Chromatography Forum

HI,

Can anyone give me a simple method to remove organics (VOCs, PCBs, PAHs, dioxins) from a carbon trap using a solvent so that the collected extractant could be analyzed by GC/MS? Carbon disulfide has been suggested to me but it is quite toxic so I would prefer something else. We are collecting gas stack samples to analyze but concentrations may be small so we want to concentrate them by collecting on carbon. SPME is also an option but one problem is that the GC/MS we are to use (common instrument used by several others) is already set up for analyzing liquid samples using an autosampler. Not sure we could just inject gas samples.

I have noted that both acetone and dichloromethane are not easily retained by activated carbon and that organics may tend to preferentially dissolve in either one or both of these. Has anybody tried using these solvents to remove organics from activated carbon? If so, could you direct me to a method and let me know how successful it was.

For the time being, we just want to be able to identify the compounds in the stack gas, not necessarily quantitate them accurately.

I would try dichloromethane or toluene. Residence time of the solvent on the sorbent needs to be long enough...

Thanks Don.

Any idea of an appropriate residence time (several minutes or several hours) or do we just need several trials to find optimum time?

Probably several minutes. You may need to do some fractionation trials.