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- Posts: 6
- Joined: Wed Oct 25, 2017 11:49 am
Can I apply column baking when the MS is joined to the GC and without venting the MS vacuum?
And how?
Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.
Rndirk wrote:
Short answer: yes.
The disadvantage is that, depending what you're baking off, it might get stuck in your MS. Therefore, if you don't want to disconnect the column, i suggest to heat your transfer line, MS source and quad(s) to their maximum temperature during the column baking.
Most importantly, make sure there are no leaks when you put everything at max temperatures (perform MS air/water check).
James_Ball wrote:Rndirk wrote:
Short answer: yes.
The disadvantage is that, depending what you're baking off, it might get stuck in your MS. Therefore, if you don't want to disconnect the column, i suggest to heat your transfer line, MS source and quad(s) to their maximum temperature during the column baking.
Most importantly, make sure there are no leaks when you put everything at max temperatures (perform MS air/water check).
If you can use Hydrogen carrier gas while baking it will help keep the MS clean if anything bakes off the column, and will provide cleaning for the inlet as well.
If I haven't injected anything very dirty and I just want to bake out the column to remove any extra column bleed I often raise the oven temperature and put the MS into manual tune mode and monitor the masses that come off as column bleed. For a 5 phase column it is most often m/z 207. I watch this maximize then fall off until it is a lower steady value then I know any oxidized phase has been baked out, you can also monitor m/z 18 to see that any residual water is also baked completely out of the column. Often new columns will have water adsorbed into the phase that you want to remove before using them for analysis. Most new columns are low bleed and there is not enough when conditioning to foul up the MS source.
James_Ball wrote:
I installed a two way valve where I have He on one in port and H2 on the other in port and the out port goes to the instrument. I can switch to H2 and set the oven to 250C for the weekend and let it clean the system.
Agilent is now selling a setup similar to that which bleeds H2 into the source for cleaning either during a run or at the end of a sequence. They call it the Self Cleaning Source. It is supposed to keep the source cleaner longer.
When you run H2 through a system that normally runs He, it can take a week of baking to bring the baseline back down to where it was on He, but if you then switch back to He, it will have the cleanest background you can imagine
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