I am a new, very inexperienced gc analyst trying to come up with a method for analyzing an organic solvent profile with a RTX-VRX 60m capillary column. I am trying to separate acetone, benzene, butyl acetate,chlorobenzene,cyclohexanone,decane, 1,2-dichloroethane, ethyl acetate,heptane, hexane, isooctane,methyl ethyl ketone, methyl isobutyl ketone, methylene chloride, xylene,octane,pentane,perchloroethylene, tetrahydrofuran,toluene, 1,1,1-trichloroethane, trichloroethylene,and 1,2,4-trimethylbenzene. I am able to separate all the analytes except for the Methyl Ethyl Ketone and Hexane. I was hoping to find out if anyone know a good temperature program to separate the analytes with this column, or with a RTX-1 or RTX-5 column. I am very inexperienced so any guidance or suggestions would be greatly appreciated.
By Anonymous on Thursday, May 13, 2004 - 01:15 am:
By Mike on Thursday, May 13, 2004 - 08:42 am:
One co-elution may be as good as you can get. RTX-VRX is custom-made to do a certain job, but not the one you want. On RTX-1 I think the two pairs 1,2-dichloroethane/THF and iso-octane/trichloroethylene will co-elute. I don't know about RTX-5. On 1701 phase MEK and 1,1,1-trichloroethane co-elute. The probability of no co-elutions of 20+ components of different polarity is low and can be calculated as a function of resolving power and n peaks randomly distributed, but I don't have the references. This is why you need GC-MS or two columns. Adjusting temperature ramps can help a tiny bit but not usually enough to waste time on it.
By Anonymous on Thursday, May 13, 2004 - 08:48 am:
Call Restek. The VRX is designed to be used with mass spec where most co-elutions are not as critical. The VGC column may give better results since it is designed to work with GC where the co-elutions are more critical.