Chromatography Forum

Hi,

I am going to be performing a separation on a sample and collecting the fraction containing the peak that we are interested in. I have been asked to then dry the sample down and reconstitute at the original concentration. The peak is a completely unknown molecule and I have no idea what concentration is in my original sample. Is the dilution factor simply my injection volume divided by the volume of eluent that I collect or are there other factors that I need to take into account? If this is the case, I could then dry the same down and reconstitute to the injection volume.

Thanks,

Karen

yes, if your recovery is 100%. I think, in practise you won't get 100%. You should be able to determine this by reinjecting the collected fraction followed by comparison to original peak.

Why does the collected material need to be reinjected at an identical concentration to the original sample? My guess is that your calculation is only applicable if you inject a pure compound and collect it with 100% recovery. When does this kind of thing happen?

How about reducing both your crude sample and collected fractions to dryness and make up your own, known, concentration.