trong nude lieu la chi sd khach quan va quan trgng de danh gia su cung cap idt tCi" ihiic an, nude udng va khong khf Su can bang giua idt nhap viio ca the qua Ihiic

an va su bill liel idl theo dudng lieu cd gia tri quan trgng trong vice danh gia diing nhu cau idl hang ngay cCia ca the

1.3.5 Nguy ca thieu va thua idt [10], [11], [38] , [134], [137]

1.3.5.1 Nguy ca thieu idt

Khi nhu cau idt ciia ca the khong du se keo theo mgl chudi bien chiing bat thudng cho ca the, bao gdm bieii ddi chiic nang va hinh thai tuyen giiip nhu; budu giap, chiing diin don, giam sinh san, tir vong chu sinh va sa sinh cac bieii chiing nay lii mot trd ngiii that su ddi vdi phiil trien ciia con ngudi va xa hoi, dugc tdm

V-l////?^

tat dudi cum tii' "cac rdi loan thieu hut idt" (IDD- iodine deficiency disorders) do Basin S Hetzel de nghi nam 1983 nham neu rang: thieu idt khong chi gay ra budu giiip nhu quan nieni cu, ma cdn gay ra nhieu hau quii khac Dung chir "rdi loiin",

de chi lang nhung hau qua do thieu idt cd the de phdng dugc

1.3.5.2 Ciic rdi loan thieu hut idt tren the gidi [14], [17], [22], [133]

Thieu hut idt la va'n de loan cau ma Lien Hiep Qudc ggi la "niin ddi idt liem an" Niun 1990, theo ICCIDD/ UNICEF/ WHO, tren the gidi cd khoang 1 ly ngudi cd nguy ca bi thieu hut idt Rieng d ciic nude dang phiit trien la khoiing 800 irieu, 190 trieu ngudi bi budu giap va 3,15 Irieu ngudi bi mfic chiing dan don Nhung viing thieu hut idl Iricn mien va lau dai la d cac day niii Alpes, Hymalaya, Hoang Lien Son, nhung vung niii rgng Idn d Trung Qudc, An Do, Dong Nam A, Niim My Cung theo WHO (1992), ly le mac budu giap loan cau la 12% (655 trieu ngudi mac) Chau Au, niiic du da sii" dung mudi Iron idl va cac bien phap bd sung idl kluic tii" hang chuc iiiim nay, nhung CRLTHI van cdn idn lai d nhidu nude Theo "Hoi tuyeii giap qudc te ", tren the gidi chi cd hai nude Nhat va Hoa Ky (miic idl nieu trung vi Ian lugt la 200 l-ig/L va 165|.ig/L) la kliong mac CRLTHI, cac nude cdn lai vfm cdn ton liii viiii de nay, d cac miic do kliiic nhau tiiy theo moi viing

1.3.5.3 Nguy ca thiia idt [38]

ThCia idl cdn dugc ggi la nhiSm hoac qua tai idt, do sir dung cac phuang lien

bd sung idt keo dai, hoac sii' dung thude hoac cac chii'l can quang chii'a mgl lugng idl qua ciio, vugt qua nhu cau sinh If De phdng ngiia cac nguy ca va hau quii ciia thua idt, Td chiic Y le The gidi (WHO) khuyeii cao cac nude dang sii" dung ciic phuang lien bd sung idt de phdng chdng thieu hut idt, can phiii cd chuang lihih giam sat ham lugng idl d cong ddng

1.3.6 Nhung chi thi sinh hgc thudng dung de danh gia tinh trang dinh dudng idt d ngudi [133]

1.3.6.1 Idt trong mau

Day la chiit dich sinh hgc quan trgng de danh giii dinli duang idl tren ngudi, tuy nhien khi nghien ciiu idt d cong ddng, vice lay niiiu cung nhu phan Ifch

idt trong hai loiii nay luang ddi phiic lap han so vdi nude lieu De chan doan diing mgl sd benh do thiia idt gay ra nhal thiet phiii xac dinh ham lugng idt trong mau (idt d diing T3 va T4 hoac idt d diing PBI)

1.3.6.2 lot trong tdc va mdng

Cii'u tiio sinh hgc ciia idc ngudi kha phiic liip, gdm ba lap, trong ciing lii lap tiiy, ben ngoai gdm nhung te bao siing hda chiia chat keratin Phan Idn nhung nguyen td vet phat hien trong tdc nam d Idp bieu bi ben ngoai ciia tdc [122] Hien nay ngudi la da phiil hien trong tdc ngudi chua khoiing 30 nguyen td, trong dd cd idt [79] 0 ngudi irudng thanh tdc phat trien iCi' 0,3-0,5 inm/ngay Cac nguyen id vet hien dien trong tdc cd the dugc diio thiii tii' niiiu hoi)c dugc hii'p phu lii" moi trudng khong khf ben ngoai [78], [79], [103]

Sii dung tdc va mdng lam yeu id chi thi cho viec danh gia tinh triing idt

dang cdn iranh luan chua cd y kieii thdng nhat Vi vice lay mSu cung nhu xac dinh idt trong tdc va mdng rat phiic liip, do vay, sd cong Irinh nghien ciiu ve idt trong hai ddi tugng nay dang cdn hiin che [122]

1.3.6.3 Idt trong nu'dc tieu va sua me Nhu da trinh bay trong muc 1.3.5, tren ca

the: ngu'di, nude lieu va sua me la hai con dudng bai liel chinh yeu ciia idt ra khdi

ca the, cd the xem nude lieu va sua me la hai ddi tugng Ihuan lien nhii't de la'y miiu xac dinh idt nham danh gia tinh trang dinh duang idt ddi vdi Cii nhan cung nhu cong ddng Vi the, hien nay, hiiu liel ciie cong Irinh nghien ciiu ve idt Iren ngudi,

ngudi ta dt^u sii" dung nude tidu va sua me lam yeu td chi thi

1.3.7 Pluin loai va danh gia muc do thieu va du idt dua vao ndng do idt-nieu

Dua vao muc idt-nieu trung vj, Td chiic Y le the gidi da phan loai su thieu hut idl nhu sau:

Bdng 1.3 Phan loiii muc do thieu hut idl dua vao ndng do idt-nieu

Tinh triing thieu hut idt Khong Ihieu idt

Thieu nhe Thieu vii'a Thieu nang

Idt-nieu trungvi (pgl/dl)

> 10 5-9,9 2-4,9

< 2

De dcinh gia miic thieu hut idt, ngoai miic idt-nieu quy dinh tren day, ngudi

la cdn yen Ciiu them:

- So mau nude lieu cd ham lugng idt-nieu < 10 pgl/dl phiii < 50% tdng sd

miu nghien ciiu

- So mfiu nude lieu cd ham lugng idt-nieu < 5 i-igl/dl phiii < 20% tdng

sdinfiu nghien ciiu [135],

1.4 M O T SO PHUONG PHAP PHAN HUY M A U NGHIEM DE XAC DINH LUONG VET I O T

Trude khi lieii hanh phan tfch lugng vet idl trong cac mSu sinh hgc, can phiii phan luiy mfiu nghiem Muc dfch ciia giai doiin nay la loiii trir cac chat huu ca vii v6

ca cd mat trong mfiu phan tfch, cac chat nay cd the se iinh hudng deii lieii trinh pluin tfch Tiiy ihugc vao piiuang pluip phan tfch cung nhu ddi lugng phan ifch de lua chgn phuong phiip phan hiiy mfiu thfch hgp Khi chgn phuang phiip phan huy mfiu

de phan tfch idt can phai quan lam 66n dac tfnh hda hgc ciia idl de Iranh su mil't idt

cd the Xiiy ra trong giai doan phan hiiy mSu Trong moi Irudng kiem hoac trong moi trudng cd cac chat oxi hda miinh idl tdn tiii d diing 10 3 rat ben va chi bay hai d nhiet do > 650"C [43], Sau day la mgl sd phuang phap phan hiiy mSu nghiem de Xiic dinh lugng vet idl trong Ciic mau sinh hgc [3], [26], [63], [121]

1.4.1 Phuong pliiip udt

Tiieo phuang phap nay, mfiu dugc phan hiiy bang cac dung dich cd tfnh oxi hda niiinh Tdc do phan hiiy phu thuge vao ban chat ciia cau tii* can xac dinh,lugng miiu, kfch thude mfiu, dung dich phan hiiy, nhiet do va khuay ca hgc Nhung dung

dich thudng dugc six dung la:

Hdn hgp iixit dac gdm: H2SO4 + HNO3 + HCIO4, vdi hdn hgp niiy, ciin phiii dua nhiet do trong binh phan hiiy tu' 200**C-250'"C de dudi cac axil cdn du vii khii nang ket tiia ciia mot sd mudi trong dung dich [52], [65]

Dung dich axit cloric (HCIO3) 28% (trong mgl sd trudng hgp ngudi ta cd the them mot lugng nhd Na2Cr04 de tang tfnh oxi hda) Khi sii" dung dung dich niiy ciln dun ndng binh phan ii'ng d nhiet do tu I05"C den I60''C tuy theo biin chii'l

ciia Cii'u ui phiin tfch Can luu y la d nhiet do > 105"C, axil percioric bdc khdi gay doc hiii vii nhung mudi Uxo thanh cd the gay nd neu khong cd he thdng thong hiil hoi khf doc thfch hgp [65], [142]

Ddi vdi nhung dich sinh hgc (nude lieu, sua), cd the six dung nhuiig chiit oxi hda miinh nhu: (NH4)2S20ji bao hda, hoac K2S2OX+ biic Xii cue tfm, liim lac nhan phan hiiy mAu [72], [92], [127]

1.4.2 Phuong phap kho

Trong mgl sd trudng hgp, dac biel la cac mSu ran hoac mau cd chiia thanh phan phiic liip, cd the sii' dung phuang phap "klio", nguyen tdc ciia phuang phiip nay la tro

hda miiu cdn phan hiiy trong moi trudng kiem vdi cac hdn hgp kiem thfch hgp

De Xiic dinh idl trong mSu sinh hgc, ngudi la da su dung niiung quy irhih phan hiiy biing phuong phap kho, bang ciich nung mfiu d nhiet do 600-620"C vdi mgl Irong ciic chai sau:

KOH ; K2CO3; Na2C03 + ZnS04; Na2C03+KN03 (hdn hgp aiecti cd nhiel

do soi Ihitp nhat); KCIO3+ glycin + Na2COv [3], [65]

Sau khi tig hda, hda tan miu vdi dung dich axit, da sd cac ion chuyen vao dung dich Ly tam loai bd can lay dich trong de dinh lugng idt (khong dugc Igc bang giay Igc Whatman, vi giay Igc cd the hap phu idl, gay sai sd kel quii phan ifch)

1.4.3 Pliuoiig phap thuy nhiet phan

Nguyen tac ciia phuang phiip nhu sau: cho hai nude (hoac khong khf riii

am) di qua mSu da dugc nghien nhd va dugc ddi ndng (180**C trong 30 phiil, rdi nang nhiel do len 300"C trong 30 phiil, cudi cLing nang nhiet do Id ddi len I000"C trong 90 phut) bilng mgl dung cu dilc biel (dung cu nay phai kfn Itr khi ddi den khi thu giu' idl) Thu dung dich idt cudn theo hai nude vao bg phan cd chiia dung dich 0,1M KOH Trong nluing Irudng hgp khd khan, khi cac phuang phiip kliac dinh lugng idt khong thanh cong, phuang phap nay cho ket qua kha tdi Cac tac gia [72], [138] da sii" dung phuang phiip nay de xac dinh idl trong mfiu dii'l va mSu sua

1,4.4 Ciic phuang phap khac [65]

Ngoiii ba phuang phap tren, khi xac dinh idt trong mgl sd miu diing long, ngudi la cd SLI" dung nhieu phuang phiip khac de phan hiiy mau:

PhiUip J Garry va cong su dCing niiing Ihrim tfch (dialysis) de xii" h' miiu nude tieu,

va xac dinh idl trong mSu da xu If bang phuang phap phan tfch tu dong Analyzer), Cac tac gia ket luan phuang phap nay chi xac dinh idl trong miiu nude tieu cd hiim lugng > 5 pgl'/dl [65]

(Aulo-Tiic giii [92] dinig Id vi sdng (microwiives) de phiin hiiy mfiu nude lieu, khi

dd r irong niiiu dugc chuyen thanh lO';, bang KIO4 vdi su trg giiip nang lugng biic Xii (520W) ciia Id vi sdng Phuang phap nay cd hieu quii ciio so vdi Ciic phuang phiip phan hiiy khac

Kazhide Tsuda da xiic dinh idt trong nude lieu bang phuang phiip lu dong vdi vice phiin hiiy mfiu bang hue xa cue tfm (ullraviolel iiTadiation)[127]

1.5 TONG QUAN CAC PHUONG PHAP XAC DINH LUONG VET IOT 1.5.1 Ciic phuong phap xac djnh lugng vet idt

1.5.1.1 Ciic phuong phap phan tich quang phd

''' Phuong phap trac quang

Theo Ciic lac gia trong tai lieu [66] , cd the xac dinh idl (1) trong nude lieu bang phuang phap trac quang vdi thude thii tao mau la telramethylbenzidine Ca sd ciia phuang phap nay nhu sau: loai tru' cac lap chat irong nude lieu bfmg ciich cho nude tieu chiiy qua cot cd chiia cacbon hoiit tfnh, sau dd axit hda dung dich nude lieu (pH: 4) bang dung dich dem citrat, them vao telramethylbenzidine (2,5 mM), chill nay se tiic dung vdi T de liio thanh mot phiic chat mau xanh luc, do Iruc licp

mat do quang dung dich ciia phiic dd d budc sdng (k) 646 nm Cd the diing mgl sd

amin tham khiic lam chat Uio phiic mau nhu: o va p-phenylendiamine, benzidine, nhuiig diui xuitl ciia benzidine Bang phuang phap nay cd the xac dinh ndng do idt trong nude lieu khoiing 6 ^100 pg/dl Vdi dieu kien trong dung dich nghien ciiu khong cd Uip chat huu ca, GHPH ciia phuang phap nay diU deii 0,2pgr/dl

"^"^ Phuong phap chiet trdc quang [34], [46]

Phuang phap nay dua tren nguyen tac: oxi hda I" trong dung dich thanh IO3 bang nude brom, loiii bd lugng brdm du bang axit fomic Trong moi trudng axit iixelic (pH: 4,5H-5,5), IO"^ se oxi hda KI Ihanh I2, va I2 oxi hda leucocrystal violet

(CH[Cf,H4'^(CH3)2].0 thanh diing crystal violet, chiet crystal violet bang clorofom rdi do mat do quang ciia dich chiet d budc sdng 588 nm Dinh luiU Bia luycii tfnh trong khoiing ndng do tii" 0,8 -^8,0 jagl'/dl, vdi he sd hap thu plmn lii gam s va do nhay theo Siindell Mn lugt la l,01x 10^' 1 moi'' cm"' va 0,00012pg c m ' l Tac giii trong lai lieu tren da dung phuang phiip nay de xac dinh idt trong nude bien

Ciing cd the xac dinh idt bang phuang phap trac quiing hoiic chiet trdc quang vdi viec oxi hda I" thanh I2, cho I2 liic dung vdi hd linh bgt se tao thanh phiic mau xiinh tfm cd hap thu cue diii d budc sdng 590 nm, bang phuang phap nay cd ihe xiic dinh idl trong dung dich d ndng do khoang 1,0 j-igl'/dl Phuang phap iiiiy dugc sii' dung de xac dinh idt trong mudi an [34], [46]

:!;:i:=i= Phuong phiip quang plid phat xa nguyen tii plasma (ICP-AES) va phd khdi plasma (ICP-MS)

Theo phuang phap ICP-AES, mSu dugc bam true tiep vao ngudn kfch thfch plasma (ICP) cd nhiet do khoang 6000"C, d nhiet do dd thanh phan ciia mau bi nguyen tii" hda hoan loan va phiil ra cac biic xa cd budc sdng xac dinh Do cudng

do ciia biic xa dac trung cho nguyen td can phan tfch de suy ra ndng do nguyen id can phan ifch Vdi phuang phap ICP-MS, mSu cQng dugc bam true liep vao ngudn ICP va sau khi da bi ion hda, cac ddng ion dugc dua vao he phan lich khdi lugng

de Uich Ciic ion dua vao ly sd m/z ciia chiing (m va z la khdi lugng va hda tri ciia ion) Sau dd cac ddng ion dugc dua vao budng detecia va dugc chuyen ihanh tfn hieu dien Do Idn ciia tin hieu thu dugc lii' delecta la thong tin de dinh lugng

Tac gia [110] da sii' dung phuang phap ICP-MS de dinh lugng idl Irong

nude lieu, vdi khoang tuyen tfnh [0,1-rlO pgl'/dl] Mac dij thiet bi ICP-MS dat

lien va kl thuat van hanh phiic tap, tuy nhien klii so sanh phuang phap ICP-MS vdi nam phudng phiip kliiic hien dang dugc sii' dung de djnh lugng idt tren the gidi, Sandia L May va cong su cho ling cung nhu phuang phap NAA, phuang phap ICP-MS dugc xem la phuong phap "chuan vang" de xac dinh lugng v6'l va sieu vet idt [92]

1.5.1.2 Phuong phap sdc ki

Theo phuang phiip sdc kf khf, I" trong dung dich dugc giin viio hgp clui'l huu

ca pentanon-3 de tao thanh dSn xual iodo cd ten: 2-iodopenlanon-3, sau 66 ngudi

ta chiel hgp chat nay bang liexane va do 2-iodopentanon-3 tren may sac ki vdi nhung ihong sd kl thuat nhu sau:

- cot mao quan: (30 m x 0,53 mm)

- khf mang: He ( 5,45 ml/phiil)

- nhiet do nai bam mfiu: I50"C, nhiel do Id nung 300"C

- detector bat dien tir (electron-capture detector)

Tac gia trong tai lieu [72] da diing phuang phap nay de xac dinh idt Irong sua da loiii chitl beo vdi gidi han dinh lugng la 6.10'^M

Tac gia [112] da xac dinh idt bang phuang phap HPLC diio plia sii' dung detecia dien hda vdi dien cue Ag GHPH la 0,06 |-imol/L Do thu hdi khi them idt vao miiu phan tfch la 96%

Tac giii [44] sii: dung phuang phap sac ki ion vdi detecia amperomelric de xac djnh idt trong nude lieu, mau va tdc ngudi GHPH Idn lugt la: 0,003pg/ml; 0,007|.ig/ml va 0,046 pg/g Do thu hdi khi them idt vao mfiu phan tfch: 82-93%

He sd bieii dong < 9%

1.5.1.3 Phuong phiip dien hda

''' Phuong phap do the dung dien cue chgn Igc ion [19], [59]

Dien cue chgn Igc ion diing trong phuang phap do the de dinh lugng idt la cue miing rfin, dugc che tao tii* hdn hgp AgI/Ag2S Cau iriic cua le bao do nhu sau:

Ag/AgCl/KI (0,lM)/mang rfin Agl + AgjS/dung dich pluin lich/KCl/AgCl/Ag

Dinh lugng idt theo phuang phap dudng chuan-la dudng bi6u di6n su phu thuge cua the do dugc vao lg[r] Phuang phap nay cd mot sd diem han che nhu: ion

clorua va sunfit can trd phep do, vi the citn phai loai trii' 2 ion nay ra khdi dung dich do Trong qua trinh Xiic dinh idl, dien cue thudng xuyen bi mgl Idp mang biio phii, nen phiii can than loai trii' Idp mang phii tren dien cue

Goltardi va cong su da diing phuang phap nay de Xiic dinh idt trong nude tieu, va luu y rang ion CI" anh hudng nhieu deii kel qua phan tfch Cd the loiii trir

cac ion can trd bang ky thuat sfic ki ion; trudc het CÍ va I" dugc gfin len nhua amberlile, sau đ riia giiii loan bg CI" bfing dung dich 0,2 mol/L NaNÔ, rdi liep

tuc riía giiii T bfing dung dich 5 mol/L NaNỘ Sau 66 xac dinh Í trong dung dich

riia giiiị GHDL ciia phuang phiip la 5,l^g/dl Nhieu tac gia khiic [65] cung dĩi nghien ciiu ap dung phuang phap dien cue chgn Igc ion de xac dinh idt trong sua ngudi va nude lieu, song deu dua den kel luan la phep do nay bi han chẹ Mile dii

cd cac hcin che đ, phuang phap nay vfin cdn thfch hgp de xac dinh idt trong nude lieu d nhung benh nhan dieu Iri bfing amiodaroue, hoiic sií dung ciie dugc pham cd chiia idl khac [52]

M:.t Phuang phap cue phd đng mot chieu (cue phd DC) [19]

Tiong phuang phap nay, ngúdi ta chuyen idt trong mfiu thanh dang lÓ-^, theo Ciich nhu d muc 1.4, sau đ ghi cue phd DC ciia ion lÔ trong n6n NaCl hoac

KCl, rdi dinh lugng idt bfing phuang phap dudng chufin hoac phuang phap them Ion lÓi bi khií tren dien cue gigt thiiy ngan theo phan ling:

I0-, + 6H^ + 6e - ^ r + 3H2O

Quii Irinh phan ling dien hda cd su tham gia ciia mot sd Idn electron (6e), nen phuong phap nay cd do chinh xac kha caọ Phuang phap nay cho phep xac dinh nhung ndng do idt cd lÓ^'M

:ii^:^: Phuang phap cue phd đng xoay chieu (cue phd AC) [19]

Phuang phap nay dua vao tfnh thuan nghich ciia qua trinh dien hda ciia cap 12/21-

21- - 2e -> I2 Ghi cue phd đng xoay chieu ciia qua trinh đ Chi6u cao cue dai (pic) quan sal dugc li le vdi ndng do I" trong dung dich phan Ifch Dinh lugng 1" bfing phuang phiip dudng chuan hoac phuang phap them

1.5.1.4 Phuong phap phan tich kich hoat natron (neutron activation

analysis-NAA) [41], [52], [78], [79], [103]

Phuang phiip phan tich kfch hoat natron dua tren su bfin phii chiim nótron vao mfiu phan tfch Qua trinh luang lac ciia natron vdi trudng hiU nhan ciia cac

nguyen ui cd trong mfiu; cac phan ling (n,y); (n,P); (n,a) xay ra, tiio thiuih Ciic ddng vi phdng Xii Nhung ddng vi nay phan ra vdi chu ki biin ra xac dinh va ciic biic xa CO nang lugng diic trung dugc ghi bfing cac loiii detector thfch hgp Cac ngudn nolron thudng dung: Id phan ling hiit nhan, ngudn natron ddng vi, ngudn natron tii' miiy gia tdc

t2x, t2.s • ll^di gian ra ciia mfiu va chuan tuang ling t3x, 13^ : thdi gian do ciia mfiu va chuan tuang ling

X : hang sd phan ra ciia hiit nhan dugc kfch hoat

Su cd mat ciia brom va clo trong mfiu se can trd phuang phap xiic dinh nen can phai uich cluing trudc khi phan tich; cd the hap thu idt tren nhua anionit AG 1x8 diing NO3", s'lu dd dong gdi mfiu nhua va chieu trong Id phan ling Gidi hiin dinh lugng ciia phuang phap la 2,4-r5 pg/dl

Cd nhieu loai phan tfch NAA, tren day la phuang phap phan tfch kfch hoat notion cd xii' If mfiu (radiochemiciil neutron activation analysis-RNAA); ngoai ra, ngudi la cdn diing phuang phap plmn tfch kich hoiil natron dung cu (instrument neutron iictivation analysis-INAA), la phuang phap phan tfch kliong can xii" If mfiu; nguyen tfic ciia phuang phap INAA nliu sau: Diing mgl cha't chuan cd phd y tdt, phan liug (n,y) & T]/2 thfch hgp Ngudi ta chieu ddng thdi chat chuan va mfiu can phan tfch; tfnh he sd K(, tiii ciic diem cliieu, tfnh cac he rieng ciia chuan va chiit so siinh theo cong thiic:

KI -f r \ / \ SI

A3^ = (0„.a + ^ e p i l o ) ^ va: K,, = ^ ; Trong do :

Agp va Agp: hoiit do rieng ciia chuiin va chill so siinh tuang ling

c]),^ va cpgpi: thong lugng neutron nhiel va tren nhiel

N.,: hi'uig sd Avogadro = 6,023x10^^

£ : hieu suat ghi ciia thiet bi

0 : do phd bien ddng vi

f : hieu sufil phat ciia dinh ghi nhan

a : liel dien phan ii'ng (barn)

M : nguyen lii* lugng ciia nguyen td cfin phan tfch

Thiel lap bang cac he sd Ko ddi vdi cac nguyen td tai kenh chieu chufin

trong Id phan ling da biel ti sd F = 0^^/(l>^p^

Hiim lugng C,^ ciia mfiu phan tfch dugc tfnh theo cong ihiic :

[Fana, + ( — ) ] [ F e , + ( - ' M * ]

Q = , : , Kong do K,„„ = f i^ K

Vanal + ( ) Jl'~ref

Phuong phiip nay cdn dugc ggi phuang phap chuan hda K-zero

Vi phuang phap NAA ddi hdi thiet bi hiem (Id phan ii'ng hiit nhan, may gia tdc ), do dd phuang phap phan tfch nay khd thuc hien rgng rai, tuy nhien day la

phuong phap cd do chfnh xac cao, non ngudi ta thudng diing phuang phiip NAA

lam chuan de diinh giii do diing ciia cac phuang phap khac Ngudi la da su dung phuong phiip NAA de Xiic dinh idt trong: tdc, mdng, sua, nude lieu, nude sinh hoat, dugc pham

1.5.1.5 Phuong phap mien dich phdng xii (radio-iininuno-assay - R.I.A) [8]

Idt trong huyet thanh tdn tai d hai diing v6 ca ( I ) va huu ca, dang idt huu

ca trong huyet thanh cdn dugc ggi la idt gfin protein (protein bound iodine- PBI) bao gdm 90% (T4 va T3) va 10% idt phi ngi liel (iodotyrosin va cac dfin xuiil) Hien nay ngudi ta su dung phuang phap RIA de xac dinh T;, va T4 trong niiiu

Phuang phap R.I.A dua tren ca sd ciia phuang pluip miSn dich hgc, dd lii phan ling tuang Uic giii'a khiing nguyen (iintigen-Ag) va kluing the (anlibody-Ab)

Trong phuong phap nay, cac hocmon T4 va T3 ddng vai trd khiing nguyen, cdn

khiing the dric hieu \ai hocmon dugc tiio thanh tii" ca the dong vat thi nghiem

(chugt, ihd, ciiu ) sau khi liem nhidu Ifin hocm6n vao con vat theo quy trinh nhii't

dinh Ngudi ta long hgp cac hocmon T4 va T3 va thay the ciic nguyen lii' 1 trong

phan tu Ciic hocmon nay bfing '^^I, va dugc ggi la hocmon phdng xii (Ag*)

Su ciinh Iranh giua Ag va Ag* khi chiing ket hgp vdi khang the Ab, theo phuong llinh sau:

Ab + Ag + Ag* ±1^ Ag.Ab + Ab.Ag*

Phan ling ket hgp giua Ab vdi Ag*se dat tdi trang thai can bfing sau mgl thdi gian niiii'l dinh Neu trong moi trudng phan ling, lugng khang nguyen khong danh dau Ag nhi6u len thi chiing se day mgl sd khang nguyen danh dau Ag* ra di khdi phuc hgp Ab.Ag* him cho lugng phiic hgp Ab.Ag* ft di Bfing kT Ihuill, ngudi

la cd ihe Uich rieng re phiic hgp Ab.Ag* cung nhu Ab.Ag ra khdi cac Ag va Ag* tu

do Do dugc hoat tfnh phdng xa ciia Ag* trong phuc Ab.Ag* se biel dugc lugng Ag tham gia vao phan ling Vdi thang ndng do hocmon khong ghi dii'u da bict trudc (cac mfiu chuan) va vdi mot lugng hocmon ghi da'u (T4 '^^I, T3 '^''I) hfing dinh cho trudc, ngudi ta thiet lap dugc ciic diing dd thi bieu di6n su ciinh Iranh ndi tren

1,5.1.6 Ciic phuang phap khac [42], [44], [73], [110], [116], [133], [143]

Ngoai nhu'ng phuang phap trinh bay d tren, de xac dinh lugng vet idl, ngudi

ta cd the su dung nhi6u phuang phap phan lich khac nhu: huynh quang tia X (XRF), pha loang ddng vi , phan tfch nhiel, quang phd hap thu nguyen tii' (AAS)

1.5.2 Phuong phiip dong hgc xiic lac xiic djnh idt

1.5.2.1 Phuong phap phan tich dong hgc xuc tac ddng chay (DHXT-DC)

Trong he FIA mfiu phan tfch dugc chuyen lu' van bam mfiu deii vdng pluin ling, Uic dung vdi thude Ihii* de tao ra san phfim nhat dinh cd the phiil hien vii dinh lugng nhd mgl delecta thfch hgp J M Burguera va cong su da sii' dung phuang phcip DHXT-DC de xac djnh idt trong nude lieu Theo phuang phiip nay, I' trong nude lieu dugc oxi hda thanh I2 bdi K2Cr207, rdi I2 dugc mang bdi mgl ddng nitrogen Phuang phiip nay diing detecia hda phat quang vdi chat pluit quang lii dung dich cobalt (II); GHPH la lOpgl/L [55], [75], [76], [100]

Tiic gia [100] da xiic dinh lugng vet idt trong sua bfing phuang piuip DHXT-DC Theo dd mfiu siia dugc phan hiiy bfing phuang pluip v6 ca hda irong

moi Irudng kiem (KOH + ZnS04) d 600"C , sau 66 dua mau da xu If viio he FIA

ba kenh su dung phiin ling chi Ihi lii KSCN-NaN02 vii detecia UV-VIS, phuong phap uiiy cd do lap Uii cao (94,5-100,7%), GHPH la 0,99|.igl7L vdi du lech chuan

tuang ddi la 5%

O Viet Niim, Chu Xuan Anh va cong su da iip dung phuang pluip

DHXT-DC de Xiic dinh idt trong nude bien va mudi an; he phiin ling chi thj [Ce'^^- As^^],

he FIA ba kenh, delecta UV-VIS [2]

1.5.2.2 Phuong phiip DHXT khong su dung phan ling chi Ihi [Cc'**- As^"^]

Ti^i' sau khi Sandell E B va Kolhoff I M nghien ciiu phuang phiip dinh lugng idl hfing ciich dua Viio hieu ling xiic Uic ciia idt len he pluin ting [Ce'"- As^"*] ( 1937), cho den niiy, ngudi ta da nghien ciiu them nhieu phan liiig chi Ihi kluic thiiy the cho he [Ce"*"^- As"^^] de xiic dinh lugng vel idt [51]

TiCii biing 1.7, liel ke idm lai mgl sd cong Irinh ngliien cLiu xac dinh lugng vet idl bang phuong phap DHXT khong sii" dung he [Cc"^"^- As^^]

1,6 Phuoiig phap ke hoiich hda thuc nghiem [31], [37], [47], [95]

Trong thuc nghiem Hda hgc phan tfch, de lieii hiinh thn dieu kien tdi uu cho mot ihi nghiem cd nhieu yeu id anh hudng len ket qua pluin tfch, ngudi ta thudng Sli dung phuong phap dan bieii, tuy nhien piiuang phap nay thudng mac phai mgl sd nhugc diem, chang hiin nhu khong diinh gia dugc anh hudng luang lid cila Ciic ycu td len kel qua thf nghiem, hofic khong the biel dugc miic do anh hudng cuii Umg yeu td VI the, de khfic phuc nhu'ng nhugc diem niiy, can phai lieii hanh ciic thf nghiem theo phuang phap ke hoiich hda lliuc nghiem Ciie phuang iin tim dieu kien tdi uu theo phuang phiip ke hoiich Iida thuc nghiem hiio gdm: phuang phiip mien gan diing, phuang phiip miing don hinh, phuang pluip mat muc lieu (res]-)onse surface), phuang phiip dudng ddc nhat (the steepest ascent palh); trong dd phuong phiip mat muc lieu va du'dng ddc nhii't la thudng dugc sii dung nhidu trong Hda phan tfch de thay the cho phuang phiip dan bieii

* Phuang phap khao sat mat muc tieu: ngudi ta lien hiinh nhung ihii luc

toiin hgc de tim cue tri ciia ham muc lieu can khao sat Ham muc lieu dugc bieu

di6n bfing mgl phuang trinh hdi qui diing da thiic:

y = bo + Zb.Xi + bijXiXj + SbiiX;^ ( 1 1 4 )

Phuong trinh hdi qui bac hai mo la mot mat muc lieu trong khong giiin n

chieu, cd Idi lom tuang ling vdi cac giii tri cue tri ciia ham muc lieu Lii'y diio ham

rieng theo liing yeu td ciia ham muc lieu de lim cue tri va cac gia tri cue tri tim

dugc se la dieu kien thuc nghiem tdi uu nhfim tdi uu hda thuc nghiem

De tap trung khao sat cac mien cue tri cua ham muc lieu, ngudi la phai dua

ham muc lieu bac hai ve diing chfnh tfic:

/ = 1 / = 1

Neu n = 2 ta dugc: Y- Y, = B, jX,^ + B22X2I

Khi dd: Bn, B22 tim dugc nhd dinh thii'c:

Y,: gia tri ciia ham muc tieu d gdc tga do mdi

Y: gia tri ciia ham muc lieu

X| X„: cac bieii chufin, la ham tuyen Ifnh ciia cac yeu td x,, X2-'-K

B|,, B22 -B,,: he sd ciia phuang trinh hdi qui diing chfnh tfic

Dieu kien de xet tinh diing ciia viec lim cac gia tri B nhu sau:

/ = ! ;=l

Khiio sat y nghla hinh hgc ciia ham muc lieu dang chhih tfic se biel diem

cue tri la cue diii hay cue lieu

* Phuang phap du'dng ddc nhat (cdn ggi la phuang phap Box-

Wilson-dudng ddc nhat :1a du'dng chuyen dich theo vecta gradient y(x), vecta nay bieu thi

su bicii thien nhanh nhitt ve phfa cue tri y(x) lii ham muc lieu bieu thi cho diii