anyone can help me with it? subject: food analytical chemistry Exercise 2: Gas e

Question

anyone can help me with it?
subject: food analytical chemistry

Exercise 2: Gas ehromatography The fatty acid of different oils (one is a coconut oil and the other a mixture of coconut and rapeseed oils) are analyzed in gas chromatography (GC). A standard of known fatty acids is previously analyzed and gives the following values Fatty acid Fatty acid methylRetention methyl Retention ester time (min) ester time (min) C6:0 C14:0 CI4:1 C16:0 C16:1 18.3 | C20:31 247 C18:0 22,9 C20:1 23,2 15,9 16,3 C20:4 24,5 20,3 C22:0 25,6 C18:1(n-9) 2 C22:1 76 29,5 30,2 C22:6 30,4 (D-1) 20,7 C24:0 21,2 C18:2 C18:3 Questions: 1-What main characteristic must have a molecule to be analyzed in GC? What parameters have an effect on it? 2 -What is a derivation in chromatography? Has a derivation been used in this case? 3 -Identify as much ofthe peaks as possible in following chromatograms: 500 Coconut B100 300 200 100 50 wt% Rapeseed B100 50 wt% Coconut B100 50 400 300 200 100 20 15 10

Explanation / Answer

1- The compound to be analyzed by GC must be volatile, that means the compounds can be converted into vapor state at the gc injection temperature.

2- The derivation is formation of a derrivative of a compound by reacting it with another reagent to make it more volalite. No derrivatives are used in this case.

3- Identification of peaks in GC

comparing gc chart with the data in the table,

The two charts have the following compounds in it,

retention time            Compound

      7.7                             C6:0

     16.0                           C14:0

     18.0                           C16:0

     20.3                           C18:0

     20.7                           C18:1(n-9)

     21.2                           C18:2

     22.1                           C18:3

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