Simultaneous MS and FID runs on GC

[rambiochem]

We are working with Perkin-Elmer Clarus 500 GC-MS (TurboMass) and GC-FID (TotalChrom). For each of the sample we have to take separate runs on MS and then on FID. Sometime ago, I was Agilent machine where a single injection is divided into two parts each for MS and FID. The data is acquired at the same time and remains connected (for example, as many of you would be knowing, when you re-open the data you can magnify the both with a single drag). I inquired immediately to our engineer. He said, although the sample can be divided in the same way, data cannot be acquired at the same time with Clarus 500, since the softwares cannot be operated at the same time because of their non-compatibility. Can anybody comment on this, like is it really the case; if yes, why? If doing this is possible as seen with Agilent instrument, why PE is not providing such provision? Is either of this the case with any other company?

[WG]

TurboMass is able to acquire both MS and GC detector data.

You need to go into the GC method editor, under instrument, click data channels. In that window you can choose A, B, or Dual. Once you do that you will be able to edit the parameters on the instruments tab in the GC method.

To view GC Detector traces in the chromatogram window go to display, GC Detector trace.

If you want to use the detector trace for quant, in your quant method editor, change the data source from MS to detector A or B for the compounds needed.

Splitting the effluent can be done a number of ways, a 2 hole ferrule into 2 columns, a 'y' splitter or the 'swafer' that is up to you.

I hope that this helps.

[Peter Apps]

How you split to the two detectors needs some thought. If you split at the inlet into two columns the retention times will never match (mainly because the MS column is running to vacuum). If you split at the detector end you have to have the transfer line to the MS long enough and narrow enough to stop the MS vacuum sucking all the column flow, and an interesting portion of the FID flame gasses into the MS.

Peter

[WG]

very true Peter, my suggestion is to use the Swafer (purged splitter) from PerkinElmer. There is a calculator included, that will allow you to tune the length and diameter of restrictors for the MS and ambient pressure detectors so that you get the desired split ratio between each detector. Also you can split 5 ways if needed.

the 'y' splitters are hard to balance correctly between vacuum and ambient.