I tried the temperature program below to draw my calibration curve using splitless injection but the peaks I got were so small and broad in the concentration range of 5 to 50 ppm. I was wondering if there is anyway to improve my peaks and if there is any problem with my temp program!
initial temp: 40 deg
hold for: 3 min
ramp at: 1.5 deg/min
final temp: 120 deg
Refer to one of my three publications from 2012 and 2013 about liquid-liquid equilibria and you can find the method I used with details on the column. Look in my profile and then in my publications.
Increase programming rate to 2 degrees./ min. Check for detector temp which should be more by 20 to 30 degrees than your final column temp. Preconcentrate your sample if possible. Cut down a hold time a bit too.
Dear Mr. Behrad Farzinfar
BETX aromatics belong to the volatile organic compounds. You write that you inject the samples spliless and that your peaks are very broad. This is normal for volatile compounds. Splitless injections only give sharp peaks if the analytes can be refocused on the column. You can achieve this by 2 effects:
1: Solvent Effect - The solvent forms a sharp back front where the analytes concentrate and focus.
2: Cold trap effect - the analytes recondense in a sharp zone on the cold column and will be focused there.
The 2nd effect is most effective and leads to sharp peaks for higher boiling analytes.
However, your analytes will not recondense even at 40 ° for 3 min, so that the peak width is not reduced. I think Peakwidth is around your spliless time?
My recommendation would be a sample injection with a low split ratio
You should pay attention to the split ratio in your GC that still generates replicable results. In most instrumens this is the case with a split of 10:1. Split valves also have a limited control ranges in which they can control correctly. Outside this range, the results are no longer reproducible.
I hope that my information is helpful for you.
Best regards and stay healthy
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