Career_Seminar_EACHA key ability in today’s world is applying for a job. In order to be successful, writing CV and job application is of critical importance. For this reason these topics are included in the EACH/AMS programme.

On Wednesday 13.04.2016 Ms Heleri Olo from the UT Career service conducted a seminar (jointly for EACH and AMS students) on the “DO-s and DON’T-s” of writing a CV and motivation letter when applying for a job.

This seminar was the follow-up of the Employment/career session conducted by prof. Reiner Salzer at the EACH 2016 Winter School. At the winter school all participants were given a task to find a job offer at the RSC Jobs website and compose suitable CV and motivation letter. The CVs and motivation letters of students were then analysed both by prof. Salzer and by the UT Career service experts and the feedback was given by Heleri during the seminar.

Students found the whole exercise very useful. The employment-related session was one of the most liked sessions at the Winter school.

 

EC4LE_TrainMiCOn 9-11 June, 2016 a Master Class on Quality Assurance in Analytical Measurements, jointly organized by the European Centre for Laboratory Excellence and the TrainMiC training community.

There are still some places available, so be quick and check it out at www.ec4le.eu/program

This Master Class targets those teaching or training in the area of metrology and quality assurance in chemical analysis (Metrology in Chemictry, MiC), either regularly (as teacher) or occasionally (e.g. adult learning). The aim of the master class is to:

  • Keep up to date trainers’ technical knowledge, expertise and competence through a continuing professional development course
  • Enhance training effectiveness and efficiency by raising knowledge on adult learning strategies and active learning theories through workshop and discussion
  • Establish a long term community of practice

It will also be an opportunity for you to network with the TrainMiC® and EC4LE communities and participate in the TrainMiC® convention as well as celebrate its 15th Anniversary. You can also join to brainstorm about the future. Who knows, if you are a newcomer, you might be interested in joining one of these communities?

We look forward to seeing you in Zagreb in June 2016! We promise you an educational experience unlike any other!

 

UT_Measurement_Uncertainty_MOOC_Participants_2016On Monday, March 28, 2016 the web course “Estimation of Measurement Uncertainty in Chemical Analysis” was launched the third time as a MOOC (Massive Online Open Course).

The popularity of the course is this year somewhat higher than it was in 2014 and 2015: 744 participants from 85 countries (ranging from Bahama to Vietnam and from Zambia to Canada) have registered! (in 2014: 270 participants, in 2015: 400+) Image on the left shows the countries where the participants come from. As in the previous years, the majority of participants are from analytical laboratories, once again demonstrating the continuing need for training in measurement uncertainty estimation in analytical chemistry.

The full course material is accessible from the web page https://sisu.ut.ee/measurement/uncertainty. Some developments and improvements have been made to the course material, in particular, some more self-tests ave been added. 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 take six graded tests and get higher than 50% score. 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.

It is planned to run this course as MOOC again in Spring 2017.

(Image: Wikimedia Commons)

 

Measurement_Uncertainty_MOOC_Course_UTThe third edition of the MOOC (Massive Open Online Course) Estimation of Measurement Uncertainty in Chemical Analysis will be running during Mar 28 – May 8, 2016. Registration is open!

We currently have more than 250 registered participants from more than 50 countries.

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 take six graded tests and get higher than 50% score. 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.

You are welcome to distribute this message to potentially interested people!

 

EACH_Winter_School_2016_Dissolved_oxygen_intercomparisonThe second day of the EACH Winter school was full of excitement.
The key event of the second day was dissolved oxygen intercomparison between the student teams. The samples were water samples from the nearby lake Pühajärv. The student teams used optical oxygen sensors (based on luminescence), see the photo on the left. The seriousness of the intercomparison is underpinned by the independent reference values determined using the highly accurate primary Winkler titration procedure (developed by Irja Helm in her PhD thesis).
EACH_Winter_School_2016_Group_PhotoThe results of the intercomparison will be summarized at the closing of the Winter school.

On the right you can see the group photo (Lake pühajärv is behind the trees) taken right after the lunch and followed by a spontaneous snow fight (photo on the left) where the “African team” (Ime and Olivier, in the centre) performed stunningly well in comparison to the Nordic snow fighters!

EACH_Winter_School_2016_Snow_FightThe consortium committee spent most of the day interviewing students and discussing (including negotiations with university officials about maximum possible numbers of students) for distributing students to study tracks. The day ended with the long-awaited announcement that it will be possible to grant every student the preferred study track!

EACH_Winter_School_2016_Students_of_the_Uppsala_Study_trackOn the photo on the right you can see prof. Bergquist and his team taking pictures of the students selected for the Uppsala study track.

 

 

 

 

EACH_Winter_School_2016_LectureToday, on Jan 25, 2016, the first Winter School of the EACH programme started in Pühajärve (Estonia). Altogether 24 students from 17 countries participate (besides EACH students, also some other international students from Tartu have been invited, most of them from the AMS programme). Leading European analytical chemistry experts act as teachers and supervisors at the Winter School.

The Winter School offers a diverse set of activities to the participants. There are lectures on advanced analytical chemistry topics, tasks on data analysis and choosing analytical strategies. One of the sessions is specifically dedicated to employment opportunities of analytical chemists. The most ambitious part, a full-fledged in situ intercomparison measurement (between student teams) of dissolved oxygen concentration in lake water, will be carried out on the second day of the Winter School.

The intense working is counterbalanced by winter sports activities and relaxing in spa/swimming pool.

Full information about the Winter School activities is available at http://www.ut.ee/EACH/each-winter-school/

 

Random_and_Systematic_Effects_TimelineIn a recent edition of the premier journal devoted to quality and metrology in chemistry Accreditation and Quality Assurance Ivo Leito has attempted to express in very simple terms the essence of Metrology in Chemistry. In the article Accred. Qual. Assur. 2015, 20, 229–231 he arrived at three main recommendations:

1. Whenever possible, comparisons with reference values should be carried out. The reference values can be realized in different ways: Certified reference materials (CRMs), Laboratory reference materials (LRMs), Measurements with reference methods, etc.

2. Data on stable samples should be collected over long time periods (e.g. as the X chart), in order to evaluate as many sources of variability in the analysis method, as possible. The longer the time period, the more systematic effects will become random and thus easier to evaluate (more on this topic can be found in a recent review on bias).

3. “Do not stop there!”, meaning that the above mentioned activities should run in a lab on a continuous basis.

As a conclusion, it can be said that constant improvement is the key to reliable analytical results.

 

LogoWe are glad to announce that registration for the EcoBalt 2016 conference has been officially opened today! Please see the address http://www.ut.ee/akki/ecobalt-2016

The First Circular contains all the important information and is available from the above page.

EcoBalt 2016 is an international research conference that will address all scientific and technological developments in the field of environment and its protection: air, water, soil, contamination assessment and options for its reduction, environmentally friendly technologies and products, recycling, biodiversity, environmental education, etc. The conference will be held on 9.-12. October 2016 in Tartu, Estonia, in the Dorpat conference centre.

EcoBalt 2016 is organised by the Estonian Center of Analytical Chemistry. You are welcome to contact us (Dr. Riin Rebane, riin.rebane@ut.ee) with any questions or requests that you have.

 

IsoFood Hg Training_Draft Programme_2.11.2015_Page_1
During Nov 25-27, 2015 the training seminar “Quality assurance for Hg measurements in food and environmental samples” was held at the Jožef Stefan Institute in Ljubljana. Ivo Leito participated as a teacher and conducted discussion sessions Validation data (Reproducibility, recovery, etc) and their meaning, Measurement uncertainty and Traceability: what it is and how to demonstrate it?.

Ivo_Leito_teaching_metrology_in_chemistry_in_Ljubljana_Nov_2015The seminar was highly successful – there was in-depth discussion during each of the sessions and the discussions continued during coffee breaks. The measurement uncertainty session featured a full-fledged uncertainty estimation (contaminant determination by LC-MS), which the participants carried out themselves on laptop computers that they had brought with them.

It is expected that the collaboration between UT and Jožef Stefan Institute (and other research centres in the region) will continue and deepen.

 

Analuutilise_Keemia_Kvaliteedi_Infrastruktuur_ENGOn Oct 14, 2015 Tallinn University of Technology and University of Tartu jointly organized the first cooperation festival “Right time, right place” (“Õigel ajal õiges kohas”), venue: Mektory innovation centre, Tallinn).

The festival aimed first of all at intensifying collaboration between Estonian industry and academia, but also between different research teams of the two universities. The interest in the event was so large that at some point pre-registration was stopped because of too many participants. The participant number who eventually participated in the event reached 430.

The analytical chemistry research group of UT was also present at the festival and promoted the ECAC distributed interdisciplinary research infrastructure. ECAC unites the competence and analytical capabilities of three prominent organizations in Estonia: University of Tartu, Tallinn University of Technology and the Estonian Environmental Research Centre and offers access to analytical instruments as well as services and collaboration both to academia and industry. Ivo Leito made a presentation about the analytical possibilities of ECAC that can be of interest to the Industry: Analüütilise Keemia Kvaliteedi Infrastruktuur (AKKI) (in Estonian).

Signe Vahur with ATR-FT-IR Instrument at Cooperation Festival Oct 2015

Signe Vahur with ATR-FT-IR Instrument at Cooperation Festival Oct 2015

In addition, we demonstrated our FT-IR analysis capability and had a fully operational ATR-FT-IR instrument with us (image on the right), enabling any interested person to run material analysis of either the samples that we brought with us or almost anything that could be found on site. People were very interested in the analysis of wood coatings, different polymers and also of their own clothes (e.g. for determining whether a necktie is made of silk or polyester) and research fellow Signe Vahur – our main FT-IR expert – was busy all the day to record and interpret spectra and give explanations to interested people.

This possibility of instant ATR-FT-IR analysis proved to be the most popular topic in the Chemistry thematic room of the festival and attracted much attention from people with very different backgrounds. This is not surprising – this instrumental method has been in the core of a number of research collaboration projects with industry in the past and is expected to be so also in the future.

EACH and AMS students strongly benefit from the expertise and instrumentation that has been accumulated by ECAC (AKKI). Several of the EACH/AMS teachers are directly involved in ECAC and a number of ECAC’s instruments are used in teaching and thesis work.

 

Leito_Measurement_Uncertainty_MOOC_Euroanalysis_2015On Sept 07, 2015 Ivo Leito gave a presentation Using MOOCs for teaching analytical chemistry: experience at University of Tartu at the Euroanalysis XVIII (Bordeaux, France).

The presentation outlined the contents and organisation of the material in the on-line course Estimation of measurement uncertainty in chemical analysis, the ways of using it (for independent learning, for self-testing, as an information source and as a basis for running as a MOOC) and the experience of running it as a MOOC (Massive Open Online Course) at University of Tartu in spring 2014 and 2015. Part of the presentation was devoted to analyzing the pros and cons of MOOCs as a way of teaching and in particular as a way of teaching analytical chemistry (or its subdisciplines). It was concluded that MOOCs do have advantages, especially if compared to short training courses for practitioners. The talk created quite some interest and discussions after the session.

Detailed discussion of this topic has been published: I. Leito, I. Helm, L. Jalukse. Anal Bioanal Chem 2015, 407, 1277–1281.
The course material as well as the link to registration for the spring 2016 edition of the course is available from https://sisu.ut.ee/measurement/

 

EACH_Student_Introductory_Meeting_2015Today (Aug 31, 2015) the introductory meeting of the EACH Erasmus Mundus (running on teh basis of the AMS programme) students with the programme coordinators took place at UT Chemicum.

All the 18 students (originating from Ukraine, China, India, Jordan, Congo, Nepal, Nigeria, Montenegro, Serbia, Macedonia, USA and Estonia), who start their studies in EACH in this autumn were participating. An overview of the programme was given (the slides are available from here) and a large number of questions were asked and answered, accompanied by tea/coffee and cake.

This is the first group of students who start their studies in the EACH Erasmus Mundus programme, so, exciting months are ahead, both for students and programme teachers/coordinators!

Photo on the left: EACH Students and their Tutor Kaisa Tihkan (on the right).

 

UT_Students_at_MSC_Euromaster_Summer_School_2015The MSC Euromaster Summer School 2015 in Pulawy (Jul 12-24, 2015) was again a success and the student feedback were very positive. Two reflections from AMS students are presented here:

Sagar Patel: I will remember my time spent in summer school held at Pulawy (Poland) for a lifetime. It was amazing and I don’t have words to express my feelings. I got very useful and practical knowledge about Metrology in Chemistry, statistics, interactions with customers, ISO 17025 and many more. Apart from studies I got a chance to work with students and professionals from different countries.

Karl Kütt: The MSC Summer school on metrology in chemistry has been a great addition to my studies. It combines the theoretical knowledge that I have learned in my program with the teamwork skills and real world problem solving skills that one encounters when running a real laboratory or a project. The course had extensive lessons on both uncertainties in chemistry and validation (a key aspect in the ISO 17025 standard). The neat thing about the summer school is that in its practical exercises you’re not presented with a wrong or a right way, but a situation in which every decision has its pros and cons. I think going to the summer school greatly improved my skills in working in a group, solving complicated problems as well as helped me make important contacts and great friends in the field of metrology.

Image on the left: UT students who participated in the MSC Summer School 2015, from left to right: Sagar Patel (India), Sylvestre Pagkeu (Cameroon), Martins Jansons (Latvia), Karl Kütt (Estonia)

Group_Photo_MSC_SS_2015This week saw the start (on Mon, Jul 13, 2015) of the 8th MSC Euromaster summer school 2015 in Puławy (Poland).

As in previous years, a core aim of the Summer school is shifting the activities away from the classical lecture-type of teaching by increasing the share of discussions, hands-on work, teamwork. As usual, a key activity of the summer school is the contest of student teams (setting up virtual laboratories and interacting with customers), which tests their knowledge and skills in all areas of metrology in chemistry.

This year the summer school makes further advances in terms of this “core shift”. One of the modules, which was carried out differently, was measurement uncertainty, which was the the main responsibility of UT during the summer school. Instead of the classical way – starting with lecture and then moving to discussion – the students were well in advance of the Summer school asked to learn the basic (and quite some not so basic) topics of measurement uncertainty using the web course Estimation of Measurement Uncertainty in Chemical Analysis. This way the lecturing part was omitted completely from the Summer school, as students had the necessary preparation. Thus, the whole measurement uncertainty module at the Summer school consisted of a big session of discussions and problem solving.

Another module, where hands-on work was very important was the Internal and external quality control module (delivered mainly by Ricardo Da Silva from University of Lisbon). He organised an “interlaboratory comparison” between students (in visual photometry) as a part of the session! Students were very excited to see how their results compared to their colleagues’ results.

The summer school still has one week to go and will finish on Fri, Jul 24, 2015.

 

 

Graphical_AbstractThe LC-MS group at the UT Institute of Chemistry were recently invited by the journal Analytica Chimica Acta to write a tutorial review on the topic of validation of liquid chromatography mass spectrometry (LC-MS) methods. This LC-MS method validation guide has now been completed. The tutorial review intends to give an overview of the state of the art of method validation in liquid chromatography mass spectrometry (LC–MS), especially with electrospray ionisation (LC-ESI-MS), and discuss specific issues that arise with MS (and MS-MS) detection (i.e. LC-MS-MS) in LC (as opposed to the “conventional” detectors). The review was eventually split in two parts (because of its large volume):

(as an April joke from Elsevier, part II appears page-wise before part I)

The review addresses and compares all the major validation guidelines published by international organizations: ICH, IUPAC, AOAC, FDA, EMA (EMEA), Eurachem, SANCO, NordVal, European Commission Decision 2002/657/EC. With every performance characteristic the tutorial review briefly compares the recommendations of the guidelines.

The Part I briefly introduces the principles of operation of LC–MS (emphasizing the aspects important from the validation point of view, in particular the ionization process and ionization suppression/enhancement); reviews the main validation guideline documents and discusses in detail the following performance parameters: selectivity/specificity/identity, ruggedness/robustness, limit of detection, limit of quantification, decision limit and detection capability. The Part II starts with briefly introducing the main quantitation methods and then addresses the performance related to quantification: linearity of signal, sensitivity, precision, trueness, accuracy, stability and measurement uncertainty. The last section of Part II is devoted to practical considerations in validation and a possible step by step validation plan specifically suitable for LC-MS-MS is presented.

With every method performance characteristic its essence and terminology are addressed, the current status of treating it is reviewed and recommendations and help are given, how to determine it, specifically in the case of validation of LC–MS methods. In many cases the published guidelines remain too general for being of help to practicing analyst. This LC-MS method validation tutorial review gives more specific advice based on the best available practice and can be used as a kind of LC-MS method validation manual.

Based on the recommended approaches presented in this guide to LC-MS method validation an LC-MS validation software ValChrom is currently under development by the UT team. The software development is supported by the EU Regional Development Fund (Development of software for validation of chromatographic methods, Project No. 3.2.1201.13-0020).

 

kvaliteedimark_sOn Apr 16, 2015 the consortium Estonian e-University awarded the title “e-course of the year” to the web course (MOOC) Estimation of Measurement Uncertainty in Chemical Analysis! This, together with the very positive feedback of the participants is a strong motivator for us to continue developing and delivering this course. Delivery of the next edition is planned in Spring 2016.

The 2015 edition of the “Estimation of Measurement Uncertainty in Chemical Analysis” course finished on Sunday, Apr 19, 2015. The overall number of registered participants was 489 (from 70 countries). The majority of the participants were practitioners from analysis laboratories and industry. Sadly, in spite of the reminders, more than 200 of them never actually started the course. Out of the 279 participants who started their studies 169 completed the course successfully. Thus, the overall completion rate (with respect to registered participants) is 34% and the completion rate of the participants who started the course is 60%, which can be considered reasonably good. Clearly the most difficult tests were the ones of weeks 5 and 6 containing full-fledged measurement uncertainty estimation using the ISO GUM and the Nordtest approaches. The ability to carry out uncertainty estimation of such analyses is essential and we are glad that so many participants managed to successfully complete these tests!

There were many interesting discussions of which some are still ongoing. By interacting with the participants we also learned a lot and we again got good suggestions for developing the course.

Many thanks to all our participants, without whom all this would have never become true!

 

(Image: private collection)

 

Agnes_Suu_in_Lab
Agnes Suu, an AMS and MSC alumna (graduated in 2013), has in the course of her PhD work made an achievement that literally redefines the way the pH of HPLC mobile phase (eluent) is measured. Her work (a continuation of her AMS master’s thesis) introduces a conceptually new approach of measuring pH of mixed-solvent liquid chromatography (LC) mobile phases and has been published in the Analytical Chemistry journal: Agnes Suu et al, Unified pH Values of Liquid Chromatography Mobile Phases. Anal. Chem. 2015, 87, 2623–2630.

Mobile phase pH is very important in LC, but its correct measurement is not straightforward and all commonly used approaches have deficiencies. The new approach is based on the recently introduced unified pH (pHabs) scale, which enables direct comparison of acidities of solutions made in different solvents, based on chemical potential of the proton in the solutions.

The work by Agnes represents the first experimental realization of the pHabs concept using differential potentiometric measurement for comparison of the chemical potentials of the proton in different solutions (connected by a salt bridge), together with earlier published reference points for obtaining the pHabs values (referenced to the gas phase) or pHabsH2O values (referenced to the aqueous solution). The liquid junction potentials were estimated in the framework of Izutsu’s three-component method.
pHabs values for a number of common LC and LC-MS mobile phases have been determined. The pHabs scale enables for the first time direct comparison of acidities of any LC mobile phases: with different organic additives, different buffer components etc. Agnes has developed a possible experimental protocol of putting this new approach into chromatographic practice and has tested its applicability. She has demonstrated that the ionization behavior of bases (cationic acids) in the mobile phases can be better predicted by using the pHabsH2O values and aqueous pKa values than by using the alternative means of expressing mobile phase acidity. Description of the ionization behavior of acids on the basis of pHabsH2O values is possible if the change of their pKa values with solvent composition change is taken into account.

 

Sander_SannikFour years ago, I was very fortunate to have the professor of Analytical Chemistry at Tartu University to invite me to join the international master degree programme AMS – Applied Measurement Science. At that time I was working as an analytical chemist at a national environmental chemistry laboratory. It all started with me contacting the professor to ask for help with problems I was facing in analytical method validation and after sending few emails back and forth, he suggested me to apply for the master programme, since clearly my thirst for the topic was bigger than could be satisfied with few emails. This was no easy decision, since the university is located at Tartu and my job was in Tallinn. This meant traveling every week between the two cities. But I remember thinking: this could be once in a lifetime opportunity – no matter what, take it.

Now, I am happier than ever for taking the opportunity. Because, even if this meant a lot of hard work and studying, traveling and pushing the limits, the benefits I got from this journey weigh more than the hard times I had to live through. Knowledge and experience being the utmost important, I met lot of new colleagues and friends from the University of Tartu and from the analytical chemistry community around my homeland. More than this, I found many exciting international friends from around Europe, Africa and even Asia. One of the highlights of my journey was the international summer school of Metrology in Chemistry – Measurement of Science in Chemistry, which took place in Portugal, where I met even more international new friends, who I am still friends with today. Some of them I talk to every week now and I have been visiting them in their homelands. Last autumn, all of the students who participated met in Brussels, Belgium for a ceremonial meeting and celebrations where we received an official diploma and an extra certificate for our Master degree – EUROMASTER of Measurement Science in Chemistry.
Now, I am working at a laboratory located at my homeland. It is a daughter-company of a Finnish environmental analytical laboratory, which is a part of worldwide global environmental company. For the last 8 months, I have had a most wonderful experience to build up an analytical laboratory from the scratch. This means starting with looking up the appropriate facility and designing the rooms on papers and ending with making the last arrangements of furniture and hiring and training the laboratory staff. This is not an easy job. This cannot be studied in any school or university. This can be learned only by experience, but I am most thankful for the prerequisites I gained from my study years. There is no practice without theory. Now the laboratory is finishing developing and validating the first analytical methods to be taken into routine use and to apply for accreditation. One might say that the hardest part is over, but I somehow doubt that, because future seems even more interesting and nothing can really be interesting without being difficult at start at least.

More than ever, I can now say that the Master programme – Applied Measurement Science – was 101% meant for me: I am “applying” measurement science now every day at my workplace. I consider myself very happy and I am very thankful for my family, friends, colleagues and professor for helping me in the last few years. Knowledge is worth more than gold and I hope my story would inspire others to take risks, accept challenges and eventually catch their dreams.

 

EACH_Qualifying_Applications_2015_by_CountryLast week the check of eligibility and ranking of the EACH applications was completed and Thursday-Friday the admission notifications were sent out to all eligible candidates.

We are glad to announce that there were altogether 46 qualifying applications, which were ranked based on the average grade of the previous study level and on the contents of the motivation letter (as is explained in the EACH admission page). 13 EU scholarships were offered (ten to partner country applicants and three to programme country applicants). The remaining qualifying applicants were offered either a tuition waiver scholarship a fee-based study place, based on their position in the ranking list. The coverage of the scholarships is explained in the EACH Scholarships page.

Most probably not all applicants who were awarded the EU scholarship will accept the study place, therefore it is still possible that the applicants who are topmost in the list of tuition waiver scholarship awardees will receive the EU scholarship (in principle, all qualifying candidates are in the “reserve list” for the EU scholarship). In order to proceed with the admission process it is requested that all applicants who received admission notification will inform us of their decision as soon as possible and in any case not later than on March 23, 2015.

We thank all the applicants for their interest in the EACH programme and we hope that those who will start their studies in EACH will have a useful and enjoyable study experience!

 

Binding_of_acetate_lactate_benzoate_trimethylacetate_to_different_receptorsStudies of host-guest chemistry, in particular, binding of anions by synthetic receptors has become a prominent research topic at the Analytical chemistry research group at UT. This fundamental research prepares ground for developing sensor devices for fast and selective anion determination. Carboxylate anions are among the most interesting, because the carboxylate group is by far the most widespread anionic group in biological objects.

One of the challenges lies in the fact that it is not easy to design synthetic receptors that have very high binding affinity towards a given carboxylate anion and are insensitive towards all others. Thus, it is envisaged that rather than designing highly selective individual receptor molecules, it may be more practical to utilize a number of receptor molecules, having different affinities for different anions, as a receptor array. Applying chemometric tools to the responses (e.g. optical or potentiometric) from such arrays it is in principle possible to determine individual anions from mixtures.

At our group highly accurate methods anion-receptor binding constant (logKass) measurement have been developed recently, based on UV-Vis spectrophotometry (J. Org. Chem. 2013, 78, 7796−7808) and NMR spectrometry (J. Org. Chem. 2014, 79, 2501−2513). Applying these methods, the binding constants of small synthetic receptor molecules based on indolocarbazole, carbazole, indole, urea and some others, as well as their combinations were measured for small carboxylate anions of different basicity, hydrophilicity and steric demand: trimethylacetate, acetate, benzoate and lactate. As a result, four separate binding affinity scales (ladders) including thirty-eight receptors were obtained. The results are graphically depicted in the Figure on the left. The high accuracy of the measurement methods enables distinguishing between small changes in binding affinity. It can be seen that many “crossing” points between the lines (denoting switching of affinity orders) exist, which are the basis of designing useful receptor arrays. This work has recently been published (Chem. Eur. J. 2015, DOI: 10.1002/chem.201405858) and presented in the SupraChem 2015 conference (see the presentation).

 

Work is in progress to measure the binding constants between more anions and receptors with different molecular structures with the aim of compiling the most voluminous dataset available for predicting trends in anion-receptor binding as function of the structural features of the anions and the receptors.

 

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