User:Melissa Novy/Notebook/CHEM-571/2012/11/28

Objectives

• Analyze AuADA solutions made on 2012/11/27 with UV-vis and AA spectroscopy.
  • Please refer to Keyun Wang's entry for observations on and photographs of the solutions.
• Resuspend AuADA fibers in solutions made on 2012/11/27 with Tris buffer.

UV-Vis Analysis of AuADA Solutions

• The spectra of AuADA solutions were collected over 200 nm to 800 nm.
• 3 mL of AuADA solution was pipetted into a quartz cuvette and then placed in the UV-vis spectrophotometer.

• A peak at around 520 nm was visible in the spectra of the following mole ratio Au:ADA solutions: 60 through 130. This peak is likely due to the presence of GNPs in these solutions.
• Purple fibers were observed in all of the solutions. The liquid in each test tube was transparent purple.
• Whereas undialyzed ADA did not form GNPs, these solutions using dialyzed ADA appeared to form GNPs. It is possible that either the decrease in concentration of buffer salts between undialyzed and dialyzed ADA or the use of plastic test tubes to contain the Au and dialyzed ADA solutions contributed to the formation of GNP-ADA fibers.

• The absorbance of 60 AuADA was the highest and the absorbance decreased as the mole ratio of the solutions increased. Overlooking any experimental error, which is discussed below, this indicates that 60 AuADA created the most GNPs in solution and that this mole ratio was the best at forming the maximum number of GNPs out of the solutions tested.
• One source of experimental error is resuspension of AuADA fibers that contain GNPs. If they were resuspended, the GNPs in these fibers would be released into solution and contribute to the absorbance at 520 nm.

Analysis of AuADA AAS Data

• Please refer to Keyun Wang's entry for the concentration of Au in AuADA solutions obtained from AAS, and the calibration curve used to calibrate the AAS with standard solutions of HAuCl₄ in 1 N HCl.
•  % change Au ppm analysis

Resuspension of ADA Fibers

• Tris buffer was made on 2012/09/04.
• Please refer to Keyun Wang's entry for volumes and concentrations of Tris buffer added to