# Difference between revisions of "User:Michael F. Nagle/Notebook/Chem 571/2012/09/25"

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## Objectives

• Extract ADA from E. Coli
• Obtain two sets of UV/Vis spectra for Au/BSA solutions with varying concentrations of Tris, to see how absorbance changes over time

## Procedure

1. Protein extraction
1. Mary Mendoza and Puja Moody extracted the protein prepared last week
2. Solutions of Au/BSA at a mole ratio of 70 (at which fibers are not produced) with Tris at molarities of .05mM, .5mM, 5mM, 50mM, 100mM, 200mM, 500mM, and 1M went through two rounds each of UV/Vis.
1. Stock solution for Tris was made
1. 1mol/L *.025L = .025mol Tris needed
2. .025mol * 121.14g/mol = 3.0285g Tris weighed
2. The equation M1V1=M2V2 was used to calculate the amount of stock and water needed in the 100mM, 200mM, 500mM and 1M tubes. A serial dilution was done from 500mM to .05mM to fill the rest of the tubes. 1mL from each tube was moved to the next with a pipette.

## Data

Amount of Tris stock and water in each tube
Tris Buffer concentration amount of water (mL) amount of tris (mL)
.05 mM 0.9938 0.0625
.5 mM 0.9875 0.0125
5 mM 0.975 0.025
50 mM 0.95 0.05
100 mM 0.9 0.1
200 mM 0.8 0.2
500 mM 0.5 0.5
1 M 0 1

## Data and Conclusions

Results of other team:

• No significant difference is seen between our two UV/Vis trials, except for 5mM in the second trial, which has a much higher absorbency peak. This may be due to random error.
• Opposite trends can be seen between the two teams' trials. In ours, lower molarities of Tris resulted in higher absorbance, while the Chem-571 class last year, lower absorbance for lower molarities of Tris could be seen. Their absorbance values were also much higher. The fact that opposite trends are seen in all samples means that if this was due to error, it was a systematic error.