Chapter 22 GC & LC 22.1 Gas Chromatography -1 Schematic - PowerPoint PPT Presentation

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Chapter 22 GC & LC 22.1 Gas Chromatography -1 Schematic

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Chapter 22 GC & LC 22.1 Gas Chromatography -1 Schematic diagram 22.1 Gas Chromatography -2 Columns : open tubular columns 22.1 Gas Chromatography -3 m.p.(gas) - s.p ... – PowerPoint PPT presentation

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Title: Chapter 22 GC & LC 22.1 Gas Chromatography -1 Schematic


1
Chapter 22
  • GC LC

2
22.1 Gas Chromatography -1
  • Schematic diagram

3
22.1 Gas Chromatography -2
  • Columns open tubular columns

4
22.1 Gas Chromatography -3
  • m.p.(gas) - s.p.
  • s.p. solid(using adsorption)ex SiO2
  • 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
  • Resolution? (H?)
  • tr?
  • Sample capacity?

5
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6
22.1 Gas Chromatography -4
ex
b.p.?
7
22.1 Gas Chromatography -5
  • B) The effects of column polarity on separation
  • Like dissolves like
  • S.P nonpolar
  • b.p. dependent

8
22.1 Gas Chromatography -6
S.P. Polar
-oneCO -ol OH
9
22.1 Gas Chromatography -7
  • C) Common solid s.p.
  • Porous carbon larger molecules bind more
    tightly than small ones, flexible molecules bind
    more than rigid ones
  • Molecular sieves retain separate small
    molecules H2, O2, N2, CO2, CH4. (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
  • Temperature programming
  • ? temp of column ? ? v.p. solute,
  • ? ? tr
  • ? sharpens peaks
  • isothermal constant temp.
  • temp. programming (gradient)
  • raise the column temp. during the separation.

12
22.1 Gas Chromatography -10
13
22.1 Gas Chromatography -11
  • Carrier Gas

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
  • .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 (Tsolvent lt 40?)
  • cold trapping (Tsolute lt 150?)

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

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

20
22.1 Gas Chromatography -17
  • Electron capture detector
  • for compounds containing atoms with high electron
    affinities.
  • sensitive for halogen, CO, NOx, orgaometallic
    compounds.
  • Other detectors p 476

21
22.2 Liquid Chromatography -1
  • open, gravity-feed column
  • closed column (under high pressure) packed with
    micron-size particles. (HPLC)
  • stationary phase
  • adsorption silica (SiO2?xH2O), alumina
    (Al2O3?xH2O),
  • molecular exclusion,
  • ion-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
  • ? ? tr
  • 5. Gradient elution increased the eluent
    strength during the separation in liquid
    chromatography.

24
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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
22.3 High-Performance Liquid
Chromatography (HPLC) -8
  • 4. Column
  • Guard column
  • Injection valve

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 KH2PO4(aq) B CH3CN(l)
35
22.3 High-Performance Liquid
Chromatography (HPLC)-11
Reversed-phase column eluent strength ?,
solvent polarity ?, tr ?
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.
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