K thut TO DN XUT TIN CT

TRONG HPLC(Pre-Column Derivatization)

HPLC (High-Performance Liquid Chromatography) l mt trong nhng phng php kh ph bin dng xc nh cc cht v c v hu c ring bit trong nhiu hn hp khc nhau.

Tuy nhin mt vi cht quang trng khng nhn bit c bng HPLC v n khng cha nhm to mu, nhm huznh quang hoc nhm oxy ho-kh cn thit. Nhng vn ny c th c khc phc bng cch to phn ng dn xut ho- cng mt trong cc nhm trn vo phn t ang nghing cu.

Phn ng dn xut ho c th cho ra cht dn xut bn v nhanh chng bng hai cch: 1. Phn ng tin ct (pre-column) 2. Phn ng hu ct (post-column)

K thut to dn xut tin ct Phn ng tin ct (trc khi cho cht phn tch vo ct), phn ng thng c thc hin bng tay trong cc l nh trc khi a mu vo ct phn tch, nhng cng c th c t ng ho. K thut ny cho php linh hot hn v iu kin lm vic (thi gian phn ng, dung mi phn ng, loi b cc cht khng cn thit trong phn ng)

K thut to dn xut tin ct S tch cc cht din ra sau khi phn ng dn xut ho c thc hin. Cht dn xut phi bn.

Phn ng dn xut ho thng c thc hin v n lm tng nhy v tnh chn lc ca sc k bng cch nhn bit c th. V d nh s hp th v pht quang ca cc cht trong vng nh sng kh kin, bc sng di.

Phn ng dn xut ho c th c thc hin bng phn ng hu c hoc phn ng in ho. Tuy nhin, kt qu cui cng thng t mt tc nhn thn in t hoc thn hch c xc nhn bng hot tnh ca cht nn. Cc phn ng oxy ho-kh th t r rng, v th t c s dng rng ri hn.

iu kin ca mu c dn xut:

mu c to dn xut c pht quang cao bn vi nhit nhy vi cc u d ca hplc mu to dn xut phi tinh khit Mu to dn xut bn vi thi gian.

Mt s phn ng dn xut ho:phn ng dn xut c thc hin l cc phn ng hu c, in ho. Phn ng acylation ho: l phn ng thay th mt nguyn t hydro linh ng trong R-COOH, ROH, RSH, RNH2 bng nhm alkyl. v d cc cht to dn xut dng: Trifluoroacetic anhydride (TFAA): dung cho amino, hydroxy, and thiol groups Pentafluoropropionic anhydride ( PFPA) Heptafluorobutyric anhydride (HFBA) 1-(Trifluoroacetyl)imidazole (TFAI)

Mt s phn ng to dn xut Ester ho:Phn ng este ha dng dn xut cc axit cacboxylic v cc cht c cha nhm axit khc phn ng dung cht xc tc: HCl, H2SO4,BF3, Thionylclorua, borotriclorua hoc nha trao i ion. Phn ng este ha l mt phn ng cn bng, dn xut nh lng cn phi loi b nc to thnh. V d cht dung ester ho: Hydrogen chloride ~3 M in 1-Butanol (Butanol-HCl

Cc cht to dn xut trong hplcChia lm ba nhm chinh: thuc th khng huznh quang: thuc th huznh quang: thuc th oxy ho kh:

Thuc th khng huznh quang: l thuc th khng pht quang hp th nng lng. Thng dng trong uv-vis. Vi d:R(-)-1-(1-Naphthyl)ethyl isocyanate. Benzoyl chloride dng to dn xut vi polyamines.

Thuc th huznh quang:ngc li thuc th khng hunh quang l cht hp th nng lng pht quang. V d: 1-Fluoro-2,4-dinitrobenzene phn ng vi cc amino acid hay cc amine bc 1 hoc 2. o-phtaldehyde (OPA) dng trong xc nh cc amine bc 1 (histamine, methylamine, ethylamine, tyramine, tryptamine, 2phenylethylamine,putrescine and cadaverine

Thuc th oxy ho kh:l cht c tnh oxy ho hay kh phn ng vi cht cht tng nhy. V d: cht oxy ho kh iod, brom to dn xut vi aflatoxin tng nhy trong xc nh aflatoxin.

u im phng php to dn xuat tin ct trong hplc tng nhy phn tch c cc cht pht quang km ,km bn s dng dung mi t thi gian thc hin nhanh iu kin trang thit b d s dng hn to dn xut hu ct v gi thanh my s dng phng to dn xut hu ct mt.

Nhc im phng php to dn xuat tin ct trong hplc khi thc hin to dn xut tin ct do cn phi c mt bc chuyn ho ho hc trc khi chy sc k tim mu vo ct phn ny khng th lp li do c th dn dn phn ng xy ra mt khng nh lng.

V d xc nh hm lng aflatoxin bng k thut to dn xut tin ct hplc Thm phng trnh vo.

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