Chromatography Forum

Hello:

We have been using our Archon autosamplers in the water mode and ketones look good. We started calibrating the VOCs in the soil mode and aside from ketones all the other compounds look good. Acetone and MEK have very low responses and we have not been able to get any calibration for these two compounds! We are preheating the container to 40C and using 5ml sample amount. Any suggestions?

Thank you very much.

It could be an active site in the transfer line or soil probe. Compare the recovery of a high point and low point purged in water mode to soil mode. If the high points are similar but the low point has a low response in soil mode it suggest an active site.

If that is the case try backflushing the transfer line or replacing it.

I would also wonder if the soil transfer line and valve heaters are on and working.