Julius, Entry #1, The Wonders of TLC

I finished an interesting first week at UPenn, working on chemical synthesis and Alzheimer's disease under Dr. Carlo Ballatore. The day before I officially went to the lab, I attended a seminar at the EHRS offices at UPenn (Environmental Health and Radiation Safety), a relatively harmless, mandatory presentation given to all first-time lab students. I was surprised at how similar the safety precautions were to the ones at the Peddie AP Chem Lab class and after a few videos, thoroughly scared into following them.

The first day at the lab, I found myself under the instruction of Anne-Sophie Cornec, a post-doc from France.(The entire lab only has three members, making the general atmosphere rather quiet). After some small talk and procuring a Penn Card as a "visiting scholar", the work began. The main purpose of the lab is organic synthesis, for compounds specifically related to Alzheimer's Disease. Reactions are constantly run in order to isolate potential drugs, which are then tested at the Perelman School of Medicine nearby. My main experience, therefore, will be based around learning the proper lab techniques involved in chemical synthesis.

For the beginning, Anne-Sophie taught me "TLC" (Thin Layer Chromatography) which is as, my PI says, the "bread and butter" of organic chemistry (in a booming voice). The process, which is based on the relative polarity/non-polarity of substances, is a relatively quick and simple way to separate and distinguish compounds present in a mixture. After dotting silica gel plates with the mixture, using capillary tubes, the plate is placed in a jar, partially immersed in a solvent. Over time, the solvent will move upwards (due to capillary action), but the different compounds present in the mixture will move different lengths (due to the different polarities of the compounds). This movement can be detected under infrared light.

TLC Plate before immersion

TLC Plate after immersion; note the movement and different location of blots

The TLC, as I learned, plays an important role in identifying compounds present in reaction mixtures. Its a relatively quick and cheap way to do this, without bringing out the "big guns", machines that are able to perform the task. Two primary methods would be LCMS (liquid chromatography-mass spectrometry) and the NMR (Nuclear magnetic resonance), methods that utilize large machines that require a great deal of experience (meaning I won't be using them for a while probably). Overall, the first week has compromised mostly of TLCing different compounds from reactions that my post-doc has run, a long but important process.

I've also been able to observe Anne-Sophie conduct reactions, which involve a large number of complicated steps (separation of organic and inorganic layers, Biotage/column chromatography) that I will probably learn over my time at the lab.