SPE extraction for PFOS and related compounds

Discussions about sample preparation: extraction, cleanup, derivatization, etc.

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I have been having trouble with low recoveries (<10%) for these 4 compounds (MeFOSE/MeFOSA/EtFOSE/EtFOSA) and PFOSA ~60%. PFOS and MPFHxS is around 100%. This is a method I've validated before (2 years ago) and had acceptable recoveries (~100%) for all of these analytes. Use HLB Oasis 3ml 60mg cartridges and eluted to 6ml Methanol. The only thing I can think of is the manifold is a different one than what was used before. Is that possible that recoveries can be affected by a new manifold?? Tried eluting with another column volume of methanol - no change. Any ideas would be greatly appreciated.
No, a different manifold won't cause big recovery change if you're applying samples at similar flow rates.
You can try collect the sample passed through the SPE column and analyze to see if there's any breakthrough.
A group I work with does PFOS and related compounds. They use the EPA draft method.

What I found is that the SPE is very sensitive to the sample preparation before SPE extraction. Our group here was doing waste water, landfill leachate, and sewage sludge, all of which required different sample prep and gave very different recovery values.

So I'd look at the samples coming in. Are they in the same matrix as when you developed this method before? Can you do a more thorough washing step on the SPE to eliminate matrix junk?
3 posts Page 1 of 1

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