My research on the Density Functional Theory and Raman spectroscopy of ten different sulfonamide antibiotic derivatives has really been coming along. I have now completed the assigning of the different vibrational modes for all of the bonds in all ten of the antibiotics. This part of the experiment has taken me the longest to complete. As I was creating the graphs of the Raman spectra data, I noticed that my signal to noise ratio was a little low. This means that the peaks weren’t intense enough compared to the background interferences. To improve the signal to noise ratio, I ran my samples three more times each under the same conditions. Then I used to average of all three runs to plot new graphs with more intense data.
Being a part of this project has taught me a lot so far. Not only have I become quite comfortable using the portable Raman spectrometer that we have here at Pace and using the computer program Gaussian to analyze the theoretical data but I have learned that running an experiment requires a lot of patience. A lot of my time is spent waiting for the samples to finish a run and then I am able to analyze it. It also requires a lot of thinking on your feet because not everything goes as planned and you have to be ready for that.
I have finally been able to create a poster to show the results that I have obtained so far. The next step is to assign the functional groups in charge for the molecular vibrations at the particular peaks.
My research on the computational studies and Raman spectra of ten different sulfa antibiotics has been going well. I have assigned functional groups to most of the peaks that are in the spectra. I have identified peaks that are common throughout the different antibiotics and I have also identified a few distinguishing peaks between them. I have begun to assign bond movements to each of the peaks as well. This process includes inputting the entire structure of the antibiotic into the computer program Gaussian and looking at the theoretical peaks that can be generated after performing an optimization and frequency test. Then I observe and record what movement I see when looking at each peak that is present in the spectra. By the end of the study I will have done this for all 10 of the antibiotics. It is a very time consuming process but in the end it can tell us a lot about the molecule.
This past week I worked in the lab here at Pace and ran the samples of 7 out of the 10 antibiotics again using the mini Raman Spectrometer. I had to determine what settings for the time average and multiplier, which are settings on the program that determine how long the sample is run for, would give me the most intense peaks. I did this by running a sample of Tylenol as a control first, since we know what the Raman spectra of Tylenol should look like. Once I found the best setting I ran the sulfa antibiotics under the same conditions. I am going to compare the new spectra that I obtained with the older data that I have from before. I will be looking for any abnormalities in the data, if there is anything new, and if the data is just better overall.
For this study I am continuing to do research with Dr. Mojica in the Mojica research group on the vibrational spectroscopy of antibiotics, focusing on the computational studies and Raman spectra of ten sulfa drugs. Sulfa antibiotics are most commonly used in the treatment of respiratory and urinary tract infections in humans and in aquaculture as herbicides. The goal of this study is to identify the chemical bonds that are unique to sulfa drugs, which will not only provide a way to quantitate amounts of the drug in a sample but it will also help in the understanding of the chemical properties of the drugs. To do this study I must use Raman spectroscopy, which is a way to obtain information about the molecular vibrations of a compound. The particular sulfa drugs that I have tested and will continue to test are sulfamethazine, sulfamethoxazole, sulfachloropyridazine, sulfadimethoxine, sulfathiazole, sulfamerazine, sulfisoxazole, sulfamethizole, sulfameter, and sulfadiazine.
As of now I have obtained the complete first round of Raman spectra and I am processing the data by assigning the functional groups on the peaks that I have observed. I have also obtained the theoretical Raman spectra for each of the drugs using the computer program Gaussian and am currently assigning the bond movements that are observed at the different wavelengths of the spectra. I plan on doing another round of testing using the portable Raman as well.