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Week 6 - Closing in on Results

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 Tuesday, I was able to use the HPLC to analyze some of my tests from Monday. I only had the HPLC in the morning, and we had some professional development meetings, so I unfortunately was not able to test all of the time points from all of my experiments. However, I was able to narrow down the range of concentrations we should test.

On Wednesday, I performed additional experiments informed by my partial HPLC results from Tuesday, and tested them with the HPLC. I obtained some interesting data, but none of it was entirely reproducible. The first few time points of my experiments always seemed anomalous. Fortunately, we found a concentration that at least gave results resembling a smooth reaction curve, so we resolved to retest these conditions and see if we could get consistent data.

On Thursday, I ran multiple experiments at the concentration we had settled on Wednesday.  I took more time points than usual, and ran two identical experiments in order to see if our setup was reproducible. Later in the day we gave our midterm presentations, wherein I had the opportunity to tell everyone about my lack of results. It went well.

On Friday, I ran HPLC data for my experiments from Thursday. Both experiments showed the same pattern, which unfortunately included very low concentrations at the earlier time points. This told us two things: that our method was reproducible and consistent, and that something needed to be changed if we wanted early time points that look sensible. I ran another experiment using ascorbic acid to quench the reaction rather than a filter, on the hunch that some 4-chloroaniline may be adsorbing to the MnO2 and getting removed from the filter. I will run the HPLC on this experiment on Monday.