Gas Chromatography
description
Transcript of Gas Chromatography
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Gas Chromatography
2004.
Kim, Wang-Yu Ph.D.Interface Engineering Co., Ltd.
- 이론과 실제 -
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GC 의 정의• 두개의 상 ( 고정상 , 이동상 ) 사이에서
혼합물 각각의 성분이 분배 ( 혹은 흡착 )되는 정도가 다른 성질을 이용하여 각각의 성분을 분리하는 크로마토그래피 기술이다 . 이동상으로는 혼합물과 반응하지 않는 기체를 사용하는 것이 HPLC 와 크게 다른 점이다 .
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GC vs. LCMobile phase
Sample state
Gas Liquid
Gas Liquid
Stationary phase
Liquid
Liquid or solid
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Outside GC
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Inside GC
Injecting and vaporizing
Separating
Detecting
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Septum
Nut
Graphite ferrule
Injection Port
Inlet liner
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Septum
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Ferrule
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1. Stationary phase2. Inner Diameter(mm)3. Length(m)4. Film Thickness(um)
Capillary columns
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FIDFlame Ionization Detector
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GC Column 종류 ( 단면 )
PackedOpen (Capillary)
Regular
BeadColumn
PorousLayerBead
ConventionalPacked andMicropacked
Porous LayerOpen Tube(PLOT)
Wall CoatedOpen Tube(WCOT)
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Capillary Column Types
Wall Coated Open Tubular (WCOT)
Liquid Phase
Porous Layer Open Tubular (PLOT)
Carrier Gas
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2. Inner Diameter(mm)3. Length(m)4. Film Thickness(um)
1. Stationary phase
GC column 의 특성
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Polarity
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Polarity SolubilityPhase = Solute HighPhase Solute Low
High solubility = High retention and capacity
POLARITY
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DISPERSION INTERACTIONKcal/mole
DB-1 (non-polar)0 2 4 6 8 10
Benzene
Phenol
C10 C12
8.1
11.9
10.9 11.9
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DIPOLE INTERACTIONCompounds With Dipole
Differences
C=CCl Cl
H HC=C
Cl
Cl
H
H
1,2-dichloroethylene 1,1-dichloroethylene
• Smaller differences require a stronger dipole phase
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HYDROGEN BONDING INTERACTIONExample Compounds
•Strong: alcohols, carboxylic acids, 1° and 2° amines
•Moderate: aldehydes, esters, ketones
•Weak: hydrocarbons, halocarbons, ethers
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SELECTIVITYInteraction Strengths
Phase Dipersion Dipole H Bonding
Methyl Strong None None
Phenyl Strong None Weak
Cyanopropyl Strong Strong Moderate
Trifluoropropyl Strong Moderate Weak
PEG Strong Strong Moderate
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COMPOUNDSProperties
Compounds Polar Aromatic HydrogenBonding Dipole
Toluene no yes no inducedHexanol yes no yes yesPhenol yes yes yes yesDecane no no no no
Naphthalene no yes no inducedDodecane no no no no
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50% CYANOPROPYL
0 2 4 6 8 10 12 14 16
100% Methyl
1 23 4
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0 2 4 6 8 10 12 14 16
4 16 2
5 350%Cyanopropyl
1. Toluene2. Hexanol3. Phenol4. Decane (C10)5. Naphthalene6. Dodecane (C12)
Strong DispersionStrong DipoleModerate H Bonding
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Polysiloxanes(Methyl Substituted)
100 % methyl (HP-1, DB-1 etc.) Nonpolar
Si
Me
Me
O
n
% = # of sites on silicon atoms occupied
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Polysiloxanes(Phenyl methyl Substituted)
5% phenyl (HP-5, DB-5, etc.)35% phenyl (HP-35, DB-35, etc.)50% phenyl (HP-50+, DB-17, etc.)
NonpolarMid-polarMid-polar
Si
Me
Me
O
m
OSiO
Ph
Ph n
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Polysiloxanes(Cyanopropylphenyl methyl Substituted)
6% cyanopropylphenyl (HP-1301, DB-1301, etc.)14% cyanopropylphenyl (HP-1701, DB-1701etc.)50% cyanopropylphenyl (HP-225, DB-225, etc.)
Mid-polarMid-polarPolar
Si
Me
Me
O
n
OSiO
R
R' m
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HP-17: 50% phenyl and 50% methyl siloxanevs
HP-50+ : (50%)-Diphenyl (50%)-Dimethylpolysiloxane
CH3 n
Si O
3CH
CH3
m n
Si SiO O
Two columns are different !!
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Poly(ethylene) Glycol
100% PEG (HP-WAX)
Less stable than polysiloxanesUnique separation characteristics
Polar
HH
HO - - C-C-O- -H
H H n
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POLARITYSolubility And Retention
Same GC conditionsSame column dimensionsOnly differ in stationary phase
0 2 4 6 8
0 2 4 6 8
C10 C12
Hexanol 100% PEG(polar)
HexanolC10 C12
100% Methyl(non-polar)
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1. Stationary phase
3. Length(m)4. Film Thickness(um)
2. Inner Diameter(mm)
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COLUMN DIAMETERRetention
80°C isothermal
Isothermal: Retention is inversely proportional to column diameterTemperature program: 1/3-1/2 of isothermal values
0.25 mm
0 5 10 15 20
21.81
0.32 mm
0 2 4 6 8 10 12 14 16
16.06
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COLUMN DIAMETER(0.05~0.53mm)
0.32 mm0.53 mm
n =58,700 n =107,250
Sample capacity : < 2 ug < 500 ngInstrumental condition
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Phase RatioThe combined effect of the column diameter andfilm thickness is described by the phase ratio.
=
where
,
r = column radius ( m)df = film thickness ( m)
r/2d f
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Differing Column Inner Diameter, Equal Betas
Time (min)0 5 10 15 20
Carrier:Oven: 65°CInjection: SplitDetector: FID
ColumnA: HP-624
ColumnB: HP-624
HP part no. 19091V-41330 m, 0.32 mm, 1.8 m
Helium,40 (m/sec)
HP part no. 19095V-42330 m, 0.53 mm, 3 m
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1. Stationary phase2. Inner Diameter(mm)
4. Film Thickness(um)3. Length(m)
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COLUMN LENGTHTheoretical Efficiency
0.25 mm IDN/m = 4762 (for k = 5)
Length (m) N15 71,43030 142,86060 285,720
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COLUMN LENGTH(10~120m)Resolution and Retention:
Isothermal
Double the plates, double the time but not double the the resolution
15 m 60 m30 m
R=0.842.29 min
R=1.688.73 min
R=1.164.82 min
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1. Stationary phase2. Inner Diameter(mm)3. Length(m)4. Film Thickness(um)
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FILM THICKNESS(0.1~5um)Retention: Isothermal
0 5 10 15 20 25
0 2 4 6 8
7.00
25.00
0.25 µm
1.00 µm
Thermal stabilitySample b.p.
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FILM THICKNESSBleed
More stationary phase = More degradation products
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+
Again
Si Si Si Si Si Si SiO O O O O O OHCH3 CH3 CH3 CH3 CH3 CH3 CH3
CH3 CH3 CH3 CH3 CH3 CH3 CH3
OHSiSi O Si O Si OCH3 CH3 CH3 CH3
CH3 CH3 CH3 CH3Si
O O
O
CH3H3C
H3CH3C
SiSiCH3
CH3
OO O O O
OSi
HO
H3C
CH3 CH3 CH3 CH3
Si SiSi Si Si SiCH3
CH3
CH3
CH3CH3 CH3
CH3
CH3CH3
“Back biting” Mechanism of Bleed Formation
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Phases tailored to “mimic” currently existing polymers-Examples: DB-5ms, DB-35ms, DB-17ms
New phases unrelated to any previously existing polymers-Example: DB-XLB
Optimized manufacturing processes-Example: DB-1ms
Four Types Of Low Bleed Phases
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Column Installation1) Choosing ferrule2) Cutting the capillary column3) Inlet installation4) Leak-checking5) Outlet installation6) Establishing flow7) Conditioning
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Ferrule• Graphite(100%) - 450℃ - general purpose and reused - FID, NPD, ECD - Not good for Mass
• Vespel(100%) - 280℃ - reused - for only isothermal operation
1) Choosing ferrule2) Cutting the capillary column3) Inlet installation4) Leak-checking5) Outlet installation6) Establishing flow7) Conditioning
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Cutting
• Jagged silica edges or exposed polyimide cause adsorption and tailing peaks, so it is very important that the column ends are cut uniformly.
1) Choosing ferrule2) Cutting the capillary column3) Inlet installation4) Leak-checking5) Outlet installation6) Establishing flow7) Conditioning
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Inlet installation① 먼저 column nut 를 capillary column 에 끼우고
ferrule 을 끼운다 .② 3cm 이상 capillary 가 나오게 한 후 먼저 inlet
에 조여 capillary 가 ferrule 에 적당히 물리게 한다 .
③ 일단 푼다 .④ capillary 를 5mm 정도 남겨놓고 자른다 .⑤ 다시 inlet 에 연결한다 .⑥ 손으로 꽉 조인 상태에서 ¼~ 반바퀴 더 wrench
로 돌린다 . ⑦ 이동상을 흘렸을 때 이 부분에 Leak 가 있을
경우 injector 압력 gauge 가 올라가지 않는다 .
1) Choosing ferrule2) Cutting the capillary column3) Inlet installation4) Leak-checking5) Outlet installation6) Establishing flow7) Conditioning
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Leak-checking
Use acetone in vial
1) Choosing ferrule2) Cutting the capillary column3) Inlet installation4) Leak-checking5) Outlet installation6) Establishing flow7) Conditioning
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Outlet installation• 보통 detector jet orifice 보다 1-3mm 아래쪽에 column end 가 있게 한다 ( 보통
capillary 를 detector 안쪽으로 끝까지 밀어 넣어 넣은 후 2mm 정도 뒤로 뺀다 ).• column nut 와 ferrule 을 끼우는 요령은 inlet과 같다 .
1) Choosing ferrule2) Cutting the capillary column3) Inlet installation4) Leak-checking5) Outlet installation6) Establishing flow7) Conditioning
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Carrier gas Flow
1) Choosing ferrule2) Cutting the capillary column3) Inlet installation4) Leak-checking5) Outlet installation6) Establishing flow7) Conditioning
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Conditioning• 40℃ start and 5~10℃/min• below 20~25℃
1) Choosing ferrule2) Cutting the capillary column3) Inlet installation4) Leak-checking5) Outlet installation6) Establishing flow7) Conditioning
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Storage• septum on each end of the
column• Especially for PEG type column
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Split/Splitless Injection
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Splitless Injection
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And Now Let’s do Some
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DB-624 COLUMNQC Test Mix
Column: DB-624 30m x 53mm I.D., 3.0µm
Carrier: Helium at 40 cm/sec measured at 35°C
Injector: Mega Direct, 260°CDetector: FID, 300°COven: 35°C for 1.50 min 30°/min to 65° for 10 min
1. 1,2-Dichloropropane2. Octane3. Tetrachloroethylene4. Chlorobenzene5. Nonane
5 10 15 20 25
1.0e4
2.0e4
3.0e4
4.0e4
5.0e4
6.0e4
7.0e4
8.0e4
Time (min.)
2.71
7.4310.92
12.4917.42
20.78
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Example of Column Contamination
DB-624 QC Test Mix* After 75 Injections of Oily Sample
0 5 10 15 20
6000
7000
8000
9000
1.0e4
1.1e4
1.2e4
1.3e4
1.4e4
1.5e4
Time (min.)
2.21
3.30
6.03
9.26
10.46 14.40 17.86
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Column and Liner Contamination
Inlet coil of column
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Example of Column Contamination
Removed 1 1/2 m from injector end *
Time (min.)0 5 10 15 20 255000
6000
7000
8000
9000
1.0e4
1.1e4
1.2e4 2.80
7.3410.79
12.33
17.19
20.56
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Backflush Column
1/16" flexible teflon line to regulated pressure source
Beaker for solvent collection
Capillary column
Special connectorand ferrule
Flexible teflontubing
Special adapter
CapVial
Capillary column
Rinse with 10ml each:Methanol, Methylene Chloride, Hexane
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Multiple cause and effect
Do not change too many variables at once
Complete system = Carrier Gas + Injector + Column + Detector + Data System
Remember