Erika Cremer and Gas Chromatography

In 1952 Archer J. P. Martin and Richard L. M. Synge won the Nobel Prize for the invention of partition chromatography. Sadly, a woman who (also) deserved the prize could not be awarded. She wrote the first paper on Gas Chromatography based on the results of one of her students. It was 1945 when the paper was approved by the Naturwissenschaften journal, but due to the WW II the journal did not publish the paper.

In 1972 the journal Chromatographia managed to get an old manuscript with the printed proofs Erika still kept. You can read here the paper entitled Über die Wanderungsgeschwindigkeit der Zonen bei der chromatographischen Analyse. If you understand German, of course. If not, you can know more about this researcher in this nice article by Yanko Iruin.

Here you can find more stories about women and Science (in Spanish).

Flame tests and emission spectroscopy (LW2)

In labwork 2 we used an atomic absorption spectrometer in order to quantify copper amount in soils. The analyte was atomised using a flame at high temperatures. This flame can also be used to “excite” atoms. In this case, the electrons of the atoms jump to a higher energetic level and when returning to their original level they release energy in form of light. Since this energy is element dependent, it can be useful to obtain information about the composition of a sample. In the laboratory, we observed the colour of the flame of different salts containing: lithium, boron, sodium, potassium, calcium, copper, strontium and cesium.

The emission of energy is not only useful to obtain qualitative information, but also quantitative. The energy released by a specific analyte can be measured at a certain wavelength and employed for quantitative purposes. That is the basis of atomic emission spectroscopy (AES). Finally, just let you know that this phenomenon is used to make fireworks. Here you have a nice infographic by Compound of Interest.

Building calibration curves

Building a good calibration curve is a critical point when applying a quantitative method. As you know, in order to know if the calibration is suitable we can check out (among others) the R² value. But, be careful, we tend to overestimate the importance of this parameter. Look at the following figure called the Anscombe’s quartet. All the dataset have the same mean value for x and y and… the same R²! Thus, as you can see, graphs are very useful to study our calibration curves (the residual graphs can be very useful too).

Reading a paper: a touch of humor

Reading papers is part of the daily live of a researcher. It is the way to know which are the latest innovations in our field and also the way to learn about unknown areas.

That is why during this course you will learn how to read and how to write scientific papers, especially in the field of Analytical Chemistry.

I took some comics from PhDComis website related to this topic. If you do not know the website, check it out. Perhaps you do not find it amusing but, if you decide to follow a research career, you will.

But, please, take into account that the facts are exaggerated. Reading papers is not that boring!

Fluorescence Friday (LW1)

In this lab work we quantified quinine in tonic water using fluorimetric detection. We also observed the fluorescence of other products: curry, detergent, eosin dye, eggs and two cardiovascular drugs.

Curiosities related to LW1

One of the tasks of LW1 is to quantify quinine by fluorescence detection. You might have observed the fluorescence of this compound when drinking tonic water (or more probably Gin&Tonic) in a disco. But quinine is not the only fluorescence compound around you. For instance curcumin, a molecule present in some spices (such as curry) also shows fluorescence. You can check it out in the following video. This phenomenon is explained in detail in this link.

Another task you will carry out during LW1 is the determination of iron in fish. Did you know that there was a scientific explanation connected to the idea that red wine and fish don't mix?