User:Carly M. Montanero/Notebook/CHEM-571/2013/09/03

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Today we'll be determining the molar absorptivities of two different molecules, adenosine and inosine. The data that we generate today will be important when we study adenosine deaminase (ADA), which converts adenosine to inosine. The difference between these two molecules is that adenosine contains a primary amine whereas inosine contains a carboxy group. Overexpression of this protein causes anemia in humans. A shortage of this protein can lead to severe immuno-defficiency.

Adenosine and inosine have different absorption spectra. We will be observing changes in UV-Vis spectra to determine changes in concentration of both adenosine and inosine. In order to do this, we will need to know the molar absorptivity (ε) of both of these molecules. Just as each molecule has a characteristic absorption at each wavelength, this (per-wavelength) absorption can be quantified by a molar absorptivity. Or ... for a given concentration a molecule will absorb a very specific amount of light at a precise wavelength. A molecule doesn't have just one molar absorptivity; there is a molar absorptivity to describe each wavelength in a molecular absorbance spectrum.

From Dr. Hartings


Creating the Adenosine Stock Solution

  1. Add 0.0817 g of adenosine to a 100 ml volumetric flask.
  2. Add deionized water up to the 100 ml mark.
  3. The concentration of the adenosine stock solution was calculated to be 3.06x10-3 M.

Creating the Inosine Stock Solution

  1. Add 0.1261 g of inosine to a 100 ml volumetric flask.
  2. Add deionized water up to the 100 ml mark.
  3. The concentration of the inosine stock solution was calculated to be 4.70x10-3 M.

Creating the Dilutions of Adenosine and Inosine Solutions

Adenosine Solution Concentrations (M) Inosine Solution Concentrations (M)
3.00x10-5 4.80x10-5
2.50x10-5 4.00x10-5
2.00x10-5 3.20x10-5
1.50x10-5 2.40x10-5
1.00x10-5 1.60x10-5
0.50x10-5 0.80x10-5

UV-Vis Data Collection

  1. A cuvette was filled with 1 ml samples of each diluted adenosine sample.
  2. The spectra of each solution were collected.
  3. After each run, the cuvette was rinsed three times with deionized water.





  • There was not enough time, so the inosine samples were not run on the UV-Vis today. They will be run tomorrow.