Peaks broaden a little when fused silica connected?

[Anthony_Ng]

Hi all,

Yesterday I connected a deactived fused silica in front of the DB-5ms column with "Unlimate union kits". The peaks broaden a little bit. Is it normal? Should I modifiy the original temp. progame? Or is it a gap inside the connector, leading the peaks broaden?

By the way, will the classic press-fit connector with resin sealing give a better result?

Thanks for all input!

[Don_Hilton]

With any kind of union, press fit, etc. YOu need to be sure that you have a good, clean, square cut on the column. Follow the instructions carefully or you will have dead volume and/or leaks.

My own esperience with unions is that I have always had some difficulty. Pressfits have worked well for me - even without resin (it depends on the columns I am using with the press fit -- some work better than others).

If you use resin - read and follow the instructions carefully.

[carras]

I have been using precolumns with pressfit unions for a long time. In my experience they are tricky to assemble but if you do it right there is no need for resin (in fact I discourage its use since , for me at least, it has caused leaks on settling).
Now I use columns from Phenomenex that have a built-in precolumn.