HPLC low recovery

[Juan Pedro]

Hi!

I have a problem that is making me crazy.

I´m getting very low recoveries of organochlorines with a preparative HPLC method. My column is Spherisorb 5um Silica 4,6x250mm and mobile phases n-hexane and hexane:methanol:isopropanol. The column is new.

Does anyone have any suggestions?

Thanks a lot

[Uwe Neue]

Considering that you are using the alcohols in the mobile phase, I would assume that they are not reactive, and one will search somewhere else for the problem.

Consider the time delay beween waht you see in the detector and, what the end of your collection tube. Usually, the tubing before the detector is negligibly small, but the outlet tube may have a "large" diameter, and a substantial length. See if you can estimate the volume of the outlet tube and delay your sample collection by this volume.

[MestizoJoe]

If you have good resolution with other components you can overload the column and still get pure sample. Try to optimized your mass/volume load of your sample.

An analytical column should be able to handle 1-6 mg per inj.