Sunday 30 December 2018

Gas chromatography . ppt

Gas Chromatography
What is Gas Chromatography? <ul><li>It is also known as… </li></ul><ul><ul><li>Gas-Liquid Chromatography (GLC) </li></ul><...
GAS CHROMATOGRAPHY <ul><li>Separation of gaseous & volatile substances </li></ul><ul><li>Simple & efficient in regard to s...
<ul><li>Sample to be separated is converted into vapour </li></ul><ul><li>And mixed with gaseous M.P </li></ul><ul><li>Co...

What is Gas Chromatography? <ul><li>The father of modern gas chromatography is Nobel Prize winner John Porter Martin , wh...
 
The Next Generation in Gas Chromatography

How a Gas Chromatography Machine Works <ul><ul><li>First, a vaporized sample is injected onto the chromatographic column...
Chromatographic Separation <ul><ul><li>Deals with both the stationary phase and the mobile phase . </li></ul></ul><ul>...

Chromatographic Separation <ul><li>Chromatographic Separation </li></ul><ul><ul><li>In the mobile phase, components of the...

Chromatographic Separation (continued) <ul><ul><li>The peaks can then be read and analyzed by a forensic scientist to dete...

Chromatographic Analysis <ul><ul><li>The number of components in a sample is determined by the number of peaks. </li></ul>...
Peaks and Data
 

 
 
 

 
PRACTICAL REQUIREMENTS <ul><li>Carrier gas </li></ul><ul><li>Flow regulators & Flow meters </li></ul><ul><li>Injection dev...
CARRIER GAS <ul><li>» Hydrogen </li></ul><ul><li>better thermal conductivity </li></ul><ul><li>disadvantage: it reacts ...

Requirements of a carrier gas <ul><li>Inertness </li></ul><ul><li>Suitable for the detector </li></ul><ul><li>High purity ...

Flow regulators & Flow meters <ul><li>deliver the gas with uniform pressure/flow </li></ul><ul><li>rate </li></ul><ul><li>...
 
Soap Bubble Meter <ul><li>â—Š Similar to Rota meter & instead of a float, soap bubble formed indicates the flow rate </li>...
Injection Devices <ul><li>Gases can be introduced into the column by valve devices </li></ul><ul><li>liquids can be inject...

COLUMNS <ul><li>Important part of GC </li></ul><ul><li>Made up of glass or stainless steel </li></ul><ul><li>Glass column-...
<ul><li>Depending on its nature </li></ul><ul><li>1.Packed column: columns are available in a packed manner </li></ul><u...
3.SCOT columns (Support coated open tubular column <ul><li>Improved version of Golay / Capillary columns, have small samp...
Columns <ul><li>Packed </li></ul><ul><li>Capillary </li></ul>

 

 

Equilibration of the column <ul><li>Before introduction of the sample </li></ul><ul><li>Column is attached to instrument &...
Temperature Control Devices <ul><li>Preheaters : convert sample into its vapour form, present along with injecting device...
Temperature Control <ul><li>Isothermal </li></ul><ul><li>Gradient </li></ul>Instrumentation - Oven

DETECTORS <ul><li>Heart of the apparatus </li></ul><ul><li>The requirements of an ideal detector are- </li></ul><ul><li>Ap...

1.Thermal Conductivity Detector (Katharometer, Hot Wire Detector) Measures the changes of thermal conductivity due to the ...
Thermal Conductivity Basics When the carrier gas is contaminated by sample , the cooling effect of the gas changes. The d...
When a separated compound elutes from the column , the thermal conductivity of the mixture of carrier gas and compound gas...
<ul><li>􀁺 Measures heat loss from a hot filament – </li></ul><ul><li>􀁺 filament heated to const T </li></ul><ul><li>whe...

 



Relative Thermal Conductivity 0.17 Nitrogen 0.13 Methanol 1.00 Helium 0.12 Argon Relative Thermal Conductivity Compound 1....

Advantages of Katharometer <ul><li>Linearity is good </li></ul><ul><li>Applicable to most compounds </li></ul><ul><li>Non ...

Flame Ionization Detector <ul><li>Destructive detector </li></ul><ul><li>The effluent from the column is mixed with H & ai...
<ul><li>FIDs are mass sensitive rather than conc. sensitive </li></ul><ul><li>ADVANTAGES: </li></ul><ul><li>µg quantities ...

FID
 


























































































































































































































































































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