Need Advice on GC-MS Purchase

[wan]

I am totally new to GC/MS and am tasked to purchase a GC-MS system for our lab. I would appreciate any advice on the purchase.

We plan to use the system for analysis of explosives and low molecular weight compounds.

Would a quadrupole mass spectrometer or ion trap mass spectrometer be a better option for this case?

In addition, Agilent and Shimadzu seemed to be the more common ones. What about those from Perkin Elmer etc.?

Many thanks for any advice.

[rubyfan]

99% of my current work involves GC-MS analysis of explosive residues. We have both a Varian 3800 GC with 2000 ion trap MS and an Agilent 6890-5975 system. By 1-2 orders of magnitude, the Varian ion trap is more sensitive than the Agilent in full scan mode. In full scan mode, the Agilent had detect around 1 ng/uL TNT, whereas I validate the Varian system every morning with 100 pg/uL TNT and can detect around 20 pg/uL TNT in full scan. The sensitivity for RDX is a little higher, probably around 50 pg/uL on the Varian. In addition to explosives, we've done work with chem agent surrogates and can detect ~ 600 fg/uL dimethyl methylphosphonate (DMMP) using the ion trap.

I would recommend the newer Varian 240-MS for explosive analysis. My second choice would be their 320-MS, triple quad system. Negative ion CI-MS/MS would be the best way to go for explosives and this can be done on either system.

[wan]

Many thanks rubyfan!

Varian GC-MS systems looks like a better option compared to Agilent, but I am worried about after-sales support/services from Varian Inc as our lab is not located in the US and they do not have a branch where we are (Singapore).

But I appreciate the info and plan to bring that up as an issue during disscussion about the purchase.

[gah]

Wan,

Please go to the following link to preview the literature on the Thermo Scientific ion traps- I think you will be impressed with the instruments available. http://www.thermo.com/com/cda/product/d ... 37,00.html

You may also want to consider a DSQII single quad. Please see the link to the Technical Note titled "Analysis of Explosives by Chemical Ionization GC/MS." http://www.thermo.com/eThermo/CMA/PDFs/ ... _23976.pdf

If you cut and paste the links, they should take you directly to the literature. Please email me if you have any questions at gail.harrison@thermofisher.com

Have a great day!

[rubyfan]

Wan --

The nice thing about the Varian systems is that, at least in my experience, they require less maintenance than Agilent. And they are significantly more sensitive. If you want the better system, than Varian would be my recommendation. I've spent several years now doing explosive residue analyses on both systems, so my preference is based on instrument response, maintenance & reliability.

Good luck!

-Aaron

[wan]

Thank you, Gail. I will check out those literature and instruments.

And thank you again, Aaron. It is definitely worth considering Varian, yet I have to consider the fact that I am a newbie to GC/MS. Hopefully, I will make the right decision later.

[kkteng]

Hi! Wan, I work for Shimadzu in Singapore. If you are working in Singapore, I certainly can help you by running your sample in our lab for your evaluation. My email is kkteng@shimadzu.com.sg. Drop me a mail if I can help.

Cheers!!

[JoeWeit]

Wan,

If you are considering the purchase of an analytical system, you should consider all the major suppliers. Agilent is the leading supplier of GCs and GC/MS systems in Singapore. There is also an excellent support organization in Singapore. If interested you can contact our technical representative in Singapore, Jasper Chan at 62158977 email jasper.chan@agilent.com.
I work for Agilent in the US.

[chanhkja]

Dear Wan,

My name is Jasper Chan and I work for Agilent Singapore. Please do not hesitate to contact me if you need any technical or application information on GCMS.

Here is my contacts:

Email: jasper.chan@agilent.com
Tel: +65-96307337

Jasper Chan

[AICMM]

Wan,

If you want to do really low levels of explosives, I would recommend a GC-ECD. You can purchase an ECD parallel to MS (either split or two channel) and do them both. Won't add much to cost of the overall system at that point. I think all of the vendors here would agree that this is a very reasonable combination.

Best regards.

[wan]

Many thanks for the suggestion, AICMM!

I am definitely considering an additional ECD to the system. Having more than one detector should allow more flexibility.

[oscarBAL]

Hello wan; I has worked with PE GC/Ms and I sufered alot.

Regarding with Trap issues form Varian I think that Trap are not good enough for screening pourposes (correctme if I am wrong), for specific compounds Traps are not bad, if you going to analyze (I dont know) pestizides for example, maybe Quad are better than Traps.
please think what are your applications

[lmh]

I've heard it said, but don't know if it's true, that trap spectra are not exactly the same as single quad spectra. Single quad spectra generally make a very good match to NIST library spectra, so I'd want some evidence that the trap would also give me a good match before buying.

Whatever you do, don't buy anything without having the systems demonstrated, and trying some of your samples in the manufacturers' demo labs.

[Don_Hilton]

And, take a look at Time of Flight mass spec (TOFMS). You have close to the same sensitivity as a quadropole in SIM mode , but get full spectra at that sensitivity. (Instrument demos are good for helping to understand the best option for your analysis) Check out the web site for LECO Corporation (http://www.leco.com). And as noted above - have the vendor demonstrate the instrument - not just a pretty spec sheet.

And, for the record, yes, I work for LECO as an applications chemist.

[wan]

oscarBAL: Thank you for that info. I'm looking to analyse explosives (TNT, PETN, RDX, HMX etc.). Most of the lit. show that quad is more popular for that application, but those using ion trap report lower LOD and higher sensitivity.

lmh: So far I have not heard anything about the differences in trap and quad spectra. Hopefully someone can provide more info on that. I understand the need to provide the vendors with my samples, but they being explosives make the process very tricky.

Don_Hilton: I am looking at GC-TOF as well, since we are looking to measure Mr of synthesized compounds at the same time. But they are more costly than quad and that may be a problem.