XAY D I / N G
PHl/ONG PHAP DjNH Ll/ONG THUY
N G A NTRONG MOT S6 MY PHAM DANG KEM BOI DA BANG QUANG P H 6 HAP THU NGUYEN TUT (AAS)
THAI NGUYEN HUNG THU VO QUANG Trudng Bai hpc Bupc Hd Npi
LE THI HUONG HOA, LE DINH CHL DO THI THANH THIIY Vien Kiim nghiem thuoc Trung uomg
1. Dat van de
Theo Hiep djnh hda hgp qudn ly my pham cua ASEAN nam 2003, thiiy ngan va cdc hgp chat cd chiia thuy ngan khdng dugc phep cd mat frong my pham.
ASEAN ciing dua ra phuang phdp hda hgp diing de xdc dinh mdt sd kim loai nang (ma sd ACM THA 05), frong do dua ra gidi ban cho phep vdi thuy ngan la 0,5 ppm. De thuc hien viec hgi nhap ve mat ky thuat frong quan ly my pham, nghien ciiu nay dugc tien hanh dua fren ca sd phuang phdp hda hgp ciia ASEAN, ddng thdi cd thay ddi cho phii hgp vdi dieu kien thiet bj san cd cua Vien Kiem nghiem thudc TU. Muc dich cua nghien ciiu nham dua ra mgt quy trinh xdc dinh ham lugng thuy ngan frong mgt sd ddi tugng mau my pham dam bao do dac hieu, do nhay cao, ddp iing dugc gidi ban phdt hien ma phuong phdp ASEAN da quy djnh, cd kha nang thuc Men dugc vdi dieu kien ca sd hien cd cua Vien. Phuang phdp nay cung dugc dp dung de kiem fra ham lugng thuy ngan fren mdt sd mau my pham dang luu hanh fren thj trudng Viet Nam.
2. Thye nghiem
2.1. Hoa chat, chat chuan, mau nghien ciru
Do yeu cau nghiem ngat cua phuang phap AAS nen nudc cit va hod chit su dung phdi cd do tinh khilt rit cao, loai superpure hay tinh khiet diing cho AAS.
Cdc hod chit va dung mdi su dung gdm:
- Dung djch acid nitric 65% (Merck, Diic).
- Dung djch acid sulfuric 98% (Merck, Diic).
- Dung djch hydrogen peroxyd 30% (Merck, Diic).
- Magnesi perclorat khan (Merck, Diic) diing dl hiit am.
Thilc (II) clorid (Merck, Diic) dugc chuin bj thanh dung djch 10% (kl/tt) frong acid sulfiiric 5%.
Kah permanganat (Merck, Diic) dugc chuin bj thdnh dung dich 5% (kl/tt) frong acid sulfiiric 5%.
Hydroxylamin hydrobromid (Merck, Diic) dugc
chuin bj thanh dung djch 10% (kl/tt) frong nudc trao ddi ion.
- Dung djch chuan thuy ngan 1 OOO^ag/ml (J.TBaker, My).
Tat cd cdc dung dich thudc thu vd cdc budc pha loang thuc hien frong qud trinh phan tich deu dugc thuc hien vdi nudc cat dugc lam sach bang phuang phap frao ddi ion hay cdc dung dich thich hgp dugc chuan bj frong dung mdi la nudc cat dugc xu ly nhu fren.
- Mau nghien ciiu: la 6 mau my pham dang kem boi da dugc mua fren thj trudng.
2.2. Thiet bi, dung cu
- Mdy quang phd hap thu nguyen tii Z-5000 (Hitachi, Nhat Ban) dugc frang bi bg dung cu phan tich thuy ngan chuyen dvmg "A.A- Mercury Reduction Unit"
Can phan tich Mettler Toledo AB 204S co do chinh xdc 0,lmg (Denver Instrument Company, My).
He thing lgc nudc frao ddi ion (Easypure UV/UF, Bamsted, My).
- Cac dung cu thuy tinh, ndi cdch thuy.
Thiet bj vd co hda mau bang Id vi sdng Milestone Start-D.
Tat ca cdc may mdc va dung cu da dugc hieu chuin va kiem djnh theo diing tieu chuan ISO/EEC 17025, GLP.
2.3. Phuong phdp nghien cdu 2.3.1. Chi tieu nghien cicu
Chiing tdi tap trung vao nghien ciiu thilt lap dieu kien cu thi cho 2 giai doan chinh cua phuang phap phan tich Hg bing quang phd hip thu nguyen tu su dung ky thuat hda hoi lanh, gdm:
- Quy trinh xii ly miu bing ky thuat vd co hda udt frong thilt bi vd co hda miu bang Id vi sdng.
- Quy trinh do Hg bang phuang phdp hda hai lanh.
2.3.2. Phuang phdp xdc dinh cdc chi tiiu nghien cicu
24 Tap chi KIEM NGHIEM THUOC - S6 1.2011; Tip 9.(31)
a) Phuomg phdp xir ly mdu
Trong qud trinh khao sat so bd, chiing tdi da fliii nghiem vdi nhieu tac nhan oxy hda sur dung don le hoae hon hgp. NhCmg kit qua khdo sat so bd cho thiy hdn hgp acid nitricvd hydrogen peroxyd eho phep vd co hda triet dl nin miu my phim d diiu kien phdn iing khdng qud manh, thieh hgp vdi viec dp dung ti^en thilt bj vd co hoa miu bdng Id vi sdng (tiln hanh frong diiu kien kin hodn toan, qud tiinh vd co hda miu phdi khdng chi duge ve dp suat va nhiet do). Vi vay chiing tdi su dung hdn hgp trSn de vd co hda mau frong nghien ciiu ndy.
Chuong trinh nhiet do de vd ca hda gdm hai giai doan chinh:
- Giai dogn 1: Nang din nhiet do cua hdn hgp phdn ling tii nhiet do phdng len tdi nhiet do xip xi nhiet do soi ciia acid nitric 65% (120°C). Viec nang nhiet do tii tii se cho phep vd co hda cae thanh phin hiiu co dl bj oxy hda d diiu kien nhe nhdng, trdnh gay ra phan iing dot ngdt din tdi tang vgt nhiet do, dp suit.
- Giai dogn 2: Vd eo hda triet dl nhiing thdnh phin hiiu CO cdn lai, ddng thdi chuyin toan bg thiiy ngan cd frong miu vl dang vd co frong diiu kien nhiet do, dp sudt cao.
Sau khi vd co hda frong thilt bj xur ly miu bing Id vi song, thdm dung djch kali permanganat 5% dl dn djnh todn lugng thuy ngan cd frong miu vl dang Hg^^, sau do lugng kah permanganat du se duge trung tinh bdng dung djch hydroxylamin hydrobromid de ehuin
bj sin sdng eho qud trinh khu hda Hg^"^ vl Hg'' d dang hoi de phan tich bang quang phd hap thu nguyen tii.
b) Phicangphdp dinh licang thuy ngdn
De phdn ti'ch ham lugng thuy ngan frong cdc miu my phim nghien ciiu, chiing tdi su dimg ky thuat hod hoi lanh. Trong ky thuat ndy, nguyen tii thuy ngan tu do dugc tao ra dudi dang hai ngay d nhiet do thudng, dugc tdch rieng ra khdi nen miu va do do hip thu tai vach hap thu cue dai ciia thuy ngan d budc sdng 253,7 nm. Phuang phdp ndy cho phep loai bd hoan todn dnh hudng cua nen mau phan tich din kit qua do, do do rat thich hgp cho ddi tugng miu my phim cd nen miu phiic tap md chiing tdi nghien ciiu. Trong diiu kien thilt bj cua minh, chiing tdi dp dung phuang phdp do todn lugng fren bd dung cu phan tich thuy ngan chuyen dung "A.A- Mercury Reduction Unit".
3. Ket qua va ban luin
3.1. Quy ninh phdn tich thuy ngan trong my phdm 3.1.1. Quy trinh vd co hoa mdu
Cdn chinh xdc khodng 0,2 g mau my phim cin xdc djnh thuy ngan vdo cdc teflon ciia thiet bi vd ca hda mau bang Id vi sdng (Neu lugng thuy ngan do dugc frong miu qud ldn cd the dieu chinh gidm lugng can miu xudng, nhung lugng can miu dem vd ca hda phdi dam bdo khdng dudi 50 mg). Them vdo cdc 3 ml acid nitric 65%, 1 ml hydrogen peroxyd 30%. Day kin cdc, cho vdo frong thiet bj vd ea hda miu bing Id vi sdng.
Van hanh thilt bj su dung chuang trinh nhiet dg, dp suat dudi day.
Th&i pan (phdt) 15 10 10 5 10
5
Bang 1. Chuorng trinh nhiet dp cho thiit bi vd co hda mdu bdng Id vi sdng
Nhift dg CO Tit nhiet do phong tdi 120°C
120°C 120-150°C
150°C 150-180°C
180°C
Ap sudt gi&i hgn (bar)
20 20 30 30 30 30
Cong sudt gi&i hgn (W) 500 1000 1000 1000 1000 1000
Chid^gianhi^
Tang nhift dp theo gradient tuyen tinh Duy tri nhift d6
Tang nhift dp theo gradient tuydn tinh Duy tri nhift dp
Tang nhift dp theo gradient tuyen tinh Duy tri nhift dp
Sau khi qud trinh vd ca hda ket thiie, de cho nhiet do, dp suat frong cdc cde teflon frd ve can bang vdi mdi tiudng phdng thi nghiem. Lay cdc teflon ra khdi thilt bi. Chuyen dung djch frong cde teflon vao cde do thuy ngan.
Trdng ede teflon bing 20 ml dung djch acid sulftuic 5%, ehuyin djch trdng cdc sang cdc do thiiy ngan. Cho them vdo cdc do thiiy ngan 100 ml nudc trao ddi ion. Them vao cdc tiing gigt dung djch kah permanganat 5% frong acid sulfiiric 5% cho din khi dung djch frong cdc cd mdu hdng bin frong 15 phiit. Trude khi tiln hdnh do thuy ngdn, them ttmg gigt dung djch hydroxylamin hydrobromid 10% frong nudc vdo cdc din khi mit mdu hdng.
NIU kit qud do so bd cho thiy hdm lugng thiiy ngan do duge frong miu thu d muc d, 3.1.2. cao ban pham vi cua dudng ehuin d muc b, 3.1.2. (tii 100 ng din 1000 ng), tiln hdnh pha loang miu trudc khi do nhu sau: chuyin toan bg djch thu dugc frong cde teflon sau khi vd ca hda vao binh djnh miic 50 ml, trdng coc teflon bang 20 ml dung djch acid sulfiiric 5%, chuyen djch trdng ede sang binh djnh miic, them viia du tdi vach bing dung djch acid sulfuric 5%, lie diu. Hiit ehinh xdc mgt thi tt'ch thich hgp cua dung djch ndy vdo cde do thuy ngdn (thi tich hiit
T^p chf KlfeM NGHI?M THU6C - S6 1.2011; Tip 9.(31) 25
tiiy thudc vdo kit qud xdc djnh so bd de ddm bdo lugng thuy ngan do dugc nim frong pham vi dudng chuan d muc b, 3.1.2), them 20 ml dung djch acid sulfiuic 5%, 100 ml nudc frao ddi ion. Them vdo cdc ttmg gigt dimg dich kali permanganat 5% frong acid sulfiuic 5% cho den khi dung djch frong cdc cd mdu hdng ben frong 15 phiit. Trudc khi tiln hanh do thuy ngan, them ttmg gigt dung djch hydroxylamin hydrobromid 10% frong nudc vdo cdc den khi mat mdu hdng.
3.1.2. Quy trinh phdn tich thiiy ngdn bdng phucmg phdp hda hai Ignh
a) Thdng sd ciia may quang phd hdp thi4 nguyin ttr:
Den cathode rdng thuy ngan dat d budc sdng 253,7 nm.
- Do rdng khe (slit width): 1,3 nm.
- Che do do: Sample
- Che do xu ly tin hieu: Integral Thdi gian lay tin hieu: 20 giay - Cudng do den: 7,5 mA h) Chudn hi dung dich chudn:
- Du&ng chudn thu&ng quy di dinh luang Hg trong mdu my phdm: Pha loang chinh xdc dung djch chuan goc thuy ngan 1000 ppm bang nudc tiao ddi ion de dugc dung djch chuan trung gian co ndng do thiiy ngan 100 ppb. Hiit chinh xdc lan lugt 1 ml, 5 ml, 10 ml cua dung djch chuan trung gian vao ba cdc do thuy ngan rieng biet. Them vao tiing cdc 20 ml dung djch acid sulfiiric 5% va 100 ml nudc frao ddi ion. Them vdo cdc tiing gigt dung djch kali permanganat 5% frong acid sulfuric 5% cho den khi dung dich frong cdc cd mau hdng ben frong 15 phiit. Trudc khi tien hdnh do thiiy ngan, them ttmg gigt dung djch hydroxylamin hydrobromid 10% frong nudc vao cdc den khi mat mau hdng. Nam cdc do chiia thuy ngan chuin dtmg dl xay dung dudng chuan dugc chuan bj nhu fren cd tdng lugng thiiy ngan Ian lugt la 100 ng, 200 ng, 500 ng, 700 ngva 1000 ng.
- Du&ng chudn di khdo sdt dp tuyin tinh: Hiit chinh xdc lin lugt 1 ml, 2 ml, 5 ml, 7 ml vd 10 ml dung djch chuan trung gian cd ndng do thuy ngan 100 ppb vao nam cde do thuy ngan rieng biet. Tien hdnh tiep nhu vdi dudng chuan thudng quy tii "Them vdo ttmg cic...
mat mau hdng." Dudng chuan de khdo sdt do tuyen ti'nh se gdm cdc dung dich cd tong lugng thuy ngan lan lugt Id 100 ng, 200 ng, 500 ng, 700 ng va 1000 ng.
c) Thdng sd cua thiit biphdn tich thiiy ngdn:
- Tdc do bom nhu ddng 300 vdng/ phiit.
d) Qud trinh do:
Chuyen dung djch can do thuy ngan vao binh do cua bg phan tich thiiy ngan, them 10 ml dung djch thilc (D) clorid 10%, day ngay nap binh do lai lac deu 10 giay.
Chuyin thilt bj vl cbl do tiiin hoan (CIRCULATE), bat bom nhu ddng. Khi tin hieu hip thu cao nhit va In djnh tiln hanh do dl ghi lai do hip thu. Sau khi thuc hien phep do, chuyin sang cbl do md (OPEN). Khi do hap thu do dugc fren mdy quang phd hip thu nguygn tii frd ve 0 cd nghia la he thdng da dugc ldm sach thuy ngan va cd the lap lai qud trinh do fren mdt miu khac.
Thuc hien do do hap thu cua cdc dung djch chuan thuy ngan trudc de thiet lap dudng chuin thuc nghiem. Sau do do do hip thu cua cdc dung djch thu, dua vao dudng chuan thuc nghiem de tinh ra lugng thiiy ngan frong mau thu.
3.2. Tham Mnh quy trinh 3.2.1. Khodng tuyin tinh
Trong phuong phdp chiing tdi xay dung, dudng chudn tuyen tinh the hien mdi quan he givta tdng lugng thuy ngan frong cdc dung djch chuan va do hap thu dugc thilt lap bing thuc nghiem hang ngay trudc khi do thuy ngan frong miu thu. Kit qua thuc ngbiSm cho thiy quy trinh phan tieh cho ddp iing tuyen tinh tit voi thuy ngan frong khoang lugng thuy ngan tii 100 ng den
1000 ng (bdng 2 vd hinh 1).
Bdng 2. Kit qud khdo sdt khodng tuyin tinh.
Lupng Hg chuan (ng) 100 200 500 700 1000
Dp hap thu 0,0144 0,0381 0,0920 0,1282 0,1753
Phuong trinh h6i quy tuyln tinh: y = 1,77963.10"* x + 6,18518.10"*
Hf s6 tuygn tinh: r = 0,9987
>0.1S
^ 0.1
S'o.os
0
(
^
> 200 400 600 800 1000 L»f>ngt«(iig)
26 Tap chi KIEM NGHIEM THUOC - S6 1.2011; Tap 9.(31)
3.2.2. Gi&i hgn dinh luong, gi&i hgn phdt hiin Ket qud ddnh gid thuc nghiem eho thiy lugng thuy ngan 100 ng eho do hip tiiu In djnh frong cdc diiu kien phan tich d muc 3.1.2. cao gip. 10 lin so vdi nhiiu dudng nen. Tii kit qua ndy, chiing tdi xdc djnh gidi ban djnh lugng (LOQ) cua phuong phdp la 100 ng thiiy ngan ti'nh tiieo tdng lugng thuy ngan cd frong phin miu dem phan tich.
Kit qud ddnh gid thuc nghiem cho thiy lugng thuy ngan 30 ng cho do hip thu In djnh frong cdc diiu kien phdn tieh d muc 3.1.2. cao gip 3 lin so vdi nhieu dudng nin. Ttr ket qua nay, chiing tdi xdc djnh gidi ban phdt hien (LOD) ciia phuang phdp la 30 ng thuy ngan tinh theo tdng lugng thuy ngan cd frong phin miu dem phan fr'ch.
3.2.3. Dp lap lgi
Do lap lai cua phuang phdp dugc thuc hien bang each so sdnh hdm lugng thuy ngan xdc djnh dugc frong Cling miu my phim da bilt cd chiia thuy ngan qua khdo sdt so bg sau 6 lan tien hanh phan tich dgc lap theo cdc dieu kien va budc tien hanh da quy djnh d 3.1.1 va 3.1.2. Trong mdi lan phdn tich, mgt lugng mau khoang 0,1 g dugc vd co hda frong thiet bi vd ca hoa bang vi sdng. Dung djch thu dugc sau khi vd ca hoa dugc chuyin vdo binh djnh miic 50 ml, them nudc vira dii den vach. Hiit chinh xdc 10,0 ml cua dung djch nay de do thiiy ngan. Kit qua trinh bay frong bdng 3 cho thiy kit qua djnh lugng sau 6 lin phan tich dgc lap CO do lech chuin tuong ddi (RSD) d miic 5,8%, chip nhan dugc vdi phuang phdp phan tich dtmg de kiem fra phdt hien thuy ngan frong miu my phim.
Bdng 3. Kit qud ddnh gid dp lap lgi
STT 1 2 3 4 5 6
Lugmg cdn mdu(g)
0,1087 0,1012 0,1163 0,1127 0,1055 0,1103
Dgpha lodng D
5 5 5 5 5 5
Lupng thuy ngdn do dupc
(ng) 654,25 670,80 668,89 653,62 640,89 626,89 TB
RSD (%)
Hdm lupng thuy ngdn trong mdu
(ppm) 30,1 33,1 28,8 29,0 30,4 28,4 29,9 5,8
khi cho mdt lugng chinh xdc thuy ngan chuan vao nen miu my pham da bilt khdng chiia thiiy ngan (qua qud trinh ddnh gid so bd) va tien hanh xu Iy mau vd phan tich 6 Ian ddc lap. Ket qud thu dugc fren 3 nen mau kem boi da khde nhau (bdng 4) cho thiy ty Ie tim lai dao ddng tii 88,7% (fren nen mau kem bdi da 3) den 125,2% (fren nen mau kem bdi da 2), chap nhan dugc vdi lugng thiiy ngan cho vao nen miu rat nhd (d gidi ban dinh lugng cua phuang phdp, xem 3.2.2).
Bdng 4. Kit qud ddnh gid do ditng:
a). Trin nin mdu kem bdi da 1;
b). Trin nin mdu kem bdi da 2;
c). Tren nin mdu kem bdi da 3.
a).
3.2.4. Dp dung
Dg diing cua phuong phdp dugc tiiuc hien bing cdch xdc dinh lugng tiiuy ngan chuin tim lai dugc sau
Tap chf KltM NGHI$M THU6C - So 1.2011; TSp 9.(31)
STT 1 2 3 4 5 6
Lugmg mdu nen
(g) 0,2021 0,2074 0,2117 0,2063 0,2203 0,2145
Lucmg thuy ngdn chudn them vdo (ng)
100,0 100,0 100,0 100,0 100,0 100,0
Lugmg thuy ngdn chudn dm lgi duac
(ng) 95,1 105,1
97,6 88,8 110,2 116,5 TB
RSD (%)
Tylf tim lgi
(%) 95,1 105,1 97,6 88,8 110,2 116,5 102,2 10,05
b).
STT 1 2 3 4 5 6
Lupng mdu nen
(g) 0,1908 0,2147 0,2241 0,2063 0,2135 0,2078
Lugmg thuy ngdn chuin them vdo (ng)
100,0 100,0 100,0 100,0 100,0 100,0
Lugmg thuy ngdn chuan dm lgi dupc
(ng) 125,17 115,23 108,61 100,00 90,07 103,31 TB
RSD (%)
Tylf tim lgi
(%) 125,2 115,3 108,6 100,0 90,1 103,3 107,1 11,4 c).
STT 1 2 3 4 5 6
Lupng mdu nen
(g) 0,2305 0,2033 0,1997 0,2138 0,2204 0,2096
Lupng thuy ngdn chudn them vdo (ng)
100,0 100,0 100,0 100,0 100,0 100,0
Lupng thuy ngdn chudn dm lgi dupc
(ng) 107,28 107,95 101,99 96,03 90,73 88,74 TB
RSD (%)
Tylf tim lgi
(%) 107,3 108,0 102,0 96,0 90,7 88,7 98,8 8,4
27
3.3. Ap dung quy trinh da tham Mnh de Mnh lupfng thuy ngan tren mpt so mau my pham
Kit qua thim djnh cho thiy quy trinh phan ti'ch thuy ngan chiing tdi xay dung phu hgp eho viec dp dtuig xdc djnh thuy ngan frong ddi tugng miu my pham. Tren thuc tl, chiing tdi da dp dtmg quy trinh ndy dl xdc dinh ham lugng thiiy ngan frong 6 mau my pham dang kem bdi da. Ket qua phan tich da phdt hien ra 1 miu cd hdm lugng thuy ngan 29,9 ppm, 1 miu cd ham lugng thiiy ngan 1,4 ppm, deu eao hon miic do khuyen cdo frong phuang phdp hda hgp cua ASEAN.
4. Ket luan
Quy trinh djnh lugng thuy ngan frong my phim bang quang phd hap thu nguyen tu da dugc chiing tdi xay dung fren ca sd thiet bj hien cd d Vien KNTTW:
su diing vd CO hda frong thiet bj vd co hda mau bang Id vi sdng vd thilt bj do thuy ngan todn lugng loai tieu chuan, khdng ddi hdi phai frang bj them mdy mdc
ehuyen dung ben canh mdy quang phd hap thu nguyen tii. (^ud tiinh vd co hda miu dugc thitc hien frong 16 vi sdng su dimg hdn hgp acid nitric 65% vd hydrogen peroxyd 30%. C^id tiinh phan tich thuy ngan duge thuc hien bang phuang phdp nguyen tii hda lanh su diing den cathod rdng thiiy ngan d budc sdng 253,7 nm va dimg djch thilc (II) clorid 10% lam tac nhan khu. Gidi ban djnh lugng cua quy trinh Id 100 ng thuy ngan frong phin miu phan tich. Quy trinh da dugc khao sdt tii uu hda, dugc thim djnh vl khoang tuyln tinh, do lap lai, do diing fren miu my phim thuc vdi kit qud tdt, phii hgp cho ling dimg dl ra ban diu ciia nghien ciiu la su dung dl xdc djnh ham lugng thuy ngan frong my phim dang kem bdi da. Quy trinh da dugc dp dung kilm tra thiiy ngan frong 6 miu kem bdi da, kit qud da phdt hien cd hai miu cd ham lugng thuy ngan lin lugt la 1,4 ppm va 29,9 ppm, cao hon gidi ban quy djnh cua phuang phdp hda hgp ASEAN (0,5 ppm).
Tai lifu tham khao 1. Hiep dinh he thong hoa hgp ASEAN frong quan ly my pham.
2. Determination of heavy metals (arsenic, cadmium, lead and mercury) in cosmetic products (Phuomg phap hoa hcrp ASEAN, ma sl ACM THA 05).
3. Hitachi: Instmction Manual for 180 - 0450 Mercury Analyzer Accessory.
SUMMARY
A simple AAS method based on microwave digestion and cold evaporation atomization techniques was developed for determination of mercury in cosmetic creams. Microwave digestion procedure used 65% nitric acid and 30% solution of hydrogen peroxide as oxydation agents. The measurement of mercury was carried out by using cold evaporation atomization technique with a mercury hollow cathode lamp at 253.7 nm and 10% solution of tin (II) chloride as reduction agent. LOQ of the method is 100 ng, and LOD is 30 ng as total amount of mercury in the sample portion to be analyzed This method was proved in terms of linearity range, reproducibility and recovery as being suitable for routine application in detecting the present of mercury in cosmetic cream. The developed method was used for determination of mercury in 6 cosmetic creams, in which 2 samples revealed mercury levels (1.4 ppm and 29.9 ppm, respectively) higher than that tolerated by the ASEAN Harmonized Method (0.5 ppm).
XAC DjNH DANH
P H A PCHUNG VI SINH TRONG CAC CHE PHAM PROBIOTICS C6 THANH PHAN TREN NHAN LA VI KHUAN LACTIC HOAC
LACTOBACILLUS SPOROGENES
1. Dat van de
Probiotics dugc djnh nghia Id nhiing vi sinh vat sdng cd dnh hudng cd lgi cho siic khde cua ngudi su dung. Probiotics cd the dugc dimg nhu thudc, thuc phim chiic ndng hoac thuc phim [3], [6], [7]. Cdc vi khuin thugc chi Lactobacillus va Bifidobacterium
PHAM THI MNH TAM VA CS
Vien Kiem nghiem thudc thdnh pho Hd ChiMinh
thudng dugc ua chudng lam probiotics [7]. Mgt so vi sinh vdt khde cdng lam probiotics thugc chi Bacillus, Clostridium va Saccharomyces.
EAO va WHO da dua ra 4 tieu chi dl chgn lua mot vi sinh vdt lam probiotics, dd Id: djnh danh chinh xdc t6n chung, thii nghiem in vitro dl ddnh gid khd ndng
28 Tap chf KltM NGHIEM THU6C - S6 1.2011; TSp 9.(31)
