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Mass spectrometry and gas chromatography are widely used instrumental techniques in chemistry - Leaving Cert Chemistry - Question 7 - 2002
Question 7
Mass spectrometry and gas chromatography are widely used instrumental techniques in chemistry. (a) Give one application of each of those techniques. (b) What are t... show full transcript
Worked Solution & Example Answer:Mass spectrometry and gas chromatography are widely used instrumental techniques in chemistry - Leaving Cert Chemistry - Question 7 - 2002
Step 1
(a) Give one application of each of those techniques.
Answer
Mass Spectrometry Application: One prominent application of mass spectrometry is in the analysis of isotopes in biological samples. For instance, it is used in determining the carbon-13 to carbon-12 ratio in plants, which can help assess their metabolic pathways.
Gas Chromatography Application: Gas chromatography is frequently used in environmental analysis to monitor air quality by detecting pollutants and toxic compounds in the atmosphere.
Step 2
(b) What are the main principles on which each of these techniques is based?
Answer
Mass Spectrometry Principles:
- Ionization: The sample is transformed into charged particles (ions) which can be manipulated using electric and magnetic fields.
- Acceleration and Deflection: Ions are accelerated by an electric field and then deflected in a magnetic field, causing them to travel in circular paths based on their mass-to-charge ratio.
- Detection: The ions are detected, and their abundance is measured to generate a mass spectrum, allowing for the identification of the sample's components.
Gas Chromatography Principles:
- Carrier Gas: The sample is vaporized and carried by a gas through a stationary phase.
- Separation: Different compounds in the mixture interact differently with the stationary phase, leading to separation.
- Detection: The separated components are detected and quantified as they leave the column.
Step 3
(c) What are the fundamental processes that occur in a mass spectrometer?
Answer
- Vaporization of Sample: The sample is first vaporized in the ion source.
- Ionization: The vaporized sample undergoes ionization to form charged particles, typically using methods like electron impact or chemical ionization.
- Acceleration: The ions are accelerated towards the mass analyzer using an electric field.
- Deflection: The accelerated ions experience a magnetic field allowing them to be deflected according to their mass-to-charge ratio.
- Detection: Finally, the ions are detected, and the result is a mass spectrum indicative of the sample's composition.
Step 4
(d) What do the letters HPLC stand for? State one application of this technique.
Answer
HPLC Stands For: High-Performance Liquid Chromatography.
Application of HPLC: HPLC is commonly used in pharmacology for the testing of drugs and analysis of food samples for vitamins and impurities. This technique provides accurate and precise quantification of components present in a complex mixture.