GC-MS/MS

[willnatalie]

I have heard now about companies like Agilent coming out with a triple quad GC/MS.
If the sources are EI, and CID, what are the advantages? Ususally I have a problem with compounds getting blown apart with just EI. There had got to be some if they are taking the time to put these instruments out on the line.
Just curious.


Will

[Ron]

In a GC triple quad in many applications the ionization voltage used is less than 70eV to enhance the formation of the parent ion. GC triple quads are not new, the institute I worked at in the late 1980's had an old VG triple quad system. Manual tuning with a scope, a real character building experience.

[jh1]

A significant increase in signal to noise due to reduced background noise in difficult matrices.

[Suresh Seethapathy]

Better Specificity with triple quad.

[thohry]

May I borrow this thread.
In SCAN mode, is the MS/MS as good as single MS?

Thanks

[stb75]

The main advantage of a Triple Quad GCMS is to eliminate the noise/interference due to matrix. One typically uses the same source parameters as in single quad mode. Most Triple Quad instruments can still run in Single Quad mode. Triple Quads are widely used with great success in Europe. In the US, the use is not as common yet, but if you look at the number of instruments on the market, it is catching on fast.

[stb75]

I meant to add that for labs with single quad Agilent instruments (5973 and 5975), it is possible to upgrade those to Triple Quads at a fraction of the cost of full new Triple Quads. The firm Chromsys apparently does this in the US (their parent company Chromtech GmbH in Germany markets it abroad).

The upgraded system has pretty impressive specs (about the same as the best Triple Quads on the market), and even better if a brand new 5975 is upgraded. I've heard from a colleague that it's the next big thing. Sensitivity is a whole order of magnitude better, at least. I would assume the reason for the impressive performance is the fact that the source, quad 1, detector, GC etc. are all top-notch components from Agilent.

[CE Instruments]

As is in most industries the latest greatest thing turns out to be a new slant on an old solution
Do you by any chance work for a "new" triple supplier ?
When I first started in GC/MS back in 91 the top labs in pesticide analysis had Triples , usually Finnegans. However with Quads like the MD800 and the 5972 the sensitivity and cost meant that single quads became dominant. Those determined to be different used Ion traps and MS/MS. More recently Varian did a great job bolting a new data system and some mods on the old Bear labs triple and the buzz has changed back to low cost triples. How is everyone getting on with GC x GC and Tof saw some great data before I moved on to other products in 02 ? None of these techniques can now be considered new and all offer a solution vs price compromise.
My 2c , take your samples to the vendors and see what they can provide and always check to see if the "latest" solution really offers a benefit against the norm,

[stb75]

I saw them at a show and have talked to a user. Sensitivity is 5x, 10x and in some cases 20x higher than before upgrade. Triple Quads are better than single quads for target analysis. Period.

[mfiligenzi]

We have been using our Waters Quattro GC for a little over 6 months now. Application has been low level PCB analysis in serum and other biological matrices. I'd say it works pretty well using MRM mode. We've dropped our detection limits an order of magnitude or two from where they were on the single quad instruments although this is somewhat compound dependent.

As was mentioned earlier, I would recommend demo'ing a triple quad thoroughly before buying to make sure you really need its capabilities.