Why Extraction Still Matters in Food Analysis

ExTech, the International Symposium on Advances in Extraction Technologies, brings together researchers and industry to focus on one of analytical science’s core processes: sample preparation. The 2026 meeting will highlight new materials, automation strategies, and approaches to extraction across applications ranging from food to environmental analysis.

Hans-Gerd Janssen, part-time professor at Wageningen University and science leader in food compositional analysis at Unilever R&D, has spent decades developing chromatographic methods for complex samples. His work spans edible oils, packaging materials, and flavor analysis, with a focus on making analyses more reliable and efficient. In this interview, he outlines the practical challenges of sample preparation in food analysis, reflects on how new techniques are evaluated in real laboratory settings, and explains what he will be looking for at ExTech 2026.

How central is sample preparation to your work in food analysis – and what can go wrong without it?

Sample preparation is a critical step in food analysis. Food samples are complex and contain various components – such as fats, proteins, sugars, salts, fibers (or polysaccharides), and water – that can interfere with chromatographic systems. These classes of compounds are really problematic for chromatography: high fat levels can clog reversed-phase LC columns; excessive sugars in GC may cause unwanted peaks due to caramelization at high temperatures; proteins can both contaminate GC inlets and columns and block LC columns; and water, especially at elevated temperatures, can damage the GC stationary phase. Additionally, salt can induce ion suppression in LC-MS and should be removed as well. Clearly, careful sample preparation is essential in food analysis, as failing to adequately remove these main ingredients can quickly lead to damage or malfunction of expensive LC-MS or GC-MS instruments.

Sample preparation is widely recognized as essential, but does it receive the attention it deserves in practice?

The significance of sample preparation is well recognized within the scientific community. But the field suffers from the perceptions that it lacks sophistication compared to other analytical advances. Also, I think in literature there is a lot of ‘overpromising’ regarding their practical effectiveness. For instance, direct mass spectrometry techniques are promoted as analytical methods that eliminate the need for sample preparation; however, in practice, they often lack sensitivity and, sooner rather than later, tend to contaminate your mass spectrometer.

We have some methods where we use direct inlet of food samples, such as the application of direct thermal desorption for flavor analysis – where an intact food sample is placed in a desorption tube, and gas-phase extraction is employed to collect volatiles for GC-MS analysis following cryofocusing. Paper spray ionization-MS we have also used successfully in our tea research. Despite these advances, it is evident that most food analyses will continue to require processes such as extraction, clean-up, and derivatization.

Another important consideration is the challenge of evaluating the advantages of newly developed sample preparation techniques without actual hands-on testing using your own samples. While claims regarding chromatographic columns – such as a significantly improved peak capacity – may be readily verified based on theoretical principles, novel extraction methods for chromatography require substantial practical evaluation. This process often involves significant investment, including acquisition costs, adaptation, and comparison with current methodologies. It is insufficient to assess the suitability of a new method solely based on published literature; empirical testing is essential. In practice, the initial investment to evaluate a new sample prep technique is substantial, particularly for automated systems. For example, our laboratory delayed transitioning from fiber-SPME to SPME arrow methods for several years due to the high investment required. Evaluation only commenced after we did a number of tests in a nearby academic lab that had the system. As a result, we have now updated nearly all our fiber SPME devices to SPME-arrow systems. Clearly, when the required investment in equipment for evaluation is considerable, it often results in laboratories choosing not to pursue the evaluation of new methods.

What makes meetings like ExTech valuable – and what are you hoping to see discussed there this year?

Some may debate the value of attending physical conferences. Since all conference information eventually appears in scientific literature, is the main benefit simply learning about new methods a year ahead of time? Attending a conference requires a significant time commitment – usually four days – which could be spent reading numerous scientific articles instead. Relying solely on published literature is also an effective way to stay informed about recent advancements.

For me, the real benefit of going to conferences isn't just early access to new ideas; it's the opportunity to discuss these innovations directly with their creators. Trying out new developments in your own lab involves considerable risks and resources – you must persuade management to invest time and money, and if things don't work out, you have to admit your mistake. Engaging with inventors in person at conferences is vital because it allows me to better assess the potential success, advantages, and limitations of emerging techniques.

In my experience, there are still numerous challenges in sample preparation for food analysis. We continue to rely on large amounts of organic solvents and use extensive glassware that requires tedious cleaning. The process involves significant manual labor, and sometimes errors go unnoticed. Early warning systems to detect mistakes during sample prep would be highly valuable. At Extech, I'm confident we'll hear about solutions to these issues, including direct mass spectrometry techniques, sustainable deep eutectic solvents, and molecularly imprinted polymers. We'll also learn about new materials for sample extraction, such as metal-organic frameworks and covalent organic frameworks, along with methods like emulsification extraction, derivatization, and dispersive liquid-liquid extraction, among others. Most importantly, we'll have the opportunity to engage directly with developers and assess how these new methods could be applied in our own laboratory for our own analyses.

What major trends are you seeing in sample preparation and chromatography – and where do they need to go next?

In chromatography, particularly liquid chromatography, there is an increasing tendency towards a "one column fits all" approach. Commonly, a C18 column is employed, utilizing a wide gradient of acetonitrile, water, and buffer to accommodate a broad range of compound classes in a single run; mass spectrometry then provides the selectivity required for targeted analysis. A similar trend can be observed in sample preparation techniques. For instance, the QUECHERS method demonstrates broad applicability beyond pesticide analysis in foods. Additionally, headspace SPME is an automated technique with extensive utility in food flavor analysis.

This prompts several important questions: Is it possible to develop additional universally applicable methods? Could a single solid phase extraction material facilitate isolation across all compound classes? Might it be feasible to create a 'Swiss army knife' approach for both sample preparation and chromatography? Furthermore, could advances in artificial intelligence enable systems that, based on matrix properties and analyte characteristics, recommend optimized sample preparation protocols? These solutions would need to be both rapid and amenable to automation, while also prioritizing sustainability to reduce the environmental impact of analytical chemistry. Such advancements have become increasingly urgent as spectroscopic techniques, such as infrared and NMR, are being adopted to replace certain chromatographic applications. Moreover, sensors utilizing highly specific bio-recognition principles are seeing greater implementation. Continuous improvement and innovation in chromatographic techniques are essential to prevent non-chromatographic methods from becoming the preferred option.

What practical barriers still limit the adoption of new sample preparation methods?

There are not many factors truly hindering us in developing new sample preparation techniques. Reducing toxic solvent use remains a priority, and chlorinated solvents are typically permitted in labs only when alternatives are unavailable. Beyond this, it largely comes down to our own practical creativity or imagination, although we should not forget the considerable investment needed to experiment with new approaches. Academia and instrument manufacturers could do more to provide resources for preliminary sample testing. Novel sample preparation methods are particularly valuable when large-scale analyses are involved, such as those common in food analysis worldwide. When introducing new techniques, instrument manufacturers should supply thorough application notes and instructions. Additionally, it is essential to compare the quantitative results from any newly proposed method with those obtained through established standardized techniques. While it's beneficial that the new approach may be faster, more environmentally friendly, or less expensive, these advantages mean little if its results do not match those of the standard method.

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