Chromatography Forum

Does anyone know of a confirmed PFAS contamination-free brand/model manual vacuum manifolds that are in use for EPA 533, EPA 537.1 and EPA 1633?

We have tested a couple (including the 24-port version of the EPA 533 recommend model) and they all contain significant background contamination of at least 1 or 2 analytes found in those methods. Possibly some of the parts have changed since method was written. I know most manifolds contain PTFE parts, but the extracts only contact the Luer ports, valves and guide tubing to the polypropylene collection tubes.

Our production automated systems are actually far cleaner than the manual SPE devices we have tested.

I'm testing various manifolds myself. Usually, I've isolated the problem to the valves/stopcocks, possibly a lubricant being used in production.
What analytes/levels are you typically seeing?

We are seeing 100-200 ppt of mainly 6:2-FTS when performing EPA 533 using an older generation of the same manifold part # specifically named in the EPA method. That translates into several of ppb concentration in the sample vial. The rest of the compounds have a slightly elevated but not high background.

It doesn't seem to be decreasing much, so you may be right about the inlet stopcocks, which are supplied from another company. We'll try a deep cleaning or different vendor for those. The elution solvent doesn't contact any of the manifold, except the inlet.