Looking for LC method for polymethacrylates

[H2Oh]

I'm looking for an IC or HPLC method for polymethacrylate determination. I've seen peaks using my Dionex phosphonate column with UV detection and a post column reaction with perchloric acid and ferric nitrate, but I think that's just a coincidence and isn't the best method.

I saw a reference to a method in a fuel and lubricants journal but wonder if I can find a method without subscribing to it. I'm running mostly Dionex equipment and have UV, PDA, CD and ECD detectors handy. Anyone have suggestions? Would something like a C18 do the trick?

Thanks,
Brian

[Uwe Neue]

The common technique for the determination of a polymer would be size-exclusion chromatography, which separates the polymer from small junk. The common technique for a polymethacrylate is to use THF with a suitable Styragel column. What pore size of the packing is suitable depends on the molecular weight range of the polymethacrylate.

[Mark Tracy]

If the polymers are very small (n<20) you can also use RP-HPLC on wide-pore C18. Acetonitrile/water gradient and pH appropriate to your polymer.

[H2Oh]

My current systems are mostly peek although I have one SST pump set up with PEEK tubing in the rest of the system. Will the Dionex PEEK handle acetonitrile well? Someone mentioned that high concentrations would require a stainless steel setup.
Thanks for the tips.

[Mark Tracy]

PEEK systems can handle acetonitrile, but the tubing has a lower pressure limit for pure acetonitrile than for water. The PEEK pump heads are heavy enough that there is normally no problem. I've been doing it for years. Fortunately, for most RP-HPLC applications everything works fine. However, if you plan to do solvent-based size-exclusion (a.k.a gel-permeation) chromatography, or you plan to use high concentrations of THF, then a steel system is recommended.

[Uwe Neue]

OK, THF is out...

What is the approximate molecular weight of the polymethacrylate?