I bought the wrong Jet

[MestizoJoe]

Hi,

Does it matter much that I bought a jet optimized for packed columns? I use only capillary columns. What's the difference and is it significant?

Thanks,

[KM-USA]

With Agilent (maybe others), the capillary column actually fits into the "tail" of the FID jet. Is your old capillary jet clogged?

Anyway, you could try with the packed column jet if that's all you have, and if system suitability is OK, that gives credibility to your results. If this is for a regulated assay, check with your QA person. And/or get correct jet overnighted.

[MestizoJoe]

Luckily I have other jets and I was just updating our inventory. Now I have to see if I can return these and get the right one.

[LCbob]

Be careful with the Agilent jets. I seem to remember having an issue where the normal capillary jet was used with a 0.53mm column. This column fits very snugly into the jet, to the point where the hydrogen flow was restricted and the flame was unstable.

[MestizoJoe]

What did you do to get a stable flame?

[uzman]

The jet for packed columns reduces sensitivity for capillary columns, especially for 0.25mm and 0.32mm ID columns.

To get a stable flame , simply pull the column back ,around half a milimeter , from where it stops in the jet.

[chromatographer1]

I think the capillary jet has a hole of 0.010 inch diameter. The packed column has a hole of twice that. (if the memory is working correctly.) The flame geometry changes with the change in the hole diameter. Thus if you have a bigger hole the flame changes shape and the sensitivity changes. The capillary jet expects a column flow of less than 3mL per min while the packed column jet expects a flow of at least 5 mL per min.

If you are using capillary columns then the only detriment is a slight loss of sensitivity.

But use the proper tip if at all possible.

Rod

[rb6banjo]

Did you try to clean the old jet? I've never purchased one (20+ years) as I can usually clean them up and get them back to where they were.

[chromatographer1]

You should use a brass brush on them to clean them, inside and out.

Test mixes are a good idea (sensitive analytes should be included) unless you don't feel the need for them.

And remember, nothing lasts forever, and a few dollars investment in hardware can save hundreds of dollars in labor and lost productivity.

Be smart, not cheap.

best wishes,

Rod