2 injectors into 1 column

[WK]

Hi All,
Is it possible to connect 2 injectors into the 1 column.
I routinely change over liners from packed liner to SPME liner and back
sometimes several times a day.
All literature points to splitting column effluent to 2 detectors.
I have Saturn 2000 with 2 x 1079 injectors.
Regards
WK

[Peter Apps]

The plumbing would be easy - just a press-fit Y connector - but I foresee problems with gas flows and pressures. If you are running both injectors with a split (which is unlikely for SPME) there might be a way of setting it up as a sort of Deans' switch in reverse, but changing liners would probably look like the preferred option pretty quickly.

Peter

[WK]

Thanks Peter,
The other option would be to use 2 injectors and 2 columns using the connection before the MS - but this would mean more gas used, 2x bleed and 2 columns used.
Regards
WK

[Peter Apps]

And more carrier gas than the MS pump could handle perhaps. How about one type of liner in each inlet, and swap the column between the two ? - it would be cleaner than changing liners, and perhaps marginally quicker.

Peter

[Don_Hilton]

And, keep in mind flow control through the split vents of the inlets. You will have to be careful with how you set flows and pressures between inlets if you connect the inlets with a Y connector. Assuming that you have electronic flow control, if there is a differential in pressure between inlets, you may have a significant flow out of the split vent of the inlet attempting to control for the lower pressure at the time - resulting in an excessive, uncontrolled split of the sample.

[giacomo56]

In order to use two injectors into one column...the solution is very simple...and gas flows do not matter when you are working on the injector that is not "in use"...
from Injectior 1 to a 6port valve (use a retention gap) Inject 2 to six port valve ( use a retention gap)...from 6 port valve to column to MS interface (use your column of choice)
switching valve from pos 1 you will be using Injector 1 switch valve to position 2 you will be using injector 2.....when the injector you are not using you can do all sorts of maintenance without effecting the run......also the flows will be OK by the MS.....

Injector 1 ---(inert capillary)--------X
................................................X 6 port valve -------------column---- to MS
Injector 2 ---( inert capillary)--------X

Hope this helps........

[chhubert]

From my experience, two columns connected by y-pressfit near MS is not easy to manipulate, especially without leak 'cos the connection is too close to a high vacuum source. In that case, you may need to consider those connectors with nuts and ferrules.

Hubert

[WK]

Hi All,
Thanks for all your replies.
As I suspected - its probably going to be easier all round to stay
as I am !
Best Regards
WK

[IsotopeC12]

Yes and the best way is to use two columns and a HTC PAL Dual Autosampler Multiplex system with Aria software. You stagger your injections from each autosampler. You can use different methods on each system and also shorten the amount of time the CPU is looking at each sample injection. By cutting down the CPU time, you tell the software to only record the period where the peaks come out. It uses the dead space time to start working on the next sample. Beware that you should not introduce significantly different Mobile phases to the MS. The best scenario is running with the same Mobile phases on each side.

[ods-at-pacific]

Another possibility might be to have two different columns of the same type from two different injectors going into the mass spectrometer. Unfortunately, the device I found to do this appears to be specific to the Agilent.

Joint Analytical Systems GmbH, headquartered in Moeros Germany, with subsidiaries in the U.S.A. (Joint Analytical Systems Inc. in Hainesport, NJ), Austria (Joint Analytical Systems GmbH in Kumberg), and Singapore (Joint Analytical Systems PTE LTD) has several products that may be helpful. One is a Two-column interface to an MSD. Switching between columns can be automated with the ChemStation. There are no details as to how this works on their Web site; therefore you will need to contact JAS for details.

The other product is a Swap’n Go GC/MS Interface which allows for tools free column exchange without having to vent the mass spectrometer. This product is available for the Agilent and Thermo GCs and works with 200, 250, and 320 µm i.d. columns.

You can get to JAS at http://www.jas-usa.com.

[ajae11]

I would go with the swapable inlet nut. Phenomenex keeps trying to seel me them and I have no use for it, but you may find it convinient. 2 inlets to 1 column could work, but then you have to worry about more leaks and more area to get contaminated/active.