gas chromatography-mass spectrometry, GC-MS 82-83

Question 1

What are the strengths/weaknesses of GC and MS?

Answer 1

GC can separate components in a mixture, but cannot identify them conclusively.

MS can provide detailed structural information on most compounds for exact identification, but it cannot separate them.

Question 2

Explain how GC-MS works.

Answer 2

• The components in a mixture are first separated using GC. Retention time may provide a preliminary identification.
• The separated components are directed into a mass spectrometer, where they are detected.
• The generated mass spectrum can be analysed or compared with a spectral database by computer.
• A mass spectrum is unique and definitive for a single compound, so MS allows positive identification of each component in the original mixture.

Question 3

What are some applications of GC-MS?

Answer 3

Applications of GC-MS include forensic and drug analysis, environmental analysis, airport security and space probes.

Question 4

What does GC-MS detect in forensics?

Answer 4

• Detects minute particles from the scene of the crime.

- Can detect minute samples of drug in someones air weeks after the drug was used.

Question 5

What does GC-MS detect in environmental analysis?

Answer 5

GC-MS is used for monitoring and analysing organic pollutants in the environment including quality of waste water and drinking water, and detecting the presence of pesticides in food.

Question 6

What does GC-MS detect in airport security?

Answer 6

Security systems have been put in place at airports to detect explosives in luggage and on human beings.

Question 7

What does GC-MS detect in space probes?

Answer 7

Analyse planets atmospheres and surfaces.