Chromatography Forum

Running a GC-MS configuration. GC: 5890. MS: 5973. Dual inlet: front - PVT, back - S/SL. Columns: front - 30 m x 0.25 mm x 0.245 um, back - 10 m x 0.1 mm x 0.1 um. Need to be able to switch columns easily (would be nice to avoid venting). Have read about the Ms-NoVent, EZ No-Vent, Swap/n Go, QuickSwap etc. accessories. Has anyone used these with success (with this model GC-MS configuration). Any duds? I noticed that JAS has a Swap'n Go DUO which would allow switching between columns on the fly (which would be great - but does it work well)? Are there any others? Also, what I'm seeing in the sales publications is references to 0.25 mm and 0.32 mm columns, since one of my columns is a 0.1 mm, will ANY of these accessories work? Any advice would be appreciated.

Not sure about the compatibility of your column size but these devices do work, however they are not always ideal. I saw customers with issues with one design where the column could break in the valve and the only option was full vent and buy another at £600 If you work fast and don't wait for the transfer line to cool it is possible to remove you old column, cap the interface temporally with a septa over the end (Vacuum holds it on) while to chage the column. Not sure how the turbo pump will cope with the sudden depresurisations long term but probably best not done if yours has a diff pump ?
If you are running 0.1mm id columns, do you have two injectors , leave both connected ?

The 5973 does have a diffusion pump. I have used the "quick change" method in the past, often, but not always, without repercussions. Right now, we are not keeping both columns connected to the injection ports.

I have done the quick change many times even using a diffusion pump. You can set it to vent mode, let the diff pump cool, do the swap then do pump down and it will be back up pretty quickly since you never introduced a huge amount of air.

Another way we have done it is to us a Y connector into a piece of transfer line and leave both columns attached to the inlets. When you run the front column have it at normal flows, with the rear set to a minimal flow of maybe 0.1 or 0.2ml/min, or vice versa when needing to run the opposite column. With the .25 and .1 ID columns it should be able to handle a low flow and still have at least a few psi head pressure on the idle column. With the suction of the mass spec you don't have to worry about back flowing into the idle column either.

I have the Agilent Quickswap. It works OK but getting it to make a seal on the transferline is a nightmare. Also the pressure settings are tricky to learn. The back flatside of the siltite ferrule on the restictor has to seal against the transferline weldment. If either has scratches or scoring you will get leaks. It took me weeks and dozens of attempts, I had to buy a new transferline weldment and Agilent had to send me a second Quickswap insert but I managed to get a seal. I am afraid to touch the thing. I considered using a narrowbore (.18) column a few times but because the flow out of it would be significantly less I'd have to use a narrower restricter and I am not going to take that thing off and go through the above again.

It uses an auxilary EPC I use the 100um transferline at 4 psig/280deg the flow into the MSD is always 1.3 ml/min. I can turn it up for pulse splitless. I use it to switch between a db-5 and innowax column for flavors analysis, a db-1 at the back for trace analysis of 3-mcpd.

Agilent discontinued the Quickswap due to the widespread issues people were having and now they use the two way splitter with makeup to achieve the above.

I have tried the NoVent from SGE and it always had a leak no matter what you did. I have given up on it a long time ago. For the record I’ve tried the old version (early 2000 vintage) and the new one. In my hands both never worked (even Agilent had a go with the old one and were as successful as me).