Chromatography Forum

Hi everyone,

I am a new learner. I did some experiments with Toluene and now I need to find best temperature program for MIBK. Actually first I tried to use the same method, that I used for toluene, for MIBK but it did not work. Finally I tried to use another method which is injection 90 C, Column 60 C (Rate 0) then 190 C(Rate 20) and finally 225 C(Rate 50) 1.5 min, Detector is 225 C.
Split mode 20.0
Pressure 40.4 kPa
19.4 mL/min
Clolumn Flow 0.78 mL/min
24.5 cm/sec Linear velocity and 3 mL/min purge flow
Column Length 15m (capillary)
Inner Diam 0.25 mm
Film Thickness 0.25 um

I am not sure what I am doing wrong, and If you can suggest me, I will really glad. In Chromatogram, I saw more than one peak.

Thanks in advance.

Osman

I would suggest you try isothermal analysis. Keeping your flow rate at about 20 cm/sec try different temperatures until your retention time is about 10 min. Collect data for 20 min. You can try ramping the temperature AFTER the main peak elutes if you wish.

Then keep increasing your split until the main peak doesn't show any loss in height. You want to find a split that is not overloading the column you have which is not a thick film and is easily overloaded.

Good luck and best wishes,

Rod

If you are injecting only MIBK (i.e. you are not diluting it in a solvent) then the extra peaks that you see are probably impurities in the MIBK.

Peter

I really appreciate with your answers , and I did my experiments. I used the same parameters just changed temperature of oven. Now, trying to figure out for benzene if you have any suggestion me to find method, let me know please.

thanks,

Osman