TRUCJNG DAI HOC EXDNG THAP Tap Chi Khoa hgc sd 16 (11-2015)
NGHIEN ClfU XAC DEVH lOT TRONG MQT S6 DOI TI/0NG BANG PHlJONG PHAP VON-AMPE HOA TAN
TREN DIEN C^C BAC BIEN TESH HlTU Cd
• ThS. Ho Sy Linhn Tdm tit
lot Id nguyen to cdn thi^t hdng ngdy cho con ngudi, viic tim dugc phuong phdp xdc dinh id't nhanii, chinh xdc trong cdc doi tugng thuc phdm Id hudng nghiin ciiu rdt quan trgng. Nghiin cdu cda chdng toi ji?
dung phinmg phdp Von-Ampe hda tan tren diin cue bgc biin tinh hOu co de xdc dinh lot trong mot sodSi tugng. Ket qua cho thdy cdc dieu kiin td'i Uu nhUsau: dung dich nen N/l^H^O^ 0,1 M; bien tinh difn cuic vdi muoi p-NH^-Cfl^-N*OTs- 0,1 mM; the diin phdn ldm gidu 0,0 V: thdi gian diin phdn ldm gidu 30 j.
Cdc nguyen td khdng cdn trd viec xdc dinh id't khi nong dd [M] < 30[I] (vdi M = CI; Zn^*, Cu'*, Fe'*, F^\
CS", Pb^*, AsO^). Dd xdc dfnh dugc do thu hSi > 85%; khodng xdc dinh idt trong nUdc Id 3 - 1200 figfl, trong thuc phdm 0,05 - 100 mg/kg.
Tit khda: Von-Ampe. iot, diin cue bii'n tinh, aryl diazo tosylat, thuc phdm.
1. D$t vSn d^ tich Von-Ampe STA effa Lidn bang Nga (LB Nga).
Nhu ciu id't cua cd the dupe tinh b^ng microgam He 3 didn cure g6m: didn effe so sdnh Ag/AgCl (KQ IM), dien cffe phu trd Ag/AgCl v& didn eUc l&m vi^
Ag bid^n tinh vdi ciic mu^i aryl diazo tosylat.
- HCl, HNO3, H^SO^, KNO3, KjSjOj, KI.
NjH^.HjSO^ tinh khiet phan tich.
- CSc muoi aryl diazo tosylat ArNj^OTs" tinh khiet phan tich.
- Diing nUdc eS^t 2 iln d^ pha chd^ cSc dung dich.
2.2. Tid'n hanh phdn ti'cfa 2.2.1. Phdn hdy mdu
Vide phan hu^ mlu dU0e tien b^nh theo Ti6u ehuan LB Nga (GOST) [1] b^ng phUdng ph4p kh6 nhu sau: can 0,2 g mSu eho v&o cdc thuy tinh dung tich 20-25 ml; eho thdm dung dieh hdn hdp KNO, v& KOH; sau dd dun d nbi$t dd 130''C±10°C cho l(3i khi can khd; tiep theo nung mau d nhidt d6 300^;
trong 10 phlit; sau dd, tang nhidt do ldn 580°C vl nung mlu trong 30 phiit.
2.2.2. Tien trinh thi nghiim
Dung dich n ^ d n cfiu chto nen (KNO3, K^SjOj, N^^.H2SO^, dung dich dem pH = 4,5 diftfc chu^ ^ vk eho vko Wnh dien ph^n 3 didn cut: dien cijfc ^m vi6c MAgE kieu ex situ (hoac in situ), didn cvfc so s ^ Ag/
AgCl va dien cifc phu ttd Ag/AgCI. Sau dd, chiing t8i tidn hanh lam giau b ^ g eSch di^n phan ket tfia i6t 18n b^ mat didn cifc ki^u ex situ (hoae in situ) d&ng lh£fi ghi dudng Von-Ampe hoa tan va xSe dinh E^, Ip. Viec ghi dudng Von-Ampe hoa tan va xdc ifinh E . I ^ u dUW thilt hidn ttf ^ n g tren mSy phSn tich Vcm-Ampe STA , (LB Nga) va Aftfc dieu khien thong qua mky vi tinh.
3. K^t qua va thao lufin
3.1. Khao sat cdc y^u tCTanh hifdng dlTn tfn hi$u hoa tan cua id^t
(meg) nhiftig neu thieu nd, nhieu bieu hidn bdnh 1^
quan ttong se xuat hidn, dae biet la benh Iy tuyen giap. Theo [5], nhu elu bang ngay eho ngtfdi Idn la 150 mg iot/ngay. Thtfc ph^m la nhihig ngu6n cung c^p iot ehinh, chi^m khoing 90% lUdng iot di vao ed thi. Thid'u idt c6 thi dtfdc giii quyet bang cde hdp chl't giau id't hoac chS^t phu gia boat tinh sinh bpc ciia tiitfc pham: mud'i, do ud'ng, sin ph^m binh mi, cSc sin phim thit, thtfc pham ddng hop...
De xic dinh id't tiitfdng s^ dung cde phtfdng phip nhtf chuan do, tr^c quang, s^c k^, phSn tich kieh boat ncflron va phtfdng phdp Von-Ampe boa tan (SV) [2], [4). Phtfdng phdp SV ed lAi tii^ la dp nhay cao, tiiao tde de ddng va chi phi thid't hi th^p.
Hidn nay, phtfdng phdp xdc dinh id't bang SV ehu yd'u s^ dung dien ctfc mdng tiiuy ngdn kim loai (MFE). Day chinh la nhtfdc diem cua phtfdng phdp SV do thiiy ngdn Id kim Ioai dpc hai, Vi vay, vide tarn ki^m cdc didn ctfc mdi, cung nhUnghidn ciJu edc dac diem cua chung Id mpt htfdng phdt trien mdi, ttong dd ngtfdi ta quan tdm den vide SIJ" dung cdc didn etfe bi^n tinh, dac bidt la bi^n tinh didn ctfc bang ehat hi?u cd. Theo [3] cho tbl'y cdc mud'i aryl diazo tosylat ArNj*0Tse6 hidu iJng bien tinh didn ctfc tdt, chung cd tinh on dinh cao, de hda tan trong nifdc vk nhilu dung mdi hi?u cd khdc.
2. Tfai^c nghidm 2.1. Hda chS't, thid't bi
- Cdc phep do dtfdc thtfc hien ttdn mdy phan '•'Khoa Sif pham Hoa - Smh - Ky thuat N6ng nghi?p, Tnrdng Dai hpc D6ng Thdp.
82
mJONGmiHOC £ ) 6 N G T H A P Tap chi Khoa hoc so 16 (11-2015) Qua khdo sdt sd bd, chung tdi ed dinh cdc dieu
ki?n tin nghidm ban diu cho cde nghidn cvtu tid^p theo nhtf Bdng 1.
B&ng 1. C i c d i l u kifn thi nghidm trong phan tich itft T
T 1 2 3 4 5 6
Thdngsfi*
The' di^n phan lkm gi^u Thdi gian difin phSn ]kto giiu Thf l i m sach di$n aic TbSi gian l i m s^ch di#n circ Thdi gian ngh!
Khoing t h ^ k h l o sdt
ma
Edp (dp E.i„„
t.lc.n t,»<
E™,^
Dcfn vj V s V s s mV
G M t r j 0.0
30 -1,2 20 5 I>^(-1,2)
1 nen va muoi 3.1.1. Anh hudng cda dung dich aryl diazo tosylat
Chdng tdi tid'n hanh nghidn cthi inh hUdng cda tin hidu hda tan khi bi^n tinh didn crfe vdi cdc mudi aryl diazo tosylat ArN^^OTs" khdc nhau (vdi: Ar = p-NH^-CgH,; p-HOOC-C^H^; p-NO^-C^H^) ttong cde n^n khdc nhau (KNO3, K^S^O,, N^H^.H^SO^). Kd't qui cho th^y dO nhay tdt nhS^t Idii sij* dung dung dich n k NjH^.HjSO^ (Hhih 1) vd bid'n tinb didn ctfe b^ng muoi p-NH^-CgH^-N/OTs- (Hinh 2).
Hlnh 1. St^ phv thuOc I vko n6ng dO iSit trSn cSc dung djch nin khic nhau
Chii thick I: Nfi^H^O,. 2: K ^ , 0 , 3: KNO^
Hi«h2.S^phvlhu$cI vdo nSng d0 iol trin cdclogi di^n ctfc khdc nhau Chii thick 1. MAgE - 'NH,; 2: MFE; 3. AgE; 4: MAgE - NO^ 5: MAgE - COOH.
Cdc nghidn eihi cung cho th^y, ndng dd tdi tfu ciia dung dich ndn N H^.H^SO^Id 0,1 M, cbn eua mudi p-NHj-CgH^-Nj^OTs- la 0,1 mM. Khi tSng nong dd mucfi diazo eung cd hidn ttfdng lam giim tin hidu phan tich, dieu ndy eung ed the do tao da mang mdng va cde minh vd be mat didn ctfe. Vi vSy tixmg cde nghidn
cdu tiep theo cua chung tdi sur dung didn ctfc bien tinh vdi mudi p-NH^-C^H^-N^^OTs" (MAgE - NH^).
3.1.2. Anh hudng cda cdc chd't cdn trd Anh htfdng eiia cde ch^t cin ttd den tin hieu boa tan ciia iot dtfdc ddnh gid qua dd sai Idcfa cua ddng dinh boa tan (AI^) khi cd mdt chlit ein ttd so vdi khi khdng ed mat ch^t cin ttd, dtfdc tinh theo cdng fliUc: AI =11 -1° I/I" .100%. Trong dd I M Iln
p p p p =• p p ^
Itfdt Id ddng dmh boa tan cua iot khi khdng cd chat cin ttd vd kbi cd chSt cin 0^.
Chdng tdi da tien hdnh nghidn ciJu inh htfdng eua cdc nguyen to CI, Fe, Zn, Pb, Cd, Cu, As d^n tin hidu hda tan cia iot. Ket qui phdn tich dtfdc ttinh bdy d Hinh 3.
Hinh 3. Tl If C^C,- gSy Snh d^n tin hjfu ciia ifTt bdi mOt stf nguydn td
Ket qui khio sdt inh htfdng eua cdc nguydn to CI, Zn, Pb, Cu, Fe, As, Cd dd'n tin hidu hda tan eua i6^t vdi didn ctfc MAgE - NH^ cho thiy phep xde dinh iot khong bi ein trd khi nong dp cde nguydn t^CI, Zn, Cu nhd hdn ndng dd cfia i6t 100 iln vd kbi n6ng dO Fe, Cd, Pb, As nho hdn iot it nl^t 30 iln.
3 ^ . Xac djnh ham Ivtifng idt trong m$t sd'dtfi ttfdng thiXc td'
3.2.1. Ddnh gid khd ndng dng dung thuc tecua phuong phdp phdn tich
De dp dung phtfdng phdp phan tich vdo vide xdc dinh v^t idt trong cdc mlu thtfc td^, cin phii kiem tta phtfdng phdp phan tieh thdng qua dd lap lai va dp dung eiia nd. Kd^t qud cho tbd^y dp lap lai ciia phtfdng phdp cao va dd ddng dtfdc ddnh gid qua dp thu hSi (Bing 2) khi phan tieh mlu thdm chuin.
Bang 2. D$ thu hii cua phifdng ph^p khi x&c djnh itft
(P = 0,95,n = 3)
Miu
N i M c m S y ThiJc p h a m B O t t h i t
H f t m biifaf
Mlu
0 . 3 3 5
T h i m c h u ^ n 0,5
5 5
iSt (iie/1) T u n t y f y 0.7 6,8 8,9
R e v
%
87.5 8 5 8 9
83
T R 0 ( 3 N G DAI H O C 536NGTHAP Tgp chf Khoa hoc so 16 (11-2015) 3.2.2. Xdc dinh hdm lugng idt trong mat so ddi
tugng d thdnh phd Tomsk, LB Nga
Tien hinh phan tfch him Irfdng iot Hong mot s6 i6i tUcIng a thinh pho Tomsk, LB Nga hang dien crfc bac bien tinh hOu cO vi so sinh ket qua phSn tich vdi phUdng phSp GOST [1], s i dung dita cilc MFE. K^t quS difoc Binh biy 4 Bang 3 v i H n h 4.
Bang 3. Cic kft qui xic djnh him Irftfng itft trong mOt stf dtfi ti^Vng khac nliau
MSU
ThiJcSn eiacam D|u n^nh Bdlc^
Hkm Itfdns ifit (MS/1) GOST
(ddng MFE) 0,17 ±0,02 0,09 ± 0,02 0,28 ± 0,03
Phtfimg phap dlni^t 0,18 ±0,02 0,08 ±0,01 0,26 ± 0,02
—
sii.
/ /
- - •
™ ,
^ /
</
-^
' ^ 1 ^
•^
Ket qui ph3n tich theo hai phtfdng phdp dung MAgE vd MFE Id ttfdng dtfdng nhau. Nhtf vSy phtfdng phdp bid^n tinh hthi ed trdn didn ctfe bae xdc dinh iot cho dd dung td't khi so sdnh vdi phtfdng phdp ding didn ctfc MFE [1].
Ngiiid n eiJu khoing nong dp idt tuyen tfnh cho kd't q u i nhtf sau: Ndng dp id't tuyd'n tinh trong ntfdc Id 3-1200 mg/l va trong tiitfe phim la 0,05- 100 mg/kg.
4. Kd't lu^n
Phtfdng phdp SV xde dinh id't b i n g di^n ctfc bac bi^n tinh hOU ed ed dd ldp lai vd dd dung cao (dp thu hoi eao, > 85%).
K^t qui xdc dinh theo phtfdng phdp dung dScD ctfe bac bien tinh hihi ed ed dd chinh xdc vd dp dung ttfdng dtfdng vdi phtfdng phdp chuan theo GOST, diing didn ctfc MFE.
Khoing xde dinh i^t trong nUde 3-1200 mg/l vd trong thtfe phim la 0,05-100 mg/kg.
Phtfdng phip nay ed tfu diem Id khdng diing thiiy ngdn Id chl^t dpc hai, d nhilm mdi tnidngy.
Hmh 4. Dilimg hda tan nic djnh Hit trfin MAgE-NH^
d c£c di^u ki^n tafi tfu
Chii thich I: Dung djch nin. 2: Dung dfch mau. 3: MSU thim chudn.
Tai Udu tham khao
[1]. rOCT P 52689-2006 (2006), IlpodyKmbi nuufeebie. UneepcuoHHo soJibmaMnepoMempuiecKuii Memod onpedejiBHwi MaccosoU KOHiteHmpaifuu Uoda, CTaiu(apTHH(|M^PM> MocKBa.
[2]. flepfl6Hna B.A., CjienMCHKo TE., Oan KEM Hi.yHr, lOflHHa H.fl., Xo IUH Jlran. (2011), "3Kcnpecc- onpe^ejieHHe iioAa B 6HOJiorH^ecKH aicTHBHMx .QodaBKax MexoaoM BOJUiTaBijnepOMeTpHH", Haynno-
npaKmuuecKOJi KOH^epeHtfua Euonmuiectcu axmueHbie eeufecmea: 0yHdaMeHmajibHbie u npUKJiadnbie aonpocti najryucHim u npuMeueHWi, HOBUH CBCT, KpMM, VKpaHHa, c. 55-56.
[3]. Cjien4eHK0 G.B., H ap (2009), "HOBMB BOSMOXCHOCTH BojitTaMnepoMeTpHqecfHje onpefleneHM
BOJIOpaCTBOpHMblX BHTaMKHOB H ijUiaBOHOimOB HB MO;UIl|)imMpOBaHHIiIX T03HJiarHbIMH COJIXMH Z
^a^\ijOBbiX3iieKTpoa,ax",3a8odcKa}iJIa6opamopuHuJluagHocmuKa Mamepuanoe,!5(12),c. 11-14.
L4]. Pham Thi Hong Thdi (2009), Nghien cdu phumg phdp xdc dfnh vi lugng idt trong cdc ddi timg moi in^mg, Ludn vdn thac si, Trtfdng Dai hpc Stf pham - Dai hpc Thdi Nguyen, Thdi Nguyen.
[5]. Pham Thi Thuc, "lot cio rat it nhifiig khdng the thi^u". Site khoe vd Ddi song, http://www.ykhoajiet/
duoc/dinhduong/05_0} 86.htra.
DETERMINING IODINE IN SAMPLES BY THE VOLTAMMETRIC METHOD ON ORGANICALLY-MODIFIED ELECTRODES
Summary
Iodine is a daily essential element for humans. Therefore, finding methods to analyze iodine in food items is an important research approach. Oiu study applies the voltammetiic metiiod on organically-modified electrodes to determine iodine in certain specimen. The results show that optimum conditions are as follows: N^H^-H^SO^
O.IM background solution; modified electrodes witii p-NH^-CjH^-Nj^OTs- 0.1 mM saU; potential deposition O.OV; and deposition time 30s. Elements do not prevent the determination of iodine wilh the concentration [M]
< 30[r] (witii M = CI". Zn^% Cu^^ Fe^*, Fe^, Cd^*, Pb^\ AsO^")- It identified a recovery degree >85%; the delectting range of iodine in water is 3-1200 pg/I, and in food items is 0.05 - 100 mg/kg.
Keywords; voltammetiy, iodine, modified electrode, aryl diazonium tosylate, food.
Ngay nhdn bai: 03/9/2015; Ngdy nhgn lgi: 13/10/2015; Ngdy duyit ddng: 21/10/2015.
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