# A pharmaceutical company produces a painkiller tablet. Quality control scientists use gas chromatography–mass spectrometry (GC-MS) to check that the tablet contains only the correct compounds and no contaminants. Explain how GC-MS allows scientists to identify each compound present in the tablet and state two advantages of using this instrumental method rather than traditional chemical tests.

> Eduqas A-Level Chemistry — 2.8 Instrumental analysis · Explain · 5 marks

## Mark scheme (5 marks)

1. In gas chromatography, different compounds travel through the column at different speeds / have different retention times
2. The retention time is used to identify / help identify each compound
3. The mass spectrometer produces a fragmentation pattern / mass spectrum for each separated compound
4. The fragmentation pattern is compared to a reference database / library to confirm the identity of the compound
5. Any one advantage of instrumental methods: faster / more sensitive / more accurate / can detect very small quantities / can analyse complex mixtures (accept any one valid advantage stated for 1 mark; second distinct advantage not required for this mark as only 1 mark available here)

## 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 Eduqas A-Level Chemistry](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-pharmaceutical-company-produces-a-painkiller-428e864d) · Published by Druglandscape Ltd.