CNG HO X HI CH NGHA VIT NAM

QCVN 4-18:2011/BYT

QUY CHUN K THUT QUC GIA

V PH GIA THC PHM CH PHM TINH BT

National technical regulation on Food Additive Modified starches

H NI - 2011

Li ni u

QCVN 4-18:2011/BYT do Ban son tho quy chun k thut quc gia v Ph gia thc phm v cht h tr ch bin bin son, Cc An ton v sinh thc phm trnh duyt v c ban hnh theo Thng t s 01/2011/TT-BYT ngy 13 thng 01 nm 2011 ca B trng B Y t.

QUY CHUN K THUT QUC GIAV PH GIA THC PHM CH PHM TINH BTNational technical regulation on Food Additive Modified starches

I. QUY NH CHUNG

1. Phm vi iu chnh

Quy chun k thut quc gia (sau y gi tt l Quy chun) ny quy nh cc yu cu k thut v qun l v cht lng, v sinh an ton i vi cc ch phm tinh bt c s dng vi mc ch lm ph gia thc phm.

2. i tng p dng

Quy chun ny p dng i vi:

2.1. T chc, c nhn nhp khu, xut khu, sn xut, bun bn v s dng cc ch phm tinh bt lm ph gia thc phm (sau y gi tt l t chc, c nhn).

2.2. C quan qun l nh nc c lin quan.

3. Gii thch t ng v ch vit tt:

3.1. JECFA monograph 1 - Vol. 4 (JECFA monographs 1 - Combined compendium of food additive specifications; Joint FAO/WHO expert committee on food additives; Volume 4 - Analytical methods, test procedures and laboratory solutions used by and referenced in the food additive specifications; FAO, 2006): Cc yu cu k thut i vi ph gia thc phm, Tp 4 Cc phng php phn tch, quy trnh th nghim, dung dch th nghim c s dng (hoc tham chiu) trong yu cu k thut i vi ph gia thc phm; JECFA bin son; FAO ban hnh nm 2006.

3.2. M s C.A.S (Chemical Abstracts Service): M s ng k ha cht ca Hip hi Ha cht Hoa K.

3.3. TS (test solution): Dung dch thuc th.

3.4. ADI (Acceptable daily intake): Lng n vo hng ngy chp nhn c.

3.5. INS (International numbering system): H thng m s quc t v ph gia thc phm.

II. YU CU K THUT, PHNG PHP TH V LY MU

1. Yu cu k thut v phng php th i vi:

- Dextrin, tinh bt rang

- Tinh bt x l bng acid

- Tinh bt x l bng kim

- Tinh bt ty mu

- Tinh bt oxy ho

- Tinh bt x l bng enzym

- Monostarch phosphat

- Distarch phosphat

- Distarch phosphat phosphat ho

- Distarch phosphat acetylat

- Tinh bt acetat

- Distarch adipat acetylat

- Tinh bt hydroxypropyl

- Distarch phosphat hydroxypropyl

- Tinh bt natri octenylsucinat

s dng lm ch phm tinh bt c quy nh ti ph lc ban hnh km theo Quy chun ny.

2. Cc yu cu k thut quy nh trong Quy chun ny c th theo JECFA monograph 1 - Vol. 4, ngoi tr mt s php th ring c m t trong ph lc. Cc phng php th c hng dn trong Quy chun ny khng bt buc phi p dng, c th s dng cc phng php th khc tng ng.

3. Ly mu theo hng dn ti Thng t 16/2009/TT-BKHCN ngy 02 thng 6 nm 2009 ca B Khoa hc v Cng ngh v hng dn kim tra nh nc v cht lng hng ha lu thng trn th trng v cc quy nh khc ca php lut c lin quan.

III. YU CU QUN L

1. Cng b hp quy

1.1. Cc ch phm tinh bt phi c cng b ph hp vi cc quy nh ti Quy chun ny.

1.2. Phng thc, trnh t, th tc cng b hp quy c thc hin theo Quy nh v chng nhn hp chun, chng nhn hp quy v cng b hp chun, cng b hp quy ban hnh km theo Quyt nh s 24/2007/Q-BKHCN ngy 28 thng 9 nm 2007 ca B trng B Khoa hc v Cng ngh v cc quy nh ca php lut.

2. Kim tra i vi ch phm tinh bt

Vic kim tra cht lng, v sinh an ton i vi cc ch phm tinh bt phi thc hin theo cc quy nh ca php lut.

IV. TRCH NHIM CA T CHC, C NHN

1. T chc, c nhn phi cng b hp quy ph hp vi cc quy nh k thut ti Quy chun ny, ng k bn cng b hp quy ti Cc An ton v sinh thc phm v bo m cht lng, v sinh an ton theo ng ni dung cng b.

2. T chc, c nhn ch c nhp khu, xut khu, sn xut, bun bn v s dng cc ch phm tinh bt sau khi hon tt ng k bn cng b hp quy v bo m cht lng, v sinh an ton, ghi nhn ph hp vi cc quy nh ca php lut.

V. T CHC THC HIN

1. Giao Cc An ton v sinh thc phm ch tr, phi hp vi cc c quan chc nng c lin quan hng dn trin khai v t chc vic thc hin Quy chun ny.

2. Cn c vo yu cu qun l, Cc An ton v sinh thc phm c trch nhim kin ngh B Y t sa i, b sung Quy chun ny.

3. Trng hp hng dn ca quc t v phng php th v cc quy nh ca php lut vin dn trong Quy chun ny c sa i, b sung hoc thay th th p dng theo vn bn mi.

PH LC

YU CU K THUT V PHNG PHP TH I VI CH PHM TINH BT

1. Tn khc, ch s

Dextrin, tinh bt rang: INS 1400

Tinh bt x l bng acid: INS 1401

Tinh bt x l bng kim: INS 1402

Tinh bt ty mu: INS 1403

Tinh bt oxy ho: INS 1404

Tinh bt x l bng enzym: INS 1405

Monostarch phosphat: INS 1410

Distarch phosphat: INS 1412

Distarch phosphat phosphat ho: INS 1413

Distarch phosphat acetylat: INS 1414

Tinh bt acetat: INS 1420

Distarch adipat acetylat: INS 1422

Tinh bt hydroxypropyl: INS 1440

Distarch phosphat hydroxypropyl: INS 1442

Tinh bt natri octenylsucinat: INS 1450

2. nh ngha

Cc tinh bt thc phm c mt hoc vi thuc tnh gc c thay i do x l ph hp vi GMP, theo mt s quy trnh nht nh

M s C.A.S.

Tinh bt acetat : 9045-28-7

Distarch adipat acetylat: 68130-14-3

Tinh bt hydroxypropyl: 9049-76-7

Distarch phosphat hydroxypropyl: 53124-00-8

Tinh bt oxy ho acetylat: 68187-08-6

3. Cm quan

Hu ht ch phm tinh bt dng bt khng mi, mu trng hoc trng nht. Tu thuc vo phng php sy, cc bt ny c th gm cc ht tinh bt nguyn dng gc hoc cc khi gm nhiu ht (dng qu l, dng mt) hoc nu h ho trc s gm dng vy, bt v nh hnh hoc dng ht th.

4. Chc nng

Ch phm tinh bt, cht lm dy, cht n nh, cht n, cht nh ho

5. Yu cu k thut

5.1. nh tnh

tan

Khng tan trong nc lnh (nu khng h ho trc), to thnh dung dch keo nht in hnh trong nc nng; khng tan trong ethanol.

Cu trc hin vi

Xem m t trong phn Phng php th

Nhum mu iod

Phi c phn ng nhum mu iod c trng.

Kh ng

Phi c phn ng kh ng c trng.

Tnh khc bit

Xem phn th i vi dng tinh bt.

Xem m t trong phn Phng php th i vi:

- Tinh bt oxy ho hypoclorid

- Phn ng c trng i vi cc nhm acetyl

- Th dng tnh i vi cc nhm ester

5.2. tinh khit

Lu hunh dioxyd (SO2)

- Khng c qu 50,0 mg/kg i vi ch phm tinh bt t ng cc

- Khng c qu 10,0 mg/kg i vi cc loi ch phm tinh bt khc tr khi c ghi r trong bng 1

(xem m t trong phn Phng php th)

Ch

Khng c qu 2,0 mg/kg.

- Th theo JECFA monograph 1 - Vol.4.

- Xc nh bng k thut quang ph hp th nguyn t thch hp cho hm lng quy nh. La chn c mu th v phng php chun b mu da trn nguyn tc ca phng php m t trong JECFA monograph 1 - Vol.4 phn cc phng php phn tch cng c.

Cc tinh khit b sung i vi tng loi ch phm tinh bt ho hc

- Xem ct 3 bng 1

- Xem m t trong phn Phng php th

6. Phng php th

6.1. nh tnh

Soi knh hin vi

Cc dng ch phm tinh bt khng c h ho trc vn gi nguyn cu trc ht c th xc nh l tinh bt nh quan st bng knh hin vi. Hnh dng, kch thc v i khi s sp xp cc sc hoc ng vn l c trng ca ngun gc thc vt. Di nh sng phn cc qua lng knh nicol, gc ct phn cc in c th quan st c.

Nhum mu iod

Cho mt vi git kali tri-iodid 0,1N vo hn dch trong nc ca mu. Cc tinh bt ny nhum mu iod ging nh nhum mu vi tinh bt t nhin. Mu c th t mu xanh m n .

Kh ng

Cho 2,5 g mu trc c ra bng nc vo bnh chu nhit, thm 10 ml dung dch HCl long 3% v 70 ml nc, lc u, un vi sinh hn ngc trong 3 gi v lm ngui. Thm 0,5 ml dung dch thu c vo 5 ml dung dch kim nng ng (II) tartrat (TS). Kt ta mu thm c hnh thnh.

Tnh khc bit

phn bit gia cc loi tinh bt c x l khc nhau, tin hnh cc php th sau:

- Th i vi tinh bt oxy ho bng hypochlorit (khng th i vi tinh bt khoai ty oxy ho nh)

Nguyn tc:

V trong thnh phn c cha nhm carboxyl, tinh bt oxy ho bng hypochlorit c thuc tnh anion. N c th c nhum bng cc thuc nhum tch in dng nh xanh methylen.

Cch thc hin:

Gi hn dch gm 50 mg mu th trong 25 ml dung dch nc thuc nhum 1% trong 5 10 pht v thnh thong khuy. Sau khi tch dung dch d, tinh bt c ra bng nc ct. Kim tra bng knh hin vi cho mu r, nu mu l tinh bt oxy ho hypochlorit. Do vy, php th nyaf cho php phn bit c tinh bt oxy ha bng hypoclorit vi tinh bt t nhin hay ch phm tinh bt bng acid c cng ngun gc thc vt.

- Phn ng c trng ca cc nhm acetyl:

Nguyn tc: Acetat c gii phng nh qu trnh x phng ho tinh bt acetylat. Sau khi lm giu acetat c chuyn thnh aceton bng cch gia nhit vi Ca(OH)2. Nh aceton to thnh nhum thnh mu xanh bng ortho-nitrobenzaldehyd.

Cch tin hnh: To hn dch gm 10 g mu trong 25 ml nc v thm vo 20 ml dung dch NaOH 0,4N. Sau khi lc trong 1 gi tinh bt c lc ra v phn dch lc thu c c trong l 1100C. Cn c ho tan trong mt vi git nc v c chuyn sang ng th. Thm Ca(OH)2 v gia nhit ng th. Nu mu l tinh bt acetylat, hi aceton c hnh thnh. Hi ny to thnh mu xanh trn mnh giy tm dung dch bo ho o-nitrobenzaldehyd trong NaOH 2N. Mu xanh rt d nhn thy khi mu vng gc ca cc thuc th bin mt khi nh 1 git dung dch HCl 10%.

- Th dng tnh i vi cc nhm ester:

Ph hng ngoi tm film mng cho thy mt di hp th in hnh khong 1.720 cm-1 biu th s c mt ca cc nhm ester. Gii hn pht hin l khong 0,5% cc nhm acetyl, adipyl hoc succinyl trong sn phm.

6.2. tinh khit

Lu hunh dioxyd (SO2)

Phm vi p dng:

Phng php ny c p dng, vi mt vi thay i nh, i vi mu cht lng hoc rn thm ch c s c mt ca cc hp cht cha lu hunh d bay hi khc.

Nguyn tc:

SO2 c gii phng ra t mu trong mi trng acid un si v tch kh SO2 ra bng dng kh CO2. Kh tch ra c dn vo dung dch hydrogen peroxid long ni n b oxy ha thnh H2SO4 v c chun bng dung dch kim tiu chun. Mt cch khc, H2SO4 c th c nh lng bng BaSO4.

Dng c:

B dng c Monier-Williams nh lng acid sulfur, c cu to bng cc kt ni thu tinh thon tiu chun, c th mua c cc ca hng bn dng c thu tinh phc v nghin cu khoa hc ng tin cy. Tuy nhin, dng c ny thng c t lp t cc dng c thu tinh th nghim tiu chun c cc kt ni c np (xem Hnh 1).

Hnh 1

B dng c gm bnh un hai c trn dung tch 1.000 ml ni vi mt ng kh vo, mt phu nh git dung tch 60 ml c van kho kch thc l 2 mm, sinh hn ngc nghing Allihn. Mt ng dn ni vi phn trn cng ca sinh hn ti y ca bnh nhn hnh nn dung tch 250 ml, bnh ny dc ni ng Peligot.

Trong qu trnh vn hnh, lng kh CO2 thot ra c dn qua bnh by v to thnh bt khi cho qua hn hp phn ng nng, dn SO2 qua bnh ngng v vo cc bnh nhn, ni n c ht nh lng.

Chun b dung dch:

Dung dch Na2CO3: Ho tan khong 15 g Na2CO3 hoc 40 g Na2CO3.10H2O trong nc ct v pha ti th tch 100 ml.

Dung dch hydrogen peroxyd 3%: Pha 10 ml hydrogen peroxyd trung tnh 30% (ho cht tinh khit) vi nc ct cho n th tch 100 ml.

Cch tin hnh:

Cho CO2 t my sinh CO2 hoc bnh kh nn CO2 qua dung dch by Na2CO3 loi clor, t cho vo ng dn kh vo ca bnh un. Cho 15 ml dung dch hydrogen peroxyd 3% vo bnh nhn v 5 ml vo ng Peligot. Lp b dng c, cho 300 ml nc ct v 20 ml dung dch HCl m c vo bnh un bng phu nh git. un si hn hp trong khong 10 pht c sc kh CO2. Cn 100 g mu chnh xc n tng g v phn tn mu trong khong 300 ml nc ct va un si. Chuyn phn bn nho vo bnh un bng phu nh git, iu chnh tc mu thm vo v tc dng kh qua dng c nhm ngn s quay tr li ca hydrogen peroxyd, k c khng kh, hoc mi kht ca mu. un si nh hn hp trong 1 gi c sc chm dng kh CO2. Ngng dng nc trong sinh hn trc khi kt thc chng ct. Khi ng dn ngay bn trn bnh nhn tr nn nng, tho ng t sinh hn ra ngay lp tc. Ra cc thnh phn trong ng dn v ng Peligot vo trong bnh nhn, v chun bng dung dch NaOH 0,1N, s dng cht ch th xanh bromphenol (xem phn Ch ).

Thc hin th i vi mu trng, kt qu c tnh theo cng thc sau:

(S B) x 0,0032 x 100

% SO2 = -------------------------------------

W

Trong :

S: S ml dung dch NaOH 0,1N dng chun mu th

B: S ml dung dch NaOH 0,1N dng chun mu trng

W: Khi lng mu th (g)

Ch : Phn tch nh lng bng phng php cn c th c tin hnh sau khi chun . Acid ho bng HCl, kt ta bng BaCl2, n nh, lc, ra, t chy v cn tnh theo BaSO4.

Bng 1. Cc yu cu k thut v tinh khit b sung i vi tng loi ch phm tinh bt bin tnh bng ho hc

Loi tinh bt bin tnh

Tm lc phng php

Yu cu k thut i vi sn phm cui cng

Dextrin, tinh bt rang

X l nhit kh vi acid HCl hoc acid ortho-H3PO4

pH = 2,5 7,0

Tinh bt x l bng acid

X l bng acid HCl hoc ortho-H3PO4 hoc H2SO4

pH = 4,8 7,0

Tinh bt x l bng kim

X l bng NaOH hoc KOH

pH = 5,0 7,5

Tinh bt ty mu

X l bng acid peracetic v hoc hydrogen peroxid, hoc natri hypochlorit, hoc NaCl, hoc SO2 hoc cc dng c cho php khc ca sulfit, hoc kali permanganat hoc amoni persulfat

Nhm carbonyl thm vo khng c qu 0,1%; Khng c d lng ho cht; D lng SO2 khng c qu 50 mg/kg; D lng mangan khng c qu 50 mg/kg.

Tinh bt x l bng enzym

X l trong dung dch nc nhit di im to keo vi mt hoc nhiu enzym thu phn tinh bt dnh cho thc phm

D lng SO2 khng c qu 50 mg/kg

Tinh bt oxy ho

X l bng natri hypochlorit

Cc nhm carboxyl khng c qu 1,1%; D lng SO2 khng c qu 50 mg/kg

Monostarch phosphat

Ester ho bng acid ortho-H3PO4, hoc natri hoc kali ortho-phosphat, hoc natri tripolyphosphat

Hm lng phosphat tnh theo phosphor khng c qu 0,5% i vi tinh bt khoai ty hoc bt m, v khng c qu 0,4% i vi tinh bt khc.

Distarch phosphat

Ester ho bng natri trimetaphosphat hoc phospho oxychlorid

Hm lng phosphat tnh theo phosphor khng c qu 0,5% i vi tinh bt khoai ty hoc bt m, v khng c qu 0,4% i vi tinh bt khc.

Distarch phosphat phosphat ho

Kt hp cc x l i vi Monostarch phosphat v Distarch phosphat

Hm lng phosphat tnh theo phosphor khng c qu 0,5% i vi tinh bt khoai ty hoc bt m, v khng c qu 0,4% i vi tinh bt khc.

Distarch phosphat acetylat

Ester ho bng natri trimetaphosphat hoc phospho oxychlorid kt hp vi ester ho bng anhydrid acetic hoc vinyl acetat

Cc nhm acetyl khng c qu 2,5%; hm lng phosphat tnh theo phosphor khng c qu 0,14% i vi tinh bt khoai ty hoc bt m, v khng c qu 0,04% i vi tinh bt khc; v vinyl acetat khng c qu 0,1 mg/kg

Tinh bt acetat

Ester ho bng anhydrid acetic hoc vinyl acetat

Cc nhm acetyl khng c qu 2,5%

Distarch adipat acetylat

Ester ho bng anhydrid acetic v anhydrid adipic

Cc nhm acetyl khng c qu 2,5% v cc nhm adipat khng c qu 0,135%

Tinh bt hydroxypropyl

Ester ho bng propylen oxyd

Cc nhm hydroxypropyl khng c qu 7,0%; propylen chlorohydrin khng c qu 1 mg/kg

Distarch phosphat hydroxypropyl

Ester ho bng natri trimetaphosphat hoc phospho oxychlorid kt hp vi ester ho bng propylen oxyd

Cc nhm hydroxypropyl khng c qu 7,0%; propylen chlorohydrin khng c qu 1 mg/kg v d lng phosphat tnh theo phosphor khng c qu 0,14% i vi tinh bt khoai ty hoc bt m, v khng c qu 0,04% i vi tinh bt khc

Tinh bt natri octenylsuccinat

Ester ho bng anhydrid octenylsuccinic

Cc nhm octenylsuccinyl khng c qu 3%; v d lng acid octenylsuccinic khng c qu 0,3%

Tinh bt oxy ho acetylat

X l bng natri hypochlorit sau ester ho bng anhydrid acetic

Cc nhm acetyl khng c qu 2,5% v cc nhm carboxyl khng c qu 1,3%

Ch

- Th theo JECFA monograph 1 - Vol.4.

- Xc nh bng k thut quang ph hp th nguyn t thch hp cho hm lng quy nh. La chn c mu th v phng php chun b mu da trn nguyn tc ca phng php m t trong JECFA monograph 1 - Vol.4 phn cc phng php phn tch cng c.

pH

- c m t trong Ct 3 ca Bng 1.

- Ha 20 g mu vi 80 ml nc. Khuy lin tc tc trung bnh trong 5 pht (Trong trng hp mu l tinh bt keo ha s b, cn 3 g ha vi 97 ml nc).

Nhm carboxyl

c m t trong Ct 3 ca Bng 1.

Nguyn tc:

Tinh bt c cha carboxyl c cn bng vi acid v c chuyn cc mui carboxyl thnh dng acid. Cc cation v acid d c loi b bng cch ra vi nc. Mu ra c ho tan trong nc v c chun bng dung dch kim chun.

Ch : Cc nhm phosphat t nhin c mt trong tinh bt

khoai ty lm tng chun c tm thy trong phng

php ny ( Xem ghi ch 6 ).

Ho cht, thuc th:

Dung dch HCl 0,1N: Khng cn thit chun ho

Dung dch NaOH 0,1N: c chun ho

Dung dch ch th phenolphthalein 1%

Cch tin hnh:

Nu cn thit, nghin mu hon ton nh my nghin ct th nghim cho qua ry 20 mesh hoc mn hn, phng ngn nga bt k s thay i c ngha no v m v trn u.

Cn chnh xc mt mu cha khng qu 0,25 mili ng lng carboxyl (Ghi ch 1), v chuyn lng mu vo cc dung tch 150 ml. Thm vo 25 ml dung dch HCl 0,1N v thnh thong khuy trn 30 pht. Lc chn khng lp bt nho qua mt phu thy tinh xp c l xp trung bnhhoc phu nh, s dng dng nc nh t bnh ra gip chuyn ton b lng mu. Ra mu bng nc ct (thng l 300 ml) cho n khi phn dch lc c xc nh khng c clorid bng php th AgNO3 (Ghi ch 2).

Chuyn mu kh khong ton lng vo cc dung tch 600 ml cng vi nc ct v chuyn mu thnh bt nho trong 300 ml nc ct. Gia nhit hn dch mu trong cch thy si hoc trn cch thy si (Ghi ch 3), khuy lin tc cho n khi tinh bt ha h v tip tc gia nhit trong 15 pht m bo tinh bt ha h hon ton (Ghi ch 4).

Ly mu ra khi cch thy v chun khi cn nng bng dung dch NaOH 0,1N im kt thc vi ch th phenolphthalein. im kt thc cng c th pht hin bng o in ti pH = 8,3. Xc nh mu trng c tin hnh ging mu th hiu chnh cc acid t nhin (Ghi ch 5). Cn cng mt lng tinh bt nh ly chun carboxyl v trn ln vi 10 ml nc ct. Khuy u khong 5 pht mi ln trong 30 pht. Lc chn khng bt nho nh lng qua mt phu thy tinh xp c l xp trung bnh hoc phu nh, v ra mu bng 200 ml nc ct. Chuyn, lm h ha v chun mu bng dung dch NaOH 0,1N ging nh cch lm i vi mu kh khong.

Kt qu:

(Th tch NaOH chun mu th - mu trng) x 0,0045 x 100

Cc nhm carboxyl (%) = --------------------------------------------------------------------------------

Khi lng mu (g)

Ch v phng nga:

Lng mu khng nn vt qu 5,0 g i vi tinh bt oxy ho trung bnh hoc nh hn 0,15 g i vi tinh bt thng mi oxy ho cao.

Thm 1 ml dung dch AgNO3 1% pha trong nc vo 5 ml dch lc. Xut hin kt ta hoc c trong vng 1 pht nu c mt ca clorid.

Khng nn gia nhit trn a nng hoc trn n t Bunsen. S qu nhit hoc qu nng i vi lng mu nh s lm phn hy mu v kt qu carboxyl cao gi to.

H ha mu trit to iu kin chun nhanh chng v pht hin im kt thc chnh xc.

Chun mu trng c tin hnh trn mu c ra bng nc hiu chnh cc thnh phn acid khng c a vo oxy ho hoc chuyn ho. Cc acid bo t do kt hp vi amylose trong tinh bt ng thng l nhng cht c ng gp chnh i vi chun mu trng.

Hiu chnh hm lng phosphat trong tinh bt khoai ty (qui i) nn c tin hnh sau khi xc nh hm lng phospho ca mu th.

Qui i c tnh theo cng thc sau:

Trong : P l hm lng phospho (%)

Mangan

c m t trong Ct 3 Bng 1

Thit b:

Thit b quang ph hp th nguyn t vi n cathod rng mangan

Chun b dung dch:

Dung dch chun: Chun b dung dch 0,5 mg mangan/lt.

Dung dch mu th: Chuyn 10 g mu vo bnh nh mc Kohlrausch dung tch 200 ml trc c ra bng dung dch HCl 0,5N, thm 140 ml dung dch HCl 0,5N v lc mnh trong 15 pht, thch hp nht dng my lc. Pha ti th tch 200 ml bng dung dch HCl 0,5N v lc. Li tm khong 100 ml hn hp trong ng ly tm c thnh dy hoc l tc 650 xg trong 5 pht v ly dung dch lng trn b mt. Dung dch ny l dung dch mu th.

Cch tin hnh:

Thc hin theo hng dn ca nh sn xut cho vn hnh ca thit b quang ph hp th nguyn t v ht nc ct thng qua n kh acetylen trong 5 pht c mt ng nn ti bc sng 279,5 nm. Trong cng mt cch, ht mt phn ca dung dch chun v lu kt qu. Cui cng, ht dung dch mu v so snh kt qu vi kt qu ca dung dch chun, v nhn gi tr ny vi 20 c c nng tnh bng mg mangan/kg mu ban u c ly phn tch.

Phosphor

c m t trong Ct 3 ca Bng 1.

Ho cht, thuc th:

Dung dch amoni molybdat 5%: Ho 50 g amoni molybdat tetrahydrat, (NH4)6Mo7O244H2O, trong 900 ml nc m, lm ngui ti nhit phng, pha long ti 1000 ml bng nc v lc u.

Dung dch amoni Vanadat 0,25%: Ho 2,5 g amoni metavanadat, NH4VO3, trong 600 ml nc si, lm ngui ti 60 700C v thm vo 20 ml dung dch acid nitric. Lm ngui ti nhit phng, pha long ti 1000 ml bng nc v lc u.

Dung dch km acetat 10%: Ho 120 g km acetat dihydrat, Zn(C2H3O2)2,H2O, trong 880 ml nc v lc qua giy lc Whatman s 2V hoc giy lc tng ng trc khi s dng.

Dung dch acid nitric 29%: Thm 300 ml dung dch acid nitric (t trng 1,42) vo 600 ml nc v lc u.

Dung dch phosphor chun (100 (g P/ml): Ho 438,7 mg KH2PO4 trong nc trong bnh nh mc 1000 ml, pha ti 1000 ml bng nc v lc u.

ng chun:

Dng pipet ht 5; 10 v 15 ml dung dch phosphor chun cho vo cc bnh nh mc ring bit dung tch 100 ml. Thm vo mi bnh v bnh mu trng th t ln lt theo th t 10 ml dung dch acid nitric, 10 ml dung dch amoni Vanadat v 10 ml dung dch amoni molybdat, lc mnh sau mi khi thm. Pha ti th tch 100 ml bng nc, lc u v yn trong 10 pht. o hp th ca mi dung dch chun trong cng o 1 cm bc sng 460 nm bng thit b quang ph thch hp, s dng mu trng t gi tr hp th trn thit b bng 0. V ng chun trn th biu din hp th vi nng tng dung dch (mg P/100 ml).

X l mu s b:

Cho 20 25 g mu tinh bt vo cc dung tch 250 ml; thm vo 200 ml hn hp methanol/nc (7/3), phn tn mu v lc bng my trong 15 pht. Thu hi tinh bt bng cch lc chn khng vo phu thy tinh xp c l xp trung bnh dung tch 150 ml hoc phu Buchner, v ra bnh tinh bt m bng 200 ml hn hp methanol/nc. Li chuyn bnh tinh bt m thnh bt nho trong dung mi, ra ln hai theo cch tng t. Sy bnh tinh bt lc trong t sy nhit nh hn 500C, sau nghin mu qua ry 20 mesh hoc mn hn v trn u. Xc nh hm lng cht kh bng cch sy mt phn 5 g trong t sy chn khng, khng qu 100 mmHg, 1200C trong 5 gi. (Ch : x l c a ra trn ph hp vi cc sn phm tinh bt khng tan trong nc lnh. i vi tinh bt c h ha trc v cc loi tinh bt tan trong nc khc, chun b dung dch bt nho 1 2% trong nc, sau cho vo ng cellophan v thm tch nc ct lin tc trong 30 40 gi. Kt ta tinh bt bng cch dung dch vo 4 phn th tch aceton/1 phn th tch dung dch bt nho ng thi khuy. Thu hi tinh bt bng cch lc chn khng vo phu thu tinh xp c l xp trung bnh hoc phu Buchner, ra bnh lc bng ethanol tuyt i. Sy bnh lc v xc nh hm lng cht kh theo hng dn i vi cc tinh bt khng tan trong nc.

Chun b mu:

Cn chnh xc 10 g mu x l s b, tnh theo cht kh, cho vo a Vycor v thm vo 10 ml dung dch km acetat, phn tn dung dch u trong mu. C n kh trn tm gia nhit sau tng nhit v carbon ho mu trn tm gia nhit hoc trn ngn la gas. t chy trong l nung 5500C cho n khi tro khng cn carbon (khong 1 2 gi), lm ngui. Lm m tro bng 15 ml nc v ra chm xung thnh a bng 5 ml dung dch acid nitric. Gia nhit n si, lm ngui v chuyn ton lng hn hp vo bnh nh mc dung tch 200 ml, ra a bng ba phn 20 ml nc v cho nc ra vo bnh. Pha ti th tch 200 ml bng nc v lc u. Chuyn mt lng chnh xc (V ml) ca dung dch ny, cha khng c qu 1,5 mg P, vo trong bnh nh mc dung tch 100 ml v thm vo 10 ml dung dch acid nitric, 10 ml dung dch amoni Vanadat v 10 ml dung dch amoni molybdat, lc u sau mi ln thm. Pha ti th tch 100 ml bng nc, lc u v yn trong 10 pht.

Cch tin hnh:

o hp th ca dung dch mc Chun b mu trong cng o 1 cm bc sng 460 nm bng thit b quang ph ph hp, s dng mu trng ci t thit b 0. T ng chun, xc nh s mg phosphor trong lng mu ly, ghi li gi tr ny l a. Tnh hm lng mg P/kg mu gc theo cng thc sau:

Trong :

W: Khi lng mu th (g)

Cc nhm acetyl

c m t trong Ct 3 ca Bng 1.

Cn chnh xc 5 g mu v cho vo bnh nn dung tch 250 ml. To hn dch trong 50 ml nc, thm vo vi git phenolphthalein TS v chun bng dung dch NaOH 0,1N n khi xut hin mu hng nht. Thm 25 ml dung dch NaOH 0,45N, y np bnh v lc mnh trong 30 pht, thch hp nht l lc bng my. (Ch : Nhit khng c qu 300C, nu khng mt vi loi tinh bt c th b h ha). Tho np y, ra np v thnh bnh bng mt vi ml nc v chun kim d bng dung dch HCl 0,2N cho n khi mt mu hng. Ghi li th tch dung dch HCl 0,2N dng chun (S ml). Thc hin chun mu trng trn 25 ml dung dch NaOH 0,45N v ghi li th tch ca dung dch HCl 0,2N (B ml)

(B S) x N x 0,043 x 100

% cc nhm acetyl = -------------------------------------------

W

Trong :

N: Nng ng lng ca dung dch HCl

W: Khi lng mu (g)

Vinyl acetat

Xc nh bng phng php sc k kh khng gian hi.

S dng thit b sc k kh c trang b ct thu tinh nhi Porapak Q 80 100 mesh (hoc tng ng) c chiu di 2 m, ng knh trong 2 mm; detector ion ho ngn la; thc hin vi cc iu kin sau:

- Tc dng kh mang (nitrogen): 20 ml/pht

- Nhit cng bm mu: 2000C

- Nhit ct: 500C

- Nhit detector: 2000C

Chun b chun: Cn chnh xc 150 mg vinyl acetat (tinh khit) cho vo bnh nh mc dung tch 100 ml. Ho tan v nh mc n th tch 100 ml bng nc ct. Cho 1 ml dung dch ny vo bnh nh mc dung tch 10 ml v nh mc ti 10 ml bng nc ct. Thm 1 ml dung dch long ny vo 30 g tinh bt cha bin tnh ca cng ngun gc thc vt nh l cht th trong bnh dung tch 100 ml c np giong. ng kn bnh ngay lp tc bng np giong. Cch lm ny thu c tinh bt chun vi hm lng vinyl acetat 5 mg/kg.

Cch tin hnh:

Cn 30 g cht th cho vo trong bnh nh mc dung tch 100 ml c np giong. ng kn bnh. bnh c cha cht th v bnh c cha tinh bt chun chu nc c nhit khng i 700C trong 30 pht. Ly 2 ml t th tch kh trong bnh cha chun, s dng syringe (xylanh) kn, bm trc tip vo cng bm ca thit b sc k kh v ghi chiu cao pick ca sc ph. Tng t bm 2 ml th tch kh t bnh cha cht th vo thit b sc k. Tnh hm lng vinyl acetat trong cht th t vic so snh chiu cao cc pick ca hai sc k .

Cc nhm adipat

c m t trong Ct 3 ca Bng 1.

Ho cht v dung dch:

N,N-Bis-trimethylsilyltrifluoroacetamid (BSTFA): ca Macherey-Nagel, D 5160 Dueren, c hoc tng ng.

Dung dch acid glutaric: Ho tan 1 g acid glutaric (ca Merck hoc tng ng) trong nc v pha ti 1.000 ml.

Dung dch acid adipic: Ho tan 1 g acid adipic (UCB, Brussels, B hoc tng ng) trong 900 ml nc m, lm ngui n nhit phng, pha ti 1.000 ml v lc u.

Dng c, thit b:

Thit b sc k kh Hewlett-Packard Model 7620A hoc tng ng c trang b detector ion ho ngn la v Thit b phn tch Model 3370A.

Cc thng s ct: lm bng thp khng r c chiu di 2 m, ng knh trong 1,83 mm, c nhi bng OV-17 5% trn Chromosorb GAW-DMCS 80 - 100 mesh (Alltech Europe, Inc,. B 9731 Eke, B); luyn ct 3500C trong 24 gi vi tc kh mang nitrogen 40 ml/pht. Cc tc dng kh hot ng (ml/pht): kh mang nitrogen l 30, hydrogen l 40, khng kh l 400. Nhit : bung bm mu 2800C, detector 2500C, ct 1400C. Cc thi gian lu (pht): acid glutaric l 2,83; acid adipic l 4,5.

Hiu chun:

Cn v cho vo 4 bnh bnh tam gic dung tch 250 ml (1 g tinh bt ng dng sp/bnh). Thm vo mi bnh 50 ml nc v 1 ml dung dch nc cha 1 mg acid glutaric/ml. Thm vo bnh mt 0,25 ml dung dch nc cha 1 mg acid adipic/ml, thm vo 3 bnh cn li ln lt 0,5; 0,75 v 1 ml. Mi bnh sau cha 1 mg acid glutaric v ln lt l 0,25; 0,5; 0,75 v 1 mg acid adipic. Lc mnh cc bnh bng tay phn tn hon ton tinh bt v thm 50 ml dung dch NaOH 4N. Tip tc lc mnh trong 5 pht, mi bnh trong chu nc nhit mi trng v thm cn thn 20 ml dung dch HCl 12N cho mi bnh. Khi mi bnh ngui, chuyn ton lng hn hp trong bnh vo phu chit dung tch 250 ml. Chit vi 100 ml ethyl acetat tinh khit. Rt lp nc di vo mt cc vi; tp trung lp dung mi hu c pha trn vo mt bnh bnh tam gic dung tch 500 ml cha 20 g Na2SO4 khan. Chuyn phn tan trong nc quay tr li phu chit v lp li chit bng ethyl acetat hai ln na. Lc cc bnh nh k trong 10 pht v sau lc qua giy lc Whatman s 1 vo trong cc bnh y trn dung tch 1 lt. Ra cc bnh v cc cn khng ho tan c lc 2 ln bng 50 ml ethyl acetat. C ton b phn chit hu c v nc ra ca mi bnh nhit khng qu 400C, p sut chn khng (50 mgHg) cho n khi kh hon ton.

C ethyl acetat nn c thc hin cng nhanh cng tt bi v d xy ra cc phn ng thu phn trong qu trnh thc hin. Cc sn phm thu phn lm gim phn gii ca acid adipic trong phn tch sc k.

Thm ln lt 2 ml pyridin v 1 ml N,N-Bis-trimethylsilyltrifluoroacetamid vo cc thnh phn kh. y np tng bnh y trn v ra b mt bn trong tht k bng cch lc xoy. yn cc bnh trong 1 gi sau chuyn khong 2 ml t mi bnh vo cc l thu tinh nh v y kn ngay lp tc. Bm 4 (l vo thit b sc k kh.

Tnh kt qu:

Xc nh cc thi gian lu i vi mi acid v xc nh chiu cao pic i vi acid glutaric v i vi mi nng acid adipic. V th biu din quan h tuyn tnh gia t l chiu cao pic ca acid adipic/chiu cao pic ca acid glutaric vi hm lng acid adipic. ng hiu chun ny c th c s dng nhng n gin hn s dng mt h s p ng (RF):

Trong :

Hs v Hl: Cc chiu cao ln lt ca ca acid adipic chun v acid glutaric;

Ws: Khi lng acid adipic chun

RF nn c kim tra mi tun mt ln.

Adipat tng s:

Cn chnh xc 1 g mu cho vo bnh bnh tam gic dung tch 250 ml, thm vo 50 ml nc v 1 ml dung dch tan trong nc c 1 mg acid glutaric/ml. Tin hnh nh trong phn Hiu chun, bt u Lc cc bnh bng tay....

Acid adipic t do:

Cn chnh xc 5 g mu cho bnh bnh tam gic dung tch 250 ml, thm vo 100 ml nc v 1 ml dung dch acid glutaric. Lc mnh trong 1 gi, lc qua dng c lc Milipore 0,45 (m, thm 1 ml dung dch HCl m c vo phn lc c v chuyn ton lng vo phu chit dung tch 250 ml. Tin hnh nh trong phn Hiu chun, bt u Chit vi 100 ml....

Tnh kt qu:

i vi c hai php nh lng (Hm lng adipat tng v Hm lng acid adipic t do) ghi chiu cao cc pic i vi acid adipic v acid glutaric (ni chun). Tnh hm lng ln lt adipat tng s v acid adipic t do c trong mu theo cng thc sau:

Trong :

A: Hm lng adipat tng s hoc acid adipic t do (%)

HX: Chiu cao pic ca acid adipic trong dung dch mu thc

HIX: Chiu cao pic ca acid glutaric trong dung dch mu thc

RF: H s p ng i vi acid adipic

S: Khi lng mu trong dung dch mu thc (g)

Cc nhm adipat (%) = Hm lng adipat tng s (%) hm lng acid adipic t do (%)

Cc nhm hydroxypropyl

c m t trong Ct 3 ca Bng 1.

Thuc th Ninhydrin:

Dung dch 3% tinh th 1,2,3,-triketohydrinden trong dung dch natri bisulfit 5% trong nc.

Cch tin hnh:

Cn chnh xc 50 100 mg mu cho vo trong bnh nh mc dung tch 100 ml v thm 25 ml dung dch H2SO4 1N. Chun b mt mu tinh bt cha bin tnh c cng ngun gc (tc l ng hoc khoai ty) trong cng cch thc hin. t cc bnh trong cch thy si v gia nhit cho n khi cc mu to thnh dung dch. Lm ngui v pha ti th tch 100 ml bng nc. Nu cn thit pha long mu hn m bo khng c qu 4 mg nhm hydroxypropyl/100 ml, sau pha mu trng tinh bt tng ng. Dng pipet ly 1 ml cc dung dch cho vo cc ng th nh mc 25 ml c cc np thu tinh c ngm trong nc lnh, thm tng git 8 ml dung dch H2SO4 m c vo mi ng. Lc u v t cc ng trong cch thy si chnh xc 3 pht. Chuyn ngay lp tc cc ng vo chu cho n khi dung dch lnh. Thm 0,6 ml ninhydrin, cn thn cho thuc th chy xung theo thnh ca cc ng th. Lc u ngay lp tc v t cc ng trong chu nc 250C trong 100 pht. iu chnh th tch trong mi ng ti 25 ml bng acid H2SO4 v lc ngc cc ng vi ln. (Khng c lc). Ngay lp tc chuyn cc phn ca cc dung dch vo cc cng o 1 cm v sau chnh xc 5 pht o hp th (A) bc sng 590 nm, s dng mu trng tinh bt nh l mu i chng. Chun b ng chun bng cc phn 1 ml ca cc dung dch chun tan trong nc c 10, 20, 30, 40 v 50 (g propylen glycol/ml.

Tnh kt qu:

C x 0,7763 x 10 F

Cc nhm hydroxypropyl (%) =-----------------------------

W

Trong :

C: Hm lng propylen glycol trong dung dch mu tnh c da vo ng chun ((g/ml)

F: H s pha long (nu cn mt pha long hn)

W: Khi lng mu (mg)

Propylen clorhydrin

c m t trong Ct 3 ca Bng 1.

Thit b sc k kh:

S dng thit b Hewlett-Packard Model 5750 hoc tng ng. Mt thit b ct kp c trang b detector ion ho ngn la. Mt thit b tch phn l mt phn ca h thng ghi.

Ct sc k kh: S dng ct thp khng r, di 3 m, ng knh ngoi 3,2 mm, c nhi 10% Carbowax 20M trn 80/100 mesh Gas Chrom 2, hoc tng ng. Sau khi nhi, trc khi s dng, luyn ct qua m trong iu kin nhit 2000C, s dng dng kh heli vi tc 25 ml/pht.

Dng c c c: S dng dng c c c Kuderna-Danish c mt bnh dung tch 500 ml, c sn ca Cng ty Kontes Glass,.. Vineland, N.J., M, (Catalog s K-57000), hoc tng ng.

Cc bnh p lc: S dng cc bnh p lc dung tch 200 ml, c giong Neoprene, np y thu tinh v gn vi mt ci kp kim loi, c sn ca Cng ty Fisher Scientific, Pittsburgh, PA, M. (Vitro 400, catalog s 3 100). hoc tng ng.

Ho cht, thuc th:

Diethyl ether: S dng diethyl ether khan, tinh khit dnh cho phn tch.

Florisil: S dng vt liu 60/100 mesh, c sn ca Cng ty Floridin, 3 Penn Center, PA 15235, M, hoc sn phm tng ng.

Propylen chlorohydrin: S dng Eastman s P1325 1-Chloro-2-propanol thch hp, cha 25% 2-chloro-1-propanol, c sn ca Cng ty Eastman Kodak, Rochester, N.Y.14650, M hoc tng ng.

Chun b dung dch chun: Ly 25 (l hn hp cc ng phn propylen chlorohydrin cha 75% 1-chloro-2-propanol v 25% 2-chloro-1-propanol cho vo syringe (xylanh) dung tch 50 (l. Cn chnh xc syringe v bm mt phn vo bnh nh mc dung tch 500 ml, cha mt phn nc. Cn li syringe v ghi trng lng cc chlorohydrin ly. Pha ti th tch 500 ml bng nc v lc u. Dung dch ny cha khong 27,5 mg hn hp cc chlorohydrin, hoc khong 55 (g/ml. Chun b dung dch ny mi trong ngy s dng.

Chun b mu th:

Cho 50 g mu i din c trn vo Bnh p lc v thm vo 125 ml dung dch H2SO4 2N. Kp v tr pha trn bnh v lc xoy hn hp cho n khi mu c phn tn hon ton. t bnh trong cch thy si, gia nhit trong 10 pht sau lc xoy bnh trn cc thnh phn, v gia nhit trong cch thy thm 15 pht na. Lm ngui trong khng kh ti nhit phng sau trung ho mu thu phn ti pH = 7 bng dung dch NaOH 25% v lc qua giy lc Whatman s 1, hoc tng ng, vo phu Buchner, s dng lc ht. Ra bnh v giy lc bng 25 ml nc v tp hp cc nc ra vi phn lc c. Thm vo 30 g Na2SO4 khan v khuy bng my khuy t trong 5 10 pht, hoc cho n khi Na2SO4 c ho tan hon ton. Chuyn dung dch ny vo mt phu tch dung tch 500 ml c trang b vi kho teflon, ra bnh bng 25 ml nc v tp hp cc nc ra vi dung dch mu. Chit vi 5 phn x 50 ml diethyl ether, t nht 5 pht trong mi qu trnh chit tch pha hon ton. Chuyn cc phn dch chit ether vo dng c c c, t bnh hng chia ca dng c c c trong cch thy duy tr 50 550C v c c dch chit ti th tch 4 ml.

(Ch : Dch chit ether ca mu c th cha tp cht l gy tr ngi n phn tch v/hoc bin gii cc sc . Cc tp cht ny l cc sn phm c sinh ra trong qua trnh thu phn. Cc kh khn phn tch to ra bi s xut hin ca cc tp cht c th trnh c thng qua vic s dng bin php x l lm sch sau:

C c dch chit ether ti 8 ml, thay v 4 ml nh cp trn. Thm vo 10 g Florisil, trc c gia nhit n 1300C trong 16 gi ngay trc khi dng, vo ct sc k c kch thc thch hp, sau v nh v thm vo 1 g Na2SO4 khan vo nh trn ca ct. Lm m ct bng 25 ml diethyl ether v chuyn ton lng dch chit c c vo ct vi s tr gip ca cc phn nh ether. Ra gii bng 3 phn x 25 ml ether, ly tt c phn ra gii chuyn vo dng c c c v c c n 4 ml).

Lm ngui dch chit ti nhit phng, chuyn ton lng vo bnh nh mc dung tch 5 ml vi s h tr ca cc phn nh diethyl ether, pha ti th tch 5 ml bng ether v lc u.

Chun b mu i chng:

Chuyn cc phn 50 g tinh bt ng dng sp cha bin tnh (cha c chuyn ho) vo 5 bnh p lc ring bit v thm vo mi bnh 125 ml dung dch H2SO4 2N. Thm 0; 0,5; 1; 2 v 5 ml dung dch chun ln lt vo cc bnh, c c cc nng propylen chlorohydrin so vi tinh bt ln lt l 0; 0,5; 1; 2 v 5 mg/kg. Tnh nng chnh xc trong mi bnh t trng lng cc propylen chlorohydrin s dng trong cch lm Chun b dung dch chun. Kp vo v tr u bnh, lc xoy cho n khi cc cht trong mi bnh c ho tan hon ton, tin hnh thu phn, trung ho, lc, chit, c phn dch chit v cui cng pha nh hng dn trong phn Chun b mu th.

Cch tin hnh:

Cc iu kin vn hnh c th khc nhau ph thuc vo thit b c th s dng, nhng sc ph hp thu c bng thit b Hewlett-Packard Model 5750 s dng nhit ct 1100C ng nhit; nhit cng bm 2100C; nhit detector 2400C; tc dng kh hydrogen 30 ml/pht; tc dng kh heli 25 ml/pht, hoc tc khng kh 350 ml/pht nh kh mang. C b ghi n 1 mV; tc sp xp, lm long v giy ghi c la chn ti u ho cc c tnh tn hiu. Bm cc phn 2 (l ca mi dch chit c c c chun b theo hng dn trong phn Chun b mu i chng, thi gian gia cc ln bm i vi cc pic tn hiu tng ng vi hai ng phn chlorohydrin ghi c (v tch phn c) v ct c lm sch. Ghi v tnh tng cc din tch tn hiu (thit b phn tch tn hiu ra) t hai ng phn chlorohydrin i vi mi mu i chng. S dng cc iu kin hot ng thng nht, bm 2 (l phn chit c c chun b theo hng dn trong phn Chun b mu th, ghi v tnh tng cc din tch tn hiu (thit b phn tch tn hiu ra) t mu th.

Tnh kt qu:

Chun b th ng chun trn giy bng cch v cc din tch tn hiu tng ca mi mu i chng vi cc nng propylen chlorohydrin (mg/kg), xut pht t trng lng thc ca ng phn chlorohydrin s dng. S dng cc din tch tn hiu tng tng ng vi 1-chloro-2-propanol v 2-chloro-1-propanol t mu th, xc nh nng ca hn hp cc propylen chlorohydrin (mg/kg) trong mu th lin quan ti th ng chun xut pht t cc mu i chng. Sau khi c c kinh nghim v cch tin hnh v biu th c th ng chun t cc mu i chng tuyn tnh v lp li, s mu i chng c th c gim n mt mu c cha khong 5 mg/kg hn hp cc ng phn propylen chlorohydrin. Hm lng propylen chlorohydrin trong mu khi c th c tnh theo cng thc sau:

Trong :

C: Nng (mg/kg) ca cc propylen chlorohydrin (tng ca cc ng phn) trong mu i chng

a: Tng din tch tn hiu c to ra bi cc ng phn propylen chlorohydrin trong mu th

A: Tng din tch tn hiu c to ra bi cc ng phn propylen chlorohydrin trong i chng

ester ha ca natri octenyl succinat tinh bt

Nguyn tc:

ester ha c xc nh bi lng kim tiu th sau khi acid ho v ra k monoester ca acid octenylsuccinic vi tinh bt.

Cch tin hnh:

Cn v cho 5 g mu vo cc dung tch 150 ml. Lm m bng mt vi ml isopropyl alcol tinh khit. Dng pipet thm vo 25 ml dung dch HCl 2,5N trong isopropanol, dng acid ra mu bm trn thnh cc. Khuy trong 30 pht bng my khuy t. Thm vo 100 ml isopropanol 90% t ng ong chia . Khuy trong 10 pht. Lc mu qua phu Buchner v ra bnh lc bng isopropanol 90% cho n khi dch lc thu c khng cn ion clorid. S dng AgNO3 0,1N kim tra cc ion clorid. Chuyn bnh lc vo cc dung tch 600 ml v ra nh phu Buchner ra tinh bt trong cc. Thm nc ct vo cho n th tch 300 ml. t trong cch thy si c khuy trong 10 pht. Chun trong khi cn nng bng dung dch NaOH 0,1N cho n im kt thc c pht hin bng phenolphthalein.

Kt qu:

0,162 x A

ester ha (DS) = -------------------------

1 0,210 x A

Trong :

A: s mili ng lng ca NaOH s dng/g octenyl succinat tinh bt

D lng acid octenyl sucinic trong natri octenyl sucinat tinh bt

Chit xut v chun b dung dch mu:

Chit xut khong 500 mg tinh bt vi 15 ml methanol qua m vi lc thng xuyn (cn chnh xc lng tinh bt). Lc hn hp chit. Ra tinh bt trn dng c lc bng 7 ml methanol. Lp li 3 ln. Tp hp cc phn dch lc (khong 80% d lng c chit xut bi cch lm ny). Thm vo cc phn dch chit thu c 1 ml KOH 0,16N trong methanol. Lm kh cc phn dch chit thu c bng thit b c nhanh 300C. Ho tan cn thu c trong 2 ml methanol. Ly 0,5 ml dung dch cn cho vo l phn ng. Thm vo l phn ng 0,5 ml thuc th to dn xut (2,8 g 2-p-dibromoacetophenon v 0,28 g 18-Crown-6 trong 50 ml CH3CN). Thm 2 ml CH3CN vo l phn ng. y np kn l phn ng v gia nhit 800C trong 30 pht. Lm ngui dung dch phn ng n nhit phng (s dng trong 24 gi).

Phn tch sc k lng:

- Ct: Micro-Bondapark C18 (Waters) hoc tng ng

- Pha ng: ra gii Gradient methanol 70% trong nc n methanol 80% trong nc trong 5 pht. ng 6 (thit b lp trnh dung mi Waters 660).

Tc dng: 1,5 ml/pht

Detector: UV ti bc sng 254 nm, tt dn 0,16 AUFS

Th tch bm: 5 (l

Chun b ng chun:

Chun b dung dch natri octenyl succinat 0,5 M (Dung dch A). Ly 0,25 ml Dung dch A bng syringe cho vo bnh nh mc dung tch 25 ml. Pha ti 25 ml bng methanol (Dung dch B). Chun b ba chun hiu chun bng cch ly 0,5; 1 v 2 ml Dung dch B cho vo 3 bnh y trn dung tch 50 ml. Thm vo mi bnh 1 ml dung dch KOH 0,16N trong methanol. Lm kh mi dung dch bng thit b c nhanh 300C. Ho tan cn thu c trong 2 ml methanol (Dung dch C1, C2 v C3). Cho 0,5 ml dung dch cn vo l phn ng. Thm 0,5 ml thuc th to dn xut (2,8 g 2-p-dibromoacetophenon v 0,28 g 18-Crown-6 trong 50 ml CH3CN) vo l phn ng. Thm vo 2 ml CH3CN. y np kn v gia nhit ti 800C trong 30 pht. Lm ngui dung dch phn ng n nhit phng (cht dn xut nn c chun b khi cn v s dng ngay). Bm 5 (l vo thit b sc k lng. Hm lng cht tn d trong mi ln bm 5 (l nh sau:

i vi Dung dch C1 0,2375 (g

i vi Dung dch C2 0,4750 (g

i vi Dung dch C3 0,9500 (g

V th biu din mi tng quan gia chiu cao pic thu c t trn sc k vi (g cht tn d/5 ml dung dch.

Tnh kt qu:

Chun b ng chun da vo cch tin hnh. S dng chiu cao pic ca mu cha bit t sc k , xc nh hm lng cht tn d (tnh theo acid octenyl succinic) trong th tch bm t ng chun.

300 x gi tr t th

% Cht tn d trong tinh bt = ---------------------------------------

Khi lng tinh bt (mg)

Ghi ch: Cng thc ny c hiu chnh v thu hi 100% bng cch chia cho 0,80; do vy 240/0,80 = 300.