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May 27 2015: Determining Size and Concentration of Au Nanoparticles from UV-Vis Spectra
1) Spectrometer was set up to laptop, where a blank cuvette filled with water was used to calibrate the system.
2) The cuvette was filled with 1 mL of solution from the sample being tested and 1 mL of water. This was done because the absorbancy level of an undiluted solution exceeded one, so this measure was done in accordance to beers law concentrations. This procedure was followed for each of the 20 samples, which in turn created 20 diluted samples, which were marked and sealed separately.
3) Raw data was recorded into excel for each of the 20 samples, where size and concentrations of the gold nanoparticles were calculated (see results).
4) The average absorbancy of each raw sample was then base lined using the Gaussian equation on excel, and recalculated to determine size and concentration of the gold nanoparticles (see results)
The first table contains raw calculations. Average size of nanoparticle was approximately 12.75 nm with a standard deviation of 3.5075 nm. The second table contains calculations corrected by baseline data. Recalculated average size of nanoparticle was 13.85 nm with a standard deviation of 3.33 nm. The recalculated average concentration (nm/M^-1 cm^–1) was approximately 7.27E-09 with a standard deviation of 0.000000004892202255.
The last column in the second table represents the concentration of the undiluted sample. This is due to the sample being diluted in half with water in accordance to beers law concentrations.
Haiss, Wolfgang, Ngyuyen T.K. Thanh, Jenny Aveyard, and David G. Fernig. Determination of Size and Concentration of Gold Nanoparticles from UV-Vis Spectra. Thesis. University of Liverpool, 2007.