1. Chapter 22 GC & LC

2. 22.1 Gas Chromatography -1 1.Schematic diagram

3. 22.1 Gas Chromatography -2 2.Columns : open tubular columns

4. 22.1 Gas Chromatography -3 A)m.p.(gas) - s.p. 1)s.p.: solid （ using adsorption ） ex: SiO 2 column ages: Si-O-H cause tailing peak. 2) s.p.: liquid （ GLC, using partition ） Table 22-1 Decrease thickness of stationary phase leads to a)Resolution  (H  ) b) t r  c)Sample capacity 

6. b.p.  22.1 Gas Chromatography -4 ex

7. 22.1 Gas Chromatography -5 B) The effects of column polarity on separation Like dissolves like (a)S.P: nonpolar b.p. dependent

8. 22.1 Gas Chromatography -6 -one:C=O -ol: OH S.P. : Polar

9. 22.1 Gas Chromatography -7 C) Common solid s.p. : a)Porous carbon : larger molecules bind more tightly than small ones, flexible molecules bind more than rigid ones b)Molecular sieves : retain & separate small molecules : H 2, O 2, N 2, CO 2, CH 4. (Fig. 22-5)

10. 22.1 Gas Chromatography -8 packed column vs. open tubular column higher resolution lower sample capacity

11. 22.1 Gas Chromatography -9 3.Temperature programming  temp of column   v.p. solute,   t r  sharpens peaks isothermal : constant temp. temp. programming (gradient) : raise the column temp. during the separation.

12. 22.1 Gas Chromatography -10

13. 4.Carrier Gas 22.1 Gas Chromatography -11

14. 22.1 Gas Chromatography -12 5. Sample Injection-1 1) gasses, liquids, or solids  vaporized, not decomposition 2) injection time   bands broader 3) injected by syringe (manual or automatic injection)

15. 22.1 Gas Chromatography -12

16. 22.1 Gas Chromatography -13 5. Sample injection-2 : 4) operation a).on-column injection (50 ℃ ) -best for quantitative analysis -thermally sensitive compounds -low resolution

17. 22.1 Gas Chromatography -14 b) split injection (350 ℃ ) (only 0.1-10% sample) - concentrated sample - high resolution - dirty samples -could cause thermal decomposition c) splitless injection (220 ℃ ) (80%) - dilute sample - high resolution -solvent trapping (T solvent < 40 ℃ ) -cold trapping (T solute < 150 ℃ )

18. 22.1 Gas Chromatography -15 5.Detectors Qualitative analysis : mass spectrometer, IR Quantitative analysis : area of a chromatographic peak.

19. 22.1 Gas Chromatography -16 a)Thermal conductivity detector: -most general way -responds to everything -not sensitive enough for high resolution. b)Flame ionization detector : -most popular -mainly responds hydrocarbons (C-H)

20. 22.1 Gas Chromatography -17 c)Electron capture detector : -for compounds containing atoms with high electron affinities. -sensitive for halogen, C=O, NOx, & orgaometallic compounds. d)Other detectors : p 476

21. 22.2 Liquid Chromatography -1 1.open, gravity-feed column 2.closed column (under high pressure) packed with micron-size particles. (HPLC) 3.stationary phase : adsorption : silica (SiO 2  xH 2 O), alumina (Al 2 O 3  xH 2 O), ‚molecular exclusion, ƒion-exchange,  affinity

22. 22.2 Liquid Chromatography -2 compete with ▲ for binding on s.p. the more strongly bind to s.p.   eluent strength 

23. 22.2 Liquid Chromatography -3 4. Eluent strength : Table 22.2 The more polar solvent   eluent strength   t r 5. Gradient elution : increased the eluent strength during the separation in liquid chromatography.

25. 22.3 High-Performance Liquid Chromatography (HPLC) -1

26. 22.3 High-Performance Liquid Chromatography (HPLC) -2 1. Through a closed column, and needs high pressure. 2. s.p. particles size  (s.p. m.p. faster, i.e. C  in van Deemter eqn.)  resolution 

27. 22.3 High-Performance Liquid Chromatography (HPLC) -3

28. 22.3 High-Performance Liquid Chromatography (HPLC) -4

29. 22.3 High-Performance Liquid Chromatography (HPLC) -5 3. Stationary phase a) Normal-phase chromatography : polar s.p. and less polar solvent. Eluent strength is increased by adding a more polar solvent. b) Reversed-phase chromatography : low-polarity s.p. and polar solvent. Eluent strength is increased by adding a less polar solvent.

30. 22.3 High-Performance Liquid Chromatography (HPLC) -6 c) Bonded stationary phase. polar vs. nonpolar p.461 d) Optical isomers D- & L-amino acids

31. 22.3 High-Performance Liquid Chromatography (HPLC) -7 d) Optical isomers separation for ant-inflammatory drug Naproxen

32. 4. Column a)Guard column b)Injection valve 22.3 High-Performance Liquid Chromatography (HPLC) -8

33. 22.3 High-Performance Liquid Chromatography (HPLC) -9 5. Solvents a) Isocratic elution : elution with single solvent or a constant solvent mixture b) Gradient elution : solvent is changed continuously from a weak eluent strength to a strong eluent strength by mixing more and more of a strong solvent to a weak solvent during the chromatography.

34. 22.3 High-Performance Liquid Chromatography (HPLC) -10 A : KH 2 PO 4 (aq) B: CH 3 CN (l)

35. 22.3 High-Performance Liquid Chromatography (HPLC)-11 Reversed-phase column : eluent strength , solvent polarity , t r 

36. 22.3 High-Performance Liquid Chromatography (HPLC)-12 The gradient can be used to resolve all peaks by reducing the time from 2 h to 38 min.