بنام خدا عباس بهرامی عضو هیات علمی گروه بهداشت حرفه ای دانشکده بهداشت دانشگاه علوم پزشکی کاشان

1. بنام خدا عباس بهرامی عضو هیات علمی گروه بهداشت حرفه ای دانشکده بهداشت دانشگاه علوم پزشکی کاشان Bahrami_a@kaums.ac.ir

3. انتظار میرود در پایان جلسه دانشجویان بتوانند: 1- اساس کار دستگاه گاز کروماتوگرافی را شرح دهند . 2- اجزای دستگاه گاز کروماتوگرافی را نام ببرند. 3- تعدادی از موادی را که در بهداشت حرفه 1- اجزاء دستگاه گازکروماتوگرافی را بیان کند. 2- انواع دستگاه کروماتوگرافی را بیان کند. 3- مکانیسم های به تعادل رسیدن نمونه در فاز متحرک و ثابت را شرح دهد. 4- کاربردهای کروماتوگرافی را توضیح دهد. 5- انواع دتکتورهای مورد استفاده در گازکروماتوگرافی را بیان کند.

4. Gas Chromatography

5. Gas Chromatography Basics Gas Liquid Chromatography (GLC) Gas Solid Chromatography (GSC) Mobile phase does not interact with analyte Separation occurs by interaction of analyte differentially w/liquid stationary phase and temperature GC preferred method, only applicable to volatile substances derivitiazation

6. Carrier Gas Supply • Must be at a constant flow rate so that retention times & retention volumes may be equated • Choice of detector will often • Dictate the gases that are used, need to be inert Ex. FID used H2, air, and He

7. Injection Port • Heated so sample virtually instantly turns into a vapor as sample plug goes onto column • Septum • Split/ Splitless Want to reproducibly get in & get out Sample focus

8. Flow rate Measurement • Why is a known flow rate critical?

9. GC Columns Capillary: - have i.d. <1mm - have wide unrestricted flow through center & inner surface is coated with liquid stationary phase • Variety of functional groups have been blended into polysiloxane chain to provide different polarity & selectivity

10. Advantages Disadvantages Capillary columns

12. HO-CH2-CH2-(O-CH2-CH2)n-OH polyethylene glycol

14. Temperature

15. Chromatography Catalog Exercise • Determine the best type of column to achieve separation for drugs of abuse. • Draw the chemical structures of the stationary phase as best you can. • Indicate what chromatographic conditions you would do your separation under. • Why do you think the catalog recommended the conditions they did? • Compare with someone else who used a different catalog, explain any differences.

16. Detectors in GCThe ideal detector should:

17. Flame Ionization Detector

18. Thermal conductivity detector

19. Thermionic Detector (NPD)

20. Electron Capture Detector (ECD)

21. Atomic Emission Detector

22. Mass Spectrometer as a GC Detector

23. Total Ion Chromatogram

24. Selected (single) ion chromatogram:

25. Connecting the GC to the MS This is difficult! Why?

26. How is a GC interfaced to an MS? 1. Direct Connection

27. Open Split Interface How is a GC interfaced to an MS? (2)

28. Advantages of Open Split Design

29. Jet Separator

30. Cryogenic Focussing Technique for Beer Headspace Analysis

31. Kovat’s Retention Index

34. Gas Chromatography

35. انتظار میرود در پایان جلسه دانشجو بتواند: 1- اجزاي دستگاه كاز گروماتو گراف را نام ببرد. 2- اساس كار دستگاه كاز گروماتو گراف را توضيح دهد. 3- انواع آشكارسازها را نام ببرد.

36. H RESET Air Hydrogen Gas Carrier Gas Chromatography Filters/Traps Data system • gas system • inlet • column • detector • data system Regulators Syringe/Sampler Inlets Detectors Column

37. Schematic Diagram of Gas Chromatography

38. Schematic Diagram of Gas Chromatography

39. DETECTORS Flame Ionization Detector (Nanogram - ng) High temperature of hydrogen flame (H2 +O2 + N2) ionizes compounds eluted from column into flame. The ions collected on collector or electrode and were recorded on recorder due to electric current.

40. Exhaust Chimney Collector Electrode Igniter Polarizing Electrode Column Hydrogen Effluent Inlet Schematic Diagram of Flame Ionization Detector

41. Schematic Diagram of Flame Ionization Detector Collector Detector electronics  - 220 volts Flame Chassis ground Jet Signal output Column

42. Thermal Conductivity Detector Measures the changes of thermal conductivity due to the sample (mg). Sample can be recovered.

43. Thermal Conductivity Detector Principal: The thermal balance of a heated filament Electrical power is converted to heat in a resistant filament and the temperature will climb until heat power loss form the filament equals the electrical power input. The filament may loose heat by radiation to a cooler surface and by conduction to the molecules coming into contact with it.

44. The TCD is a nondestructive, concentration sensing detector. A heated filament is cooled by the flow of carrier gas . Thermal Conductivity Basics When the carrier gas is contaminated by sample , the cooling effect of the gas changes. The difference in cooling is used to generate the detector signal. Flow Flow

45. Thermal Conductivity Detector When a compound elutes, the thermal conductivity of the gaseous mixture of carrier gas and compound gas is lowered, and the filament in the sample column becomes hotter than the other control column. Its resistance increased, and this imbalance between control and sample filament resistances is measured by a simple gadget and a signal is recorded

46. Thermal Conductivity Detector

47. Relative Thermal Conductivity

48. Thermal Conductivity Detector • Responds to all compounds • Adequate sensitivity for many compounds • Good linear range of signal • Simple construction • Signal quite stable provided carrier gas glow rate, block temperature, and filament power are controlled • Nondestructive detection

49. Electron Capture Detector For pesticide analysis (picogram). Accept electrons of carrier gas.

50. Electron Capture Detector ECD detects ions in the exiting from the gas chromatographic column by the anode electrode. 3H or 63Ni which emits  particles. Ionization : N2 (Nitrogen carrier gas) +  (e) = N2+ + 2e These N2+ establish a “base line” X (F, Cl and Br) containing sample +  (e)  X- Ion recombination : X- + N2+ = X + N2 The “base line” will decrease and this decrease constitutes the signal. Insecticides, pesticides, vinyl chloride, and fluorocarbons