For maximum effect, I probably should have written this on October 21st 2015, but I’d like to take you back to the future. Or rather, back to a time when I shared a glimpse of the future, with my colleagues Jason Cole and Richard Fussell. Back in the summer of 2014, in Austin, Texas (far too hot for two Englishmen) we were together in a secret, windowless (luckily, fully air-conditioned) room, when it happened.Actually, if you read my last post on pesticides screening, you will realise there was a distinctly prophetic theme throughout. This is because, that summer in Texas, I was so convinced by what I experienced, it has stayed with me ever since. This is the story that really made me think the game is changing in GC-MS analysis, and also convinced Richard to switch careers after 30 years.
Before I detail that experience, I’ll leave you in suspense a little while longer, and while I do, I will reveal to you exclusively, that the information Richard was searching for, that night in the bar at the 128th AOAC meeting: he went on to find out very soon after; in fact, the week after. Richard and I headed off together to our Austin R&D facility to see the first Q Exactive GC system. At the time, Richard was working at the Food and Environment Research Agency, UK and a collaborator/customer of Thermo Fisher Scientific. He was the first person to see the instrument outside of the project team and he was sworn to secrecy.
It was not lost on me that there was some irony in how secretive we were: the fact we were working on GC Orbitrap technology was probably the worst kept secret in analytical chemistry, but actually nobody knew really what it would be like, and how good it would be. It was this aspect that was closely guarded information.
Into the Lab
When we arrived at Jason’s GC-MS lair, I already had an idea from data I’d seen that this instrument was something special, but this was the first time I had seen it “in the flesh.” Naturally, with Richard being present, we immediately prepared for pesticides analysis. When I say “prepared,” I mean we tuned the source (~25 seconds) and calibrated the Orbitrap (~10 seconds). We used fairly typical GC-MS conditions, typed out a sequence and hit “go.” That was it. It was so easy.
First matrix injection was a very low level spiked orange oil matrix sample, if I recall correctly. We jumped straight into the challenge with a tough sample type. The usual wait ensued for the first peak to elute and the anticipation unbearable (why does it seem to always take so long?). Of course, with this being a full scan analysis, the first peak, or indeed peaks, were not our analytes. We had to mine the data to find our targets. We used TraceFinder software to extract exact masses automatically from the data. When we saw them, we were truly amazed. The selectivity on offer was like I’d never seen before and the pesticides’ peaks stood tall, proud and alone. The sensitivity was fantastic too and we didn’t believe it. No really, we didn’t believe it. We started checking and rechecking standard solutions concentrations, but of course, everything was correct. When we realised what we were experiencing was true and real, it was a wonderful moment. This was a fully untargeted acquisition and I felt like we’d seen to future of routine GC-MS analysis there and then.
The Search for Interference
The selectivity was great as I mentioned, but as scientists we just had to find some interference. We hunted around as best we could for another matrix. We decided to perform a QuEChERS extraction of some suspicious looking green tea lurking in the back of the cupboard. The extract looked horrendous:
Then we spiked it with a pesticide mix to 10 ppb level and injected it directly with no clean-up. A half hour later and we were staring again at a screen full of crystal clear automatically integrated peaks, with mass errors <1ppm. No interference and on top detecting incurred residues for pesticides we did not spike at what seemed like sub- ppb concentrations. We had failed in our search. In fact, we went on to learn that running this analysis in full scan at 60k resolving power (@ m/z 200) makes finding examples of interference a real challenge. As rare as hens teeth, some might say (See some example data from our GC-MS lab in Runcorn, UK). You have to work at 30k and below to see this happen more frequently it turns out.
A Career Changing Experience
If I were more gifted with the pen in hand, maybe I could do a better job of communicating how amazed and excited we were with the experience we had during those few days in Austin. But I’m not, so I think you can get a better sense of it here in this video interview with Richard (albeit in a very British way J). There is also an article complementing this video where Richard states, “When I visited Austin, Texas, to see the pre-launched Q Exactive GC, I was amazed; the performance of the instrument was almost unbelievable” and he goes on to suggest that the time we shared in Austin on that instrument formed part of his decision to join Thermo Fisher Scientific. So for Richard, it was a career changing experience and I think that is truly amazing. So, where is all this headed?
Once again, I think Orbitrap is the future in GC-MS analysis, and also pesticide analysis, too. The flexibility, high performance and simplicity that high selectivity, untargeted full scan analysis with Orbitrap brings is game changing. New analytical technology like this with such a high potential and broad appeal, inevitably will find its way into routine analysis. This is already evidenced on the LC-MS side with Q Exactive focus, with one example already highlighted by my colleague Maciej Bromirski here in his interview with Dr. Susanne Ekroth. GC-MS is now starting that journey and first extended datasets are coming out from the pesticide community, with the latest report (at time of writing) from Hans Mol presented in this webinar.
One thing for sure is that the pioneers and early adopters of this technology in the community will be able to cut their own path and create the future with respect to pesticide analysis, and with that, a chance to gain a differentiating edge in this increasingly competitive world. For me, I am going to enjoy watching this space develop, remembering fondly the great experience (not the weather) we had together in Austin, with the Q Exactive GC.
Additional Resources
Visit the great resources below for more useful information about screening for pesticides with Orbitrap GC-MS technology.
- Application Note: Fast Screening, Identification, and Quantification of Pesticide Residues in Baby Food Using GC Orbit.... Demonstrates the Q Exactive GC system has the quantitative power of a GC triple quadrupole MS combined with the high precision, full scan high resolution/accurate mass capability that only Orbitrap technology can offer.
- Technical Note: High Mass Resolution is Essential for Confident Compound Detection. Describes how excellent sub-ppm mass accuracy accelerates the identification of unknown peaks by allowing the use of narrow mass tolerances to reduce the number of suggested elemental compositions.
- White Paper: The Power of High Resolution Accurate Mass Using Orbitrap Based GC-MS. Demonstrates the extremely consistent mass accuracy achieved across a chromatographic peak, at low and high concentrations, at low and high masses, and for various compound classes and matrix types.
- Downloadable PDF: High Efficiency, Broad Scope Screening of Pesticides Using Gas Chromatography High Resolution Orbitr....
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