Stuart Ness's blog

On Monday, I created fits for my various plots of 4-chloroaniline experiments, and compared them to the literature values we have been studying. While there is a bit of variation in the reaction constants between our replicates, overall the data fits well with what is represented in the literature. This is exciting news, and means we can move forward in our project.

On Monday, I had a fortunate and embarrassing realization. Late last week, we seemed to have finally got our method down to a replicable state, but the concentration still seemed to be dropping from the initial spiked amount down to around 3 or 4 μM too quickly. This bothered me, so I rechecked my math, and realized I had completely miscalculated how much aniline I needed to inject into the reaction vial, and was starting the reaction off at 4 μM of aniline rather than 20 μM. This reality meant that our results made much more sense, and that I had an embarrassing talk with Ali.

On Monday, I ran experiments with varying concentrations of MnO₂ and 4-chloroaniline. We hope to narrow down the reaction setup to concentrations of MnO₂ and 4-chloroaniline that give consistent results. Once we know our experiment is reproducible, we will be able to determine the kinetics of 4-chloroaniline. 4-chloroaniline is the compound we wish to compare all of our other tests to, so this will be a big step.

On Monday, I prepared a variety of solutions to test in the HPLC on Tuesday. Because the ascorbic acid had so obscured the 4-chloroaniline spike during last week’s HPLC run, I prepared less concentrated solutions, and also tested solutions of acetic acid and sodium hydrosulfite. Unfortunately, acetic acid did not dissolve the MnO₂ much at all, and sodium hydrosulfite was insoluble in methanol, an important requirement for our HPLC setup. Therefore, I determined that low concentrations of ascorbic acid would be our best bet for creating usable HPLC data.

This week was a short week due to Independence Day and a field trip, and the week was mostly spent trouble-shooting. On Monday, we tried something new to be able to read the 4-chloroaniline concentration on the HPLC. Our conclusion as to why we were seeing no 4-chloroaniline in our HPLC output was that the aniline was adsorbing to MnO₂, so when we filtered out the MnO₂, we also effectively filtered out the 4-chloroaniline.

This week, my mentor, primary investigator, and just about every other researcher in my lab was gone at a conference. This means that I have been mostly unable to perform any experiments, as nobody is around to help with troubleshooting the HPLC or to ensure we interns do not blow anything up. Instead of running additional experiments to attempt to explain our results from last week, I have been reading up on the literature and ensuring that I have a firm grasp of the theory behind our project.

This week, I set up the practices I would need to run my experiments. On Monday, I created more MnO₂ and flash dried it to send off to the XRD. I also created known concentrations of 4-chloroaniline solutions to create a calibration curve for the HPLC. Unfortunately, I overlooked a key step in my experimental procedure. When I perform my experiments, the aqueous solution will be extracted from our extraction vessel and diluted to half concentration with methanol. This is because our HPLC runs with 50/50 methanol/water, and we want our sample to match our HPLC’s composition.

Hello, this is Stuart Ness, an undergraduate intern at IEH for the summer of 2014. I will be working this year with my mentor Ali Salter-Blanc studying the Environmental Degradation of Munition Compounds. Specifically, I will be focused on the kinetics of oxidation reactions between MnO₂ and aromatic amines. Various authors have looked at the reactions of specific amines with manganese oxides, but not nearly as comprehensive a set as we hope to study.