Hello, I am analyzing 37 component FAME mix using GC. I have got 37 peaks and 25 of them show expected order and height. However, others are not in the similar order with the reference for same column type. I am attaching the reference peaks and my result. I tried different run time (40 min, 65 min, 75 min). Every time it gives peaks with same order. How can I identify the rest of the peaks?
column: SP-2560, 100 m x 0.25 mm I.D., 0.20 µm (24056)
oven: 140 C (5 min) to 240 C (5 min) at 2.5 C/min
carrier gas: helium, 20 cm/sec
sample volume: 1 µL split 100:1, 260 C
detector: FID, 260 C
Your chromatogram shows co-elution. The method has failed. With the aid of someone local who is experienced in GC method development, please troubleshoot the issue. Baseline resolved peaks are needed for the program's integration results to be accurate. Accuracy is directly related to the quality of the GC method used, training of the user and the data acquired.
Verify the instrument is clean and operating correctly. Verify the column is clean and appropriate for the analysis. Make sure the sample concentration is within the range of the calibration and detector (and the injection method, volume, temperature and solution are appropriate). Inject standards to verify the method works properly. Once standards reveal a clean result, then proceed to test samples.
Do you have any individual fatty acid standard of which can be identified as the mismatched peak? Perform methylation to one of them and inject this standard at a similar concentration with your FAME mix.
Do you observe any interference peak at your reagent blank injection? You need to eliminate a false positiveness that could arise from the noisy baseline and it would also be useful for the validation of your GC system.
By the way, you can inject mixture at linear concentrations for peak purity identification and if applicable you can transfer the method to GC-MS to verify the orders of the peaks.
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