分析化学英文课件11 气相色谱分析GC
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mainly decided by stationary phase.
(3) K is different for different solutes.
(4)Choosing suitable stationary phase can improve the separation.
(5) Different K is the basis for separation.
Support:
Requirements for suport: ① Uniform pore diameter; 60~80, 80~100 mesh ② Large surface area. ③ Particles should be of regular shape. ④ Be of good mechanical strength.
Stationary liquid：
high b.p., non-volatile compounds
(1) How to select: “like dissolves like”, is a good rule to select liquid phase；
(2) Max and min temperature for use: (3) Mixed stationary liquid:
phases.
§11.1.5. Distribution ratios K
Under certain temperaturwk.baidu.com，ratio of concentration (g / mL) at equilibrium ：
K concn.of solutein stationary phase concn.of solute inmobile phase
2. Gas-liquid chromatograph
Stationary phase: stationary liquid + support Stationary liquid: generally organic compounds Requirements for stationary liquid: ① Thermally stable. ② Non-volatile at the temperature used. ③ Chemically unreactive toward the solutes to be separated.
§11.2.2 Stationary Phase
1. Gas solid chromatograph
Activated carbon： Activated alumina： Can be used for separation of O2, N2, CO, CH4, C2H4. Can not be used for separation of CO2 Silica gel： similar to activated alumina Molecular sieve： widely used for separation of H2, O2, N2, CH4, CO and He, Ne, Ar, NO, N2O.
§11.1.2 Characteristics Classification of Chromatography
Chromatography is a technique of
separation.
Separation process of a sample mixture is
the partitioning process of the constituents
Analytical Chemistry 分析化学
Chap 11 Gas Chromatography
§ 11.1 Introduction § 11.2 Gas Chromatographs § 11.3 Theory of Gas Chromatography § 11.4 Qualitative Analysis and
(6) When K = 0, the solute is not retained by the stationary phase, and will be eluted first.
§11.2 Gas Chromatograph
§11.2.1 Gas Chromatograph §11.2.2 Stationary Phase §11.2.3 Detector
Discussion:
(1) The smaller the distribution ratio for a solute, the faster that solute will move down the column
DISCUSSK IOcSN: cM
(2) For a certain solute，K is
(1) High performance
complex mixture，homologues, isomer.
(2) High sensitivity
g.g-1(10-6) ~ ng.g-1(10-9).
(3) Fast
An analysis can be finished within several to tens of minutes.
between two phase in the separation
column.
moving
Chromatography
Stationary phase (liquid or solid)； Mobile phase (eluent or carrier). Separation occurs because sample components have different affinities for the stationary and mobile phases and therefore move at different rates along a column, So they have different retention times.
Quantitative Analysis
§ 11.1 Introduction
§11.1.1 History
In 1906, Tswett devised a method for separating chlorophylls and other plant pigments using a tube (column). He called this method “chromatography”.
1．Characteristic 2．Thermal Conductivity Detector(TCD) 3．Flame-Ionization Detector(FID) 4. Electron-Capture Detector(ECD)
§11.2.1 Gas Chromatographs
1-gas cylinder；2-pressure regulator；3-drying tube for purification of gas；4needle valve；5-flow meter;6-pressure gauge；7sample injector；8column;9-detector；10amplifier；11-temperature controller；12-recorder；
1. Carrier gas system：gas cylinder, pressure regulator, drying tube ;
2. Sample injection system：sample injector and preheater； 3. Separation column：
4. Detector：thermal conductivity detector or flame ionization detector； 5. Recorder：amplifier, recorder, integrator; 6. Temperature controller：
can be used for complex samples
(4) Relative polarity：
squalane = 0 β,β’—oxydipropionitrile=100
§11.2.3 Detector
Key element in chromatograph. Some are common detectors, like thermal conductivity detector；some have high selectivety.
Classification
Gas chromatography, GC
Mobile phase: gas(nitrogen or helium).
Column：packed or open tubular. Stationary phase: solid or liquid. Gas-solid and gas-liquid chromatography
White support: mixed with flux before calcined;
with large pore size, less surface area and poor mechanical strength ; little adsorptivity;
can be used for separation of polar samples.
§11.1.4. Separation Process of GC
Packed column GC: gas-solid ,gas-liquid chromatography.
Stationary phase of gas-solid GC: porous solid adsorbants.
Stationary phase of gas-liquid GC : composed of support and liquid phase.
(4) Wide application
Can be applied for analysis of organic or inorganic substances with boiling points less than 400℃.
Disadvantages：
（1）Can not be used for high bp., nonvolatile, thermal-instable compounds （2）Difficult for qualitative analysis
The term “chromatography” refers to any separation method in which the components are distributed between a stationary phase and a moving (mobile) phase.
Separation process of gas-solid GC: continuous adsorption and desorption process.
Separation process of gas-liquid GC： continuous solvation and evaporation between two
Liquid chromatography, LC
Mobile phase : liquid(eluent). Stationary phase： solid or liquid. Liquid-solid and liquid-liquid chromatography .
§11.1.3 Characteristics of GC
Support
Pink support: smaller pore size，more pores; larger surface area; good mechanical strength; used for non-polar samples; having active adsorptive points at surface.
(3) K is different for different solutes.
(4)Choosing suitable stationary phase can improve the separation.
(5) Different K is the basis for separation.
Support:
Requirements for suport: ① Uniform pore diameter; 60~80, 80~100 mesh ② Large surface area. ③ Particles should be of regular shape. ④ Be of good mechanical strength.
Stationary liquid：
high b.p., non-volatile compounds
(1) How to select: “like dissolves like”, is a good rule to select liquid phase；
(2) Max and min temperature for use: (3) Mixed stationary liquid:
phases.
§11.1.5. Distribution ratios K
Under certain temperaturwk.baidu.com，ratio of concentration (g / mL) at equilibrium ：
K concn.of solutein stationary phase concn.of solute inmobile phase
2. Gas-liquid chromatograph
Stationary phase: stationary liquid + support Stationary liquid: generally organic compounds Requirements for stationary liquid: ① Thermally stable. ② Non-volatile at the temperature used. ③ Chemically unreactive toward the solutes to be separated.
§11.2.2 Stationary Phase
1. Gas solid chromatograph
Activated carbon： Activated alumina： Can be used for separation of O2, N2, CO, CH4, C2H4. Can not be used for separation of CO2 Silica gel： similar to activated alumina Molecular sieve： widely used for separation of H2, O2, N2, CH4, CO and He, Ne, Ar, NO, N2O.
§11.1.2 Characteristics Classification of Chromatography
Chromatography is a technique of
separation.
Separation process of a sample mixture is
the partitioning process of the constituents
Analytical Chemistry 分析化学
Chap 11 Gas Chromatography
§ 11.1 Introduction § 11.2 Gas Chromatographs § 11.3 Theory of Gas Chromatography § 11.4 Qualitative Analysis and
(6) When K = 0, the solute is not retained by the stationary phase, and will be eluted first.
§11.2 Gas Chromatograph
§11.2.1 Gas Chromatograph §11.2.2 Stationary Phase §11.2.3 Detector
Discussion:
(1) The smaller the distribution ratio for a solute, the faster that solute will move down the column
DISCUSSK IOcSN: cM
(2) For a certain solute，K is
(1) High performance
complex mixture，homologues, isomer.
(2) High sensitivity
g.g-1(10-6) ~ ng.g-1(10-9).
(3) Fast
An analysis can be finished within several to tens of minutes.
between two phase in the separation
column.
moving
Chromatography
Stationary phase (liquid or solid)； Mobile phase (eluent or carrier). Separation occurs because sample components have different affinities for the stationary and mobile phases and therefore move at different rates along a column, So they have different retention times.
Quantitative Analysis
§ 11.1 Introduction
§11.1.1 History
In 1906, Tswett devised a method for separating chlorophylls and other plant pigments using a tube (column). He called this method “chromatography”.
1．Characteristic 2．Thermal Conductivity Detector(TCD) 3．Flame-Ionization Detector(FID) 4. Electron-Capture Detector(ECD)
§11.2.1 Gas Chromatographs
1-gas cylinder；2-pressure regulator；3-drying tube for purification of gas；4needle valve；5-flow meter;6-pressure gauge；7sample injector；8column;9-detector；10amplifier；11-temperature controller；12-recorder；
1. Carrier gas system：gas cylinder, pressure regulator, drying tube ;
2. Sample injection system：sample injector and preheater； 3. Separation column：
4. Detector：thermal conductivity detector or flame ionization detector； 5. Recorder：amplifier, recorder, integrator; 6. Temperature controller：
can be used for complex samples
(4) Relative polarity：
squalane = 0 β,β’—oxydipropionitrile=100
§11.2.3 Detector
Key element in chromatograph. Some are common detectors, like thermal conductivity detector；some have high selectivety.
Classification
Gas chromatography, GC
Mobile phase: gas(nitrogen or helium).
Column：packed or open tubular. Stationary phase: solid or liquid. Gas-solid and gas-liquid chromatography
White support: mixed with flux before calcined;
with large pore size, less surface area and poor mechanical strength ; little adsorptivity;
can be used for separation of polar samples.
§11.1.4. Separation Process of GC
Packed column GC: gas-solid ,gas-liquid chromatography.
Stationary phase of gas-solid GC: porous solid adsorbants.
Stationary phase of gas-liquid GC : composed of support and liquid phase.
(4) Wide application
Can be applied for analysis of organic or inorganic substances with boiling points less than 400℃.
Disadvantages：
（1）Can not be used for high bp., nonvolatile, thermal-instable compounds （2）Difficult for qualitative analysis
The term “chromatography” refers to any separation method in which the components are distributed between a stationary phase and a moving (mobile) phase.
Separation process of gas-solid GC: continuous adsorption and desorption process.
Separation process of gas-liquid GC： continuous solvation and evaporation between two
Liquid chromatography, LC
Mobile phase : liquid(eluent). Stationary phase： solid or liquid. Liquid-solid and liquid-liquid chromatography .
§11.1.3 Characteristics of GC
Support
Pink support: smaller pore size，more pores; larger surface area; good mechanical strength; used for non-polar samples; having active adsorptive points at surface.