Any other way than switching columns in GCMS

[pincer]

I try to use my Shimadzu GCMS to do semi-volatiles(ppm level), pesticides(ppb) and volatiles (ppb). Due to the difference requirement on sensitivity, I have 3 columns for these three applications. Currently, I switch columns to do these analysis. However, after 3 weeks, I feel it is not a very good idea since I have to turn off the instrument, change column, and condition the column (sometime take overnight to do it), all of which take me at least a day, no mention I have to redo my calibration curve and sometimes I have to re-install the column due to the bad cut or position the column. I also worry about the contamination of ion source.

Is it possible to have these 3 columns install paralleled and share MS? I can install a new injection ports which I think there are space and ports 3 more injection ports. Or anything I can do to reduce the down time for the instrument due to the switching columns and avoid the bad cut or position the column?

Any suggestion is welcome.

Thanks a lot!

[Alexandre]

I had 2, guess 3 is possible too, but sensitivity will drop as you will dilute your sample with flow/s from other column/s. So address this.

But you really need more instruments, tell your boss.

[Hornet]

Dedicated instruments is the only (good) way. Anyway i'm sure you could use the same column for both semi-volatiles and pesticides, this is better than using the same MS for multiple columns.

[mckrause]

You can put an interface into the MS so that you can change columns without venting. Look in the Restek or Scientific Glass Engineering catalogs.

No reason to have a separate semis and pesticides column - use a RXi-5Sil-MS or similar and you'll have more than adequate separation for everything. If you're very careful, and use low starting temps you can use the 5Sil for volatiles - takes some chromatographic skill. Normally you'd want to change columns to run vols - you'll need to change liners anyway, so it's a good time.

Hard to run vols and semis on the same system. I have done it, but you're better off with separate systems for vols and semis/pesticides.

[pincer]

Thanks a lot, for all suggestion. I may combine SVOC with pesticides in one column.