Gas Chromatography
Made using OCR chemistry textbook. Pages 80- 83. Gent and Richie.
- Created by: Former Member
- Created on: 19-12-12 18:34
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- Gas Chromatography
- Technique used to separate volatile components in a mixture.
- Useful as many organic comp. have low boiling points
- Phases
- SP= thin layer of solid/liquid coated on inside of capillary tube (the inert support)
- Tubing= chromatography column.
- Liquid SP often long-chain alkene with high bp.
- Solid SP include silicon polymers
- MP= carrier gas which moves through column
- Usually inert/ unreactive gas i.e. He/N
- SP= thin layer of solid/liquid coated on inside of capillary tube (the inert support)
- Producing the chromatogram
- Mixture injected into GC and vapourised
- Mobile carrier gas flushes mixture through column
- Components slow down as they interact with SP. Greater solubility/ adsorption= slow more
- Result= components leave column at different times and are detected. Computer displays gas chromatogram
- Components slow down as they interact with SP. Greater solubility/ adsorption= slow more
- Mobile carrier gas flushes mixture through column
- Area under peaks proportional to amount of compound in sample
- Mixture injected into GC and vapourised
- Retention time
- Time for component to pass from column inlet to detector
- Diff compound= diff RT. Compare with known RTs to identify
- Limitations
- 1000s of chemicals= same RT, peak shape and detector response
- Some substances may 'hide' beneath one with a high conc. and same RT
- Unknown compounds= no reference RT
- GC-MS
- Components separated by GC. Then analysed by MS= unique which allows +ve identification of each component in original mixture
- Uses
- Airport security Forensics, Space probes, Environmental analysis
- Technique used to separate volatile components in a mixture.
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