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Artikelaktionen

Research

  • Analysis of functional food or health food, botanicals, environmental samples, pharmaceuticals etc.
  • Pattern recognition and fingerprints
  • Analysis of bioactive compounds (healthy compounds, but also toxins, active contaminants or residues etc.)
  • Efficient bioprofiling and effect-directed analysis combined with chromatography (HPTLC-EDA)
  • Developement of straightforward validated methods for planar chromatography
  • Miniaturization of planar chromatography
  • Open sopurce-based, all-in-one planar chromatographic system (Office Chromatography)
  • Hyphenated techniques like HPTLC-UV/Vis/FLD-EDA-HRMS
  • Open source-based automatization of interfaces for mass spectrometry
  • Quantitative surface scanning by desorption-based mass spectrometry (DART-MS)

More than ever, consumers are getting concerned about the food or food supplements they consume. Botanical extracts play an important role in commercial food products with increasing tendency, though frauds are quite common. Food control, specifications and regulation need to be re-evalutated, as food contains thousands of different, mostly unknown compounds. Product changes are not only caused by natural variances or processing, but also by residues and contaminations along the global product chain, by addition of illicit compounds or adulterations.

Except for a minor portion of known bioactive compounds in a food sample, it is hardly known which of the other thousands of compounds are bioactive. Also we know that trace amounts do matter and show effects, as it is for hormones to mention one. Small changes do matter, if active components at the trace level have impact on the consumer`s health, especially when consumed regularly. Which analytical effort is rational? Which non-target method can point to relevant effects? All the thousands of compounds in a botanical extract under control? Which instrumentation is affordable?

An analytical technique that could cope with this complex task should be matrix-tolerant, and thus avoid a discrimination of ingredients by extended sample preparation steps. As we only see what is detectable with the given detection system, different detection principles are a must. So far, chemical marker compounds have been used to evaluate the product quality. How can these few marker compounds represent the whole sample complexity, including its activity?

“…we know there are known knowns.
These are things we know that we know.
We also know that there are known unknowns.
That is to say, there are things that we know we do not know.
But there are also unknown unknowns
the ones we do not know we do not know…”     D. Rumsfeld, 2002

 How to analyze unknown unknowns?

How to contribute to this daunting challenge? Let us try the impossible! Let us develop straigthforward image-based bioanalytical hyphenated techniques/methods that can deal with the unknown unknowns. Why not including bioprofiling or effect-directed fingerprints in routine quality control to ensure the product quality and food safety more comprehensively? By this, food fraud and food adulteration will easier be detected. Such bioanalytical techniques for bioprofiling are also able to detect the active principle of health food, functional food, traditional medicines, plant extracts etc.

Besides our research in the above mentioned field of bioprofiling, we focus on miniaturization and think differently! By using totally new technologies in the field of chromatography, we try to set new perspectives and  impulses. For example by exploiting open source technologies, 3D printing and inkjet printing, pattern recognition algorithms and image evaluation by artificial neural networks, we work on a miniaturized, all-in-one planar chromatography system (Office Chromatography). Further research is in the field of quantitative surface scanning using direct analysis in real time mass spectrometry (DART-MS), analysis of food, commodities, botanicals, pharmaceutical formulations, environmental samples, trace analysis, etc.

Konfuzius wisely said "Reaching the water source, you have to swim against mainstream". This is particularly true for planar chromatography. Still a decade ago, a handful of colleagues recommended me to change my subject - a well-meant advice for my academic career.

For teaching in the time of ultrarapid separations, I developed a metaphor in 2005:

No styling is needed if you go by metro, meaning raw extracts are transported in HPTLC!
Imagine any metropolis like New York, Beijing, Tokyo, Paris or Moscow without the metro?
What about separation science? No metro/subway needed? Really?
Of course, I explained my thoughts in early papers, but the following figure also helps to understand.

HPTLC is the hairline! Not seen as option. If you understand the why, one can not change the subject (except for system users). By the way, the increase of the papers caused by the hyphenation to mass spectrometry is evident in the figure as well.

 

We curiously focussed our research on aspects of HPTLC that are unique like..

  1. Spotlight on the zone! Targeted mass spectrometry avoids waste data or MS system contamination!
    Since 2004, we have investigated the elution head-based coupling of planar chromatography with mass spectrometry. Since 2005, we have investigated desorption-based couplings as well. Up to now, we made over 100 peer-reviewed research papers that proved the progress in and benefit of the HPTLC-MS coupling, essential for the progress of HPTLC.
    Thank is owed to the Landesstiftung Baden-Württemberg for funding a PhD position 2006-2009 and DFG/JLU for funding the high-resolution mass spectrometry system.
  2. Bacteria on the plate! The open format is suited best among all chromatographic techniques!
    Though our first papers were made in 2008, we mainly started with the development of quantitative bioautography in 2013. In 2014, sharply bounded active zones were reported for the first time  after 70 years (in 1946, a Nature paper reported first on direct bioautography). New knowledge is obtained with this quantitative bioanalytical tool: We can deal with the unknown unknowns! We discover traces that matter. Our food is our medicine (attributed to Hippocrates) - so true! In over 50 peer-reviewed research papers, we brought forward this idea.
    Thank is owed to Merck that instantly recognized the potential. Thank is also owed to DFG who granted a postdoc position, though the position was not fulfilled.
  3. Print on the plate like on paper! We showed printing on the plate for the first time in 2007. We developed it further and printed sample solutions, the mobile phase or the HPTLC layer itsself. The current state is an open source Office Chromatography system.
    The exploited open source technologies also offered potential for own tailormade automatizations with regard to automated HPTLC-MS, for which we submitted 2 papers.
    I learned that such too novel ideas have to be evoked by mainly own privat resources. It was said, you can do it by yourself. So, doing it and being successful should be no problem, right? How can scientists bear the unbearable disrespect? Passion is the key. Recently, funding of a PhD position has been obtained.
Since I went back to academia in 2004, I noticed the beauty in the valleys passed - success is a journey. Crises are opportunities and chances to grow!
Meanwhile, we made around 900 scientific contributions, including more than 70 practical workshops, to give HPTLC an independent voice, trained and inspired more than a hundred guest researchers from over 25 countries in the potential of HPTLC, solved severe challenges of industrial processes and do have many requests from and projects with other academic groups and industries.

 

 
Flavonoid profiles of German propolis
(as CHROMart in our laboratory)

 

More details on three subjects, if you are interested...

Office Chromatography
Why not? The miniaturized all-in-one open source system!

In 2010, we have founded the new discipline combining planar chromatography with office peripherals, we called Office Chromatography. Focussing the open planar concept and participating in the worldwide progress of print & media technology, office chromatography will provide an ideal platform for miniaturized planar chromatography on ultrathin or nano-structured plates. Chromatographic runs are performed within a minute for many samples in parallel, meaning runs/sample below a second in a user-friendly environment. This new discipline is at its infancy, however, the fundamental proof was given in 2010. Read more in a review and the latest original research paper ...

 

 Effect-directed analysis
Better glasses? You want to see more?
HPTLC-EDA-HRMS as quantitative bioanalytical tool that points to effects

HPTLC coupled with bioactivity-based detection by Aliivibrio fischeri and Bacillus subtilis bacteria or a genetically modified yeast strain (pYES/pYAS assays) is combined with high resolution mass spectrometry (HRMS). On the example of screening for bioactive natural products in marine sponges this effective analytical approach was demonstrated via HPTLC-UV/Vis/FLD-bioactivity-HRMS (6, Chinese). All the following information was reached by a single HPTLC separation: (I) up to 30 sponges (just lyophilized, dissolved and centrifuged) were screened matrix-robust at one go for natural bioactive secondary products (UV/Vis/FLD/EDA images), (II) high producers of bioactive products were identified, (III) information on the range of bioactive products produced by the sponge was given and (IV) the sum formula was obtained from bioactive zones of interest. Read more in the latest original research paper and review or latest updated review (in Encyclopedia of Analytical Science).

Hyphenation HPTLC-MS
Targeted and fast. Say NO to waste data or unnecessary MS system contaminations!

During my Postdoctoral Lecture Qualification (professorial thesis) I successfully focussed on hyphenations and particularly on coupling of HPTLC with mass spectrometry (HPTLC-MS) because there has not been available any rational and practical coupling technique at the beginning. A key feature of HPTLC-MS is the cost-effective, targeted recording of mass spectra. Different approaches via open ionization sources, working under ambient pressure, were investigated. Direct analysis in real time (DART) was first coupled to planar chromatography by us (5) as well as atmospheric pressure glow discharge (APGD, later called FAPA). Meanwhile optimized solutions are existent. We substantially modified the DART SVPA interface and achieved mass signals that were by a factor of 34 more intense. Our modifications also enable a quantitative surface scanning, not only on TLC/HPTLC plates. A company worked on a dedicated TLC-MALDI software and we adapted the protocol for matrix-assisted laser desorption & ionization (MALDI). Using this technqiue, HPTLC-MALDI-TOFMS achieved repeatabilites of about 10 % directly from the plate via Imaging MS.
We successfully modified an interface, invented by Dr. Luftmann from University of Münster. In April 2004, his paper came out, and one month later I was in his lab, as I was excited to get such interface. He was very happy and surprised at the same time, as he had approached all companies in the field several times over 3 years - but persistently no interest! At that time the interface worked on flexible TLC foils/carriers, and we modified it for its usage on TLC/HPTLC glass plates first. Then, we showed that, using this modified interface, detectabilities were comparable to HPLC-MS and reliable quantification was possible as well. By our research reported in over 15 original research papers, we pointed out that the modified interface was the most reliable and universal plug & play tool for HPTLC-MS coupling worldwide. After four years (!), a company took over this successful approach in 2008 and started marketing of the interface in spring 2009 (flyer TLC-MS Interface). To conclude several practical options are now available for recording of mass spectra of zones of interest from the HPTLC plate within seconds. Read more in the latest original research paper and review...

 

 

Streamlined analysis
One can do it the way around or straigthforward - your decision. Who pays for inefficiency?

 "Wer etwas will, findet Wege. Wer etwas nicht will, findet Gründe."    Albert Camus, 1913-1960