Schematic of a GC - PowerPoint PPT Presentation

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Schematic of a GC

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  1. GC

  2. Schematic of a GC

  3. Typical GC Computer Controls for Method and Output Carrier gas/ Regulator Varian 3350 Gas Chromatograph

  4. Separation Flow of Mobile Phase Injector Detector T=0 T=10’ T=20’ MostInteraction with Stationary PhaseLeast

  5. GC – Peak Broadening

  6. Carrier gas velocity in the column

  7. Chromatography – Dead Volume Mixing

  8. GC - Column

  9. Columns

  10. GC – Capillary Column

  11. Separation

  12. GC Liquid Phases

  13. GC – Column Efficiency Capillary Packed

  14. GC – Sample Capacity Effect 0.53 mm 0.25 mm

  15. GC – Column Flows

  16. GC – Column Performance

  17. GC – Film Thickness Effect 0.25mm 1.0mm 3.0mm 5.0mm

  18. GC – Isothermal and Programming 500C 3min To 1400C at 100C/min 1050C 500C

  19. Mobile Phase

  20. GC – Gases Properties

  21. GC – van Deemter Plots/Curves N2 He H2

  22. GC - Injectors

  23. GCCapillaryInjection Modes

  24. GC – Injector Inserts

  25. GC – Injector Linear & Repeatability of Peak Area

  26. 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

  27. 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)

  28. Injection Technique and Peak Discrimination Filled Needle Hot Needle Cold On-Column

  29. GC – Injector Solvent Vapours Volume

  30. GC – On-Column Injector

  31. 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

  32. GC - Detectors

  33. GC - FID

  34. GC – Flame Ionization Detector (FID)

  35. GC – FID Response to Gases Flows

  36. GC – Alkali Ionization Detector (N,P)

  37. GC – FID & AFID Response

  38. GC – Electron Capture Detector (ECD)

  39. GC - Thermal Conductivity Detector

  40. GC – Atomic Emission Detector

  41. GC – Detectors Performance

  42. GC – IR – Detector Gas Cell

  43. Peak Area IntegrationQualitative and Quantitative

  44. Chromatography – Sampling Rate and Accuracy 2 Hz 25 Hz

  45. Chromatography – Integration Problems

  46. GC – Integration Problems - Deconvolution

  47. Kovatc’s Index

  48. GC – Retention Indexes