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Procedure for the use of Pyridine Containing Reagents

Systems Components:
  1. Two bottles of solution, one labeled “A” and the other labeled “B”.
  2. One bottle of neutralizing solution which is 2-3% water in methanol.
  3. One box of 10 ampoules of generator solution. (At present, we are using the same generator solution for the pyridine-free and pyridine-containing systems).
Solution Preparation:
  1. Pour the contents of bottle “B” into bottle “A”. Swirl to mix well. Best to do this in a fume hood for the pyridine smell is quite pungent.
  2. This mixture may occasionally become warm due to the chemical reaction taking place. This should be of no concern.
  3. Allow the mixture to stand for about ½ hour to mix well and cool.
  4. Pour about 150 cm3 into the titration vessel and add an ampoule of the generator solution to the generator. *
  5. Turn on the AQUATEST 1010 or 2010 and set the stir action to an appropriate level.
  6. Note that the display will read DRY and probably show 0.00 micrograms as the titration rate.
  7. Slowly add one drop at a time of the neutralizing solution and note the color change. It will rapidly change from a deep brown to a pale yellow as you add the neutralizing solution drop-wise.
  8. The color shows that the free iodine is being changed to iodides. Take care to add only enough neutralizing solution to go to the pale yellow color, otherwise you will have added too much water and then it will take some time to get to the DRY state.
  9. When the display reads DRY, RDY, or ADD SAMPLE, the system is ready for sample analysis.
* NOTE:  The leftover reagent can be added to the vessel to keep the level at about 150 cm^3 at any time. Since this solution is extremely dry, a drop or two of neutralizing solution may have to be added to the vessel to get to the slightly wet state and then to “set-point”.