9700 Quality-evaluated pKa values of more than 5000 acids in 7 dipolar aprotic solvents!

The Zenodo data collection (Image on the right)) recently published as IUPAC technical report Acid dissociation constants in selected dipolar non-hydrogen-bond-donor solvents. Pure and Applied Chemistry. 2025, 97, 973, https://doi.org/10.1515/pac-2024-0276 has been updated for the first time by new pKa values so that its version 1.5.0 now contains more than 9700 quality-evaluated pKa values of more than 5000 acids in 7 dipolar aprotic solvents (DMSO, MeCN, DMF, pyridine, acetone, propylene carbonate and THF). The values have been collected from around 800 original works. The widest possible selection of compound classes is covered (Table below). The results of this large-scale pKa data collection and evaluation work are now available for the scientific community to use in reaction mechanism analysis and modelling, catalyst design, computational method development, etc.

Very importantly, the collected pKa data have been critically evaluated based on predefined quality criteria and depending on situation, kept as they were originally published, flagged as doubtful/unreliable (around 2700 values) or corrected (around 2500 values).

To enable automated processing and data mining, as well as other kinds of cheminformatics, the data are presented as a set of spreadsheets, together with structural codes (SMILES and InChI strings), compound class qualifiers and comments.

The published IUPAC Technical Report contains also comprehensive educational background information on the acid-base processes in non-aqueous media, as well as brief descriptions of the main measurement methods, with focus on the reliability of the data and sources of uncertainty.

The data collection has been deposited in the Zenodo repository and is freely available at https://doi.org/10.5281/zenodo.12608876.

The work has been carried out in the framework of the IUPAC project 2015-020-2-500. It was additionally funded by numerous sources, most importantly the EMPIR programme (project 17FUN09 “UnipHied”, www.uniphied.eu), by the Estonian Research Council grants (PRG690, PRG2557) and by the Estonian Ministry of Education and Research (TK210).

Measurement Uncertainty online course: 797 participants from 96 countries!

On Tuesday, March 24, 2025 the web course Estimation of Measurement Uncertainty in Chemical Analysis was launched the twelfth time as a MOOC (Massive Online Open Course)!Altogether 797 participants from 96 countries are registered! In the map presented above, the yellow color marks the countries from where participants come. True, the map is coarse and some countries are small. Therefore, not all countries are visible. We are very happy that we have 4 participants also from Ukraine this year. Slava Ukraini!
Registration for this run is closed. But good news: if you did not manage to register this time, you are welcome to register for the 2027 edition of the course.

The full course material is accessible from the web page https://sisu.ut.ee/measurement/uncertainty. The course materials include videos, schemes, calculation files and numerous self-tests (among them also full-fledged measurement uncertainty calculation exercises). In order to pass the course, the registered participants have to pass six graded tests and get higher than 50% score from each of them. These tests are available to registered participants via the Moodle e-learning platform.

This course is run under the umbrella of the Estonian Center of Analytical chemistry (https://www.akki.ee/) and forms a part of the Excellence in Analytical Chemistry (https://www.analyticalchemistry.eu/) Erasmus Mundus master’s programme.

LC-MS Validation online course 10th run has finished!

On March 6, 2026 the on-line course (MOOC) LC-MS Method Validation offered by University of Tartu finished successfully.

Eventually, altogether 995 people registered from 95 countries. Roughly half of them, 486 participants, actually started the course (i.e. tried at least one graded test at least once), and out of them, 337 successfully completed the course. The overall completion rate was 34%. The completion rate of participants who started the studies was 69%. The completion rates of active participants (i.e. who started the course) seem to have stabilised at around 60% and have increased during the current run. In any case, there is some food for thought for us on how we could improve the participation rate…

At the same time, those participants who actually took part in the course were very active and asked lots of questions. The questions were often very much to the point and addressed things that are really important to analysts in their everyday work. The course has several forums (general and by topic). During the course period, the overall number of forum posts was around 200 (overall number of posts, both from participants and from teachers), and the forums are still active, and posts are still coming in.

This active participation made teaching this MOOC a great experience also for us, the teachers. The discussion threads gave a lot of added value to the course.

We want to thank all participants for helping to make this course a success!

We plan to repeat this course again in Autumn 2026.

The Cultural Heritage Research Group started with a new PRG project!

In January 2026, the cultural heritage research group – in collaboration with physicists, material scientists, conservators, and IT specialists – launched a challenging new five-year Personal Research Funding Team (PRG) project, led by Dr Signe Vahur. The main goal of the PRG3112 project is to develop a novel, portable, automated laser ablation sampling probe. This tool will enable minimally destructive stratigraphic and imaging analysis of artefacts directly on the object under ambient conditions. In the future, the probe could be coupled with various analytical devices (MS, Py-GC-MS, and FORS) and sampling containers.

We will keep you updated on the progress of this demanding and exciting project!

The research team remains largely the same as in our previous project.

The main members of the PRG team: team leader Dr Signe Vahur (in the centre), from left Dr Aleksei Treshchalov, Prof. Hilkka Hiiop, Dr Anu Teearu-Ojakäär, Dr Rünno Lõhmus and specialist Martin Leissoo.

Estimating measurement uncertainty in chemical measurements: difficulties and misconceptions

At the recent 10th Conference on Chemometrics, Metrology and Artificial Intelligence in Analytics conference in Poznań, Ivo Leito presented a keynote talk titled Estimating measurement uncertainty in chemical measurements: difficulties and misconceptions.

The presentation outlined three important misconceptions in estimation of measurement uncertainty in chemical measurements: (1) Uncertainty is primarily determined by the accuracy of the instrument; (2) Uncertainty is quantitatively expressed by (dis)agreement between results of repeated measurements and (3) „Simple“ measurements are simple.

All three misconceptions were debunked during the talk on the basis of the research of our group from the recent years: (1) In chemistry, uncertainty mostly comes from the object, not from the instrument; (2) In chemistry, uncertainty usually comes mainly from systematic effects, not from (within-day) random effects and (3) In chemistry, even for „simple“ measurement, adequate modeling and evaluation of individual uncertainty components is usually challenging.

The presentation made use of the recent work of our group: S. Pawade et al “A quantitative approach to determine water and moisture content of different types of lignin using attenuated total reflectance Fourier transform infrared spectroscopy combined with partial least squares regression” Biofuels, Bioprod. Bioref. 2026; L. Sooväli et al “Uncertainty sources in UV-Vis spectrophotometric measurement” Accred. Qual. Assur. 2006, 11, 246-255; “Critical compilation of acid pKa values  in polar aprotic solvents” Pure and Applied Chemistry, 2025, 97, 973-998; I. Helm et al “Comparative validation of amperometric and optical analyzers of dissolved oxygen: a case study” Environ. Monit. Assess. 2018, 190.

The presentation presented a pragmatic solution to measurement uncertainty evaluation of chemical measurement results: the approach based on validation and quality control data (also known as the single-lab validation approach).

The presentation was warmly received by the participants, receiving a number of quations and coffee break discussions!

(This research presented in the talk has been supported by the IUPAC project 2015-020-2-500, MetPart 23RPT03 GrainMet, Estonian Ministry of Education and Research (TK210), Estonian Research Council grants IUT20-14, PRG690 and PRG1557, Estonian Center of Analytical Chemistry, www.akki.ee)

New article on ancient dietary analysis by Archemy Group

The Archemy group is happy to share the latest article published in the Journal of Archaeological Method and Theory – Food Equality: Multiproxy Biomolecular Dietary Analysis Shows Unstratified Foodways Among Protohistoric E Baltic Communities.

The paper is crucial milestone for the group serving as an excellent example of collaborative analytical work combining all the multiple expertises of the Archemy.  The results do not only challenge our previous understanding of Conversion period social dietary practices in Estonia, but will serve as a key-reference for future multi-proxy and multi-method dietary analysis. The main findings include:

*There was no major dietary difference between men, women and children in the 12th-13th century AD Pada community: all had equal access to food sources!

*Meat-based foods were preferred in burial ritual contexts, whilst plant-based foods formed majority in daily food consumption.

*No single proxy approach or method can reveal the full spectrum of ancient dietary practices.

Many thanks to all the amazing collaborators who contributed to this work!

 

New publication: determining water content in lignin using ATR-FTIR

Shrikant performing the FTIR measurements

We are delighted to share that our latest article titled “A quantitative approach to determine water and moisture content of different types of lignin using attenuated total reflectance Fourier transform infrared spectroscopy combined with partial least squares regression” has been published in the journal of Biofuels, Bioproducts and Biorefining (Volume 20, 2026). The article was authored by Shrikant Shivaji Pawade, together with Dr Martin Vilbaste, Andres Siiman, Dr Lauri Toom, Associate Professor Koit Herodes, and Professor Ivo Leito. The article is Open Access and available online; click here to access it.

The study presents a quantitative methodology for determining water and moisture content in diverse lignin types using ATR-FTIR spectroscopy combined with partial least squares regression, with vapourisation–coulometric Karl Fischer titration (vap-C-KFT) and gravimetric methods used as reference techniques. In addition, the work introduces a sigmoid curve approach to temperature optimisation for vap-C-KFT and evaluates sampling and modelling uncertainties, thereby providing practical insights for reliable lignin characterisation. The robustness of the method was assessed by validation against vap-C-KFT, oven drying (7 h and 48 h), and freeze-drying, utilising diverse lignin types (Kraft, Dealkaline, and Lignova Fibenol) and achieving RMSEP values ranging from 0.33 to 1%.

The results demonstrate that ATR-FTIR combined with chemometrics modelling can provide a rapid, simple, and cost-effective alternative to conventional methods, while maintaining good accuracy across diverse lignin types.

Measurement Uncertainty MOOC: Registration is now open!

The 2026 edition of the web course (MOOC) Estimation of Measurement Uncertainty in Chemical Analysis will run from March 24 to May 6, 2026. Registration is now open!

The full course material (as well as the registration link) is accessible from the web page. The course materials include videos, schemes, calculation files, and numerous self-tests (among them also full-fledged measurement uncertainty calculation exercises) and examples. Almost all areas of analytical chemistry are addressed, ranging from simple volumetric operations and titrations to sophisticated instrumental analysis, such as determining pesticide residues by LC-MS. Efforts are made in the course to address also such uncertainty sources encountered in chemical analysis that are difficult to quantify, e.g. uncertainty due to possible interference effects (incomplete selectivity), analyte losses, etc.

In order to pass the course, the registered participants have to take six graded tests and get a higher than 50% score in every graded test. These tests are available to registered participants via the Moodle e-learning platform.

Participants who successfully pass the course will get a certificate from the University of Tartu. A digital certificate of completion is free of charge. A certificate of completion on paper can be requested for a fee of 62 euros.

You are welcome to distribute this message to potentially interested people!

A new article about a developed laser ablation-based mass spectrometric system for the analysis of cultural heritage materials has now been published!

The Cultural Heritage research group, as part of this year-end PRG1198 research project, has published an open-access article titled “Laser ablation APCI-HRMS method for the analysis of cultural heritage materials” by Anu Teearu, Martin Leissoo, Rynno Lohmus, Alexey Treshchalov, Tõiv Haljasorg, Victor Augusto Xavier da Silveira, Hilkka Hiiop, and Signe Vahur in the Journal of the American Society for Mass Spectrometry. The article is available here.

Graphical Abstract for the publication

This research article highlights a novel 355 nm optical fibre-coupled laser ablation (LA)-APCI-FT-ICR-MS system, developed for direct, controllable, rapid, and accurate analysis of organic materials from the solid surface of an artefact under ambient conditions with minimal surface damage and without the need for sample removal or sample preparation for the analysis. In this study, the effectiveness and capabilities of the developed LA-APCI-HRMS system for analysing five aged mock-up materials (copper resinate, Prussian blue oil and egg tempera paints, lead white oil paint and matte dammar varnish) and the blackish-brown material from an ointment jar from a 16th-century shipwreck were investigated. The results can be read in the article.

The PRG1198 project team has done excellent work over the past five years, culminating in a working laser-based HRMS system. The same team will begin next year with a new project, and we will continue to keep you updated on all new developments.

In the photo, the main members of the PRG team: team leader Dr Signe Vahur (in the centre), from left Dr Aleksei Treshchalov, Prof. Hilkka Hiiop, Dr Anu Teearu-Ojakäär, Dr Rünno Lõhmus and specialist Martin Leissoo.

 

LC-MS Method Validation web course: 999 participants from 95 countries!

On Tuesday, December 16, 2025 the web course LC-MS Method Validation was launched for the tenth time as a MOOC (Massive Online Open Course). There are 999 registered participants from 95 countries, ranging from Canada to New Zealand and from Peru to Thailand. The image above shows the countries where the participants come from.

This is a practice-oriented on-line course on validation of analytical methods, specifically using LC-MS as the technique. The course introduces the main concepts and mathematical apparatus of validation, covers the most important method performance parameters and ways of estimating them. The LC-MS validation course is delivered by a team of 7 teachers, each with their own specific area of competence. This way it is expected to offer the best possible knowledge in all the different subtopics of analytical method validation.

The full set of course materials is accessible from the web page https://sisu.ut.ee/lcms_method_validation/. The course materials include videos, schemes, calculation files and numerous self-tests (among them also full-fledged calculation exercises). In order to pass the course, the registered participants have to take all tests and get higher than 50% score from each of them. These tests are available to registered participants via the Moodle e-learning platform. Participants who successfully pass the course will get a certificate from the University of Tartu.