Dr. Ernesto de Jesus Zapata Flores – PhD thesis on LC-MS derivatization reagents

Last Wednesday, August 30th, 2023, a moment that marks the culmination of years of hard work and determination of Ernesto de Jesus Zapata Flores – an AMS alumnus. He successfully defended his PhD thesis titled Derivatization Reagents used in negative mode electrospray LC-MS. The opponent was Associate Professor Jeffrey Hawkes from the University of Uppsala, Sweden.

In the vast application of derivatization reagents in RPLC-UV and RPLC-MS positive mode, Ernesto’s thesis delved into the question: What about LC-MS negative mode? Why don’t we compare both modes and see the best of both worlds?

Firstly, the thesis has been inspired by DEEMM – a commercial reagent – which also was one of the earliest reagents studied in our department. The comparison of the ionization mode in the determination of free amino acids in beers showed that (1) the matrix effects were less severe in the negative mode.

Later on, the method applying two azobenzene-based reagents, which were called AzoB and AzoC  (synthesized in our lab), has been fully developed specifically for LC-QqQ. The “gourmet” part that Ernesto has brought to the table of the analytical chemistry community was the study of (2) MS/MS fragmentations of all three reagents with different amino compounds in both ionization modes.

Moreover, his thesis has demonstrated comprehensive research about (3) optimization for the derivatization process and the ion source, (4) the confirmation of reaction yields, and (5) the correlation between ionization efficiency and LOD/LOQ of derivatives. Finally, applications of the validated method (7) for real-world samples (different beverages: beers, Kali, juices) and (8) neutral loss scan have been showcased.

Alongside the road, (9) side reactions managed to be worth some of his sweat and tears. At the end of his PhD journey, he (10) evaluated an identification tool using the transition of derivatives in both MS polarities.

10 out of 10 – that should be given for Ernesto’s dedication on the road to becoming an expert in LC-MS derivatization. Congratulations, Ernesto! We eagerly await your next academic steps. Hopefully, all your goals will be achieved.

ASMS 2023 – Conference on mass spectrometry and allied topics

During June 4-8, 2023, Signe Vahur and Anu Teearu-Ojakäär attended the 71st ASMS Conference on Mass Spectrometry and Allied Topics, held in Houston, USA.

Signe and Anu presenting their poster

At the ASMS conference, Signe and Anu presented their poster “MALDI-MS for the analysis of cultural heritage materials” during the Monday (June 5) poster session.

On Wednesday evening (June 7), Signe was an invited panelist (along with Dr G. Asher Newsome from Smithsonian Museum Conservation Institute, USA; Prof Paul Haynes from Macquarie University, Australia; Dr Aleksandra Popowich from the Metropolitan Museum of Art, USA; Assoc Prof Enrico Cappellini from University of Copenhagen, Denmark; and Assoc Prof Troy Wood from University of Buffalo, USA) in the workshop “Art, Museums, and Archaeology” and had a very interesting discussion with approximately 70 attendees.

Altogether, the ASMS 2023 conference had more than 6300 attendees from all over the World. During four days there were 384 oral presentations (that ran in 8 parallel panels) and 4 presentations by invited speakers; 2939 poster presentations (more than 700 posters per day) and 178 corporate members presenting their products – instruments, labware, sample preparation, software solutions, etc. In addition, there were 50 evening workshops, 49 breakfast seminars, and 16 daily corporate hospitality suits.

All in all, the 71st ASMS Conference was a great experience with a lot of new connections, great discussions, and networking opportunities. Thank you to the organisers of the 71st ASMS Conference for delivering such a high-level event!

Signe talking during the panel session
Signe in the main conference hall

Dr. Andre Leesment – PhD thesis on the acidity in biphasic systems and gas-phase

Last Friday, June 9th, 2023, Andre Leesment successfully defended his PhD thesis titled Quantitative studies of Brønsted acidity in biphasic systems and gas-phase. The opponent was Prof. Kiyohiko Sugano from the Ritsumeikan University, Japan.

Dr. Andre Leesment (on the right) after his PhD defence with his supervisor Prof. Ivo Leito (on the left).

Experiments for measuring acidity of medicines, catalysts, and other chemicals are almost always performed under monophasic conditions. However, many of them are lipophilic compounds, and in biphasic systems they prefer the nonpolar organic phase, where their properties are much different from their properties in an aqueous phase. Yet the interactions with the organic phase are completely ignored in a typical acidity measurement. It’s like seeing only half of the picture. Why is such an incomplete approach being used for something this important?

Until recently, there was no theoretical basis or experimental method to conduct measurements of acidity under more relevant conditions. Andre’s PhD thesis focuses on providing the tools to measure acidity, and by extension, many other properties of molecules in biphasic systems in a more realistic and accurate way. Hopefully, these tools lead to a more effective drug development, catalyst research, etc.

Congratulations to you, Andre!  

 

Tris(benzophenoneimino)phosphane and Related compounds

Our group recently published a new article titled “Tris(benzophenoneimino)phosphane and Related Compounds” led by Marta and Agnes.

Marta working in glovebox

In this work, a new group of bases with benzophenoneiminyl (bpi) moiety was synthesized and characterized. A convenient one-pot approach was employed to synthesize the starting compound tris(benzophenoneimino)phosphane (P(bpi)3): benzophenone imine was deprotonated using MeMgCl, followed by its reaction with PBr3 in diglyme. This method offers an alternative for preparing other (amino)phosphanes as well when lithio-intermediates and/or protonated phosphanes are not viable options. P(bpi)3 was subsequently utilized to synthesize a variety of related phosphonium cations and phosphazenes.

Crystals from synthesis

The stability of the resulting phosphonium ylides was assessed through their deprotonation. In certain cases, the bulky substances demonstrated the ability to form P-N heterocycles with adjacent P and N atoms and P=C double bonds which are quite rare and only some representatives of this type of heterocycles have been reported before. The basicities of benzophenone imine, P(bpi)3, phosphonium ylides, and phosphazenes were evaluated experimentally (in MeCN) or computationally (in MeCN, THF, and gas-phase). Additionally, representative X-ray crystallography (XRD) structures were presented and discussed. Although the bpi-compounds are not as strong as many existing bases, they still exhibit considerable basicity and could be employed as reagents to overcome common challenges such as solubility, ion-pairing, lack of UV-Vis properties, and other issues.

 

Measurement uncertainty online course 10th run has successfully finished!

On May 11, 2023, the on-line course (MOOC) Estimation of measurement uncertainty in chemical analysis offered by the University of Tartu finished successfully.

Eventually, altogether 993 people registered from 99 countries. From them, 523 participants actually started the course (i.e. tried at least one graded test at least once). The overall completion rate was 34%. The participation rate was this year 53%. So, it seems that we may be recovering from the COVID pandemic! The completion rate of the participants who started the studies was 64% with 333 successfully finished participants. This result is quite stable during the 10 runs and can be considered good for a MOOC, especially for one that has quite difficult calculation exercises, which need to be done correctly with a limited number of attempts for completing the course. All statistics during the 10 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 over 450 (!) (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 2024.

Conference on Phosphorus, Boron and Silicon

From the 22nd to the 24th of March, Marta attended the 4th International Conference On Phosphorus, Boron and Silicon (PBSi2023) in Berlin.
 
PBSi2023 brought together a wide range of scientists from all over the world who love these three elements and want to share the advances they have made in PBSi chemistry. It was Marta’s (presenting on the picture) first conference and she had the pleasure of giving an oral presentation about her current work on benzophenoneiminyl-substituted novel organophosphorus bases.
 
In her words, it was a great experience from the perspective of science, but it was also exciting to meet new people in her field and create lasting memories, and she hopes that there are many more conferences to come.
 
 
 
 

First prize at the Estonian contest for student research

Elo Joandi (in the picture on the right), a gymnasium student of the Miina Härma Gymnasium, won the first prize at the Estonian Research Council’s contest for student research. Congratulations to Elo and her supervisors!

In her work “Identifying diet based on hair isotopic analysis: a case study of modern and archaeological material” Elo studied the dietary habits of present and past individuals through the stable isotope analysis of hair keratin.

A thorough theoretical work with the literature allowed her to conduct real experiments in our Archemy lab to analyse contemporary and archaeological hair samples. She demonstrated that the nitrogen values are clearly different for vegan and carnivorous people, and that both carbon and nitrogen isotope values change when a person changes their diet from omnivorous to that of a vegetarian one.

Elo’s work is the first of its kind at the University of Tartu, aiming to understand and develop the stable isotope analysis on hair keratin. She demonstrated that the pre-treatment has an effect on the stable isotope values, allowing a better-informed sample strategy for archaeological specimens in the future. Elo’s work is an exceptional example of bridging humanities and natural sciences in the study of cultural heritage.

The research was supervised by Holar Sepp, Helen Semilarski, and by two members of our group – Mari Tõrv and Ester Oras. 

Here you can find more information about the contest and awardees (in Estonian).

 

 

Measurement Uncertainty online course: 914 participants from 98 countries!

On Tuesday, March 21, 2023 the web course Estimation of Measurement Uncertainty in Chemical Analysis was launched for the tenth time as a MOOC (Massive Online Open Course)!Currently, 914 participants from 98 countries are registered. In the map presented above, the yellow color marks the countries where participants come from. True, the map is coarse and some countries are small. Therefore, not all countries are visible. We are very happy that we have two participants also from Ukraine this year. Slava Ukraini!

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 a 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/).

Unified pH – what, why and how?

On March 10, 2023, Ivo Leito presented “Unified pH – what, why and how?” at the Chemistry and Chemical Technology 2023 Vilnius (Lithuania).

Acidity is one of the most critical characteristics of solutions. Its measurement is crucial to understanding and controlling essential processes in fundamental chemistry, industry and living organisms, such as catalysis, extraction, chromatography, processes in micelles/bilayers, etc.

Acidity refers to the activity of the solvated proton and is typically expressed as pH. However, the conventional pH scale is well established only in dilute aqueous solutions at medium pH values. It has severe limitations at extreme values, in other solvents or more complex media where most real-life chemistry occurs. Most importantly, comparing the conventional pH values between different media is impossible because every solvent has its pH scale.

Given the above, a decade ago, the concept of a “unified pH scale” was put forward, defining unified pH via the absolute chemical potential of the solvated proton. The merits of this approach are a strict thermodynamic foundation and direct comparability of values between any media.

In recent years, to a large part thanks to the European Union UnipHied (17FUN09) project, the measurement possibilities have been developed and the concept has now been published as an IUPAC technical report.

The first part of the presentation gave theoretical background and explained the need for unified pH. The second part described the experimental method, and the last part gave an overview of the work done and future perspectives.

 

Prof. Ivo Leito – recipient of the UT teaching staff awards

This year’s recipients of the teaching staff awards in the University of Tartu have been announced. The UT Student Union chose the recipients based on proposals submitted by the students. We are glad to announce that the Faculty of Science and Technology award was given to prof. Ivo Leito!

According to his students, prof. Ivo Leito is an incredibly charismatic and lively lecturer who is a role model for all. In each lecture, he gives real-life examples of how analytical chemistry can be applied to study the environment around us. Using the flipped learning method, he constantly engages students in discussions and creates a safe environment for asking questions. It is worth noting that Professor Leito does not proceed with the lecture until he is convinced that every last person in the room has understood what he has just said. 

In addition to his dedication to educating students in the classroom, he is always available for every student outside of lecture hours. It is not an exaggeration to say that he is available 24/7, even when he is abroad. He takes a genuine interest in the progress and development of every student. Ivo Leito also holds regular meetings with all his students planning to graduate in the spring to see if their thesis is going well and to give advice on how to advance with the task.  

Here is more information about the award and the other recipients. 

Congratulations!