Pan-European Network of Fundamental pH Research: UnipHied

Initiated by our group, the pan-European research network of fundamental pH Research UnipHied started in May 2018.

Why is such network needed? As of now, it is not possible to compare pH values of solutions made in different solvents, as every solvent has its own pH scale. This situation is highly unfortunate, since it causes confusion and inaccuracies into many fields, extending far beyond the specific field of acid-base chemistry. Examples are industrial catalytic processes, food chemistry, liquid chromatograpy, etc. The central goal of UnipHied is to overcome this situation by putting the new theoretical concept of the recently introduced unified pHabs scale on a metrologically well-founded basis into practice.

The most important specific objectives of UnipHied are (1) to develop and validate a reliable and universally applicable measurement procedure that enables the measurement of pHabs; (2) to create a reliable method for the experimental or computational evaluation of the liquid junction potential between aqueous and non-aqueous solutions; (3) to develop a coherent and validated suite of calibration standards for standardizing routine measurement systems in terms of pHabs values for a variety of widespread systems (e.g., industrial mixtures, soils/waters, food products, biomaterials).

The first version of the pHabs measurement procedure has been created by Agnes Heering (Suu) in the framework of her PhD thesis. The main experimental difficulty is evaluation of the liquid junction potential (LJP), which will be thoroughly addressed by UnipHied. The first important steps towards this goal have very recently been made and published as two back-to-back papers: Angew. Chem. Int. Ed. 2018, 57, 2344–2347 and Angew. Chem. Int. Ed. 2018, 57, 2348–2352
The key achievement described in the papers is finding an ionic liquid, namely [N2225][NTf2], that can be used as salt bridge electrolyte and has such properties that two out of three main sources of LJP are eliminated.

The partners of the UnipHied network are LNE (France, coordinator), BFKH (Hungary), CMI (Czech Republic), DFM (Denmark), IPQ (Portugal), PTB (Germany), SYKE (Finland), TÜBITAK-UME (Turkey), Freiburg University (Germany), ANBSensors (United Kingdom), FCiencias.ID (Portugal), UT (Estonia).

UnipHied is funded from the EMPIR programme (project 17FUN09) co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation programme.


ASMS 2018 in San Diego

Piia Liigand giving her talk

On 3rd-7th June three members of our group focusing on ionization efficiency studies Dr. Anneli Kruve-Viil, PhD students Piia Liigand and Jaanus Liigand, participated in the 66th Annual Conference of American Society for Mass Spectrometry (ASMS) in San Diego, CA. The conference was a huge success. There were altogether about 7500 scientists participating, ca 200 oral presentations and 3300 of posters. We had two oral presentations and one poster presentation.

The conference was kicked off by a presentation by Lisa Shipley from Merck who gave a very informative talk about smart trials and moving to patient-centric clinical trials – most probably the future of clinical trials. It was very inspiring to see how a field that is considered to be relatively conservative is picking up the most modern technical solutions such as clever packages and home-based sample collection.

The first full day of the conference started with a presentation by our PhD student Piia, who gave a talk about achieving more accurate semi-quantitative analysis by predicting electrospray ionization efficiencies. She first gave an overview of the research carried out so far and then, introduced her latest results. She showed that with the help of using ionization efficiencies, concentration estimation in various biological matrices was improved by more than an order of magnitude.

Jaanus Liigand presenting his poster

Jaanus presented a poster on semiquantitative LC/ESI/MS via ionization efficiency prediction. He presented the simple and user-friendly approach of predicting ionization efficiencies using only 2D structures. We are now able to predict ionization efficiencies in both ESI positive and negative mode and in different solvent compositions without time-consuming DFT-COSMO calculations. Additionally, we have shown that using ionization efficiency predictions the validation with LC gradient elution resulted in 2.7-fold mispredicted concentrations compared to 44-fold mispredictions using directly peak areas. We were happy to see that numerous groups were interested in our studies and fruitful discussions about the results did not stop until the end of the poster session.

Dr. Anneli Kruve-Viil giving her talk

Dr. Anneli Kruve-Viil presented some of the latest results obtained in FU Berlin. She talked about using mass spectrometry and ion mobility spectrometry for investigating interlocked nature of catenanes and knots. These results will soon be shared with everyone.

In conclusion, this year’s ASMS was very successful for our group. We saw a lot of interest in our work, met our collaborators and got some new friends and possible future collaborators. We are already looking forward to the next ASMS in Atlanta. We are also grateful for our financial supporters, who made this conference possible to us: instrumentation provided by Estonian Center of Analytical Chemistry (, Ministry of Education and Research of Estonia by smart specialization doctoral stipend, Graduate School of Functional Materials and Technologies, and Alexander von Humboldt Foundation.

More information about the group focusing on ionization efficiency studies can be found on the webpage

Bachelor’s and Master’s Defences 2018

Traditionally, in the first half of June, our bachelor and master students defend their theses. This year there were 3 masters students and 2 bachelor students from our group. Here is how the students described their theses.

Alo Rüütel “Synthesis of bambusuril macrocycles and investigation of their binding properties”, master’s defence
In my master’s thesis, I synthesized bambusuril macrocycles. These receptor molecules are very potent anion binders. Usually, molecular receptors do not function in water because they are not able to bind target molecules with sufficient strength. Some bambusuril derivatives are able to function in aqueous media, which makes them a very special type of macrocyclic receptors. It is possible to use these molecules as ionophores for anion selective electrodes.

Ernesto de Jesus Zapata Flores “Determination of free diisocyanates in polyurethane foam”, master’s defence
My thesis focused on the test of a proposed method to analyze free diisocyanates in polyurethane foams for two reasons, by one side those compounds can represent a danger if care is not taken when the foam is used, and by the other side, new legislation is more aggressive against those compounds. The method is a simpler alternative to achieve the derivatization of diisocyanates.

Ande Leesment “Gas phase acidity measurements of superacids using FT-ICR method”, master’s defence

My master’s thesis was based on gas-phase acidity measurements of some very strong acids. Such strong acids are widely used in organic synthesis as reactants and/or catalysts. The anions of such acids exhibit high stability, which makes the valuable components of contemporary energy storing devices. The obtained results allow us to work on expanding the self-consistent gas-phase acidity scale with acids stronger than the ones experimentally measured so far.


Lisett Kiudorv “Quantitative analysis of clay components using ATR-FT-IR spectroscopy”, bachelor’s defence
The main purpose of my bachelor’s thesis was to develop a method that enables quantitative analysis of clays using ATR-FT-IR spectroscopy combined with the chemometric partial least squares method. The developed method is quick and easy to use and reduces the required sample size to around a milligram. The dramatic decrease in sample size makes it possible to analyse samples from archaeology and art. The method was then used to analyse six archaeological samples including one of the oldest potteries found in Estonia and an Egyptian pottery, which holds a bird’s mummy.

Elisabeth Parman “Determination of pKa values of fluorocompounds in water using 19F NMR”, bachelor’s defence
The main aim of my bachelor’s thesis was to determine pKa values of fluorocompounds in water using 19F NMR. This method is not particularly commonly used, but it can be used to verify or disconfirm values that have been measured with different methods, especially in cases where the measurements with other methods are problematic. For example, the purity and accurate concentration of the measured compound need to be concerned for most of the methods, but with 19F NMR it is not problematic.


Comparative validation of amperometric and optical dissolved oxygen sensors

A comprehensive comparative validation for two different types of dissolved oxygen (DO) analyzers, amperometric and optical, together with estimation of measurement uncertainty is presented in the recently published article I. Helm, G. Karina, L. Jalukse, T. Pagano, I. Leito, Environmental Monitoring and Assessment 2018, 190, 313.

A number of performance characteristics were evaluated including drift, intermediate precision, accuracy of temperature compensation, accuracy of reading (under different measurement conditions), linearity, flow dependence of the reading, repeatability (reading stability), and matrix effects of dissolved salts. The matrix effects on readings in real samples were evaluated by analyzing the dependence of the reading on salt concentration (at saturation concentration of DO). The analyzers were also assessed in DO measurements of a number of natural waters. The uncertainty contributions of the main influencing parameters were estimated under different experimental conditions. It was found that the uncertainties of results for both analyzers are quite similar but the contributions of the uncertainty sources are different.

The results imply that the optical analyzer might not be as robust as is commonly assumed, however, it has better reading stability, lower stirring speed dependence, and typically requires less maintenance. On the other hand, the amperometric analyzer has a faster response and wider linear range.

(Photo by Lauri Jalukse: measurements of dissolved oxygen concentration with amperometric and optical analyzers at Jordan spring, Karksi-Nuia, Estonia)


Measurement uncertainty online course (MOOC) 2018 edition successfully finished!

Measurement_Uncertainty_MOOC_Successfully_FinishedOn May 14, 2018 the on-line course (MOOC) Estimation of measurement uncertainty in chemical analysis offered by University of Tartu finished successfully.
Eventually altogether 521 people registered (270 in 2014, 489 in 2015, 757 in 2016, 363 in 2017) from 76 countries (a number of participants joined after the start of the course). 358 participants actually started the course (i.e. tried at least one graded test at least once) and out of them 218 successfully completed the course (141 in 2014, 169 in 2015, 308 in 2016, 148 in 2017). The overall completion rate was 42% (52% in 2014, 34% in 2015, 40% in 2016, 41% in 2017). The completion rate of participants who started the studies was 61% (67% in 2014, 60% in 2015, 67% in 2016, 68% in 2017). The completion rates are nicely consistent over the last years and can be considered very good for a MOOC, especially one that has quite difficult calculation exercises, which need to be done correctly for completing the course.

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 the overall number of posts to them during the course period reached almost 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 of this MOOC a great experience also for us, the teachers. The discussion threads gave a lot of added value to the course and some of them triggered making important modifications to the course materials, even during the course.

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

We plan to repeat this course again in Spring 2019.