High back pressure

[brendandamm]

Hello all,

The work that I am doing with regards to HPLC analysis involves looking at preservative levels in paints and latices. The sample prep method that I have is only a liquid-liquid extraction (0.2g of paint/latex dissolved in 15grams of H2O.) I filter every sample through a 0.2um filter but still get a ton a backpressure after about 20-30 injections. I am using a guard column as a precaution but at the rate I am going I am burning through 3-4 guard columns a month. The molecule I am looking at is extremely hydrophilic so I can't really use a strong solvent during sample prep. Any suggestions on what I should do??

Thanks.

B

[Gerhard Kratz]

Take your sample after Filtration into a vial and a while into the freezer. Than use a centrifuge and take only the clear solution on the top.
Second alternative is to clean again on a C18 SPE cartridge before HPLC.
Hope that will help.

[brendandamm]

Ok I'll give that a try. How long should I leave it in the freezer? Half hour? Would it make sense to centrifuge the sample, filter, freezer and then sample again?

[Gerhard Kratz]

15 to 20 minutes schould be ok. First filter, freezer and than centrifuge. Good luck