Chromatography

1. Gas Liquid GSC GLC LSC LLC IEC GPC AC Chromatography

2. Gas Chromatography Mobile phase： gas (usually He, N2, H2) Stationary phase： non-volatile liquid or solid particles Analytes for GC • Have a significant vapor pressure • Thermal stable ex：gas, most non-ionized small and medium (C25) organic molecules, many organometallic compounds. Not for organic and inorganic salts, macromolecules • 樣品形式：solid, liquid, gas

3. carrier gas in exit septum computer or recorder injection port detector injector oven detector oven column column oven Schematic diagram of a gas chromatography

4. H C B A μ Carrier gas no reactive non flammable non-toxic N2, He, H2 N2→packed column He, H2→open tube column

5. N2 Plate height (mm) He H2 Linear velocity (cm/s) H2 and He both give optimal resolution at higher flow rates than N2

6. outer wall of column 0.1 ~ 0.53 mm inner diameter flow stationary phase (0.1 ~ 5μm thick) Column Open tubular columns Packed column contain a fine solid support coated with a nonvolatile liquid stationary phase; or the solid itself may be the stationary phase.

7. Open tubular columns Compared with packed columns, open tubular columns offer： 1. higher resolution 2. shorter analysis time 3. greater sensitivity 4. lower sample capacity

8. wall-coated open tubular column (WCOT) FSOT: fused-silica, OTC support-coated open tubular column (SCOT) porous-layer open tubular column (PLOT) Decreasing thickness of stationary phase leads to 1. decreased plate height 2. decreased retention time 3. decreased capacity for analyte

11. GSC separation based on surface adsorption Absorbent： • Molecular sieves：for H2, O2, N2, CH4, CO (PLOT) • Charcoal：for permanent gas C1 ~C4, stack gas (NOx, SOx) • Silica gel, alumina (PLOT) • Porous polymer

12. GLC a solid support coated with a liquid stationary phase Solid support for GLC： • Diatomaceous earths (diatom: single-cell algae) • graphite carbon, charcoal • Teflon Liquid phase for GLC： • Chemical stable and unreactive toward analyte • Involatile and thermal stable

13. Separation mechanism (1) selective solute-S.P. interaction (2) difference in vapor pressure of solute S.P.分類 • non-polar phase • polar phase • special phase • chiral phase

14. What is the chiral molecule？ 對掌性異構物(enantiomers): 具有相同的物性及化性。 Ex: boiling point、melting point、density、 refractive indexes、ionization、reaction properties。

15. Chiral compound的重要性 (1)可運用於製藥、農藥、食物及飲料。 (2)瞭解具有生物活性分子的生物合成及代謝。 (3)使用的分離技術：HPLC、GC、CE …etc。 譬如： 鎮靜效果 R form S form Different biological effect 畸胎原 莎痢竇邁

16. 對掌固定相 Chiral Stationary Phase(CSP) 1.Dalgiesh 1952 three-point interaction 2.暫時性的非對映異構錯合物 transient diastereomeric complex 流動沖堤方向

17. Parameters influence on selectivity • The nature of the S.P. • The conc. of S.P. • Column T • isothermal temp. control • programming temp. control • The choice & pretreatment of the solid support

19. Detector response Low T C6 C7 C8 air C9 C8 C9 C6 C7 C10 air C11 C12 Detector response High T C6 C7 C8 C9 C10 C11 C12 C13 T air Detector response time Temperature and pressure programming

25. Retention index (I) n ： # of C atoms in the smaller alkane N ：# of C atoms in the larger alkane tr(n) ：adjusted retention time of smaller alkane tr(N)：adjusted retention time of larger alkane tr(unknown)：adjusted retention time of unknown Retention index relates the retention time of a solute to the retention times of linear alkanes.

26. C9 C7 x Detector Response air 0.25 3.5 5.6 6.3 7.4 Time (min) Kovats index for linear alkanes equals 100 times the number of carbon atoms C8 I = 842

28. Injection conditions for split, splitless, and on-column injection

29. Syringe for solid-phase microextraction. The fused silica fiber is withdrawn inside the steel needle after sample collection and when the syringe is used to pierce a septum.

30. Sampling by solid-phase microextraction and desorption of analyte from the coated fiber into a gas chromatography.

31. Purge and trap apparatus for extracting volatile substances from a liquid or solid by flowing gas.

33. e- e- gas gas Detectors Thermal Conductivity detector high thermal conductivity main component entering detector • analyte appears, • T.C., Temp , Wire Resistance , • detector current  •  “read-out”

34. Thermal conductivity detector： • 104 linear response range • H2 and He give lowest detection limit • sensitivity increase with increasing filament current decreasing flow rate lower detector block temperature

35. cathode (collects CHO+ ions) anode air H2 column effluent Flame ionization detector (FID) Carbon atoms (except carbonyl and carboxyl carbons) produce CH radicals, witch are though to produce CHO+ ions in the flame： CH + O → CHO+ + e-

36. Flame ionization detector： • H2 give best detection limit • Signal proportional to number of susceptible carbon atoms • 100-fold better detection than thermal conductivity • 107 linear response range • Insensitive to non-hydrocarbons

38. Radioactive b-emitter Ni63 insulator - + standing current - + electrodes Current (I) time Electron capture detector (ECD) • - + gas - + gas+ + e- (standing current) • e- + solute  solute- (e- capture) • solute- + gas+ solute + gas

39. Electron capture detector： • Non-destructive • non-linear • selective to e- capturing solutes • detection limit  5 fg

42. Other detectors • Electron capture：halogens, conjugated C=O, -C≡N, -NO2 • nitrogen-phosphorus：highlights P, N • Photoionization：aromatics, unsaturated compounds • Sulfur chemiluminescence：S • Nitrogen chemiluminescence：N • Atomic emission：most elements (selected individually) • Mass spectrometer：most analytes • Infrared spectrometer：most analytes.