5. Below is a table showing composition data for clove oil, obtained using two d
ID: 200587 • Letter: 5
Question
5. Below is a table showing composition data for clove oil, obtained using two different detection methods (with the same sample), FID and mass spectrometry. Explain why the composition (based on relative peak areas of the GC trace) is different for these data sets. Are either of these the “real” composition of the clove oil?
Hint: Response factor
FID
MS detector
Area
Area%
Area
Area%
Eugenol
86.78
87.73
137.95
75.84
Caryophyllene
2.03
2.05
10.26
5.64
Eugenol Acetate
10.11
10.22
33.68
18.52
FID
MS detector
Area
Area%
Area
Area%
Eugenol
86.78
87.73
137.95
75.84
Caryophyllene
2.03
2.05
10.26
5.64
Eugenol Acetate
10.11
10.22
33.68
18.52
Explanation / Answer
ANS. the GS-MS is composed of two major building blocks: gas chromotograph and mass spectrometer.the gas chromotograph utilizes a capillary coulm which depends on the coulmn's dimensions(length,diameter,film thickness)as well as the phase properties. the differnce in the chemical properties between different molecules in a mixture and their relative affinity for the stationary phase of the coulmn will promote separation of the molecules as well as the samples travels the length of the coulmn. the molecules are retained by the coulmn and then elute from the coulmn at different times, and this allows the spectrometer downstream to capture ,ionize,accelerate,deflect,and detect the ionized molecules separately.the mass spectrometer does this by breaking into ionized fragments and detecting this fragments using their mass to charge ratio.the main difference between the gas chromotography and mass spectrometer is gas chromotography seperates the molecules based on their weight,size,and affinity to coulmn, since the gas used is inert.mass spectrometer makes the identification process easier,as the detector decomposes the molecule into ions identified according to their mass and use retension times.
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