Chromatography Forum

Looking to bring this online at our lab instead of subbing it out. I was feeling encouraged until I noticed an AZ DHS info update claiming the extracts would quickly "ruin the column for other analyses".... yikes.

If you run this method - is this true?

The instrument currently runs low-level PAH in soil and groundwater, and we don't get enough endothall samples to justify having to constantly change the column.

I run EPA 548.1 and 525.2 on the same instrument. I do have to swap liners and trim a little column before switching back from 548 to 525 so I can pass the DDT/Endrin breakdown check. If you are only doing PAH and are not required to pass a breakdown check then it shouldn't be a problem.

Not being careful and leaving some of the acidic methanol in the extracts is what will ruin a column. If you have enough sensitivity on the instrument run them with a 10:1 split injection and it will keep the inlet much cleaner. Also using a guard column (1-2m) in front of the analytical column helps.

Thanks James - PAH is by 8270 so my only concern would be benzidine tailing. I use a drilled uniliner for that instrument, so maybe I could get away with a microinjection/short splitless hold.

Are you using an uncoated guard column?

Do you use BioRex cartridges for extraction? Phenomenex claims their Strata-x phase reduces ionic interference, but I'm always leery of promotional science.

We use the Restek cartridges

https://www.restek.com/catalog/view/1812/26063

They seem to work really well.

I normally use the Intermediate Polarity guard column from Restek, since I also inject ethyl acetate and it is a little too polar to give good peak shapes on the non-polar 5 phase column.