Bai Giang Pho

7/30/2019 Bai Giang Pho

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cc phwng php phn tch vt l trong ho hc

Chong I

Ph t ngi, kh kin (UV/Vis-spectrum)

1. Nguyn l

1.1. Cc buc chyn in t

Sng in t }c biu din bng ph}ng trnh

.O = c

O = b}c sng

= tn s sng

c = tc nh sng

(c | 2,998.1010 cm/giy trong chn khng)

Mt l}ng t ca nh sng c tn sQ s c nng l}ng l

E = hQ

h | 6,63.1034 Jgiy (Js) (Planck-Wirkungsquantum)

Quan h qua li gia sng in t v phn t cht khi c hp th nh sng trong

vng t ngoi v kh kin s dn n kch thch cc in t ca lin kt ho tr

10 200 400 750O(nm)

Rnghen T ngoi xa T ngoi gn Vng kh

kin (nhn

thy)

Hng ngoi

Q* (cm1)

Tr}c y b}c sng th}ng dng (Angstrm), ngy nay : nm (1 nm = 107

cm,10

9 m)

Thay v Q : s1 ta hay dng s sng * : cm

1

c

vv

O

1*

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Nng l}ng : 1 eV = 23 kcal.mol1 = 96,5 kJ.mol

1 = 8066 cm1

1000 cm1 = 12 kJ.mol

1

1kJ.mol1 = 84 cm

1

Khi mt nh sng c tn sQ ph hp gp mt phn t trng thi gc \o th nh

sng c th b hp th v phn t }c nng ln trng thi kch thch in t \1. Thngqua t pht x, phn t c th tr v v tr gc c.

'E = E(\1) E(\o) = hQ


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hp th A (Absorption, absorbance, extinction) khng c th nguyn (n v). d

tnh bng cm, c : mol.l1 ; H : 1000 cm2.mol

1 = cm2.mmol1)

Th}ng ng}i ta cng khng ghi th nguyn ca H.

*) y l ni dung c bn ca nh lut Bouguer (1728)

Lambert (1760)

Beer(1852) p dng cho nh sng n sc v dung dch long (c d 10

2 mol.l1).

S hp th c tnh cng hp (tr tr}ng hp ngoi l) :

Atng =n

oi i

i 1

Ilog d c

I

H

*) Khi xc nh hp th cho tt c cc b}c sng (O) hoc * v H theo nh lut

Lambert-Beer ta s }c th hp th ( *)hoc H(O) v l ph UV/Vis.

Ta c th gii thch cc vng ph (tc cc b}c chuyn in t da vo qu o phnt hay cn gi l orbital phn t (MO).

T cc orbital khng lin kt n (i in t t do) mt in t c th }c chuyn ln

orbital trng phn lin kt (anti - bind)S* hoc *. B}c chuyn in t ny (t}ng}ng vng ph) }c k hiu l:

n V

S S n S*V V

V*

S*

n

S

V

S S

V V

n V

nS

*

E

Hnh 3: Orbital phn t vw cc buc chyn in t

Bng 1 l cc vng hp th ca nhng nhm mang mu (chromophore) bit lp. Khi

c nh h}ng lp th, hiu ng khc th thay i v tr hp th.

O

Q

200 400 750 nm

n S*S S

n S*

n S* (H c bit)

S S* (H lin hp)

V V

T ngoi trong T ngoi Kh kin

chn khng

50.103 cm-1 25.103 cm-1 13,3.103 cm-1

Hnh 4: Vng hp th ca cc buc chyn in t

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OO

O2

Q0

S

Or

EH

01

234

Q'

a) b)Ph Ph

Q0

Or

EH

01

234

Q'

S0

Hnh 5: Di hp th c to t di dao ng ca phn t gm 2 ngyn t

r = khong cch 2 nguyn t, E = nng l}nga) Di khng i xng vi b}c chuyn mnh oo

b) Di i xng vi b}c chuyn mnh 2o

i vi mt s nhm mang mu, dung mi cng c nh h}ng c tr}ng.

1.3. Mt s nh ngha

*) Chuyn dch hoc hiu ng bathochrom (bathochrom effect) :

Chuyn dch nh hp th sang vng sng di do thay i mi tr}ng hoc trong

phn t c nhm auxochrom.

*) Nhm auxochrom l nhm th gy ra chuyn dch . V d : ni i trong enamin

chuyn t 190 nm o 230 nm do lin hp vi i in t t do trong nit. Nhm th nitl auxochrom:

R2N

R '

*) Chuyn dch xanh hoc hiu ng hypsochrom : chuyn dch v sng ngn. Do thay

i mi tr}ng hoc khng cn lin hp. V d :

NH2

H

+ NH3+

O = 230 nm (H = 8600) O = 203 nm (H = 7500)

(mi tr}ng axt)

*) Hiu ng hypsochrom : Hiu ng gy gim c}ng hp th

*) Hiu ng hyperchrom : Hiu ng lm tng c}ng hp th

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1.4. Dng mi

Dung mi c hp th trong vng o th khng ph hp. Dung mi tt nht l cc

perfluor ankan nh} perfluorooctan. Cc hydrocarbon no nh}: pentan, hexan, heptan,

cyclohexan, k c n}c, acetonitril c truyn qua n 195 nm (khi d = 1 cm) hoc

180 nm (khi d = 1mm). Metanol, ethanol, dietyl ete c th s dng n 210 nm ; dichlometan : n 220

nm, chloroform : n 240 nm, CCl4 : 250 nm. Benzen, toluen, tetrahydrofuran ch

s dng }c trn 280 nm.

S t}ng tc gia dung mi cht o s lm ph khng nt, v vy c gng trnh

s dng dung mi phn cc.

2. Chun b mu vq ph

- Thng th}ng ph t ngoi }c o trong dung mi , vi nng 10-4mol/l. Vi

dy cuvet l 1cm o theo nh lut Lambert - Beer tac:

c. H 1 nu t hp th A 1

AMK

VK

ZM

l0

Q

O

l

D

S

Hnh 6:S my UV hai tia

Q = ngun sng (UV: n hydro hoc n deuteri, Vis: n wolfram-halogel)

M = lng knh tn sc nh sng (monochromator)/ hoc mng tn sc

Z = chia hai tia (l 1 g}ng quay)

MK = cuvet cha cht o trong dung mi

VK = cuvet so snh cha dung mi tinh khit

D = detect

S = my ghi, mn hnh

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3. Nhm mang mqu (chrmphre)

3.1. Nhm mang mw bit lp vw tung tc ln nha gia chng:

C OH

H

Formaldehyt

C

C

O H

OH

GlyoxalOmax = 178 nmHmax = 17.000

Omax = 205 nmHmax = 2100

Omax = 303 nmHmax = 18n oS*

Omax = 450 nmHmax = 5n oS*

2 ni i t}ng tc vi nhau mnh

H lin hp cng di th b}c chuyn ca SoS* cng v sng di v c}ng cng mnh.

Bng 1: Cc nhm mang mw (Chromophor)

3.2. Olefin, plyene

SoS* ca etylen nm vng UV chn khng vi mt nh mnh Omax = 165 nm

(Hmax = 16000)

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Bng 2: H lung gia (increment) tnhcc i hp th ca dien vw trien

u tin s - trans(v d acyclic)217 nm

Mi gc cacbonmi nhm auxochrom

Bng 3:Hp th UV sng dwi ca 1,3 - dien

Hp cht Omax (nm) Hmax

Bng 5:Hp th ca annlenHp cht Omax lgHmax Dung mi Mu dung dch Tnh cht

Bng 4: V d v tnh Omaxca dienvw trien lin hp

Hp cht Quan st Tnh ton

Hexan

Chlorophorm

Metanol

Isooctan

Cyclohexan

Benzen

Benzen

Khng mu

Vng

Vng

Nu

Xanh vng

Tm

anti-thm

thm

khngthm

khngthm

thm

khngthm

thm

khngthm

L}ng giaMi lin kt i thmMi v tr ni i exocyclic

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3.3. Benzen vw cc hp cht thm c vng benzen:

Bng 6: Hp th t ngoi ca benzen mt ln th

Nhm th B}c chuyn

sng di (mnh)

B}c chuyn

sng di (cm)

Dung mi

N}cCyclohexan

Etanol

Etanol

Hexan

Etanol

N}c

N}c

N}c

N}c

N}c

N}c

N}c

N}c

N}c

Etanol

N}c

Etanol

Hexan

N}cHexan

Etanol

N}c

N}c

Etanol

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Hnh 7:Ph t ngoi ca benzen

Bng 7:Hp th sng ca mt s benzen thpara X1-C6H4-X

2 trong nuc Hnh 8: Ph UV/Vis ca o-, m-, p-,nitrophenol:a/ trong 10-2 M HClb/ trong 5x10-3 M NaOH

3.4. Cc hp cht cacbonyl : keton, aldehyt no:

Bng 8: Buc chyn nS* hp cht

cacbonyl no

Hp cht Omax

(nm)

Hmax Dung mi

acetaldehyd 293 12 Hexan

Aceton 279 15 Hexan

Acetylclorid 235 53 Hexan

Acetalhydrid 225 50 Isooctan

Acetamit 205 160 Metanol

Etyl acetat 207 70 Eter du m

Axit acetic 204 41 Etanol

Hnh 9: S nng lungca cc buc

chyn in t trong enon lin hp, so snh

vi alken vw cacbonyl no

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Hnh 10:Ph ca benzophenon

____ Trong cyclohexan

------ Trong etanol

Dung mi km Dung miphn cc phn cc

Chuyn dch Chuyn dchbathochrom hypochrom

O1*O1 O2O2*

Hnh 11: Dch chyn bathochrom vwhypochrom ca buc chyn SS* vw

nS

* ca xeton khi tng phn cc dngmi (solvatochromy)

4. ng dng ph t ngi / kh kin

Phn tch nh l}ng, nh tnh v cu trc

Xc nh hm l}ng cn trong mu :

EtOHenzim

NADCH3 CHO

(nicotinamit adenin dinucleotid)

Qu trnh ny }c theo di bng UV (t ngoi ).

Sc k lng hiu nng cao (HPLC): detect UV l ph bin,

Nghin cu ng hc : o cc b}c trung gian.

Ngy nay c th dng laser xc nh }c nhng cht trung gian c thi gian tn

ti nna giy, pic giy, thm ch femto giy (1 fs = 1015s).

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Chong II

Ph hng ngi vq ph Raman

I. Ph hng ngi

1. M vw ngyn l:

Nng l}ng ca cc dao ng phn t hoc s quay phn t nm trong vng hng

ngoi ca ph in t.

Dao ng hoc s quay ca phn t c th o }c bng hai cch :

+) Trc tip bng hp th trong ph hng ngoi hoc

+) Gin tip bng tia tn x trong ph Raman. i vi cc nh ho hc th nhng dao ng phn t hu dng nht cho vic xc

nh cu trc phn t nm trong vng O t 2,5 n 16 Pm (1Pm = 104 cm = 104 Ao).

n v : Pm hoc th}ng l s sng Q O

11 cm . Khong hng ngoi bnh

th}ng l t 4000 cm1o 400 cm

1.

S sng t l thun vi tn s hoc nng l}ng:

Q = c. Q'E = h. c. Q

h = hng s Planck (6.626.10--34 J.s)

c = vn tc nh sng (3.1010 cm/s)

Cc nhm chc c tn s dao ng c tr}ng trong ph hng ngoi, nh ta pht

hin ra chng trong phn t cht khi xem ph hng ngoi.

Nguyn tc chn : c hp th hng ngoi th cn c s thay i dipol moment

khi phn t dao ng (thay i momen l}ng cc).

2. Thit b o ph hng ngoi

2.1. Thit b kinh in

Ngun pht hng ngoi, chia thnh 2 chm sng c cng c}ng , 1 chm i qua

dung dch o. Nu nng l}ng chm sng ph hp vi nng l}ng dao ng phn t th s

c hp th.

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chnh ph : dng vch bit ca polysterol.

C th o : dng kh, dung dch, cht lng tinh khit v cht rn.

Thi gian ghi ph : |10 pht.

2.2. Ph hng ngoi bin i Forier (FTIR)

Ngun sng cha khong tn s t 5000 400 cm1. Ton b ph ch o trong vi

giy, phn gii cao m c}ng khng b hao ht , chnh xc s sng cao. Ngy

nay ng}i ta pht trin thit b sc k ghp ni ph hng ngoi (GC/FTIR). Phn on

i ra t GC }c o FTIR pha kh.

Ngun sng

Mu S snh Thit b gia tha

Cn bng Chnh sa (Laser)

Mng hc lng knh Detect Mu

Khuych i Tch s liu

My ghiMy tnh (bin i

Furier)

Thit b ph IR thong Ph Mqn hnh, my in

Ph hng ngi

bin i Furier

Thit b ph hng ngi gm : Thit b ph hng ngi kinh in vq

thit b c bin i Furier

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2.3. Chn b m:

2.3.1. o trong pha hi:

Pha kh : ng o 10 cm, hai u c knh lm t NaCl (cho tia hng ngoi truyn

qua).2.3.2. o trong dng dch:

Trong dung dch : CCl4, CHCl3 1 o 5%, Cuvette NaCl, Cuvette th hai cha dungmi cn bng.

Nu dung mi hp th > 65% nh sng hng ngoi th khng ghi }c ph.

CHCl3 v CCl4 hp th > 65% vng khng quan trng cho ph hng ngoi, bi vy

c th dng lm dung mi o.

2.3.3. o dng lng: Cht lng tinh khit : 1 git nh p gia 2 tm NaCl.

2.3.4. o dng rn:

Pha rn : | 1 mg cht }c nghin vi 1 git nujol ( hn hp paraphin lng ) trongci m no, cho vo gia 2 tm NaCl.

Nghin | 1 mg cht vi 10 100 ln khi l}ng KBr tinh khit cho ph IR, pthnh vin trong sut bi mt my p . u im cho ph tt hn, nh}ng th}ng c thm

vch OH 3450cm1ca hi n}c do KBr l cht ht m mnh.

1(cm )

Q Hnh 12: T sc giao thoa (Interferrogram) n ph hng ngoi thng qua bin

i Fourier

Di chuyn g}ng

InterferogrammLnh vc thi gian

Bin i Fourier

Ph hng ngoi

(lnh vc tn s)

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Online Spektrenkatalog : d liu ph chun do cc hng bn, dng so snh viph ca cht nghin cu.

*) nh l}ng bng ph}ng php ph hng ngoi :

Theo nh lut Lambert - Beer : oI

lg .c.d EI O H

I = c}ng sau khi qua dung dch

Io = c}ng tr}c khi qua dung dch

E = hp th (extinction)

H = h s hp th

nh lut Lambert-Beer EO =oI 9l

0g log

I 2

0( xem hnh 14) ng trong tr}ng hp

dung dch long.

.

.

.

Cx

0,1

0,2

0,3

0,4

0,5

0,6

0

EO

10 20 30C

Hnh 13: }ng chun nh l}ngQ

Qmax

100%

20

I0

I

A

Hnh 14: nh l}ng bng IR

}ng chun: Trong gii hn nng m nh lut Lambert-Beer c gi tr, ta lp

}ng chun ca cht cn xc nh (quan h gia c v EO) nh} trong hnh 13.

ng dng : lnh vc nha tng hp, kim tra cht l}ng d}c phm v thuc bo v

thc vt.*) Ph dao ng

*) *

o r

1 f2 c m

Q S

Q* = s sng 11

[cm ]

O

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co : tc nh sng trong chn khng

f = hng s lc (dyn/cm) t}ng }ng lc lin kt (t l CC / C=C / C{C = 1 : 2 : 3)

mr = khi l}ng khi dao ng

*) S dng dao ng :

i vi phn t thng: 3N 5 (N = s nguyn t trong phn t)

i vi phn t gp: 3N 6

OH

H

O+

180o 180

o

O

*H H

O

H H*

O

H H*

O

*H H

CS S Qs(CS) CS Sdao ng ho tr

CS S Qas(CS) CS S

dao ng bin dng

G (SCS)

O

O OO

O OO

O O

Sc k kh(SKK)

Mn hnh

My tnh

SKK -

Hnh 15: C trc ca FTIR (vi n v SKK - Hng ngoi)

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Bng 8: V tr ca dao ng ho tr ni i vw giao ng dn ca N-H:(s - mnh; m - va; - y; v - thay i)

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Bng 9: V tr ca dao ng ho tr ca lin kt ba vw ni i

lin hp: (s - mnh; m - va; - y; v - thay i)

Bng 10: V tr ca lin kt ho tr ca hydro, cung vch:

(s - mnh; m - va; - y; v - thay i)

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Bng 11: V tr ca dao ng ho tr ca nhm cacbonyl

(tt c cc vch mnh)

II. Ph Raman

Hiu ng Raman }c Smekal d on v l thuyt vo nm 1923 v 5 nm sau

hiu ng Raman }c chng minh bng thc nghim.

Ph Raman nhn chung t }c s dng mt cch thng dng. Cc nh ho hc hu

c t dng ph Raman xc nh cu trc.

Tuy nhin, ph Raman trong mt s tr}ng hp c th b sung rt tt cho ph hng

ngoi. V d o trong dung dch n}c, n tinh th v polime.

ng dng k thut laser, ph Raman tr nn n gin hn v o nhanh hn

nhiu.

1. Hi ng Raman

*) Khi chiu vo dung dch ca mt cht hoc mt cht lng mt nh sng n sc

(v d laser argon : O = 488 nm = 20.492 cm1), ta s thy nhng hin t}ng sau :

Phn ln nh sng s truyn qua dung dch hoc cht lng.

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Mt phn nh (| 104) nh sng s b khuch tn i tt c cc h}ng v gi nguyn

tn s ban u (lch h}ng Rayleigh). Nguyn nhn : va chm n hi gia l}ng t nh

sng vi phn t.

Mt phn nh hn na (| 108) xut hin dng khuch tn theo tt c cc h}ng

nh}ng c nhiu tn s. N xut hin do hp th (absorption) v pht x li (re-emission)

lin quan ti kch thch dao ng hoc dp tt dao ng. C th dng mt dectect quang

in t ghi ph ca nh sng khuch tn ny. y l hiu ng Raman.

QoQRaman = Qdao ng

Qo l ca nh sng ban u.

*) Hiu ng Raman l h qu ca t}ng tc gia vt cht v nh sng in t. Ph

Raman lph pht x (Emission-spectrum). QRaman c th nh hn hoc ln hn Qo: vch

Rayleigh-(Rayleigh line). c tr}ng cho mt phn t l s khc nhau gia QRaman v Qo.*) Gii thch hiu ng Raman : Khi nh sng laser gp phn t cht (v nng l}ng

khng c b}c nhy in t) th c th xut hin va chm n hi (khuch tn

Rayleigh) ; hoc mt phn nng l}ng nh sng s }c dng nng cao nng l}ng

dao ng ca phn t, c ngha l nh sng khuch tn ngho nng l}ng hn (b}c sng

di hn). Khi nh sng laser gp mt phn t trng thi kch thch dao ng th nh sng

khuych tn s giu nng l}ng hn (b}c sng ngn hn) v mt phn nng l}ng ca

phn t s }c chuyn sang nh sng khuych tn.

OVch anti - Stokes Vch Stokes

QReyleigh)

Qo

2. Qy tc chn

c hiu ng Raman cn : phn cc ca phn t phi thay i trong khi phn

t dao ng. phn cc l mt i l}ng ca kh nng bin dng m my in t

quanh nguyn t hoc phn t. V d phn cc ca I- ln hn ca Br- v Cl-.

H qu : i vi nhng phn t i xng th nhng dao ng xy ra mt cch i

xng qua tm i xng, s khng cho ph hng ngoi (IR - inactive, v khng c s thayi dipol moment : moment l}ng cc), nh}ng li cho ph Raman (Raman active). Ng}c

li nhng dao ng khng i xng qua tm s khng cho ph Raman, m li cho ph IR.

V d phn t CO2 :

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C OO C OO C OO C OO C OO C OO

a bdc

Dao ng hotr i xng Vs

Dao ng hotr khng i xng V as

x Dao ng ho tr a v b khng gy ra thay i dipol moment o khng xut hin

trong ph IR. phn cc ca a v b thay i (khc nhau) o xut hin trong ph Raman.

x Tr}ng hp c v d th ng}c li.

Hnh 16: Ph IR ca (E) - dicloretylen

Hnh 17: Ph Laser - Ramann ca (E) - dicloretylen

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Loi dao

ng

Dao ng

khng i

xng

IR-Bande

(cm-1)

Dao ng

i xng

Raman -

Bande

(cm-1)

Trong IR

Bng 12: So snh ph IR v ph Raman ca (E) - dicloetylen

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3. Ph k Raman

nh sng n sc t ngun sng mnh c O gia vng IR v UV, v vng ny t bnhiu do hp th.

G}ng

G}ngMngG}ngDetect

Hnh 18:S c to mt thit b ph Raman kinh in

Th h my mi dng ngun laser Nd-YAG c O = 1064 nm v k thut FT (bini Fourier).

4. ng dng

c bit ph hp nghin cu nhng lin kt khng hoc t phn cc. V d :C{C, C=C, N=N, CC, OO, SS v cc h vng. o Xc nh cc h khung phn t.Ng}c li nhng nh IR mnh ca nhm phn cc nh} C=O, OH ch xut hin yu

trong ph Raman.

Li : c th ghi trong n}c v dng cuvett thu tinh v n}c l dung mi cho rt t

vch v vch yu trong ph Raman.

ng dng ln nht ca ph Raman khng phi xc nh cu trc, m gn cc

dao ng trong ph IR v ph Raman.

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23/47

Chong III

Ph khi long

1. t vn

Mc d ph}ng php khi kh t}ng i c (1910 Thomson tch }c ngv Neon 20 v 22). Song, b}c ngot ph}ng php khi ph tr thnh ph}ng php

phn tch quan trng trong Ho hu c ch t nm 1960.

Hai th mnh ng gp vo s pht trin ca ph}ng php khi ph l :

x Vi l}ng mu nh nht c th xc nh }c khi l}ng t}ng i ca phn t vthm ch thnh phn cc nguyn t ca mt hp cht.

x Qua vic phn mnh trong khi ph c th suy ra cu trc hoc thng tin v phnt.

i vi cc phn t phn cc, kh bay hi, trnh phn hu c nhng ph}ngphp ion ho nh} : EI (va chm in t), ho hc (CI), t tr}ng (field ionisation), FAB

(bn ph bng nguyn t tc cao), ph khi ion th cp (sekunder ion MS), ESI (my

in t).

C th xc nh khi l}ng t}ng i n 1200 v cao hn na.

2. Thit b, ghi ph : Hu c : MS, v c : ICP-MS

2.1. Ngyn l ca mt khi ph k:

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C 4 vng chc nng : x }a mu vo

x To ra ion

x Tch khi l}ng

x Chng minh ion

Trong chn khng

cao trnh va

chm gia cc ion

*) }a mu vo :

Vn l }a mu t p sut th}ng vo bung chn khng cao m khng cn ngt

chn khng.

C 2 ph}ng php : x }a dng kh

x}a trc tip

}a dng kh : dng cho mu lng hoc kh, bm qua xylanh cc cht d bay hi

c th qua h sc k kh (SKK) hoc sc k lng (GC/MS, HPLC/MS, LC/MS).

}a trc tip : dng cho mu dng tinh th, sn hoc keo. Mu trong mt ci

bng nhm hoc vng, I = 1mm, gn trn mt thanh t }c }a vo bung chn khng.

Sau khi ht chn khng, ci ng mu }c lm ngui v }a vo bung ion ho. y

n }c t nng t t n khi bay hi.

L}ng mu cn :

x }a dng kh : 0,1 1 mg ; qua SKK : 109o 10

15g.

x }a trc tip : 0,001 0,1mg.

*) To ion : T b phn }a mu, mt dng phn t nh, c nh }c bn vobung ion ho. Dng phn t ny va chm vung gc vi mt dng in t (nm gia

catt nng v ant). in th gia catt v ant thay i gia 0 v 300V, c ngha :

nng l}ng ca in t l : 0 300 eV.

cc ph khi in th thp : 12 15 eV.

eM .

o M ion radical

Ph khi l}ng bnh th}ng : 60 100 eV

Phn ln ghi 70 eV.

Qua va chm gia in t v phn t to thnh ion phn t o M + e o M+. + 2e

(molecular ion)

hoc M + e o M2+ + 3e

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Nhng phn khng b ion ho s b ht ra khi bung ion qua bm chn khng. Cc

ion phn t to thnh s }c tng tc v thu gn.

Vic tng tc }c thc hin bi mt in th (2 10 kV), khi ra khi bung ion

ho tc t cao nht.

Vic thu gn thnh chm ion }c thc hin bi mt in tr}ng ph khi vophn phn tch khi l mt dng ion tp trung, ng nht.

Tc ca ion }c tnh theo cng thc :

(1)2m.v

z.U2

(2)2.z.U

vm

z = in tch ion (= n.e)

m = khi l}ng ion

v = tc ion

U = in th gia tc

*) Tch khi : }c thc hin thng qua t tr}ng | 1 Tesla.

Nhng ion c cng in tch : ion nh hn b lch nhiu hn.

Bn knh lch theo cng thc.

(3)Bz

mrm

.

.Q

B = c}ng t tr}ng

T ph}ng trnh (1) v (3) ta c ph}ng trnh c bn ca khi ph l :

(4)2 2mm r .B

z 2.U

T l khi l}ng/in tch ph thuc vo c}ng t tr}ng, bn knh lch v in

th gia tc, tc l ph thuc vo cu hnh ca thit b.

Thit b dng sector t (magnetic sector)

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B phn tchtnh in (E)

B phn tcht (B)

Khe vo Khe ra

Ngun ion Thu gom

S thit b khi ph hi t kp (duble fcussed): (xem hnh trn)

x Mun phn bit ion c cng s khi nh}ng thnh phn khc nhau nh}: CO, C 2H4,N2 phi dng khi ph phn gii cao. Thit b phn gii cao c thm mt in

tr}ng tnh t tr}c t tr}ng (nh} trn)

y l thit b hi t kp (double focussed), c th xc nh khi l}ng ion ti chnh xc l ppm, v nh} th xc nh }c thnh phn nguyn t ca ion phn t.

x Thit b phn gii cao i hi khe ion phi hp, do lm gim nhy.12C 1H 16O 14N CO C2H4 N2

12,000 1,00782 15,9949 14,0031 27,9949 28,0313 28,0061

Khi mt hn hp c nhiu cht (M1+; M2

+; M3+; ...) trong bung ion ho ta la chn

1 ion phn t no (v.d. M1+

) cho qua khe, to s va chm ion ny phn mnhtip (fragmentation) v ghi ph ca ion ny. l k thut MS/MS.

*) Chng minh ion :

Khi cho in th gia tc v c}ng t tr}ng khng i ta s c ph}ng trnh (5) :

(5)mz

= hng s. 2mr

Khi cho in th gia tc v bn knh lch khng i ta c :

m

z= hng s. B2

Tc l : xc nhmz

(tr}c y lme

) mt bn knh lch cho tr}c th ch cn

thay i (qut, scan) c}ng t tr}ng. Trong tr}ng hp ny ta mt dng c thu ion

u ra ca b phn phn tch khi. tng dng in ion ta dng thit b nhn in t

(electron multiplier).

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3. S phn mnh ca cc hp cht hu c

Pic mnh nht cho c}ng t}ng i l 100% gi l pic c s (base peak). rel.%

l k hiu c}ng t}ng i.

*) Ion phn t (molecular ion).

Tr mt s ngoi l, cn li pic c khi l}ng cao nht th}ng l pic ca ion phn

t.

Cc tr}ng hp ngoi l : pic [M+1]+ hoc [M+H]+ do 1 H gn vo phn t (hay

gp c bit lp cht amin, ancol).

Thnh thong pic M+. khng ghi }c, thay vo l pic [M R]+.

ng v (isotop) : Trong cc hp cht hu c c 3 loi sau :

x Nguyn t tinh khit : 19F, 31P, 127I.

x Nguyn t vi 1 ng v chnh (> 98%) : H (1H), C (12C), N (14N), O (O16).

x Nguyn t c 2 ng v chnh : S (32S, 34S), Cl (35Cl, 37Cl), Br (79Br, 81Br).

V d : Vng pic ion phn t ca hp cht C7H6ClNO (M = 155) :

rel.Int.(%)

100%

50

160 m/z150

156

157

158

155m/z = 155 : + (1)1 35 14 1612 7 6 1 1 1C H Cl N O

m/z = 156 : + (2)13 1 35 14 1612 6 1 6 1 1C C H Cl N O1

1

1

1

1

1

+ (3)1 2 35 14 1612 7 5 1 1 1 1C H H Cl N O

+ (4)1 35 15 1612 7 6 1 1C H Cl N O

+ (5)1 35 14 1712 7 6 1 1 1C H Cl N O

m/z = 157 : (6)13 1 35 14 1612 5 2 6 1 1C C H Cl N O

+ (7)1 2 35 14 1612 7 4 2 1 1C H H Cl N O

+ (8)1 37 14 1612 7 6 1 1 1C H Cl N O

+ (9)1 35 14 1812 7 6 1 1C H Cl N O

+ (10)13 1 2 35 14 1612 6 1 5 1 1 1C C H H Cl N O

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m/z = 158 : (11)13 1 37 14 1612 6 1 6 1 1C C H Cl N O1.............................................

.............................................

Pic c khi l}ng cao nht v l thuyt l m/z = 173 . Do xc

sut mt s ng v l rt nh nn ch c (1), (2), (8) v (11) l c ng gp chnh cho

c}ng pic (xem hnh bn).

2 3713 15 187 6( C H Cl N O)

Quy tc nit : Ion phn t c khi l}ng chn th s c s chn nguyn t nit (N 0,

N2, N4, ... ), khi l}ng l o s l nguyn t nit (N1, N3, N5, ...).

Nng l}ng ion ho mt cht hu c thu ion phn t th}ng l t 7 o 14 eV (1

eV = 23,04 kcal mol1 = 96,3 kJ.mol

1).

V d : n-hexan 10,17 eV ax-acetic 10,35

cyclohexan 9,88 eV metyl amin 8,97

etanol 10,48 eV triflormetan 13,84

Xc nh chnh xc cng thc cng ca ion phn t : cn dng ph khi phn gii

cao. phn gii A ca mt khi ph k }c tnh nh} sau:

mA

m

'

Hai pic k nhau }c cho l phn gii nu chng khng trng ln nhau qu10%.

tch vch c m/z = 950 khi vch m/z = 951 th my cn c phn gii l :

9501

950

Khi ph k c phn gii thp th}ng c A = 1000 2000.

V phn gii cao :

Trong cc cng thc (2) o (5) trang tr}c ta c khi l}ng nh} sau :

156,017147 (2)

156,020069 (3)

156,010827 (4)

156,018008 (5)

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tch }c cc vch ny cn c phn gii nh} sau :

A(2)/(3) =156

533880,002922

A(2)/(4) = 156 246840,006320

A(2)/(5) =156

1807650,000863

Phn gii

Khng phn gii

o Mun ghi }c c 4 pic th thit b khi ph cn phn gii | 181.000. Thit bkhi ph phn gii cao cn thm mt in tr}ng tr}c t tr}ng, nh} vy cc ion }c

thu gom (focusse) 2 ln (double focussed - hi t kp) .

Phong php ghi ph*) Chiu sng cc knh nh :

Trong mt ph khi phn gii cao cht cn nghin cu v mt cht so snh th}ng l

perfluokerosen cng }c bay hi trong mt t tr}ng v in th gia tc khng i. Ph

}c ghi trn mt tm knh nh. o sng ti (c}ng ) ca vt en (vch) v so

snh vi ph cht chun, ta thu }c s khi l}ng phn gii cao.Tin li ca ph}ng

php ny l cng mt lc c th ghi }c tt c cc pic vi l}ng mu rt nh (khi nghin

cu trao i cht, vt liu sinh hc). Bt tin l phi c thm thit b o sng ti v

khong cch cc vt en.

*) Ghi theo qut dng (qut t tr}ng):

y ph }c ghi bng cch: 3 i l}ng l dng ion, dng ion tng, bin thin t

tr}ng }c x l theo thi gian v biu din thng qua my tnh.

Ngy nay : Cc tn hiu in }c tch trong mt my tnh trong qu trnh ghi, sau

s tnh ton v in ra ph. Ph ny s cho thng tin v khi l}ng v c}ng pic ( m/z

v rel.%).

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4. Nhng phn ng ct mnh chnh ca cc phn t hu c

4.1. Phn ct v trD

Nhng lin kt v trD i vi d nguyn t (N, O, S...) d b phn ct, v in tchsinh ra khi phn ct }c cc d nguyn t lm bn vng.

Ph khi ca 2-Butanon

S phn mnh rt gn ca 2-

Butanon

S phn mnh ca 2-Butanon

Ph khi ca 5D- Androstan-3-on-etylen-acetal

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S phn mnh ca 5D- Androstan-3-on-etylen-acetal

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Ph khi ca cyclo-hexanonm/z = 55

S phn mnh ca cyclohexanon

Ph khi ca cyclohexanol Ph khi ca 2 aminoetanol

4.2. Phn ct v tr benzyl vw allyl*)Phn ct v tr benzyl

Ph khi ca butylbenzen S phn mnh ca butylbenzen

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Ph khi ca o-clortoluen

S phn mnh ca o-clortoluen

Cp ion m/z 91/65 v m/z 77/51 l c tr}ng cho cc hp cht thm th mt ln

alkyl

Ta thy phn ct benzyl mnh hn phn ct phenyl.

m/z = 91 l pic c s ca cc hp cht n-ankyl benzen nh} toluen, etylbenzen,

propylbenzen, pentylbenzen, o-, m-, p-xylen.

*)Phn ct v tr allyl

Ph khi ca 4 metyl-1- hexen

S phn mnh ca 4 metyl-1hexen

t th hin hn phn ct benzyl

4.3. Phn ct cc lin kt khng hot ho

Ph khi ca nhng cht khng cha d ngyn t (phn ctD), khng cha nhm

phenyl (phn ct benzyl) vw lin kt C=C(phn ct allyl) th tn theo qy lt phn ct

cc lin kt khng hot ho.

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Ph khi ca 1-florheptan Ph khi ca 1-clorheptan

Ph khi ca 1-bromheptan Ph khi ca 1-iodmheptan

4.4. Phn ng Retro - Diels - Alder (RDA)

Cc h vng 6 cha mt ni i c th b ph vng to thnh hai mnh : cu t"En" v "Dien". Th}ng thy cu t "dien" mang in tch trong ph ; cu t "en" cng

thy.

Vng 6 c th khng cha, cha 1 hoc nhiu d nguyn t, n cng c th l mt

phn ca h vng ln.

Phn ng RDA c th xy ra ion phn t, cng c th xy ra phn mnh m

ni i }c hnh thnh do mt phn ct khc (v d phn ct D). Phn ng RDA lmt qu trnh trung ho in.

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Ph khi ca 1,2,3,4-tetrahydrocarbazol

C ch I:

C ch II:

(m/z = 143)

Phn ng RDA cc hp cht khc :

Ph khi ca 5,7-dihydroxy-4'-

metoxyisoflavanonS phn mnh ca

5,7-dihydroxy-4'-metoxyisoflavanon

Nhiu hp cht thin nhin nh} indol ancaloit, tetrahydroisochinolin ancaloit,

flavon, isoflavon, rotenoit c vng trung tm c th to phn ng RDA trong khi ph k.Cc mnh to thnh do phn ng RDA s cho cc thng tin rt hu ch gii cu trc

cc cht ny.

4.5. Chyn v Mc Lafferty

Chuyn v Mc Lafferty t}ng t phn ng Norrish II trong quang ho, trong nhit

phn ester, trong phn ng Tschugaev,v trong phn ng "En".

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Cn gi l phn ct E c dch chuyn H.

Nhng nhm c th tham gia chuyn v Mc Lafferty : C=O (axit carboxylic, ester,

andehyt, keton, amit, lactam, lacton) ; C=N (azometin, base Schiff, hydrazon, oxim,

semicarbazon) ; S=O (sulfonester) ; C=C (alkyl aren, alkylheterocyclen, benzyleter,

olefin).C ch I :

C ch II :

V d : CH 3 2 2CH CH COOCH 3

Ph khi ca metyl butanoat

S phn ct mnh ca metyl butanoat

Chuyn v Mc.Lafferty

Qua phn ct D

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Ph khi ca butyl benzoat

S phn ct mnh ca butyl benzoat

c tr}ng cho cc metylester l pic m/z = 74 (Mc Laffesrty) v m/z = 59 (phn

ct D), cho etyl ester l 88 v 73.

4.6. Phn ng onim

Th}ng quan st thy nhng mnh ion c d nguyn t tch in d}ng nh}

oxonium, amonium, phosphonium, sulphonium.

Ph khi ca N-isopropyl- N-

metylbutylaminS phn mnh ca N-isopropyl- N-

metylbutylamin

Qua phn ct D Qua phn ct D

phn ngonium

Chuyn v Mc.Lafferty

phn ngonium

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Ph khi ca N-butylacetamit

S phn mnh ca N-butylacetamit

in tch O

Qua phn ct D

Qua phn ct D

phn ngonium

4.7. Mt CO

Nhng cht hoc nhng mnh ion c cha nhm C=O d b mt 28 n v khi

(CO).

Ph khi ca phenol

(m/z = 65)

S phn mnh ca phenol

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Ph khi ca Dispiro[4.1.4.1]-dodecan-6,12-

dion

(m/z = 65)

S phn mnh ca Dispiro[4.1.4.1]-

dodecan-6,12-dion

5. Cc phn ng nhit trng my khi ph

5.1. Nhng loi qan trng nht ca phn ng nhit

Tch li nhng mnh nh :

Decacboxyl ho (CO2)

Decacbonyl ho (CO)

CH3COOH

HX (H2O, HCl...)

*) Phn ng retro : Retraldl :

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Retr-Diels-Alder

*) Isomer ho

*) Dehydro ho, hydro ho

*) Nhit phn cc hp cht cha nit bc 4

* Dealkyl ho

6. Cc phong php vq khi nim khc6.1. Ho va chm in t (EI)

- Do nhng cht d bay hi phn t nh hoc t phn cc.

EI : Bt li l hay mt ion phn t hoc ion phn t c}ng yu. 10 20% hpcht c PTL < 300 khng thy ion phn t.

Li : c nhiu mnh ion, c th so snh ph vi ph ca cht bit, s dng ngnhng ph.

6.2. Ion ho ho hc (CI)

- Phung php CI dng cho cc cht kh bay hi nhu: Nhng cht | 200 Dalton nh}ng nhiu nhm phn cc

Cht t 800 25.000 Dalton

CI : Dng mt cht kh (v d CH4, isobutan, NH3) vi mt p sut khong 102 Pa

}a vo bung ion ho. Cht kh ny va chm vi cc in t bn ra t mt catt nng vi nng l}ng 300 eV v b ion ho.

V d :

4 4CH e CH 2e. o

Tip theo n b phn mnh mt phn :

4 4 5CH CH CH CH.. o 3

2

3 4 2 5CH CH C H H o

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Khi ta cho bc hi cht cn nghin cu M vo hn hp ion ny, ta s c :

5 4M CH MH CH o

Ph}ng php CI c th o }c cc ion phn t v do xc nh }c trng l}ngphn t.

u tin, mt cht kh (v d hydrocacbon, H2, H2O, NH3, alcol, kh tr) qua va

chm vi electron s b ion ho (p sut kh| 1 kPa).

Trong tr}ng hp l kh metan s xut hin [CH4]+, cn dng kh isobutan hoc

NH3 s c [C4H9]+, [NH4]

+

Nu s dng cht kh khc (v d kh tr, CO2, N2) th khng xy ra proton ho m

xy ra trao i in tch (charge exchange CE) :

[He]+ + M o [M]+ + He

Cc phn ng khc nh} cng i in t :

M + [X]+ o [MX]+

Bt anion :

AB + [X]+ o [B]+ + AX

Ion ho hc l ph}ng php m du b sung cho ph}ng php EI.

Ph khi CI ca lysin metyl ester

(Kh metan)

Ph khi CI ca lysin metyl ester

(Kh isopropan)

6.3. Ion ho bi in t (electrospray ionization ESI)

Dung dch cht cn o }c phun qua mt capila vi tc 1 o 20 Pl/pht vomt bung trong thit b.

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S xut hin nhng git nh tch in, khi dung mi (MeOH/H2O ; CH3CN/H2O)

bc hi, cc git s nh hn na v }c }a vo b phn phn tch trong mt capila.

S in h bi in t (my in t , ESI)

H quang in tKapila

Dng cht lng(Dung mi + mu)

Phn tchkhi

Phun s}ng

Kim nhn Kh kh Bm chn khng

6.4. Bn ph bng dng ngyn t nhanh (Fast-Atom-Bombardment, FAB)

Dng cho nhng phn t kh hoc khng bay hi.

Nguyn l : Mt dng nguyn t trung tnh c tc nhanh }c dng bn vo

mt lp cht cn nghin cu mng trong bung ion ho. Qua xut hin ion ca cht

cn phn tch.

Dng nguyn t khng tch in, c tc cao, th}ng dng l argon (Ar), hn

hu cng dng xenon (Xe) v }c to ra bng mt sng lc, ion Ar+ }c gia tc (5

10 keV) trong mt bung va chm, khi va chm vi nguyn t Ar trung tnh s to ra Ar o

c tc cao.

Dng Aro nguyn t tc cao }c h}ng vo lp cht cn phn tch gn vo mt

matrix (th}ng dng glycerin, thioglycerin hoc 3-nitrobenzyl ancol) [1-2 Pg cht trong

1-2 Pl glycerin) trn mt mi nhn bng ng.

Vic chun b mu cng phc tp, cn s kho lo v kinh nghim.

Ph FAB/MS }c dng cho cc axit hu c (COOH, SO3H, OPO3H) v mui,polypeptit, oligosaclarit, nucleotit, ph th}ng cho ion phn t d}ng (positive ion) : MH+

; hoc ion phn t m (negative ion) : [MH]Thnh thong cng thy ion [M+Na]+,

[M+( glycerin)]+

6.5. Gii hp t trung (Field-Desorption FD) :

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Mt si kim loi mnh (5 Pm) s }c cy vi mt kim nh. Mt l}ng nh cht (~ 1

Pg) }c ho trong dung mi v }a ln si kim loi. Si kim loi t trong in k 8 kVv b t nng. V kim nh }c cy vo l rt nhn nn u kim s c mt in th

ln n 108 Vcm1, iu ny dn ti : 1 e

ca cht cn o }c chuyn vo orbital d

trng ca kim loi lm kim trn si kim loi xut hin ion phn t d}ng ca cht. Qualc y Columb, ion phn t ny s }c gii hp. Trong ph s c ion M + v c th

MH+.

Cc ph}ng php ci tin : Laser-Desorption, ph khi ion th cp (sekunder ion

mass spectrometry SIMS) v californium plasma desorption.

V cc ion phn t cht nghin cu i khi mi tr}ng lng hoc rn trong thi gian

ngn (1012s) nn hu nh} khng c phn hu do nhit o thu }c ion phn t.

O+

O+

O+

O+

ion phn tKim nh

Si kim loi

+ 8kV

+ 8kV

Katt

Si kim loi

S ca phong php gii hp t trong (FD)

*/ Californium (252Cf)-Plasma desorption :

ng v phng x 252Cfphn r thnh 2 phn chy ng}c chiu nhau vi ng nngl

79 v 104 MeV, khi gp cht nghin cu trn tm Ni s lm tng nhit o 10.000oK,phn t cht dng plasma s }c gii hp dng + v v tng tc vo bung phn

tch. Thit b MS ny dng k thut thi gian bay (time of flight TOF). Ph}ng php ny

c th xc nh }c cht c phn t l}ng t 10.000 o 20.000 Dalton vi chnh xc

r10 or 20 n v khi.

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Cc phong php in h hay oc dng

ion hoPh}ngphp Ht ion ho Loi ion Tn hiu ph khong PTL Phn ng phnhu nhit

(EI) e- M+v

cc mng ion

- C th 3,,500 c

(CI) CH5+, NH4

+, Ar+ z.B.mit NH4:

[M+H]+

[M+H4]+

M, Cluster

Sn phm cng

hp

3,500 c

(FAB) z.B.Aro , nng

l}ng cao

z.B. [M+H]+

[M+Na]+

[M+K]+

Cluster

z.B. [M+H]+

Cng cht mang

z.B. [2glycerin+H]

3,500 Rt him

(ESI) Keine

( elektrostatisch)

- 100,000 Khng

(TSI)Va chm

nhit

Th}ng xuyn

v/d

CH3CO2NH4

[M+H]+

[M+H4]+

Thnh thong cng

dung mi

3,500 Khng

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6.6. Kt ni cc thit b khc vi my khi ph

GC/MS

Ion ho v thu gom

ion trong chnKh mang

Phn tchkhi

H thngdetect

ngunionSKK MS

FID- detectv my ghi

tsMS bn cu t

tsSKK cho bn cu t v

pic dung mi (LM)

T ph khi ca hn hp 4ng phn ca dn xut

pyrrolizidin tch ph caA, B (sn phm chnh 95%,M = 223 v C, D so snh

C}ngt}

ngi

Cu trc ca ng phn chnh

Ph khi ca tng cu t

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T l ng v phng x ca Clor v Brom

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T l ng v phng x ca Clor v Brom

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