- To finish the procedure from yesterday.
- Use the Atomic Absorption Spectrometer to test gold standards, citrate-AuNP solutions and BSA-AuNP solutions.
- There was an error in placing the cuvette in the UV-Vis, so all of our data from yesterday is incorrect. We created new standards and reran each sample, correctly using the UV-Vis.
- Today, we measured the concentrations in 10ml volumetric flask and the cuvette had a path length of 3cm.
- Standard solutions of gold and previously made standards of citrate-AuNP and BSA-AuNP were analyzed with the Atomic Absorption Spectrometer.
- Atomic Absorption Data for Gold Standard, BSA-AuNP Standard, and Citrate-AuNP Standard
Calculating the Number of Gold Atoms in Citrate-AuNP
- The equation of the best fit line from the class data was y = 3x10-5x2 + 0.0209x.
- The average of our corrected citrate-AuNP concentration was 0.1444 μg/mL.
- Setting 0.1444 equal to y yields the equation 0.1444 = 3x10-5x2 + 0.0209x.
- Solving the quadratic equation gives two answers: x = -703.51 and x = 6.842.
- Disregarding the negative value, the 6.842 μg/mL corresponds to the concentration of gold.
- We diluted the sample of gold by 10, so the actual concentration is 0.06842 g/L.
- The molecular weight of gold is 196.97 g/mol.
- Converting the concentration of gold to molarity yields a concentration of 3.474x10-4 M gold.
- Dividing the concentration of gold (3.474x10-4) M by the concentration of citrate-AuNP ( 9.17×10-9M) gives the final number of gold atoms per citrate-AuNP molecule.
- Though these calculations, there are 37,884 gold atoms per citrate-AuNP molecule.
The UV-Vis spectra of trial 4 Bradford Assay of horseradish peroxidase had some serious errors. We discarded the data.