CE-Forum 2024

From 2017 to 2020, I was a co-organizer of the CE Forum. The aim was to bring together people involved in capillary electrophoretic separations in the DACH region to present and discuss their ongoing research and, in particular, the problems and questions they face. The CE Forum provides a platform for graduate students and postdocs to advance their scientific careers. It has been an annual meeting since 2009.

The Corona epidemic interrupted the series 2021-2023. On the initiative of a group of former doctoral students of Prof. Christian Neusüß, Aalen University of Applied Sciences, the CE Forum was re-established. It occurred on February 28 and 29 at the Aalen University of Applied Sciences. Prof. Neusüß arranged for the university to host the event and to provide the necessary accommodation and services. Details about the organizers and the program can be found on the CE-Forum website.

Because of my past involvement with the event, I attended the 2024 CE Forum, but due to personal commitments, I only attended on February 28th. In this article, I will share my impressions of that day.

There were about 65 participants. Most were from Germany, but others came from Switzerland, the Czech Republic, Belgium, and the Netherlands. The scientific program consisted of one keynote lecture, 17 oral presentations, and 17 posters. Please take details about the program on the following page.

Prof. Philipp Schmitt-Kopplin from the Helmholtz Center Munich gave the keynote lecture. He gave an impressive account of his work in metabolomics applied to very complex biological systems. To achieve this goal, his group developed a CE-MS platform as an alternative to HILIC. Fascinating was the study of samples from extraterrestrial sources (meteors), where they found clear indications of similar organic molecules as on Earth.

Dr. Jana Lavicka (formerly Novotná), Institute of Analytical Chemistry of the Czech Academy of Sciences, Brno, Czech Republic, and Dr. Guinevere Lageveen-Kammeijer, Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, The Netherlands, both presented papers on hydrazone formation for the CE separation and MS determination of N-glycans.

Jana used BODIPY FL hydrazide. Hydrazon formation is a slow chemical reaction, but the derivatives have improved electrophoretic mobility and better detectability. Guinevere doped the nebulizer gas with hydrazine to achieve in-spray hydrazone formation, which increases the sensitivity of MS detection.

My former Agilent colleagues, Drs. Christian Wenz and Johannes Schlecht presented the recently introduced Agilent ProteoAnalyzer system. This instrument contains 12 parallel FS capillaries for SDS Protein Gel Electrophoresis. Protein samples in a 96-well plate are derivatized with a fluorescent label before separation. The capillary length is approximately 22 cm. Detection is by LED-induced fluorescence with a CCD, which is remarkable given that CMOS sensors are replacing CCDs for imaging solutions in many industrial, medical, and scientific applications. The base technology for this system comes from Agilent's Fragment Analyzer for DNA and RNA samples.

The assay is comparable to the similar single-channel assay on the Agilent Bioanalyzer. For a comparison between the protein assay on the Bioanalyzer and the Proteome Analysis System, see the following app note from Agilent.

Agilent's apparent strategy is to become a significant player in the capillary electrophoresis business for protein analysis and to move away from single-channel CE systems such as the Bioanalyzer and the G7100 CE system. The question remains: how to couple multi-capillary CE with mass spectrometry detection.

Dr. Whitney Smith from Sciex presented an image-CIEF separation on a microchip CE system called INTABIO ZT. Intabio, a start-up company recently acquired by Sciex, developed this system. Dr. Smith started by saying that "iCIEF is the gold standard for protein charge variant analysis," a statement that I could not agree with more.

Smith's presentation clearly shows the motives for Sciex's acquisition of INTABIO. Integrating INTABIO ZT with Sciex ZenoTOF 7600 mass spectrometers has given the system an extra dimension in identifying proteins in a sample, namely the isoelectric point from the CIEF trace and structural information from the mass spectrum in one run.

Coupling a longitudinal CIEF separation, where the protein zones are focused in place, with an analysis in a vacuum analyzer is extremely difficult, as the Neusüß group has shown in their work in this field. One has to carefully manage the voltages for separation and ion spray ionization and control the movement and dispersion of the protein zones during mobilization from the separation capillary and travel into the MS.

The speaker focused very much on application results. She did not provide details on how the actual coupling is performed or details on the ampholytes, electrolytes, and markers used. The dimensions of the separation channel were left in the dark. Prof. Neusüss' question about what the TIE looks like was not answered. In a technical paper at WCBP2024, Astra Zeneca showed that the CIEF separation of some antibody-drug conjugates was well preserved in the TIE from the mass spectrometer.

Ms. S Simon Krabbe of 908-Devices presented the ZipChip, a microfluidic CE separation device intimately coupled with a commercial mass spectrometer.

The separation channel has a length of 10 or 22 cm and a width and height of 10x70 µm. It is a simple single-channel CZE separation with cross-injection of the sample and adding an auxiliary solvent just before the corner of the chip to assist the electrospray ionization. Simon focused on applying the device for routine characterization of biotherapeutics, e.g., charge variant analysis by CZE.

Life science research is a market in which 908-Devices is active. However, as an objective observer who has been involved with a company (Agilent Technologies) that has tried to grow its business in this market with microfluidic analysis systems (Bioanalyzer, HPLC chip), reservations are in order regarding 908 Devices efforts establish itself in this market with a microfluidic analysis system. Process analysis and forensics (pharmaceutical toxins and chemical warfare detection) seem more promising.

Dr. Christopher Lößner from Boehringer Ingelheim demonstrated how CE-MS is used in the analytical development of biopharmaceuticals. He showed the CE Infinite from AES, Ontario, Canada, as one of their favorite tools for iCIEF.

Overall, it was a long but very valuable day for me. I had the opportunity to meet contacts in the DACH CE area who were students before and  now industrial scientists.

The organizers deserve a big compliment for re-establishing the forum and are encouraged to promote and continue the CE forum.