Conclusion

Though Chinanu and I are done for the summer, there is still much work to be done in regards to our project.  

We are able to make a few loose conclusions based on the relative peak heights from the chromatograms obtained, but are not able to make any quantitative conclusions about the concentrations of compounds found in samples because calibration curves of the standards ran have not been completed.  We are however, able to compare compounds based on the peak area of compounds on the chromatograms.  Using the peak area, we are able to compare the compounds at each site quantitatively.  For the future, we plan to organize all of the peak areas for key compounds of compound groups and compare the sites in this way, and then determine the concentration of the compounds when all calibration curves are completed.  

For now, we have results suggesting that the aromatics found in the I-91 samples are relatively the same concentration as those found in the Medical School samples.     

Outcome of Research

The first week of August brought to Chinanu and I a new objective, to compare concentrations of specific compounds between our two most promising site, the I-91 off ramp and at Yale’s Medical School.  At both sites, we sampled during “rush hour”, for the I-91 ramp we sampled during the morning when workers were coming into New Haven, and during lunch time at the Medical School.

During our meeting with Dr. Gentner, we agreed that we would focus on toluene, xylenes, and compounds with benzenes.  In our analysis, we also found a few alkanes and oxygenated alkanes we decided were significant enough to take note of.  

Surprisingly, both sites had similar compounds.  More alkanes were found from the I-91 site than from the Medical School site which is expected, because alkanes are generally from the gasoline burned in cars.  

Though specific concentration of compounds were not determined because calibration curves from standards have not been completed yet, we are able to look at the relative concentrations of compounds by comparing the relative peak heights seen on the chromatograms produced.  Generally, the concentrations of the compounds that were seen, mainly compounds that contained benzene, in both the I-91 samples and the Medical School samples were generally the same, suggesting that emissions from the tailpipes of cars are similar to that of the food carts that park at the Medical School.

What I Learned

Throughout our stay in the lab, many new ideas, concepts, and technology was introduced to us.  We had the great opportunity to learn more about organic compounds, and how they play a role in our health and in the environment.  We also learned about the different analytical tools used to understand different properties of chemicals, such as the Mass Spectrometer and the Gas Chromatogram we used in the lab.  Most of all, I enjoyed listening to and learning about the projects others in both our lab and in Dr. Plata’s lab were working on.  All of the projects were really advanced, and required Chinanu and I to go back to the office and research terms and technologies that we have not heard of before, opening our eyes to aerogels, SEM ( Scanning Electron Microscope), and Quadrupole Time of Flight to name a few.  

I think I gained the most knowledge about organic compounds this summer, which is very valuable to me because I am looking to go into a chemistry related field in college and after.  In school, we were required to learn organic chemistry, but the information did not truly resonate with me, making it difficult to remember basic concepts such as nomenclature.  I came into the lab knowing a lot about chemistry, but not a lot about organic chemistry.  I feel like I am leaving the summer having a greater understanding of not only the different compounds and how they are classified, but also how they affect our bodies.  I once thought the effect of ozone in the troposphere had a negative impact on human lungs because it forced oxygen out of the troposphere.  This is not the case however, as Dr. Gentner explained to me, but rather ozone is an irritant when in contact with our lungs.  This is just one example of one of the things he taught Chinanu and I personally about organic chemistry.  

 

Most Challenging/Frustrating

Besides the perks of being able to go out into the community and collect air samples while telling passing audiences of our research, Chinanu and I have the opportunity to work with cutting edge technology.  

Though versions of Gas Chromatographs and Mass Spectrometers have been around for a while, we were required to work with newer versions by Agilent Technologies.  Learning how to use the analytical software MassHunter in and out was maybe the most challenging part of our internship.  Before we used the program, basic features that we would need were demonstrated to us, and a sample that we collected was even ran through the system in order to show us how to view the compounds and what standard we should use in deciding which compounds were truly in the sample or not.  

I mainly had trouble remembering how to follow the steps that were shown in opening up the NIST Library, the library that contained known compounds saved to the computer.  It also took me a while to understand how the database “matched” a compound in its library to a compound found in our sample, which made it a bit harder for us to find good constraints in determining if a matched compound was truly in our sample and to record it.  Upon our first meeting with Dr. Gentner, he made it one of our objectives to find out what many of the constraints, such as Probability, Match, and R-Match, were defined as to make it easier.  

Near the end of August, Chinanu and I were far more acquainted with the program and knew how to do things in the program that were once a challenge, such as subtracting background noise from a samples peaks.

Maya Conference

The MAYA (Mid-Atlantic-Youth-Alliance) conference was an annual 3 day conference that happens every year. About one hundred high school students that work in various science based institutions (e.g. a museum, aquarium, or zoo) attend. Every year a different institution hosts the conference, this year we were the chosen ones! Each institution that hosts the conference also picks the theme. The theme always has something to do with the environment in some way so this year we decided on urban environment, since we are right here in New Haven. We decided to have three main focuses that all connect to urban environment which were infrastructure, food justice, and biodiversity.

  When I first found that out that the Peabody was hosting the conference I was nervous because I went to one before and I didn't know if I was ready to take on something so important. But Bay and Paul had some awesome mentors this year that made sure we stayed on track and made planning the conference pretty fun. We mostly worked with an undergraduate student from Southern Connecticut State University named Dan. He worked with us every step of the way and made sure we all knew what we needed to get done and by when.  Most of us worked at least 6 hours a week planning this conference on top of the jobs and internships we were already doing this summer.

Once the MAYA conference actually came around I couldn't believe how fast time had flew! I felt as if I wasn't ready and I was nervous throughout the entire conference just hoping nothing would go wrong. As the three days of the conference went on I stopped being so nervous and just enjoyed seeing everything we worked so hard on come to life. All in all I had a grate time at the conference and also planning it. I loved talking to everyone there, telling stories, just learning about what they do at their jobs, and figuring out what they liked about the conference. The MAYA conference of 2015 is a moment that I will always remember and cherish for the rest of my life. I'm so grateful that I got to plan that conference with the wonderful students in Bay and Paul this year and the awesome mentors that we had with us every step of the way.

~ Cora Walker

Results/Outcomes of the Project- Gentner Lab 2015

At the beginning of August, Vanessa and I were given a new objective to our research. Originally, we aimed mainly to just look at our four different sites and determine exactly which compounds are at each place. However, we eventually realized that we were getting a lot of data, but we wanted to figure out how to decipher it and figure out what is most important to all of us and residents/dwellers of New Haven. Dr. Gentner suggested then that we actually choose two of our sites to look at, the two of our sites that people visit/go to most often; the I-91 off-ramp and outside Yale Medical School. We also decided to zero in on key compounds (aromatics) which we knew were present at both sites; toluene, xylenes (p-,m-, and o-), ethylbenzene, trimethylbenzene, naphthalene, and methylnaphthalene. These are all potentially dangerous compounds, and we hoped that we could actually figure out the concentrations of them at the two sites, and thus, compare the air quality at each. However, this turned out to be a task that would be very complex and time-consuming: we would have to obtain calibration curves from chromatogram standards for these compounds. This is a task that we can hopefully take up in the near future (time-willing), but for now, we have figured out another way to compare the air at the two sites.

When a sample tube is put through the three-machine system in the lab (Thermal desorber-Gas Chromatograph-Mass Spectrometer), you eventually end up with a chromatogram, or a visual representation, of the compounds found in the sample. Along with this, you also get several factors that help in identifying/defining the specific compounds in the sample. The system can not immediately identify a compound in the sample; instead, you are given a “hit list”, or a list of possible matches to what is actually in the sample, along with what is called the retention time, retention indices, peak area, peak height, match, r-match, probability, and fragmentation factors. If we, for example, have a chromatogram from one I-91 and from one med school sample, and these two graphs are scaled the same way, we can single out a specific compound and compare the peak areas of that compound in each. If, for example, 1,2,4-trimethylbenzene has a higher peak area in the graphs of the samples from the med school than in those from the highway off-ramp, you can assume that there is more there than in the other location. This is the method we have decided to use in comparing the contents of the air in our two sites.

Final results are still pending, as Vanessa and I are still working on compiling our data and using the method described above to compare the air outside Yale Med School to that at the I-91 off-ramp. We are also hoping to find the specific sources of the compounds we find in the air samples at these places, whether they be from the food being cooked or from the fuel being used to cook it. For now, we CAN say that there are a number of similar compounds (specifically aromatics) at our two sites, and we hope to go further with our data so that eventually, we can make actual conclusions.

Daily Procedure

The bulk of our lab work is in the sampling portion of our project.  Ensuring that we are taking the same steps each time when collecting samples is crucial in eliminating careless errors.  

Sampling

1. (To ensure that the pump is set for low flow), make sure that cap over regulator valve is removed, and valve is turned 4-5 times counterclockwise
2. (Once per “sampling day”) Equilibrate  while connected to flow meter for five minutes at .115 L/min
3. Make sure that the LCD screen (on pump) says “Hold”, then when sampling site is reached, press Start/Hold button to begin pulling air through pump (“Sample Running” should display) at the same flow rate for 30 min.
4. Record start time
5. When sampling time has finished, press Start/Hold button again to record stop time. Take note of Temp., Forecast, Flow Rate, Humidity, Wind Pattern, and other notes.
6. Put samples in lab freezer

Storage

1. Put samples in lab freezer