Following on from the first blog post in this series, where Christopher Brodie described how elemental analysers coupled with isotope ratio mass spectrometers (IRMSs) can be effectively applied to detecting food fraud, here I conclude the series with an interview with our other intrepid Isotope Hunters, Dieter Juchelka and Mario Tuthorn.
In this second article, Dieter and Mario, who, like Christopher, are based at our Bremen Centre of Excellence, will tell us how coupling GC and LC to their IRMS technologies extends the range of capabilities of IRMS for protecting both consumers and businesses against food fraud.
– Who are you both, and what do you do at Thermo Fisher Scientific in Bremen?
[Juchelka:] We are the team behind compound specific Isotope Fingerprints. Together with my colleague Mario Tuthorn, the application manager, we cover the relevant applications based on gas and liquid chromatography coupled with IRMS (GC-IRMS, LC-IRMS) at Thermo Fisher Scientific in Bremen, Germany. My name is Dieter Juchelka and I am responsible for new and existing products across the product life-cycle in my role as a product manager. We both have a background in chemistry and over the years we have been involved in diverse applications using isotope fingerprints to investigate food integrity. Since I have previously worked at a governmental food laboratory, I am familiar with how important food and beverage fraud prevention is to protect both retailers and consumers.
– Like your colleague Christopher Brodie, you are specialists in Isotope Fingerprinting, a technique that can be used for detecting origin and authenticity for food safety and security purposes. To unlock answers from the isotope fingerprints you use GC-IRMS and LC-IRMS. Will you explain which answers compound specific analysis can give, as opposed to using EA-IRMS (as Christopher does) for this purpose?
[Juchelka:] Elemental analysis allows users to perform bulk analyses of samples, which means that the entire sample is converted into simple gases and the isotopic composition of the entire sample is determined. However, foods are often complex, consisting of hundreds of compounds and it is of an added value to separate these complex mixtures into specific compounds. For such a distinctive approach, GC-IRMS and LC-IRMS are used as they allow for analysis of individual, value-determining compounds. These techniques enable chromatographic separation of compounds while sample matrix and interferences are removed. Isotopic profiles at the compound level can refine the information obtainable from the samples, which is necessary because food fraud is getting increasingly refined with recent technological developments. Deeper insight into sample composition is required to identify more sophisticated fraudulent practices.
– Thanks for the explanation, Dieter. Mario, can you give some application examples of how GC-IRMS and LC-IRMS are used for detecting food authenticity?
[Tuthorn:] Vanillin is one of the compounds which has been extensively investigated for authenticity. It is a flavouring compound, extracted from the cured pods of a tropical orchid of the genus Vanilla. Resources of this orchid are limited, making vanillin an expensive food item. For this reason, it is often synthetically produced at much lower cost. Detecting dilution of a natural product with a chemically created version of it is of great importance for the food industry. Thermo Scientific™ GC IsoLink II™ IRMS System allows isotope fingerprints of vanillin to be determined, which in turn enable its true origin to be revealed.
Another well know example is honey, authentication of which can be achieved using the Thermo Scientific™ LC IsoLink™ IRMS system. Honey is a high quality natural sweetener composed mainly of glucose and fructose with sucrose (which is the disaccharide of glucose and fructose) as a minor compound. Such mixtures or compounds can be added from other, cheaper sources, such as high fructose corn syrup, to adulterate honey. Adulteration of honey with low price invert sugar syrups provides an opportunity for economically motivated fraud. Since sugars carry isotopic information about their origin and processing, the analysis of sugars by LC-IRMS can be used for investigating honey adulteration and authenticity.
When it comes to beverage authenticity, production of tequila is a very interesting case. Globally, tequila is a popular alcoholic beverage, which has led to increasing demand and thus production, with a subsequent increase in export value to the Mexican economy. Tequila can come in two broad varieties: pure tequila, derived 100% from Agave tequilana, or mixed tequila, deriving from Agave tequilana with up to 49% sugar cane addition. Since tequila is produced exclusively in only five areas of Mexico, it has a well-defined isotope fingerprint. This allows differentiation of 100% pure tequila from tequila that has been mixed with corn or cane sugar and fraudulently branded as the pure product.
– Thanks, Mario. It’s really interesting to hear about the types of food fraud that occur and how our technology can tackle them. I know other technologies are available for this application, so what specifically are the benefits of IRMS over these alternative techniques for determining food origin and authenticity?
[Tuthorn:] Testing for adulteration can be done using various methods, with chromatography being a classical approach for qualitative and quantitative analysis and 1H NMR also often being applied. However, if the quantity of the compounds present or the limit of detection is not sufficient to differentiate unaltered from altered product, IRMS technology offers more by being able to identify where the compounds came from and how they were built up. Materials from nature and industrial processes have a fingerprint, which is a unique chemical signature within their structure that gives them an identity that is different from others. IRMS allows the history of organic compounds to be mapped, and provides isotope fingerprints for authentication on a compound level, which differentiates it from the capabilities offered by other techniques in the area of food testing.
– So, IRMS offers greater specificity and sensitivity compared to NMR and classical chromatography methods. Are there certain applications where the use of IRMS is required by official regulations?
[Juchelka:] Legal judgments based on IRMS analysis have begun to penetrate the food market in recent years, since governmental diagnostic laboratories are searching for techniques to refine the classical approaches in food authenticity determination. It is a comprehensive process starting with open discussion at global congresses leading to method development, running testing protocols and finally resulting in an official introduction of a method by regulatory bodies. Subsequently these methods are refined. Examples of regulation-based IRMS methods that have started to appear include methods for the analysis of vanillin, honey, tequila and wine.
GC-IRMS methodology has become mandatory in WADA accredited doping laboratories worldwide for final confirmation of drug abuse and metabolite studies, particularly with regard to distinguishing between endogenous steroids and their synthetic copies. This technique is now routinely applied for doping control during large sport events such as the Olympic Games, so it can be expected that it will ultimately become an equally invaluable tool for regulated food authentication analysis.
– There’s clearly a growing need for validated regulatory IRMS-based methods for food authenticity testing. In which other application fields can GC-IRMS and LC-IRMS unlock the information about origin and authenticity contained in the isotope fingerprints?
[Tuthorn:] In addition to the above mentioned sports doping application, GC- and LC-IRMS are used in criminal forensic applications. Isotope fingerprints provide insight into the origin of drugs of abuse and growing conditions, tracing explosives or confirming arson at sites of suspicious fires, as some examples. Drug abuse, drug production, trafficking and supply are a major global issue. Understanding the geographical region that narcotics come from has the potential to provide significant insight into movement of narcotics. This is possible since hydrogen and oxygen isotope fingerprints are related to local rainfall. Further applications in criminal forensics are related to identifying and tracking explosives to support counter-terrorism efforts.
Further applications of great importance are related to our environment, in terms of water supply and our ability as a species to produce crops to feed ourselves, especially so in the context of climate change. Isotope fingerprints are a highly informative tool with regard to understanding changes in our planet’s biogeochemical cycles and tracing the processes that govern these. This covers processes that occur in our world today and that have happened in the deep past.
Pollution is another major topic, globally, as it affects our water, soil and air. Identifying and thus tracking down the source of pollution is an important step in reducing the impact of pollution on both the environment and us.
Thanks Dieter and Mario for your detailed and interesting explanations of how of GC- and LC-IRMS technology is applied to food fraud detection.
If you’d like to learn more about isotope fingerprints in general, take a look at our Investigating Authenticity and Tracing Origin with Isotope Fingerprints page. For more information on our GC- and LC-IRMS instruments, take a look here for GC-IRMS and here for LC-IRMS.
Thermo Scientific also offers a wide range of other analytical solutions, from trace elemental analysis and chromatography to organic elemental analysis and high resolution mass spectrometry, to help you achieve your food safety, authenticity and QA/QC objectives. If you’re interested in finding out more about these other technologies, take a look at our main Food and Beverage resource page and our Food and Beverage Learning Center.
Source: analyteguru.com by Dr. Simon Nelms