The collections of experimental acidity and basicity data in non-aqueous media measured by our group are now up to date on our Chair of Analytical Chemistry webpage.
Both tables include the compounds name, CAS number and SMILES code. The acidity collection contains 190 compounds, where the compounds available experimentally measured pKa in acetonitrile (MeCN) and pKip in 1,2-dichloroethane (DCE) are given. The pKa in DCE is calculated/estimated based on pKip value.
The basicity data collection includes 353 compounds and their pKip in tetrahydrofuran (THF) and in DCE. The pKa values in MeCN were re-evaluated taking into account all (close to 700) measurements of 279 bases. Therefore, these pKa values can be considered the most reliable pKa values measured in MeCN available!
Currently 828 participants from 92 countries are registered – the largest audience the course has ever had! As was the case in the previous years, the majority of participants are from analytical laboratories. This once again demonstrates the continuing need for training in measurement uncertainty estimation for practicing analytical chemists.
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 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/).
Mayor Urmas Klaas said that the high-level international conferences make Tartu visible in the field of conference tourism. In the future, the number of these well-organized conferences could be even higher, when Tartu becomes the European Capital of Culture in 2024 and additional flights from Tartu start to operate.
One of the acknowledged conferences was the Eurachem Workshop and General Assembly 2019, which was organized by the Estonian Center of Analytical Chemistry (ECAC).
Congratulations to the main organizer Riin and her team – Ivo, Anneli, Asko, Koit, Hanno, Jaanus, Pilleriin, Eliise and Siiri from our Analytical Chemistry Group for the well-deserved recognition!
PLOS ONE has recently published a multidisciplinary paper on two Egyptian child mummies lead and participated by the members of our group. The team of 19 experts unravelled the secrets of two Graeco-Roman child mummies by applying most recent analytical techniques from archaeology, forensic sciences, analytical chemistry, medicine, entomology, and genetics. This is one of the most extensive multidisciplinary study of ancient mummies and the paper is free to download here.
The full course material (as well as the registration link) 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) and examples. Almost all areas of analytical chemistry are addressed, ranging from simple titrations to sophisticated instrumental analysis, such as determining pesticide residues by LC-MS.
In order to pass the course, the registered participants have to take six graded tests and get 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 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!
We recently had the pleasure of collaborating with the group of Daniel Seidel (University of Florida) in the field of enantioselective acidic catalysis. Prof. Seidel and his co-workers have developed Highly Acidic Conjugate‐Base‐Stabilized Enantioselective Carboxylic Acid Catalysts that are able to catalyze oxa‐Pictet–Spengler Reactions with Ketals. Our task in this endeavor was determining the acidity of the catalysts involved and elucidating the effect of the different elements of its substitution scheme on acidity. The main outcome is summarized in the scheme on the left. As can be seen, the most acidifying element is the substituted thiourea moiety, leading to one of the catalysts – the rightmost molecule. The findings strongly suggest that a key to the high acidity is the intramolecular hydrogen bond stabilizing the anion of the acid catalyst. These same substituents are also instrumental in the enantioselective catalytic ability of these catalysts.
Last week, the members of our Analytical Chemistry group celebrated Christmas together.
After the traditional and tasty Christmas dinner, the not so traditional games took place. Everyone was dived into five teams. All of the teams had the same five tasks – they had to put their main senses to the test. But of course, the tasks required some additional knowledge of chemistry.
The tasks were the following: identify common laboratory objects in a self-made and a not see-through “glove box” (touch); recognize the sounds of various laboratory machines, including the coffee maker (hearing); notice molecules and atoms in a drawing (sight); determine the concentrations of sugar solutions by tasting sugar solutions with known concentrations (taste); identify various alcohols and fragrant compounds by their aroma. The games of senses ended with a fun quiz.
Touch
HearingSightTasteSmell
Wishing you happy holidays and a wonderful new year from our Analytical Chemistry group!
Jaanus Liigand was awarded the 1st prize in category of natural sciences and technology in the Estonian National Contest for University Students supported by Estonian Research Council for his doctoral thesis.
He defended his PhD thesis on “Standard substance-free quantification for LC/ESI/MS analysis based on the predicted ionization efficiencies”. During his PhD studies, Jaanus has worked hard on understanding the mechanism of electrospray ionization in LC/ESI/MS; primarily understanding how the structure of the compound and the eluent used in the analysis influence the ionization efficiency. Jaanus has verified, based on the largest set of ionization efficiencies measured so far (roughly 400 compounds), that the more hydrophobic compounds and more basic compounds tend to have a higher response in ESI positive mode. From the mobile phase point of view, both organic solvent content, pH of the buffer, and buffer composition, influence the ionization efficiency in ESI/MS. In general, higher organic solvent content and lower pH result in higher ionization efficiency and, therefore, a higher response in positive mode ESI/MS.
Dr. Piia Liigand and Dr. Jaanus Liigand
Also, he investigated how well are the ionization efficiency values measured on one instrument transferable to other instruments and found that with the aid of 5-6 common compounds the ionization efficiency values can be transferred from one instrument to another. Combining these promising results and machine learning approaches Jaanus has been able to develop a truly universal approach for applying ionization efficiency predictions for quantification in suspect and non-targeted LC/ESI/HRMS analysis.
He is continuing his research at University of Alberta in Canada in Prof. David Wishart research group to further improve mass spectrometric analysis with machine learning.
Congratulations to you, Jaanus, for the well-deserved acknowledgment!
Another new method development in our group has been assembled into a publication. Article by Pilleriin Peets (on the picture), Karl Kaupmees, Signe Vahur, and Ivo Leito in the journal of Heritage Scienceintroduces non-invasive approach to identify all kinds of different textile fibers using reflectance-FT-IR spectroscopy and chemometry. In this work 61 single-component textile pieces were analyzed, 4000 spectra were recorded and all in all 16 different textile fiber types were characterized. As reflectance-FT-IR spectroscopy is not widely used to analyze samples with an uneven surface, in our best knowledge, this article provides the largest collection of r-FT-IR spectra from textile fibers that is recorded and published. All the r-FT-IR spectra from different fiber classes are now available for other scientists, conservators, museum workers and industries to use!
Another EU_FT-ICR-MS short course took place on the 10-12 October in Moscow, Russia, this time the topic was the basics of FT-ICR: dynamic harmonization and computer simulation. Two of our group members – Pilleriin Peets and Eliise Tammekivi – also took part in this interesting course.
In the recent EU_FT-ICR-MS short course, scientists and students from the Skolkovo Institute of Science and Technology (Skoltech) shared their work and knowledge in the field of FT-ICR. Prof. Jevgeny Nikolaev was one of the main organizers of the event and also gave lectures, where he explained the essence of a dynamically harmonized cell and the processes taking place in different ICR cells. In the seminars, the computer simulations that are used in the lab of Prof. Nikolaev for modifying ion motion were introduced and demonstrated.
Prof. J. Nikolaev explaining the processes of ICR
Dr. A. Zherebker demonstrating their FT-ICR
Besides the lectures and seminars, the participants were shown around the Mass Spectrometry Lab and the facilities of Skoltech. Skoltech is an innovative and international university with students and lecturers from all over the world. The university was established in 2011 in collaboration with MIT and by now they have a nearly finished campus where students and researchers can cooperate with start-ups and industrial companies. To give some idea about their wide possibilities, weʼll give you an example – besides numerous “common” plastic 3D printers, they have several metal, ceramic and composite 3D printers that students apply in their projects and scientists in their research.
