PCB cleanup - too fancy?

[MichaelVW]

I'm at a new lab that needs to test fuels/oils/solvents - sometimes with a lot of water - for PCBs.

The many years old (and many years unused) SOP I was given uses a column to clean up the samples for GC-ECD.

Add 1/2" silica gel
Add 3 inches Florisil
Add 1/2" silica gel
Add 3 inches acid-treated silica gel
Add 2 inches sodium sulfate

Does that seem overly complicated? For this application, is silica gel going to do anything that florisil isn't? Is there any reason to sandwich florisil between silica gel layers?

I intend to try a few samples using the above method and something simpler (maybe just omitting the silica gel). But this facility gets a wide variety of samples, and I'm not yet familiar with everything I might see. I'd rather not eliminate part of a procedure without understanding its intended purpose.

[rb6banjo]

What is the ultimate goal of the sample cleanup? Get rid of the water? Are there other materials in the extracts that interfere with the ECD? Are you trying to isolate/concentrate just the PCB's in the sample and get rid of everything else?

[itspip]

That method does feel very old. If you have some leeway in creating your own sample prep, this paper looked at PCBs by GC-ECD with dispersive liquid-liquid microextraction.

https://doi.org/10.1016/j.jhazmat.2008.02.005

[MichaelVW]

Are there other materials in the extracts that interfere with the ECD?

Big time. These are waste samples. Paint, used oil, adhesives, solvents, off spec consumer products, etc.

I'm only interested in analyzing for PCBs and I want to get rid of everything else that could interfere with that. I also want to avoid gunking up the instrument to whatever degree is reasonably achievable.

Since the original post I have switched to making columns that have Florisil on the bottom, sulfuric-acid silica gel above that, and sodium sulfate on top. About 3mL each in a 10mL glass pipette.

I'd still be interested in alternatives.

[LALman]

Back in 1994 A lab I worked at did this cleanup transformer oil for PCB's as follows...
(1) you must wear goggles and ppe.
(2) pipet 5-10 mL of isooctane into a 40mL test tube
(3) add 1-2 mL of concentrated Sulfuric acid
(4) pipet in 0.1 to 1 mL of transformer oil
(5) touch test tube to vortexer for 1 minute.
(6) take aliquot of the isooctane for analysis by GC-ECD