Today we started by reading a paper from Physics Today titled DNA-Inspired Electrostatics and by doing some textbook reading to catch up on basic biology and biochemistry. In the afternoon Brian and I learned how to pipet properly. We practiced getting the correct amount of water in 1.5 mL sample tubes with each of the six pipets. After we were done, I had less than a 1% error in the majority of my measurements. However I had significant errors in the 2 and 10 microliter pipets. So I remeasured the water for those pipets. After this second try I got much smaller errors in my measurements. At 4 pm we went to the Lab Safety Training and then called it a day.
Today, Ben and I finished working on our slides for our presentation to cap off the research. Based on suggestions from Prof Andresen and John, we made changes to our data arrangement and delivery. We did a practice session with John spotting out more ways to improve the presentation. We were finally ready but the end of the day and gave our presentation. I think it went pretty well and we are now assured that the rest of the Physics research have a good idea of what we did during the summer!
We got the results today and it was another disappointment. The Na concentration was fluctuating while the Mg concentration seemed better but not still up to expectation. Professor Andresen decided to check the parts of the spectrometer again to see if there is any problem wrong with it and he also personally made some solutions to see what happens. Ben and I also started working on our slide show for the presentation we have tomorrow. We are gathering our data and doing some final analysis on them.
Today, I made buffer solutions once again and tested them in the spectrometer. The results will be analyzed tomorrow as we are going to run it overnight.
I remade the solutions using the right concentrations of Mg today. The results we great! What a sense of relief. All the prepared concentrations fell with 1% of their intended concentration. So we decided to step it up one notch. Professor Andresen suggested that I made more solutions in ppb But this time I should make two sets: One with only Mg diluted with water and then the other one with the complete components ( tris and Nacl). I made the solutions and stored them in the fridge so we could test them on Monday and analyze the results.
Today, we ran and analyzed the results of the solutions I made in ppb (parts per billion). There was another problem today as the results showed that there was no Mg in the solutions at all. I checked through my calculations and found out that my calculations were off by a decimal place which made my calculations for the Mg concentrations 1/10th of the actual values they should have been thereby making them undetectable by the spectrometer. I decided to repeat making the solutions tomorrow.
Today, we got the results for the solutions I made yesterday. We had both good and bad news. Good news first: The Na concentrations we almost on points as we had only two samples falling of the 10mM concentration it was supposed to be(7.9 & 7.7mM).The rest were about within 5% of the 10mM intended concentration. However, the bad news is that the Mg concentrations were all off by a factor of 7. This was surprising and confusing at the same time because I was pretty sure I did not multiply my calculations by any factor at all. So, the conclusion today was that I should make some solutions of just different Mg concentrations and water without the tris and NaCl. I made about 5 samples starting form an Mg concentration of 300ppb with an increase of 600ppb between solutions.
Today, I took special care in making the solutions. I weighed them instead of the normal approach of just pippetting the needed volumes into test tubes. I also talked to Professor Andresen about possible problems with the whole experiment and we decided that we wait for the results of this run and then we can change our approach to making the buffer solutions.
After the little success we got, I decided to make more solutions today. However, the results are not looking good. The next step will have to be for me to weigh them instead of just relying on the pipette to measure the amount of solution that I put into the test tubes.
