User:Michael S. Bible/Notebook/571/2014/10/22

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Create an Iodide Ion Selective Electrode

  • Prepare iodide ion selective electrodes
    • 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
    • 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
    • Test your electrodes with a range of KI solutions
      • 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

Protocol taken from Dr. Fox.

Use this iodide ion selective electrode to create a calibration curve for [I-].

Additional Dialysis Analysis

Jake did the following:

  1. Ran Titration Analysis on KI-Colloid dialysis
  2. Ran Bradford Analysis on KI-Colloid dialysis


  1. Titration
    1. Added 3mL 1M HNO3 and 0.5mL KI solution to 10mL DI H2O
    2. Added 2 mL AgNO3 and swirl to complete precipitation
    3. Added 200 μL Ferric alum indicator
    4. Titrate with your NH4SCN solution
  2. Ran Bradford Analysis on KI-Colloid dialysis
    1. As expected, the Bradford analysis held a constant protein concentration
      • Lysozyme is too big to pass through the 3500 MWCO so it was constant on one side
      • KI is not expected to react with lysozyme so protein concentration was not affected


Electrochemical KI Calibration Curve.png

Above is the calibration curve for [I-] created using the iodide ion selective electrode.


This area is for any observations or conclusions that you would like to note.

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