GC

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GC
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Schematic of a GC
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Typical GC
Computer Controls for Method and Output
Carrier gas/ Regulator
Varian 3350 Gas Chromatograph
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Separation
Flow of Mobile Phase
Injector
Detector
T0
T10
T20
Most Interaction with Stationary Phase Least
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GC Peak Broadening
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Carrier gas velocity in the column
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Chromatography Dead Volume Mixing
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GC - Column
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Columns
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GC Capillary Column
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Separation
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GC Liquid Phases

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GC Column Efficiency
Capillary
Packed
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GC Sample Capacity Effect
0.53 mm
0.25 mm
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GC Column Flows
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GC Column Performance
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GC Film Thickness Effect
0.25mm
1.0mm
3.0mm
5.0mm
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GC Isothermal and Programming
500C 3min To 1400C at 100C/min
1050C
500C
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Mobile Phase
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GC Gases Properties
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GC van Deemter Plots/Curves
N2
He
H2
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GC - Injectors
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GCCapillaryInjection Modes
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GC Injector Inserts
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GC Injector Linear Repeatability of Peak Area
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GC - Injectors

• SPLIT INJECTOR
• Advantage - Limitations
• Injected zone narrow
• Small sample aliquot avoids overloading
• Mass discrimination of sample components
  (different range of volatility)
• Systematic errors for quantitative analysis
• In trace analysis only part of analytes to
  detector

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GC- Injectors

• SPLITLESS INJECTOR
• Advantage - Limitations
• Avoids large tailing of solvent peak
• Allows transfer of main part of sample
  components into detector
• Trace analysis favourable technique for
  insertion of diluted samples
• Recondensation of solvent at top of capillary
  possible damaging stationary phase
• Only columns with chemically bonded phases
• Necessary wettability of stationary phase for
  condensed solvent (droplets)

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Injection Technique and Peak Discrimination
Filled Needle
Hot Needle
Cold On-Column
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GC Injector Solvent Vapours Volume
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GC On-Column Injector
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GC - Injectors

• Advantage of on-column injector
• avoids mass discrimination effects
• trace analysis enables quantitative insertion
  of sample into column (and detector)
• labile components not stressed thermally

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GC - Detectors
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GC - FID
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GC Flame Ionization Detector (FID)
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GC FID Response to Gases Flows
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GC Alkali Ionization Detector (N,P)
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GC FID AFID Response
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GC Electron Capture Detector (ECD)
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GC - Thermal Conductivity Detector
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GC Atomic Emission Detector
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GC Detectors Performance
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GC IR Detector Gas Cell
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Peak Area IntegrationQualitative and Quantitative
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Chromatography Sampling Rate and Accuracy
2 Hz
25 Hz
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Chromatography Integration Problems
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GC Integration Problems - Deconvolution
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Kovatcs Index
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GC Retention Indexes
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GC Derivatization Reagents
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Fatty Acids
Marine Source
Animal Source
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Conditions Column SP-2560, 100m x 0.25mm ID,
0.20µm filmCat. No. 24056Oven 140C (5 min)
to 240C at 4C/min, hold 15 minCarrier helium,
20cm/sec, 175CDet. FID, 260CInj. 1µL
Supelco 37 Component FAME Mix (10mg/mL total),
split (1001), 250C
List of components on the next slide
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Components for SP 2560 Chromatogram

• Analyte Data Component (acid methyl ester) Weight
  ()1. C40 (Butryic) 42. C60 (Caproic) 43.
  C80 (Caprylic) 44. C100 (Capric) 45. C110
  (Undecanoic) 26. C120 (Lauric) 47. C130
  (Tridecanoic) 28. C140 (Myristic) 49. C141
  (Myristoleic) 210. C150 (Pentadecanoic) 211.
  C151 (cis-10-Pentadecenoic) 212. C160
  (Palmitic) 613. C161 (Palmitoleic) 214. C170
  (Heptadecanoic) 215. C171 (cis-10-Heptadecenoic)
  216. C180 (Stearic) 417. C181n9c (Oleic)
  418. C181n9t (Elaidic) 219. C182n6c
  (Linoleic) 2

• 20. C182n6t (Linolelaidic) 221. C183n6
  (g-Linolenic) 222. C183n3 (a-Linolenic) 223.
  C200 (Arachidic) 424. C201n9
  (cis-11-Eicosenoic) 225. C202
  (cis-11,14-Eicosadienoic) 226. C203n6
  (cis-8,11,14-Eicosatrienoic) 227. C203n3
  (cis-11,14,17-Eicosatrienoic) 228. C204n6
  (Arachidonic) 229. C205n3
• (cis-5,8,11,14,17-Eicosapentaenoic) 230. C210
  (Henicosanoic) 231. C220 (Behenic) 432.
  C221n9 (Erucic) 233. C222 (cis-13,16-Docosadien
  oic) 234. C226n3
• (cis-4,7,10,13,16,19-Docosahexaenoic) 235. C230
  (Tricosanoic) 236. C240 (Lignoceric) 437.
  C241n9 (Nervonic) 2

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