PP Ptich Pho Tu Ngoai, Pho Kha Kien

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Text of PP Ptich Pho Tu Ngoai, Pho Kha Kien

Tom tat 1) 2) 3) 4) 5) C s ly thuyet cua phng phap nh luat BEER Ky thuat nh lng bang pho UV-X Thiet b o pho UV-X ng dung

PHNG PHAP QUANG PHO LA G???Phng php phn tch quang hc da trn vic nghin cu s tng tc ca bc x nh sng trn cht kho st hoc s pht ra cc bc x nh sng di mt tc ng ha l no .

KHI NIM V PHNG PHPPhng php quang ph t ngoi kh kin, hay cn gi l phng php quang ph hp th, hay phng php o quang da trn kh nng hp th chn lc cc bc x ri vo dung dch ca cht nghin cu trong mt dung mi nht nh.

Mau sac cua anh sang: Tu theo bc song anh sang c chia thanh tng vung song : -Vung t ngoi 185 400 nm -Vung kh kin 400 760 nm

Johann Wilhelm Ritter

William Herschel

Ph thu c t mt s ngun sng ph bin

Cac bc song cc i hp th c trng cho tng cht, hoc t l hp th gia cac bc song lam c s ca vic nh tnh. hp th cac bc x ph thuc vao nng ca cht nghien cu trong dung dch cn o lam c s ca phep nh lng. Ngoai ra, vic o quang trong mt iu kin quy nh v dung moi, nng , bc song cung co the lam c s cho phep th

Phng phap o quang ngoai kha nang phan tch cac chat trong dung dch n chat tinh khiet, no con giup phan tch cac chat trong dung dch hon hp nhieu chat, nh s ho tr cua phan mem x ly vi tnh.

Ph nh sng kh kin

nh lut Lambert BeerChiu mt chm tia n sc c cng I0 qua dung dch c chiu dy 1. Sau khi b hp th, cng chm tia cn li I . truyn qua T = I / I0 . hp th A = - lg T = lg( I0 / I)

hp th A (mt quang A ) ca dung dch t l thun vi nng C ca dung dch theo biu thc : A = k . l .C

Trong : - k l h s hp th ph thuc vo cu to ca cht tan trong dung dch. - l l chiu dy lp dung dch + Trng hp C tnh theo mol/l v l tnh bng cm, ta c k = Do A = .l.C c gi l h s hp th phn t v A = khi C = 1mol/l v l = 1cm c trng cho bn cht ca cht tan trong dung dch ch ph thuc bc sng nh sng n sc.

nhn mnh c khi ngi ta vit:

A = .l.C

+ Trng hp C tnh theo phn trm (kl/tt) c biu th bng gam trong 100 ml dung dch, l theo cm, k c gi l h s hp th ring hoc h s tt ring, k hiu E A= E. l .C A=E khi C=1% &l=1cm He so hay dung trong mo ta cau truc, tnh chat quang pho cua cac chat hu c, con trong phan tch kiem nghiem ta hay dung E

Cc iu kin p dng nh lut- nh sng n sc: Khi bc sng thay i cc h s hp th cng thay i. Mt chm tia cng n sc th nh lut cng ng. - Cng mt dung dch nhng o trn cc my khc nhau c th thu c cc tr s A khc nhau. C nhiu nguyn nhn nhng trc ht l do tnh n sc ca nh sng. Khoang nong o thch hp: do nhieu nguyen nhan vat ly (s phan xa, s khuech tan anh sang), hoa hoc (s phan ly, anh hng cua lc ion)

ma nh luat Lambert- Beer ch ung trong mot gii han cua nong o. V vay khi xay dng phng phap nh lng can khao sat ky trc e tm khoang nong o o. - Cc yu t ho hc khc: Lm th no cht hp th nh sng khng b bin i bi cc phn ng ho hc trong dung dch. V vy, pH dung dch, s c mt cc cht l c kh nng phn ng vi cht cn o hoc gy nhiu (cn tr hay tng cng) s hp th nh sng ca cc cht cn o u phi tnh n.

Chn cc iu kin nh lng1.Chn bc sng Ta thng chn bc sng ng vi cc i hp th ln nht. - Khi ng chun c dc ln nht. Cng mt sai s A sai s C nh nht. - Ti max, sai s bc sng t nh hng.2. Chn khong nng thch hp

Khong nng trong quan h gia hp th v nng l tuyn tnh.

Nng phi c chn sao cho hp th thu c ri vo khong vng ti u l 0,2 0,8 v cng gn 0,43 cng tt. 3. Chn cc iu kin lm vic khc Chit cht cn kim nghim khi tp ri mi nh lng c. Lm cc phn ng mu nh hng ca pH Trong dung dch nc, pH c nh hng rt ln n bc sng hp th cc i( max) cng nh hp th cc i ca dung dch (Amax )

Khi pH thay i th max ca dung dch s chuyn dch v Amax cng thay i. Nu max chuyn v bc sng di th gi l s chuyn (bathocromic shift). Nu max chuyn v bc sng ngn th gi l s chuyn xanh (hypsocromic shift).

nh hng ca dung mi

C nhiu dung mi trong sut thch hp cho vng kh kin v phn ln vng t ngoi. Cc dung mi phi tinh khit.

-Khi chn dung mi trn c s ho tan th dung mi khng phn cc tt hn dung mi phn cc v cc dung mi khng phn cc cho cc nh hp th nhn hn. -Nc v cc alcol u c th l dung mi cho vng t ngoi, nhng nu cn etylic c ln aldehyd th s b hp th rt mnh cho nn phi lu v tinh khit ca dung mi.

Ph hp th t ngoi kh kin

Thit b o ph UV-VIS-

Phng php quang ph hp th UV-VIS da trn kh nng hp th chn lc cc bc x ri vo dung dch cht nghin cu, hp th ny ph thuc vo nng cht tan.

Mt s ch trong thc nghim- Truc khi o mu, phi bt my trc 15 pht cho my n nh - Mu em o phi bo m trong - Cc o phi tt, thng cho php sai s v dy ca cc l 0,01 mm. - thu c kt qu chnh xc, nn s dng cng cc o vi mu chun v mu th - t cc o phi thng ng trong khoang o mu, nn lun lun hng cng mt mt ca cc o v pha nh sng.

- Cc o phi oc trng ra t nht 3 ln bng dung dch nh o - Cc phi c dng cn thn trnh xc, trnh li vt tay trn b mt ca cc o, v du t vt tay c th gy ra s hp th ln. - Khi o mu c chun b trong dung mi d bay hi th phi dng np y trong qu trnh o mu, trnh sai s v nng . - i vi nhng mu yu cu nghim ngt v nhit th phi c b phn iu nhit trong sut qu trnh o..

MY QUANG PH PHN TCH THNH PHN HA HC KIM LOI

My quang ph t ngoi kh kin 2 chum tia

May quang pho t ngoai kha kiencu to - Ngun sng: cung cp cc bc x in t - B phn tn sc: c nhim v chn t ngun bc x mt bc sng c trng - B phn ng mu o - B phn detector dng o cng tia bc x

Cu to chi tit v tnh nng1. Ngun sng to ra cc bc x c cng khng i trn ton b khong bc sng, nhiu thp v n nh trong khong thi gian di 2. B phn tn sc to ra cc bc sng khc nhau t cc tia sng c tn sc cc gc khc nhau. B phn tn sc c hai loi: lng knh v cch t -Lng knh to ra nh sng nhiu mu nh cu vng t nh sng mt tri. - Cch t to ra gc tn x tuyn tnh khng ph thuc vo nhit

3. B phn ng mu o Cc o phi hon ton trong sut tt c cc bc sng v bt k s hp th no t cc cng lm gim khong hp th tuyn tnh ca mu o. a)Coc plastic. hp th mnh di 300nm b) Cc thu tinh hp th mnh vng di 320 nm c) Cc thch anh hp th di 210nm d) Cc o tt nht hin nay l cc silica tng hp vi cht lng cao, c th trong sut n di 190nm 4. Detector Detector c nhim v chuyn tn hiu nh sng thnh tn hiu in Cc my quang ph thng c detector l ng nhn quang hoc detector diode quang. - ng nhn quang c chc nng t hp cc tn hiu chuyn i qua vi giai on khuych i trong thn ca ng

-diode quang c nhy thp trong khong UV thp Gii hn pht hin xp x 170-1100 nm i vi detector s dng silicon.

Cu to ca diode pht nh sng trng

Kim tra tinh khitVt ca tp cht trong hp cht hu c tinh khit c pht hin d dng khi n c cng hp thu ln. V d, ru c bn trn th trng thng c ln Benzen, c kim tra bng cch dung cuvet c b t 4 10cm o.

Nhn bit cht v nghin cu cu trc

Bng cch so snh ph hp thu vi ph hp thu ca hp cht thin nhin hoc ph ca mu chun c th cho kt lun v mt sn phm tng hp, d l cc hp cht c mu nh carotenoit, antocxianin, porphirin,... hay khng mu nh cc alkane, alkene,...

Nghin cu s h binNhiu hp cht c th tn ti hai hay nhiu dng khc nhau nm trong mt cn bng ng gi l s h bin vi mi dng cu to c gi l mt dng h bin. Dng h bin thng gp l h bin xeto ( = 275nm; = 20) c trng cho nhm C = 0 c lp, v dng h bin enol ( = 245nm; = 18000) gy nn do ni i C=C v C=O lin hp, c th c phn bit kh d dng trong cc dung mi khc nhau.

Phn tch hn hp phn tch cc hn hp phc tp vi nhiu thnh phn, ngi ta thng dung PPSK lng vi detector UV VIS. Cc my quang ph UV VIS hin i c kh nng xc nh cc nng ring r trong hn hp gm n cu t. My s s dng tnh cht cng hp thu gii h phng trnh v cho kt qu nng tng cu t trong hn hp phn tch.

Xc nh khi lng phn t Xc nh hng s phn ly acid bazXc nh hng s phn ly acid baz l mt trong nhng phng php quan trng nghin cu cu trc cc hp cht hu c. Ni dung ca phng php l o ph hp thu ca cc cht hu c cha cc nhm c tnh cht acid hay baz ph thuc vo pH ca mi trng

Xc nh thnh phn ca phc chtThnh phn ca phc cht trong DD c th c xc nh bng phng php quang ph hp thu t ngoi v kh kin theo mt trong cc phng php khc nhau nh phng php bin s lin tc, phng php t l mol,...