User:James C. Schwabacher/Notebook/CHEM-571/2013/09/11

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Objective

  1. Finish up work from yesterday collecting UV-Vis spectras.
  2. Test gold standards, citrate-AuNP solutions and BSA-AuNP solutions on the Atomic Absorption Spectrometer.

Procedure

  • It was discovered that our method for recording the previous three trials of UV-Vis spectra were incorrect. The placement of the blank cell was in the improper location. New dilutions were made using the same stock solution from yesterday, measuring out samples of stock solution using the pipette man and diluting the samples with dye and buffer in 10mL flasks. Larger, 3ml plastic cuvettes were used with a path length of 1cm.
  • Standard gold solutions from yesterday, along with previously made citrate and BSA gold nano-particle solutions were analyzed via Atomic Absorption Spectroscopy under the supervision of Dr. Hartings.

Data: Horseradish Peroxidase

  • The data from the 4th trial of Horseradish peroxidase UV-Vis collection is yielding very negative values. It is possible that the blank was measured or made incorrectly.

Data: Atomic Absorption

  • Image:CHEM571_09.11.13_cmj_AAdata.png
  • Image:CHEM571_09.11.13_AAcalibrationCurve.png
  • Image:CHEM571_09.11.13_AAcalibrationCurve_group.png

Calculations

  1. Using the working curve from the gold standards, y=3×10-5x2+0.0209x, the concentration in the citrate-AuNP solution can be determined.
  2. The average absorption for the citrate sample was 0.1444. This is y.
  3. Solve 0.1444=3×10-5x2+0.0209x for x.
  4. x= 6.8419, x=-703.509
  5. Rejecting the negative value, the concentration of gold in the citrate-AuNP solution is 6.842 μg/mL
  6. 6.842 μg/mL = .006842 g/L
  7. Au=196.96657 g/mol, therefore .006842 g/L * (1 mol/ 196.96657 g)= 3.47×10-5 of Au. This was a diluted sample, so multiplied by 10 to get 3.47×10-4
  8. The #Au Atoms/NP = [Au]/[citrate-AuNP] = (3.47×10-4 M)/( 9.17×10-9M)= 37,884 Gold Atoms
  9. 37,884 Gold Atoms Au Atoms per citrate-AuNP

Notes

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