User:Khyra A. Neal/Notebook/Chem 571/2014/10/21

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October 21, 2014

Tasklist

1. Preparation of Dialysis for 30:1 Colloid vs CaCl2

2. Prepare ISE for Iodide

3. Determine Molecular weight of Electrophoresis gel from October 15, 2014

By comparison with Precision Plus Protein Standards, the molecular weight of all samples was close to 15 KD, slightly lower, as expected for lysozyme compounds with MW=14,300 KD. There was a very small quantity of unknown A and colloid in the gel. The very faint mark observed in well 3 could even be considered to be bleed-over from the 30:1 colloid in well 4. Therefore, electrophoresis was inconclusive with respect to the molecular weight of unknown A.

4. Prepare 10 mL 3 M NaCl

  • Carefully remove yellow plastic covering on Ag/AgCl electrode (as instructed)
  • Place electrode in 15 mL falcon tube with enough NaCl solution to match volume in electrode
  • cover and store upright until needed

5. Prepare 50 mL 4 M KNO3

  • Add KNO3 to outer double junction cell, filling narrow tube + ~ 0.5 inches further

Place electrode in small vial with enough KNO3 solution to cover the vycor tip

  • Prepare 50 mL 0.01 M KI + 0.1 M KNO3
  • Cut a short piece (~ 3 in) of silver wire
  • Place in KI/KNO3 solution
  • Electrolyze the solution using the power supply
  • The standard reduction potential for Ag/AgI is -0.15 V
  • Oxidation occurs at the anode, which is connected to the red lead
  • Electrolyze at low power (low current) until the wire appears coated

6. Test your electrodes with a range of KI solutions NEED TO DO

  • The Ag/AgCl electrode slides inside of the KNO3 bridge solution (this is a double junction electrode)
  • The Ag/AgI wire can be connected directly to a multimeter using alligator clips
  • You will continue to connect your Ag wire to the red lead on the multimeter

7. I- ISE Calibration Curve

KI Calibration Curve.jpg

Stock Solution Preparation

1. The previous KI solutions were discarded because there was an error with the dilutions that were prepared. All new KI concentrations were prepared

  • 50 mM KI = 0.83 g KI in 100 mL H2O
  • All dilutions were prepared from 50 mM stock KI
    • 25 mL 25 mM KI
    • 25 mL 10 mM KI
    • 25 mL 5 mM KI
    • 25 mL 2 mM KI

2. 10 mM NH4SCN

  • 0.7612 g NH4SCN in 1 L H2O

3. 75 mM AgNO3

  • 0.637 g AgNO3 in 50 mL H2O