Currently working on chinese pharmacopeoia method for the analysis of methanol, acetone, dichoromethane and toluene in dimethylformamide. Cannot get adequate peak shape/separation. Have tried two DB-624, (which is the column given in the method, no dimensions specified) 30M x 530id x 3um and 30M x 250id x 1.8um. Oven is 40c for 10min, 10c/min to 200c. Flow is 5ml/min for 530id and 2ml/min for the 250id. Carrier is helium. Inlet temp 180c, detector 200c and injection volume of 3ul.

Is this the best column for volatiles?

Is dimethylformamide a poor solvent and is 3ul too much sample on the column?