We’re delighted to share that members of our Archemy and Analysis of Cultural Heritage Objects groups have published a new article titled, “Influence of Mineral Composition and Firing Temperature on the Micro- and Mesoporosity of Replicate Archaeological Ceramics” in the journal of Clays and Clay Minerals (Volume 72, 2024, e13). Read the Open Access article here.
This study examines how the mineral composition of clay and temper, along with firing temperatures, influences the formation of micro- and mesopores in pottery. The porosity of ceramics is considered a significant factor in the absorption and preservation of organic compounds, such as lipids, within archaeological pottery. Our research provides the first quantitative analysis of pore structures in ceramics designed to replicate archaeological samples, establishing valuable baseline information for future investigations into ceramic porosity and organic residue analysis.
On the 5th of September 2024, PRG workgroup members Dr Signe Vahur, Dr Anu Teearu-Ojakäär, Dr Rünno Lõhmus, Dr Aleksei Treštšalov and specialist MSc student Martin Leissoo visited the Mitutoyo metrology lab at Riga Technical University (RTU) where the director of the lab Ass. Prof. Janis Lungevics kindly hosted them and introduced different new equipment in the lab.
From left: Rünno, Aleksei, Janis, Signe, Martin, and Anu
The one-day trip was undertaken for the purpose of research work. As part of the collaboration, various materials related to the PRG project have been measured with an optical 3D profilometer in Mitutoyo’s laboratory. Janis introduced the 3D profilometer and showed also very interesting research results that will be published in the joint scientific article.
All the members of the PRG group were very excited about the visit, which gave new interesting ideas for further research.
Thank you, Janis, for a very interesting day and all the support and help!
Janis demonstrating the power of the 3D profilometer
The presentation started with how acid and base strengths, typically expressed as pKa values (acids) or pKaH values (bases), depend on solvation of the proton, as well as of the neutral and ionized forms of the acid/base. Every solvent has different solvation properties. Thus, the pKa values for the same acid/base in different solvents are also different (often dramatically different).
In principle, whenever using pKa values for predicting or rationalizing chemical processes, the pKa values determined in the same solvent should be used. In some solvents, e.g. water, DMSO or acetonitrile large bodies of pKa data exist, while in most solvents either very few pKa values are available or none at all. This leads to the frequent need of estimating pKa values in one solvent from the data in other solvent(s) (Picture on the right). An additional consideration is the (often problematic) quality of pKa data in the literature.
When estimating pKa values in one solvent based on the data in another solvent it is important to clearly define the aim. Is it needed to have the absolute pKa value or is it rather necessary to have the acidity/basicity differences (or acidity/basicity order) within a set of compounds? Perhaps the question is just “can base B deprotonate acid A in solvent S”? If absolute pKa value is needed then what accuracy is necessary? Depending on the aim, there are different possibilities of estimating pKa and pKaH values in a solvent on the basis of data in other solvents.
The presentation gave an overview to what extent such estimates can be usefully done, highlighting both successes and failures, as well as how to recognize clearly erroneous pKa data. The presentation also highlighted the IUPAC project Critical compilation of acid pKa values in polar aprotic solvents that is nearing completion. The critically evaluated pKa data of acids in dimethyl sulfoxide, acetonitrile, N,N-dimethylformamide, pyridine, acetone, propylene carbonate, tetrahydrofuran are available from Ivo Leito on request.
The presentation turned out to be highly interesting for the participants, receiving a large amount of questions, which extended well into the coffee break!
(This research was supported by grant PRG690 from the Estonian Research Council)
We are delighted to announce that the prestigious ERC Starting Grant was awarded to a member of our group and head of the Archemy team – Associate Professor in Analytical Chemistry and Archaeology Ester Oras!
Ester Oras. Photo: Andres Tennus
The European Research Council (ERC) Starting Grant is awarded to early-stage researchers to carry out their outstanding ideas over the next five years. Ester’s project aims to explore our distant ancestor’s identities through diet by conducting biomolecular analysis on at least 150 burial finds, uncovering details of life from a thousand years ago.
Food is a crucial element in understanding identity, revealing details about social roles, status, and even how the person spent their childhood. By examining bones, teeth, and food residues from pottery, the team can reconstruct how a person’s diet evolved over their lifetime. This will help answer questions like whether an individual ate foods typical of their gender or social class and if they grew up in the area where they were buried.
During the project, various burial finds will be analysed, focusing primarily on sites in Estonia from the years 1000–1400. Using advanced techniques, the team will analyse various molecules, including fats, proteins, and DNA, to uncover specific details about what ancient people ate. This comprehensive approach could even identify not only if the person ate fish but also whether it was cod or herring, offering a deeper look into the lives of our ancestors.
What makes this research groundbreaking is its combination of modern scientific methods with traditional archaeology. Machine learning will be used to integrate the results from various analyses, helping to identify connections between individuals and communities. The project marks a significant step forward for archaeological research, offering new perspectives on ancient identities and social structures.
We are excited to share our latest publication titled, “pKaH values and θH angles of phosphanes to predict their electronic and steric parameters” (Dalton Trans., 2024, 53, 14226-14236. https://dx.doi.org/10.1039/d4dt01430h).
In this study, we delve into the fascinating world of phosphanes – a versatile class of organic bases that play a crucial role in a wide array of chemical applications. Phosphanes are known for their incredibly diverse range of basicities, with pKaH values spanning over 30 orders of magnitude. One of the key insights from our research is that pKaH values can be a valuable alternative to Tolman electronic parameters (TEP values) for assessing the electronic properties of phosphanes. This finding opens up new possibilities for researchers to evaluate phosphanes without the need for the time-consuming preparation or calculation of metal-ligand complexes.
In addition to electronic properties, we also propose new geometric parameters to assess the steric properties of phosphanes – the θH angles, which have the advantage of being accessible by simple computations. Together, the pKa values and θH angles provide a straightforward approach to understand and predict the behavior of phosphanes in various chemical environments and processes.
Our study combines computational and experimental findings to offer a fresh perspective on how phosphanes can be analyzed and utilized, and we believe it will be a valuable resource for researchers working with these compounds. We invite you to read the full article to explore the detailed findings and implications of our work.
From June 2 to June 6, 2024, Signe Vahur and Anu Teearu-Ojakäär attended the 72nd ASMS conference on mass spectrometry and allied topics at Anaheim Convention Center (Anaheim, USA).
Signe and Anu at ASMS
This year, the conference hosted almost 6800 attendees and 183 companies. During the four days there were 384 oral presentations that ran in 8 parallel sessions and 3288 poster presentations (more than 800 posters per day) on wide variety of topics related to mass spectrometry – developments in instrumentation, analysis of complex and problematic samples, using AI and software solutions to improve measurements, data handling, etc. In addition, there were 50 evening workshops and 49 breakfast seminars. From Monday to Wednesday evening, 15 daily corporate hospitality suits were hosted by some of the companies (e.g., Bruker, Agilent Technologies, Shimadzu, Thermo Scientific, etc.).
Anu and Signe in front of their poster
At the conference, Signe and Anu presented their poster “APCI-MS for the analysis of cultural heritage materials” during the Thursday (June 6) poster session. On Monday evening (June 3), Anu gave a 3-minute Flash talk at the evening workshop “Art, Museums, and Archaeology” for an audience of approximately 160 attendees.
Anu giving a Flash presentation
The 72nd ASMS conference was a great experience by meeting old colleagues and fellow MS enthusiasts, making new connections, having great and fruitful discussions and networking opportunities. Thank you to the organisers of the conference for delivering yet another high-level event!
This dissertation begins with the observation that while polymer membrane ion-selective electrodes (ISEs) have been well known and widely used for decades to detect small cations, determining organic anions with ISEs remains a challenge, essentially without a solution. The dissertation presents a journey starting with the study of the interactions between small monocarboxylates and numerous anion receptors – potential new ionophores.
By measuring the binding constants of eight carboxylates (formate, acetate, pivalate, lactate, ibuprofen, ketoprofen, glucuronate, and benzoate) to 44 synthetic receptor molecules using nuclear magnetic resonance, Kerli constructed eight binding affinity scales where all the binding affinities are comparable. These results were then assembled into a large overall map of the receptor-anion binding constants (Figure on the right). The results revealed that the selected synthetic hydrogen-bond donor receptors can distinguish between carboxylates with different structures.
As a result of this binding study, a 1,3-bis(carbazolyl)urea derivative (receptor 13 in the Figure on the right) was selected as the hydrogen-bonding ionophore to create prototypes of ion-selective electrodes that can detect acetate. The electrodes built by Kerli displayed a unique selectivity pattern for different anions. The addition of this ionophore to the electrode membrane significantly (by up to several orders of magnitude) reduced the interference from other common ions such as chloride, bromide and nitrate. Kerli’s work is an important step forward in designing ionophores that can specifically bind carboxylates and building sensitive and selective ion-selective electrodes for different anions.
The defence procedure itself was quite a battle for Kerli! It started with the detailed questioning by the opponent prof. Claudia Caltagirone (University of Cagliari, Italy) on all the aspects of the thesis. Particularly interesting and difficult were some of her highly technical questions regarding the fluorescence measurement of binding affinities. Then there was a long string of questions from the defence committee members. The topics of Kerli’s thesis ranged from receptor-anion binding to computational chemistry and from materials science to hard-core electrochemistry. Thus, most committee members found something familiar and worth asking about. Kerli managed nicely with all the questions and left a very good impression on everybody in the room!
Eventually altogether 1047 people registered from 104 countries. 655 participants actually started the course (i.e., tried at least one graded test at least once). The overall completion rate was 38%. The participation rate was this year 63%. The completion rate of the participants who started the studies was 61%, with 398 successfully finished participants. This result is quite stable during the 11 runs, showing also a small improving tendency compared to years after the COVID pandemic. This result can be considered good for a MOOC, especially for one that has quite difficult calculation exercises, which need to be done correctly with limited number of attempts for completing the course. All statistics during the 11 years can be found in the table below.
The participants 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 around 300 (!) (overall number of posts, both from participants and from teachers) and the forums are still active and posts are still coming in.
We want to thank all participants for helping to make this course a success!
We plan to repeat this course again in Spring 2025 with a new breath in the course appearance!
At the beginning of the presentation, Ivo gave a brief overview of why pH, a widely used value for expressing acidity, has serious limitations. Thus, it cannot be used to compare the acidities of solutions in different solvents, which can hinder the understanding of chemical, biological, environmental, and industrial processes.
A much more practical approach could be the usage of an absolute/universal pH, which would allow the comparison of acidities in different solvents. Thus, the main part of the presentation was focused on the theoretical and practical aspects of unified pH (pHabs). In recent years, our Acid-base Studies workgroup in the Analytical Chemistry Chair has worked extensively with the development and measurement of unified pH values for various systems in different solvents (liquid chromatography modile phases, electrocatalytic mixtures, strongly acidic solutions, etc). A differential potentiometry method for pHabs has been developed in the workgroup to obtain the unified pH values and has been now distributed to a number of groups in Europe in the framework of the UnipHied project.
For now, the unified pH has matured from a concept into a practical tool and has been accepted both by the European metrology community (Euramet) and by IUPAC. The unified pH could be utilized in various applications, such as liquid chromatography, catalytic systems, and acidity at the interfaces between phases.
The presented research is largely the result of the EMPIR programme project 17FUN09 “UnipHied” and was additionally supported by grant PRG690 from the Estonian Research Council.
Altogether 1048 participants from 104 countries are registered – the largest number of countries the course has ever had! 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 16 participants also from Ukraine this year. Slava Ukraini!
The entire 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 measurements and chemical analysis related master programmes at UT: Applied Measurement Science (https://ams.ut.ee/) and Excellence in Analytical Chemistry (https://www.analyticalchemistry.eu/).
