CP-Chirasil-Dex CB Columns: bad separation p&m-xylene

Hi everyone!

I have brand new PGC Yokogawa 8000 equipped CP-Chirasil-Dex CB Columns with  FID detector and Liquid Sample Valve (LSV) set at 170C deg. The problem is GC can’t separate m-Xylene from p-Xylene in low concentrations.

Component name

Concentration, Vol%

Sample 1 









Conditions: Columns: CP-Chirasil-Dex CB Columns - 20 meters long, stable temperature set at  55 C deg. during all cycle, carrier gas is N2  and flow set to 2.6 ml/min.

I would be grateful for any help and suggestions!

A few more questions about this type of column:

  • How do you think, if I will make a column longer, just for instance - 25 meters instead of 20 will it help? 
  • Will it helps to change the temperature or carrier gas flow rate?
  • The injections of various solvents, such as methanol or acetone, can help or it will destroy the column?
  • Why the Ethylbenzene in that composition goes out after the m&p-Xylene?
  • What actually could be the main cause of problems for separation of o,m,p- Xylene?
  • Can you please advise another type of column that will work under existed configuration with those components and specific ranges?

Best regards,


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