[Vitalspace]

Describe a method for identifying a compound using gas chromatography analysis.

I am kinda confused on this question...
Thanks!

[Borek]

Just read how GC works, even on wiki,general approach is pretty easy.

[marquis]

Normal GC compares a compound to a standard.  If it has a similar retention time, it is called a match.  The compound sensitivity varies depending on the detector (FID, TCD, etc), but the idea is the same.

There are other forms of GC that analyze the mass spectrum  (GC/MS).  Here you have a spectrum to compare as well as a retention time match.  Much better for identification.

[bstanley]

Describe a method for identifying a compound using gas chromatography analysis.

I am kinda confused on this question...
Thanks!

GC works by retention time. So, let's take an example of compound A, B, C and D. Each compound will have different affinity with the GC column. As a result, they should be well separated and appear as 4 distinct, Gaussian peaks in the chromatogram. Chromatogram is a plot of Intensity (y-axis) Vs time (min or sec). Provided all conditions are the same (temperature, column, gas flow rate, etc.), each compound should have a unique time when it elutes. For example, the peak A may appear at 2 min, B at 3 min, C at 4 min and D at 5 min on the chromatogram. This time associated with each compound is its retention time. If you inject an unknown compound and its retention time is 3 min, then that unknown compound is B (assuming the conditions are the same). Higher concentration will result in taller/bigger peak on the chromatogram, but the retention time will be the same.

Hope this helps.