# A conservation scientist wants to identify the chemical compounds present in a sample of ancient plant resin found at an archaeological site. Explain how gas chromatography–mass spectrometry (GC-MS) could be used to identify the compounds in the resin sample.

> Edexcel A-Level Chemistry (9CH0) — Topic 6 Modern analytical techniques · Explain · 5 marks

## Mark scheme (5 marks)

1. The sample is vaporised and carried through the gas chromatography column by a carrier gas
2. Different compounds in the mixture travel through the column at different speeds / take different times to reach the detector (different retention times)
3. The separated compounds then enter the mass spectrometer
4. The mass spectrometer produces a fragmentation pattern / mass spectrum for each compound
5. The fragmentation pattern / mass spectrum is compared to a database / library of known spectra to identify each compound

## Key terms

- [gas chromatography](https://www.gradenine.co.uk/glossary/gas-chromatography)
- [mass spectrometry](https://www.gradenine.co.uk/glossary/mass-spectrometry)

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-conservation-scientist-wants-to-identify-036ccbc1) · Published by Druglandscape Ltd.