Chromatography Forum

We are injecting vapor samples into the GC/MS using a gastight syringe.

After the sample is injected into the GC/MS we have a set up to pull a vacuum on the syringe to remove the vapor that is left behind in the syringe before the next sample is loaded in the syringe, but it is not perfect and vapor remains behind even after "evacuating" syringe.

If we use a solvent to flush the syringe, we have had problems getting the solvent out of the syringe - even heating doesn't seem to work.

This is really affecting the reproducibility of the area responses.

Is there a secret I don't know about to clean up this mess?

Thanks for your time.

My technique for manual headspace is to keep the syringe in the oven with my samples (40 or 80 °C). When I remove them I go directly to the GC and set down the sample on a warm portion of the GC. I put the plunger into the barrel and pump quickly 3-4 times. I then remove a portion of my sample with the syringe, and slide the latch on the syring to "closed". I put the syringe in the injection port and depress the plunger to about 10-20% of the volume I am injecting, then slide the switch back to "open". I hit start on the GC, then remove the needle from the GC. Finally, I pump the plunger quickly 4-5 times and unscrew it from the barrel and place both peices into my oven.