The Cultural Heritage research group published an article about their novel developed laser ablation-based analytical system (LA-APCI-MS) capabilities!
Within the framework of the PRG1198 research project Dr Signe Vahur with her team (Dr Anu Teearu, Dr Rünno Lõhmus, Martin Leissoo, Dr Alexey Treshchalov, Dr Janis Lungevics, Dr Georg Arju, Dr Hilkka Hiiop) has published a new article titled “Characterisation of laser-ablated craters of different painting materials and evaluation with modified LA-APCI-MS system” in the Journal of Talanta. The article is available here: https://doi.org/10.1016/j.talanta.2025.127856
The article presents preliminary results obtained by investigating the pulsed 355 nm Nd:YAG laser’s impact on specific painting materials (oil and acrylic paints and varnish) surfaces by characterising the area and volume of laser-ablated craters (measured with an optical microscope and 3D profilometer) obtained with different laser energies and the number of pulses at 90°, 70°, and 45° incidence angles and evaluating intensity of corresponding MS signals obtained with APCI-MS.
For the first time, potentiometric pH measurement traceable to the conventional aqueous pH scale has been successfully demonstrated in a low-polarity solvent, 1,2-dichloroethane (1,2-DCE)!
Paulo and Jaan from our group achieved this remarkable result, which has now been published: “Experimental Unified pH Scale in 1,2-Dichloroethane” (Phys. Chem. Chem. Phys., 2025, 27, 3810–3816).
The measurement approach is rooted in the unified pH scale (pHabs scale) concept and is based on pairwise differential potentiometric comparisons of solutions yielding their pHabs differences (ΔpHabs values). 85 such pair-wise measurement comparisons were carried out between solutions prepared in 1,2-DCE, some solutions in mixed solvents and aqueous standard pH buffer solutions. The resulting pHabs “ladder” is pictured in Figure 1.
Figure 1. pHabs scale of solutions in 1,2-DCE, linked to the standard aqueous buffer solutions and comparison against reported pHabs values in the literature.
Applying a least squares minimization approach to the ΔpHabs values and taking into account the reference values of the aqueous standard buffers allowed us to assign pHabs values to 19 equimolar buffer solutions in 1,2-DCE, yielding a pHabs range of −2.9 to 11.0. The consistency standard deviation of 0.17 pH units—higher than similar measurements in polar solvents—reflects the experimental challenges of working in low-polarity media.
Multiple salt bridge configurations (shown in Figure 2) were tested to improve measurement stability. Out of the four tested configurations, a separate salt bridge configuration (SB4) with PEEK capillary tubes yielded the most stable and reliable results, extending measurements for up to five hours without significant drift.
Figure 2. Different salt bridge setup configurations used in the work.
Direct pH measurement of 1,2-DCE solutions against standard aqueous pH buffers is challenging because of the very different nature of the solvents and possible water contamination of 1,2-DCE can significantly affect the measurements. Therefore, bridging solutions (a 60:40 acetonitrile/pH 4 formate solution and buffered ethanol) were employed to facilitate measurements against standard aqueous pH buffers. This approach allows the pHabs values in 1,2-DCE to be directly comparable to the aqueous pH values.
The obtained results confirm that potentiometric pHabs measurements are possible in low-polarity solvents, paving the way for experimentally linking many low-polarity solvents into a unified pH scale. Employing pHabs to compare solution acidity across different media will improve our understanding of how pH impacts processes in catalysis, liquid chromatography, sustainable energy, and the interpretation of acid-base processes in various solvents.
(This research was supported by grant PRG690 from the Estonian Research Council)
Eventually, altogether 1029 people registered from 99 countries. Roughly half of them, 509 participants actually started the course (i.e. tried at least one graded test at least once) and, out of them, 299 successfully completed the course. The overall completion rate was 29%. The completion rate of participants who started the studies was 59%. The completion rates of active participants (i.e. who started the course) seems to have stabilized at around 60%, which can be considered good. In any case, there is some food for thought for us on how we could improve the overall completion 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) and during the course period the overall number of forum posts was above 300 (!) (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 2025.
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 on 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 60 euros.
You are welcome to distribute this message to potentially interested people!
From 20-22 February, Naila attended the 18th International Joint Conference on Biomedical Engineering Systems and Technologies (BIODEVICES2025) in Porto, Portugal.
Biodevices conference was part of a joint conference (BIOSTEC) that covered different topics such as electronics, microfluidics systems, and biodevices and brought together scientists from various backgrounds worldwide. It was exciting to listen to presentations about new achievements in different areas related to biology and medicine. Topics varied from monitoring and diagnostics devices, sensors, and instrumentation systems to wearable and implantable devices.
It was her first international conference, and she had the pleasure of sharing her science in a poster presentation format. The poster was based on the article that she is working on titled “Alkaline phosphatase-based ELISA and particle-based microfluidic test for biotin detection.” She enjoyed inspiring and challenging discussions with her colleagues from diverse scientific backgrounds and checking other posters by her colleagues.
Besides, she commented on how fascinating the conference venue, a coastal city of Portugal, Porto, was with its colourful buildings, calming riverside, kind people, and warm weather. It was a perfect mix of cultural and scientific experience as her first international adventure.
On January 31, 2025, Professor Hilkka Hiiop was elected as the next rector of the Estonian Academy of Arts (EKA). Hilkka has been the Dean of the Faculty of Art and Culture since 2021 and the leading force in the Department of Cultural Heritage and Conservation for more than 10 years. Since 2021, she has also been a member of the PRG 1198 project working on the development of the laser-pen probe-MS system.
Hilkka has led numerous award-winning projects, the most recent one being the recovery and restoration of the Plafond painting in the Estonian Knighthood House. In this project, assoc. prof. Signe Vahur from our chair was also involved in performing the analysis of numerous samples to help identify the materials used in this rare work of art.
The world-famous historian and broadcaster Bettany Hughes was back in Estonia last week, and this time she visited scientists at the University of Tartu, including the members of the Archemy Lab from our chair of analytical chemistry. Ester and Mari talked about their interdisciplinary research and recent discoveries in biomolecular archaeology.
As they say in the filming industry “to be continued…”.
Below are some first shots of the filming with Ester.
On Tuesday, November 26, 2024 the web course LC-MS Method Validation was launched for the ninth time as a MOOC (Massive Online Open Course). There are 1034 registered participants from 99 countries, ranging from Mexico to Japan and from Australia to Iceland. The image below shows the countries where the participants come from.
This is a practice-oriented online course on validation of analytical methods, specifically using LC-MS as the technique. The course introduces the main concepts and mathematical apparatus of validation and 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.
We are happy to announce that a member of our group, Mari Tõrv, research fellow in the Archemy team, is one of the three Estonian researchers to receive the Baltic Women in Science fellowship this year!
From left: Mari Tõrv, Kadri-Ann Pankratov and Marju Himma (photos by Martin Mae)
Mari’s research delves into the biological and cultural diversity of ancient humans, emphasizing the duality of the human body as both a historical and cultural construct and a biological reality. She studies life and death in past cultures through the analysis of ancient human remains, highlighting the importance of understanding end-of-life rituals to fully grasp human nature, a subject often taboo in the Western world.
Tarmo Soomere, President of the Estonian Academy of Sciences emphasized “Talented and successful women scientists deserve to be highlighted and recognised across the whole spectrum of science. Their example inspires and ignites.”
The fellowships were funded by the Ministry of Education and Research and awarded within the program co-organised by the Baltic National Academies of Sciences and National Commissions for UNESCO. The fellowship is aimed to support the research of young women scientists to continue their outstanding work in the Baltic States.
See the video below, where Mari talks more about her research. The basis of this blog post and information on the work of the other two laureates can be found here.
The ninth edition of the online course LC-MS Method Validation is open for registration (registration link is here)! The course will be offered as a Massive Open On-line Course (MOOC) during November 26, 2024 – February 7, 2025.
This is a practice-oriented on-line course on validation of analytical methods, specifically using liquid chromatography-mass spectrometry (LC-MS) as technique, mostly (but not limited to) using the electrospray (ESI) ion source. The scope of the course is sufficiently broad, so that it will be useful also to chromatography practitioners using other detector types. The course introduces the main concepts and mathematical apparatus of validation, covers the most important method performance parameters and ways of estimating them. More information about the course can be found in Course introduction page.
Participation in the course is free of charge. Receiving digital certificate (in the case of successful completion) is also free of charge. Printed certificate (to be sent by post) is available for a fee of 60 EUR. Registration is possible until the start of the course. The course materials are available from the above address all the time and can be used via web by anyone who wishes to improve the knowledge and skills in analytical method validation (especially when using LC-ESI-MS).
