Plymouth University uses BenchTOF-dx to identify naphthenic acids and diamondoid acids in oil sands
ALMSCO’s mass spectrometer, BenchTOF-dx, has played a key role in the ground-breaking research into highly complex mixtures found in Canada’s oil sands.
We talked to Professor Steve Rowland, Head of the Petroleum & Environmental Geochemistry Group at Plymouth University, to find out more.
What were the findings from your research?
Using two-dimensional gas chromatography and time-of-flight mass spectrometry, we studied highly complex mixtures found in the process water from oil sands, and identified individual naphthenic acids.
Our research also uncovered the presence of tricyclic diamondoid acids, which had never before been considered as naphthenic acids, suggesting an unprecedented degree of biodegradation of some of the oil in the oil sands.
Rapid expansion of the oil sands industry of Canada has raised concerns about the potentially toxic mixtures of naphthenic acids in the process water. Our findings may help to better focus reclamation/remediation strategies for naphthenic acids, as well as in facilitating the identification of its source in contaminated surface waters.
Why are you using BenchTOF-dx in your research?
Our research is focused on super-complex mixtures of organic compounds – so complex in fact that conventional gas chromatography–mass spectrometry (GC–MS) just results in a ‘hump’, with nothing identifiable. GC–MS just didn’t work; any mass spectra we could obtain were mass spectra of multiple compounds so we couldn’t interpret them.
We needed a method that could separate these super-complex mixtures, which may comprise tens of thousands of chemicals.
With BenchTOF-dx, we could couple time-of-flight mass spectrometry with GC×GC, which offers not just the sum of the efficiencies of two columns but the product of the efficiencies. It offers massive separating power.
What motivated you to purchase a BenchTOF-dx?
Having secured a grant from the European Research Council, which enabled us to purchase a high-quality mass spectrometer, we received tenders from several leading suppliers, including ALMSCO.
We wanted to thoroughly evaluate the various systems, so we got a whole set of test samples of super-complex mixtures and took them to the manufacturers so that we could effectively test their instruments.
I was absolutely delighted when we tested ALMSCO’s BenchTOF-dx. The spectra were completely library-searchable and they had molecular ions, even for compounds where molecular ions are not abundant at the best of times. Importantly, this gives us the molecular weight of chemicals.
Most systems work with small molecules with less than 15 carbon atoms, but the BenchTOF-dx works well with larger molecules too. Everything we use is above 15 carbon atoms and it works beautifully. This wasn’t the case with some other systems that we tested, where some molecular ions were not very abundant and couldn’t be measured reliably.
In fact, we’ve been so impressed with BenchTOF-dx that we have now bought another one!
What are the other benefits of BenchTOF-dx?
BenchTOF-dx provides us with really good quality mass spectra, which allows us to interpret the super-complex mixtures that we work with. It offers good accuracy – in fact, it offers better accuracy than ALMSCO advertises, and importantly it delivers library-searchable mass spectra. We are probably dealing with more complex mixtures than anyone in the world, so obtaining reference-quality spectra is absolutely essential.
It is also a very easy-to-use system. We have post-docs currently using it who had no previous experience of GC×GC, but after quickly learning about the system from spending a bit of time with the ALMSCO team, they quickly started producing publication-quality data.
The instrument is very robust, and there’s definitely a reduced need for downtime. BenchTOF-dx has really stood the test. In fact, it had to be re-installed because we moved labs for a few months and it worked fine all the time. I was amazed.
With a small footprint, it requires no specific environmental pre-requisites in terms of the laboratory which it went into – so there was no fuss in terms of installation.
The software that comes with the BenchTOF is also very good. It’s great for use on laptops, as well as on the desktop, which is good because it means I can take data abroad with me to show our collaborators processing in real time.
When compared to other types of TOF, I found it was also very affordable. Getting the most out of the budget is always a major consideration for universities and research centres.
The support has been very good. I’ve taken out a five-year service contract, and I’m very impressed by the number and quality of engineers that are on-hand to help. There’s also remote support available, with diagnostics being undertaken online.
BenchTOF-dx produces over 10,000 spectra every second. How has this speed helped with your research?
The mixtures we work with are so complex it is very important that the mass spectrometer keeps up with the very fast elution through the two GC columns. BenchTOF-dx acquires a huge amount of data, allowing us to go through the mixture carefully and to get nice clean spectra. We haven’t needed to push it to its limits, but speed is pretty important to us.
How do other systems and techniques that you’ve used in the past compare with BenchTOF-dx?
Previously, we have tried GC×GC with a flame ionisation detector – it worked to some degree, but we needed a really good mass spectrometer as a detector. Having had trials with some other mass spectrometers, we found that the mass spectra sometimes didn’t have all the key characteristics we expected. Molecular ions were sometimes missing or at least not obvious. It wasn’t ideal and often the spectra weren’t very searchable against library spectra.
How else have you used BenchTOF-dx?
Working with experts at ALMSCO, we have actually modified one of our BenchTOF-dx instruments, and interfaced it to a high-temperature gas chromatograph. This bespoke system now provides high-temperature GC/MS, which allows us to obtain spectra of compounds with close to 100 carbon atoms.
Because the BenchTOF-dx doesn’t have parts that are temperature-sensitive, it can go up to higher temperatures than many conventional instruments. By working with ALMSCO engineers, this feature allowed us to make these innovations.
This new system works beautifully and has received a great deal of positive feedback from contemporaries and colleagues.
BenchTOF-dx delivers full-range spectra at the sensitivity levels of quadrupole instruments running in selected ion monitoring (SIM) mode. What’s your experience of this?
In our research we generally look at everything, so we have no real experience of SIM. However, through our work with Environment Canada we have actually patented a method based on use of selected ion mass chromatograms to profile samples of oil sands.
This method helps to give a fingerprint profile for oil sands, making it possible to know which oil sands pollutants are leaking from storage bunds.
What’s next for your research?
We are currently working with atmospheric chemists at Birmingham University on pollutants in aerosols. So far, we have run six aerosols using BenchTOF-dx and have got library search matches with virtually every chemical in there; it’s superb. With Birmingham University, we have also written a paper based on this research, and submitted it to a leading atmospheric science journal – and they’re delighted with it.
We’re also working with entomologists at Sheffield University to detect chemicals on the surface of insects. Using high-temperature GC/MS we’re able to look at compounds that are much bigger than many others can look at. This research may become important on a world level as invasive species can wipe out whole ecosystems, and finding new chemicals which they may use to communicate with each other is very important. Our research has looked at a variety of species including ants, hornets and bees, and we’ve shown that there is a whole host of chemicals present on insect surfaces. Previous research suggested that the chemicals stopped at 35 carbon numbers, but we’ve revealed that they go up to 65 carbon numbers through application of the high-temperature method. It remains to be seen whether these are important in communication – they may not be – but that’s what makes research exciting.
Our aim is to undertake a full study of more than 22,000 species, to determine which of the chemicals on their surface are used for communication and how important they are for this purpose.
Another exciting application we’re going to undertake involves analysis of meteorite samples from space, which have been given to us by Imperial College. We’ll look for evidence of life from organic matter given off by the complex mixture – basically the chemicals that are evident of biosynthesis. It would be a very exciting discovery.
As news of our success has spread, we’ve had chemists from across the world sending us samples to analyse all sorts of things. In situations where chemists have found that conventional gas chromatography has failed, they turn to us for support. The most recent example is analysis of complex mixtures provided by Australian scientists in some of the oldest rocks on earth, to look for evidence of early life on the planet. As geochemists that really excites us!