<div><div>Protons play a central role in many chemical reactions in living organisms. In some cases, a proton may be shared between two nearby molecular groups rather than being localized on just one. This phenomenon can strongly influence the properties and reactivity of biomolecules and is important for enzyme function.</div></div><div>Researchers led by Hanns Christian Schewe (IOCB Prague and Heyrovský Institute of the CAS) together with Lukáš Tomaník (UCT Prague and Fritz Haber Institute of the Max Planck Society) have now investigated proton sharing in a range of biologically relevant polycarboxylic acids dissolved in water, including several molecules related to the citric acid cycle (Krebs cycle).Using liquid-jet X-ray photoelectron spectroscopy (LJ-PES), a technique that reveals the chemical environment of atoms in molecules dissolved in water, the team was able to probe the position of protons on an ultrafast time scale. Unlike techniques such as NMR, which provide a time-averaged picture, photoelectron spectroscopy captures the instantaneous distribution of protons and can therefore distinguish more directly between localized and shared states.The results showed significant proton sharing only in maleic acid dissolved in water. In contrast, protons remained mostly localized at individual carboxylic groups in succinic acid, fumaric acid, malic acid, glutaric acid and citric acid. This suggests that proton sharing is not a common feature of these molecules when they are freely dissolved in water.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/IOCB_Prague_Cropped_part_of_the_cover_by_Schewe_et_al_with_the_use_of_Nano_Banana_2_0_2_2a408dbeb5.webp" alt="IOCB Prague: Cropped part of the cover by Schewe et al. with the use of Nano Banana 2.0: Full cover by Schewe et al. with the use of Nano Banana 2.0." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_IOCB_Prague_Cropped_part_of_the_cover_by_Schewe_et_al_with_the_use_of_Nano_Banana_2_0_2_2a408dbeb5.webp 117w," sizes="100vw" width="1620" height="2154">The difference appears to be largely controlled by molecular geometry. In maleic acid, the two carboxylic groups are held close together, creating favorable conditions for proton sharing. More flexible molecules can adopt conformations in which the groups are farther apart, while water molecules form strong hydrogen bonds with them and favor localized protons.However, the situation may be different inside proteins. When a carboxylic acid binds in the active site of an enzyme, its shape and position can be tightly constrained. Such an environment could bring the relevant groups close enough together to promote proton sharing and thereby influence enzymatic reactions.The study highlights an important distinction: proton sharing may be rare in freely hydrated molecules but could become important when biomolecules are held in the right geometry by enzymes. It also demonstrates that LJ-PES is a powerful tool for studying proton behavior in solutions. Its ultrafast and site-specific sensitivity could in future help researchers investigate proton sharing directly in more complex chemical and biological systems.<blockquote><h4>The original article</h4><h4><a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/jaaucr/article/6/6/3349/5084661/Proton-Sharing-in-Polycarboxylic-Acids-in-Aqueous">Proton Sharing in Polycarboxylic Acids in Aqueous Solution</a></h4>Lukáš Tomaník, Jiří Tůma, Gunnar Öhrwall, Ronny Golnak, Ngoc Lan Le Nguyen, Bruno Credidio, Harmanjot Kaur, Petr Slavíček, Bernd Winter, H. Christian Schewe<div>JACS Au, 2026, 6, 3349–3355</div><a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1021/jacsau.6c00377">https://doi.org/10.1021/jacsau.6c00377</a><h6>licenced under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a></h6></blockquote><h4>Abstract</h4>We investigate proton sharing in biologically relevant polycarboxylic acids in aqueous solutions using liquid-jet X-ray photoelectron spectroscopy. In contrast to techniques that record time-averaged proton positions, like nuclear magnetic resonance, photoelectron spectroscopy captures instantaneous proton distribution due to its ultrafast probing time scale. The method is, therefore, uniquely sensitive to the occurrence of proton sharing in an aqueous environment, as demonstrated here. We only observe significant proton sharing dynamics in maleic acid, where its monoanionic form shows a single, delocalized peak in the carbon 1s spectrum. Conversely, succinic acid, fumaric acid, malic acid, glutaric acid, and citric acid exhibit distinct peaks corresponding to separate, localized COOH and COO– groups, instead of shared protons. Our results reveal that intramolecular proton sharing in water is rather an exception for most biologically relevant polycarboxylic acids. This highlights the importance of enzyme-driven structural changes of polycarboxylic acids associated with proton sharing during metabolic processes.</div>

Proton sharing in polycarboxylic acids in aqueous solution

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Breathomics, Asthma & GC×GC: PH Stefanuto on Fighting the “Proof‑of‑Concept” Trap

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The Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB Prague) is a leading scientific institution in the Czech Republic, recognized internationally. Its primary mission is basic research in the fields of chemical biology and medicinal chemistry, organic and material oriented chemistry, chemistry of natural compounds, biochemistry and molecular biology, physical chemistry, theoretical chemistry, and analytical chemistry. 

Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences

Analytika is a Czech company that offers and produces certified reference materials (CRM) and (ultra)pure chemicals for quality control and quality assurance in laboratories, including accredited laboratories.

Our portfolio also includes pipettes and tips, digestors, PFA labware and other equipment for analytical laboratory and trace analysis.

ANALYTIKA

Organomation, founded in 1959, designs and manufactures high-quality nitrogen evaporators and extraction systems. Known for innovation and durability, their lab instruments are used globally for efficient sample preparation with strong customer support.

Organomation

Wasson Dynamic Blender for GC (DB302)

The Dynamic Blender is a portable gas blending device that dilutes a sample or a certified standard with a matrix gas of choice.

Gas chromatography (GC) analyses often include trace level detection of components requiring samples or standards at low concentrations. Some analytes are expensive or difficult to purchase at low levels due to reactivity, adsorption, or high molecular weight. Analyses may also cover a wide concentration range, requiring multi-point calibration.
The Wasson-ECE Dynamic Blender (DB302) provides a simple solution to these calibration needs. The Dynamic Blender is a portable gas blending device that dilutes a sample or a certified standard with a matrix gas of choice. One certified standard with concentrations at the upper limit of the desired calibration curve can be diluted to a lower level (&gt;2 orders of magnitude lower) to create a full calibration curve.
An inert flow path and heated bridge eliminate adsorption and condensation problems when blending gas standards that include sulfur, nitrogen, and other reactive compounds.
An on-board flow controller allows the diluent gas flow to be controlled digitally and samples are fed directly to a gas chromatograph. The Dynamic Blender eliminates the need to purchase and store multiple gas cylinders and provides an easy, cost-effective solution for gas phase calibration needs.
<h4>Dynamic Blender Features</h4>
<ul>
<li>Approximately 100 pre-programmed pure diluent gases and mixtures and twenty user configurable diluent mixture slots.
</li>
<li>Maximum Diluent Pressure of 100 psi (leak tested to this pressure)
</li>
<li>Maximum Temperature of 150°C (operation verified at this temp.)
</li>
<li>Mass Flow Controller Range of 10 – 500 cc/min
</li>
<li>7 μm in-line gas filters (treated) are also provided
</li>
<li>Specially passivated tubing for trace reactive compounds (sulfurs, oxygenates, etc.)
</li>
</ul>
*This treatment is not suitable for samples with pH &gt; 8.0, so please notify your sales representative if you have high pH samples.

ARC Polyarc System

A Breakthrough Innovation Revolutionizing GC/FID Technology. The Polyarc System is transforming the way scientists use gas chromatographs with Flame Ionization Detectors.

The Polyarc system has a catalytic microreactor that enhances new and existing gas chromatographs (GCs) with flame ionization detectors (FIDs) by converting all organic compounds to methane molecules prior to their detection by the FID. In doing so, the Polyarc system reduces the need to perform time-consuming calibrations by creating a uniform detector response for truly universal carbon detection.
The Polyarc system gives scientists the capability to determine purity, quantify unknowns, qualify products, investigate, improve development and more in a simple, fast and more economical way that is transforming the industry.
<blockquote>
Available for gas chromatographs (GC) <a href="https://gcms.labrulez.com/products?category=1&amp;manufacturerItems=10">Agilent</a> 5890, 6890, 7820, 7890, 8890, <a href="https://gcms.labrulez.com/products?category=1&amp;manufacturerItems=1">Shimadzu</a> 2030, <a href="https://gcms.labrulez.com/products?category=1&amp;manufacturerItems=3">Thermo Fisher</a>, Varian, Bruker a Scion GC.
</blockquote>
<h3>What is Polyarc?</h3>
The Polyarc is the next evolution of flame ionization detection (FID). The Polyarc converts the FID into a truly universal carbon detector using proprietary catalytic reactions that convert organic molecules to methane immediately prior to detection.
<h3>Why is it important?</h3>
The FID has two main challenges: lack of uniform response and low response to certain compounds. The Polyarc enhances your FID to solve these challenges by giving your FID a uniform response to nearly all organic molecules. The result is more accurate data, improved productivity, lab efficiencies, and the ability to detect more compounds.
<h3>How Does the Polyarc® System Work to Simplify and Improve GC/FID Quantification?</h3>
The Polyarc system has a catalytic microreactor that enhances GC/FIDs by converting all organic compounds to methane molecules prior to detection by the FID. The result?
A universal response for ALL organic molecules.
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ARC_Polyarc_FID_vs_FID_Response_Factors_0f9c958558/ARC-PolyarcFID-vs-FID-Response-Factors.jpg" alt="ARC: Comaprison of Polyarc/FID vs FID Response Factors.jpg"/>
<h3>The Polyarc System Features an Optimized Design and Seamless Integration</h3>
The Polyarc system is the first commercial technology of its kind. The device uses proprietary technologies including novel catalysts, a specially designed 3D-printed micro reactor, and fast seamless integration into existing equipment.
The optimized internal design and catalyst microstructure maintains separation performance and peak shape while increasing sensitivity and enabling accurate quantification without calibration standards.
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ARC_Optimalizovany_design_a_specialne_navrzeny_3_D_tisteny_mikroreaktor_Polyarc_70ccedc41e/ARC-Optimalizovany-design-a-specialne-navrzeny-3D-tisteny-mikroreaktor-Polyarc.jpg" alt="ARC: Specially designed 3D-printed micro reactor Polyarc"/>
<h3>Perform Cutting-Edge Chromatography on Any Organic Compound with a Polyarc® System</h3>
Realize a greater breadth of analysis with improved detection of compounds previously invisible or with an extremely low sensitivity by gas chromatography using FID only — while reducing the need for time intensive calibration.
The careful selection and robust catalyst design enables the analysis of a wide variety of compounds including a range of heteroatoms, compounds of various sizes, and samples containing common catalytic poisons (e.g., S).
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ARC_Analyza_siroke_skaly_sloucenin_pomoci_Polyarc_systemu_3e18241358/ARC-Analyza-siroke-skaly-sloucenin-pomoci-Polyarc-systemu.png" alt="ARC: Polyarc system enables the analysis of a wide variety of compounds"/>
<h3>How Does the Polyarc System Compare to a Methanizer?</h3>
A conventional methanizer converts CO and CO₂ to methane, allowing low level FID detection of CO and CO₂. The significant advantage of the Polyarc system is that it converts all compounds to methane, allowing not only for the detection of CO and CO₂ , but also millions of other organic compounds.
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ARC_Srovnani_systemu_Polyarc_s_metanizerem_7df16e09c7/ARC-Srovnani-systemu-Polyarc-s-metanizerem.jpg" alt="ARC: Comparison of the Polyarc System with a metanizer"/>

ARC Jetanizer (Methanizer)

The Jetanizer is the easiest and most robust methanizer.

<h3>What is Jetanizer™?</h3>
The Jetanizer is the easiest and most robust methanizer. A methanizer is a chemical reactor that converts carbon dioxide and carbon monoxide to methane to enable sensitive detection by a flame ionization detector (FID) from &lt;20 ppb to 100%!
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ARC_Analyza_CO_2_od_1ppm_do_100_s_pouzitim_GC_jetanizeru_FID_9c922be2e9/ARC-Analyza-CO2-od-1ppm-do-100percent-s-pouzitim-GC-jetanizeru-FID.jpg" alt="ARC: CO₂ analysis from 1ppm to 100% with GC/Jetanizer/FID"/>
<h3>Why is it important?</h3>
<h4>Low-level detection of CO and CO₂ is important in:</h4>
<ul>
<li>catalysis </li>
<li>hydrogen (H₂) purity analysis </li>
<li>dissolved gas analysis (DGA)</li>
<li>greenhouse gas (GHG) analysis, </li>
<li>transformer oil gas analysis (TOGA)</li>
<li>ethylene/propylene monomers analysis </li>
<li>safe entry analysis, and more</li>
</ul>
Traditionally, large nickel-catalyst-filled tube methanizers are used, however, they are prone to frequent failures, and they are difficult and time consuming to operate and maintain. 
<blockquote>
Legacy nickel catalyst methanizers take 2-6 hours to install and replace. Jetanizers take &lt;5 minutes.
</blockquote>
ARC’s Jetanizer solves these challenges by improving response, robustness and ease of installation, by incorporating state-of-the-art catalysts into an FID jet. Moreover, the Jetanizer enables low level &lt;1 ppm formaldehyde analysis by GC avoiding the pitfalls of HPLC analysis of formaldehyde.
<blockquote>
For use with these GC models: <a href="https://gcms.labrulez.com/products?category=1&amp;manufacturerItems=10">Agilent 5890, 6890, 7890, 8890, Intuvo</a>, <a href="https://gcms.labrulez.com/products?category=1&amp;manufacturerItems=1">Shimadzu 2010, 2030 GC</a>.
</blockquote>
<h3>Benefits over Traditional Methanizers</h3>
<ul>
<li>Lower up-front cost</li>
<li>No extra plumbing: minimize fittings and leaks</li>
<li>No extra heater or controller: utilizes heat from FID</li>
<li>FAST installation: Less than 5 minutes</li>
<li>Ability to be used with formaldehyde</li>
<li>Higher sulfur tolerance</li>
<li>Higher catalytic activity = larger linear dynamic range</li>
<li>Free up space on the GC</li>
<li>No toxic metals: The Jetanizer™ does not contain nickel catalysts</li>
</ul>
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ARC_Kalibrace_analyzy_CO_2_s_pouzitim_GC_jetanizeru_FID_2f0b6171fc/ARC-Kalibrace-analyzy-CO2-s-pouzitim-GC-jetanizeru-FID.jpg" alt="ARC: CO₂ analysis calibration with GC/Jetanizer/FID"/>

ARC Precision Split

ARC’s PrecisionSplit device allows scientists and chromatographers to take advantage of the quantitative power of the Polyarc/FID in combination with the mass identification power of the mass spectrometer, all in the same injection in real time.

<h3>Why does my MS need an FID?</h3>
A mass spectrometer (MS) provides valuable qualitative data, but poses several challenges to accurate quantification. Adding a flame ionization detector (FID) in parallel with the MS gives complementary quantitative carbon concentrations with minimal extra effort or equipment. We believe every MS needs an FID companion for quantitative analysis, especially for non-targeted analysis or tentatively identified compounds where quantification is desired.
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ARC_Precision_Split_6271ed1240/ARC-Precision-Split.jpg" alt="ARC: Precision Split"/>
<h3>The benefits of a MS/FID split:</h3>
<ul>
<li>Virtually eliminate response factor variability</li>
<li>Quantify accurately (better linearity, more consistent response, fewer calibration errors)</li>
<li>Improve sensitivity for poor ionizers with the FID</li>
<li>Save your source!</li>
</ul>
<h3>The Data</h3>
Response factor (RF) variation in the mass spectrometer (i.e., the relative response of the MS to different chemicals) can lead to significant errors in quantification. Two compounds that have the same response/area in the MS can have concentrations that differ more than 100-fold (see <a href="https://www.sciencedirect.com/science/article/pii/S0731708520304283">Jordi et al.</a>). 
As you can see below, the Polyarc/FID split can reduce this response factor variation so that accurate quantification of tentatively identified compounds is possible.
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ARC_Variance_RF_u_MS_detektoru_8e02773edc/ARC-Variance-RF-u-MS-detektoru.jpg" alt="ARC: RF variation with MS"/>
<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ARC_Variance_RF_s_Polyarc_FID_splittrem_ca7def3cb3/ARC-Variance-RF-s-Polyarc-FID-splittrem.jpg" alt="ARC: RF variation with Polyarc/FID split"/>

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Breathomics, Asthma & GC×GC: PH Stefanuto on Fighting the “Proof‑of‑Concept” Trap

Proton sharing in polycarboxylic acids in aqueous solution

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