Progenesis QI and the iKnife: the cutting edge of food monitoring

Dr Sara Stead, a Senior Strategic Collaborations Manager in the Food and Environment division at WatersEarlier this year at ASMS 2015, Waters previewed their Rapid Evaporative Ionisation Mass Spectrometry (“REIMS”) research system, incorporating the iKnife – an exciting new technology that’s already hitting the mainstream news headlines in the monitoring of food adulteration. Here at Nonlinear, we were incredibly proud to announce that Progenesis QI would provide the data analysis support, starting with Progenesis QI v2.1, which was released just last week.

In this article, we’ll talk with Dr Sara Stead, a Senior Strategic Collaborations Manager in the Food and Environment division at Waters, to learn more about the technology, its potential applications and how Progenesis QI helps.

Mal Ross: Hi Sara. Thanks for talking to us today. Can you start by telling us a little about your role at Waters, please?

Sara Stead: Thanks Mal. I’m based at the Waters mass spectrometry headquarters in Wilmslow, UK, and work within the Food and Environment market development group. I’ve been with Waters for 4 years and am responsible for strategy business development. Prior to joining, I worked at the Food and Environmental Research Agency (FERA) in York for 13 years as a senior scientist focusing on food safety, quality and integrity, gaining a lot of experience of the challenges associated with food testing, the industry needs and requirements.

At present, I’m working on the development of innovative solutions for the detection of food fraud & authenticity using MS-based techniques, including REIMS with iKnife technology.

Mal: OK, so I imagine you’ll have a strong appreciation of the benefits that a technology like REIMS can bring. First though, for those who’ve not heard, can you tell us a bit more about REIMS and the iKnife technology in particular?

Sara: REIMS with iKnife is certainly an interesting and innovative technology. REIMS is a new ionisation technique and the iKnife (Intelligent Knife) technology was originally developed for application in surgery, allowing surgeons to make real-time decisions during operations. A conventional electrosurgical generator and knife are used to generate gaseous molecular ions of the major tissue components – for example, phospholipids – via a diathermic process. The combination of surgical and MS techniques also offers a possibility for in-situ chemical analysis of tissue during surgery.

REIMS research system: iKnife and Waters Xevo G2-XS QTofREIMS offers a number of unique benefits that address the requirements of the food testing industry. One example is the direct sample analysis, which means results can be generated in near real-time, with minimal intervention. At the ASMS conference in June 2015, Waters made the technology available for research use and it’s currently available as a direct ionisation technique on the Xevo G2-XS QTof and Synapt G2-Si instruments. In combination with Progenesis QI, it’s possible to develop databases of chemical markers and generate MVA models allowing the real-time classification of unknown samples to be performed at the point of control.

Mal: Sounds great. I guess the really revolutionary thing here is the speed with which you can get results telling you exactly what you’re sampling? There’s no sample prep or chromatography step here?

Sara: That’s absolutely correct, Mal. Using the iKnife for sample introduction, there is no requirement for sample preparation, extraction or chromatographic separation, which are some of the major bottlenecks in the routine analysis of complex and diverse foodstuffs. The workflow’s greatly simplified, involving a few seconds’ “burning” of the analytical sample to generate an aerosol that’s then transferred to the MS using a pump mounted on the instrument. The use of Progenesis QI means you have a powerful multivariate statistics package to convert the MS raw data into meaningful results. And from here, you can develop databases of unique chemical markers, representative of different sample types.

Fish at market (photo courtesy of Lucas Jans)Mal: Can you give us an example of the type of analysis you’ve done using REIMS data in Progenesis QI? I imagine many people, in Europe at least, are quite familiar with the horsemeat adulteration that made the headlines last year, but I hear you’ve been doing something with fish too – is that right?

Sara: Yes, that’s right. I’ve been working on the development of a database using REIMS with iKnife and Progenesis QI for white fish speciation. Fish fraud’s thought to be one of the most widely perpetrated food frauds in the world. Estimates of the amount of fraudulent practice range from 25-75% depending on the geographic region and the species of fish involved.

Mal: Wow, that’s a lot!

Sara: Indeed! Species substitution is the most common type of fraud. This is where a higher value species e.g. cod is substituted by a lower value species e.g. whiting. It’s often used in situations where organoleptic identification may be difficult, e.g. processed foods.

So far, I’ve analysed samples of the most commonly sold white fish in UK shops using REIMS and the iKnife on the Xevo QTof. The data’s then been processed using Progenesis QI and EZinfo to develop unsupervised PCA and OPLS-DA models to separate the fish species based on their unique chemical profiles. The model can then be used to determine whether an unknown sample belongs to one of these species included in the model.

PCA plot of fish species samples in Progenesis QI v2.1

Mal: And is that as far as you’d go with this kind of application in Progenesis QI? Or would you also want to identify the molecular markers for the different species?

Sara: Oh, identifications are important too. It’s important to understand which chemical compounds are responsible for causing the differences observed in the MVA models so that we can assess both the quality and validity of the statistical models. We use the tools within Progenesis QI – such as database searching and tagging – to propose tentative identifications and generate marker libraries representative for the different fish species under investigation.

Mal: Excellent. So, I guess the applications we’ve seen so far are really just the tip of the iceberg. This kind of analysis sounds widely applicable and it seems REIMS in particular can revolutionise monitoring of the food supply chain.

Sara: Yes, REIMS technology is directly applicable to many areas of testing along the food supply chain – food authenticity, brand protection, food safety and quality, and nutritional analysis, for example. We also see applicability for the REIMS technology in areas such as environmental testing, sports doping and chemical materials analysis.

Mal: Exciting times, then! OK, thanks Sara – it’s been great talking to you. Hopefully, we’ll catch up with you again later to hear about more of the latest developments and success stories using REIMS and Progenesis QI.

Sara: Thanks for the opportunity to discuss the REIMS with iKnife work; definitely exciting times! From my prior experience in food analysis, I really believe we have a revolutionary technology platform here. It has the potential to evolve into a point-of-control analysis tool, operated in a field testing laboratory such as a border inspection post – it really could transform the way testing is performed! 🙂

If you want to see how Progenesis QI supports the analysis of REIMS data and other direct sample analysis techniques, you can download Progenesis QI v2.1 along with a quick-start guide that walks you through a small-scale version of the fish species study mentioned above. And for more information on the whole REIMS research system, visit the Waters website.