MOOC on LC-MS method validation

Already in last spring when we were writing the tutorial review on LC/MS method validation Ivo introduced us the idea of making a MOOC (massive open online course) on the same topic. By that time he had launched the first MOOC of our institute that has had hundreds of students so far, on such complex topic as measurement uncertainty.

In summer we started putting some first ideas on the “LC-MS validation course” to the paper and in autumn we started doing some first videos for clearing our ideas. By now we have been to the studio several times already and have a significant amount of course videos ready. We will cover all important aspects of method validation in the course: Trueness, Precision, Accuracy, Linearity, LoD and LoQ, Selectivity, Robustness etc. You are all welcome to post ideas or topics of specific interest! 

So we are anxiously waiting for the course to be ready by the end of spring and to launch it in September.

Optimizing sample pretreatment: temperature

In a recent semester I have been involved in several training activities. The most important of these have been the training day for water analyses laboratories organized by EKUK and the practical aspects of working in the laboratory by TÜ Katsekoda.

My lecture/seminar in the first training was about sample matrices as the source of uncertainty. In this lecture the main idea was to show how large uncertainty source may a matrix actually be. As I have been dealing with matrix effects since my masters thesis this is a very interesting point to me. On the practical aspects of working in the laboratory course my major topic was preparing samples for analyses.

Whether considering uncertainty or trueness it ends up with the understanding that a good sample pretreatment is a base for a good analytical method. It seems like an ongoing discussion on whether liquid-liquid extraction of solid phase extraction is a technique providing more possibilities for efficient sample prep. However, what I have often observed in the trainings and lectures is that one important parameter influencing sample extraction, that people do not come up with, is temperature.

Common knowledge is that higher temperatures are advantageous for extracting analytes from solid matrices and in these cases higher temperature helps to break the “bonds” between analyte and matrix. But what is not that often considered is the temperature effect on liquid-liquid extraction.

We know that water properties strongly depend on the temperature. Based on the NISTdatabase the dielectric constant of water ranges from 87.7 to 55.7. The latter value is more similar to acetonitrile then to “water” as we consider it under standard conditions. This means the enthalpy of solvatation for different species changes remarkably with temperature. For example Z. Congliang et al has observed that octanol-water distribution coefficient of an antibiotic sulfamethoxazole is reduced 5 times while working at 45 °C instead of room temperature. And for extracting the sulfamethoxazole from water with octanol the recovery would drop from 89% to 61%. Unfortunately data for lower temperatures are not available to evaluate if lower temperatures could result in higher recoveries. These effects are larger for compounds with low distribution coefficients and therefore with lower recoveries.

It is even interesting to consider how much could year-around room temperature fluctuation influence the extraction?

Recognition of Piia and Jaanus on scientific works competition

This week two of my students have been recognized by different organizations for their outstanding scientific work. Jaanus Liigand received first prize in the field of natural science for his Masters thesis “Electrospray ionisation efficiency scales: mobile phase effects and transferability” on a scientific works competition by Estonian Research Council. Also our (the theses were supervised by me and Karl Kaupmees) student Piia Liigand (Burk) was nominated and awarded by Estonian Academy of Science for her work “Expanding the electrospray ionization efficiency scale in positive and negative mode ESI”.

By now all three parts of Jaanus’ thesis have been submitted for publication. The last part on pH effect was submitted only on Tuesday. Piia has also by now submitted a paper on her first task about multiply charged compounds’ ionization efficiency.

Both of the students are continuing their work as PhD students in our lab. We hope to see a lot of good science also during next four years!

Environmental conference in Tartu

In a bit less than a year an international conference EcoBalt will be held in Tartu.  The conference will last for 4 days 9.-12.October 2016. This is the first time EcoBalt will be held in Estonia, though it has taken place in Baltics for more than 15 years now. The conference is organized by University of Tartu. The conference focuses on environmental problems as well as technological developments for environmental analyses.

A real bonus for young scientist is the special session dedicated to young researchers in the environmental field. Of course oral presentations (in parallel sessions!) and poster sessions will be part of this conference. Also a very attractive social program in planned. The abstract submission will be opened from December.

Hope to see a lot of you there!

Check out more information: http://akki.ut.ee/ecobalt-2016-2/?lang=en

Plastics and food

Yesterday for the first time I saw a catalogue of a famous company producing and selling cooking accessories. And I soon become puzzled. A lot of people fancy these products lately, however everything they produce is made out of plastic.

My family and some of my closest friends are well aware that I have never been a huge fan of plastic packed things. I try not to take a plastic bag in shops if possible. In the beginning my mom even tended to be a bit annoyed by this habit of mine. It seems to me so unsustainable to produce large sets of consumables inside packages that are only seldom reused and produce almost nondegrading waste.

Another question of course is the safety of the plastic packages to people. Though there are plastics with numbers 2 (HDPE), 4 (LDPE) and 5 (PP) that have been considered safe, it is well known that even for these plastics the research has not fully proven their safety. This discussion reminded me of a high-school student’s research on a similar topic.  

Last year in Institute of Chemistry Kerttu Taltsi carried out her student scientific work under supervision of Tõiv Haljasorg. Her topic was leaching of phthalates from plastics with FT-ICR-MS. One of the most considerable finding of this work for our everyday life is that even from plastic no. 5 a detectable amount of plastificators leached into water during 30 days (at 60 °C). She discovered leaching of 3 different phthalates and one previously unidentified plasticizer. The leaching experiment was carried out with pure water. These conditions are not directly comparable to our everyday usage of plastic storing boxes. Usually we do not store one food so long in one box. However often we store food which has low pH and/or warm it up in the micro inside the same plastic box. More information about this research is available from Tõiv Haljasorg.

It seems that more research is needed in the field of safety of plastics though their unsustainability can hardly be argued. 

Sporty chemists

Most certainly the event of the week has been the Tartu city marathon and more precisely the competition between labs held during this marathon. Our students organized a competition “which lab has the highest participation rate on the city marathon”.

The “event” for our institute actually started even a lot earlier as several people not running on everyday bases started practicing together after the work-school days.

As the race was held on 3 distances 42, 21 and 10 km there was something for everyone. Altogether 57 people from Chemistry Institute took part in this event. Including professors, scientists, and students.

It was quite nice to have that many friends on the track and by the track! Though I had not planned to make another half marathon this year the lab competition brought me to the track and it certainly was a good choice. The weather was awesome and running together with friends was a lot better than I had expected. I was even able to improve my personal best. 

Analytical chemistry group on the Tartu city marathon.

No sample pretreatment?

Do you want to screen the pesticides presence on your orange? Or do you want to determine if person has used illegal drugs? Or maybe you want to determine the contamination level of trees in the park across the street?

How many sample preparation methods do you need for this? The answer is simple. Just one.

You need a PSI/MS. This means a mass-spectrometer (MS) with a paper spray ionization (PSI) source.

Paper spray was invented approximately 5 years ago in Prof. G.R. Cooks lab. This is a technique that allows to analyse samples that have been collected on a paper with MS.

A PSI/MS setup. Author Hanno Evard.

You can analyse dried blood spots and determine metabolites indicating some disease or determine doping chemicals. Just from this one small blood spot. The beauty of the method is that you really do not need to do anything more than place the blood spot bunched out from the collection paper to the cartridge (placed in front of the MS entrance and to which the ionization voltage is applied to) and add solvent. Both sample preparation and ionization occurs then on the paper and in the spray. Sample preparation can be modified by choosing different paper type (chromatographic papers, eg containing silica or C18 modified silica).

I our lab we have mostly used PSI for pesticide determination. The easies application is for pesticides that are located on the peel of the fruit (the ones that are applied after harvesting). For example thiabendazole and imazalile on oranges, lemons, grapefruits etc. You just need to wipe the peel of the fruit with a paper wetted with solvent and put this paper into PSI/MS. It is a bit trickier for compounds that have been applied during cultivation. For these compounds a slice (or a mush) onto the paper and then apply the solvent.

You can find more about our work on paperspray here.