GC Injections and Particles/Involatiles

[Trishia]

We work with 96-well plates in my lab and do a lot of catalysis chemistry. As a result, our samples have metal catalyst residues in them. We've typically injected them regardless of their involatility since there was no practical solution to this problem. Our instrument is equipped with a guard column, and we use inlet liners packed with glass wool. We have not run into too many problems by doing this.

But now, I have some groups interested in analyzing samples that not only contain metallic catalysts but also solid supports, such as alumina, titanium dioxide, calcium oxide - things that can vary in size from 5 to 50 nm, although some types of alumina can also reach 5-150 um in size.

Now would this be a problem if we typically let the samples settle and have the autosampler sample from the top of the vial? I'm aware not all will have settled...


Thanks for any input,

Trishia.

[Don_Hilton]

Your risks involve damage to the syringe and the introduction of nonvolitile material into the GC. You seem to have the first risk covered with what you do now. Small particles can cause the syringe plunger to wear - resulting in leakage after many injectoins - and you run the risk of a particle causing the plunger to jam - resulting in the loss of the syringe.

Letting the vial stand can help. Centerfuging the sample could help as well.

While I have injected cloudy samples - I don't recall that any of them had abrasive materials suspended. Would I try it? Yes. (After at least letting the samples stand, as you suggest.) What can you loose - besides a syringe, an inlet liner, and (maybe) a guard column?

[Peter Apps]

Depending on a lot of things the most elegant solution would be headspace - there would be a lot of technical issues doing this from 96-well plates, but it might be worth a shot.

Peter