On Wed, 9 Dec 1998 PSMannan@aol.com wrote:

> I am trying to find a method to detect iodine (from betadine) by
> histochemical methods. Any suggestions?

  IF Betadine is the same as "povidone iodine" (stuff used to
  disinfect hands etc) it's a combination of iodine with
  polyvinylpyrollidone (PVP), from which the iodine is slowly
  released so that it will do its stuff on the bacteria for
  longer than a plain iodine solution. (The deposited iodine
  sublimes, and the stained skin unstains in a few hours without
  having to be washed.) This is derived from memories of the
  mid-1960s in the Casualty Department at what was then the East
  Birmingham Hospital. That's the B'ham or Brum where I was brung
  up, what competed with Glasgow for being Britain's 2nd most
  populous city. (Anyone know the current score? Ian M ?)

  To the point. There's not much chance of the elemental iodine
  staying in place for histochemical demonstration. It might bind
  covalently to double bonds of lipids and/or the phenolic ring of
  tyrosine in proteins. I've no idea how it could be made visible
  if it does.

  HOWEVER, the PVP component is a macromolecule and might well
  be detectable.  There is a staining method for PVP using Congo
  red; it may not be the only one. See Pearse's Histochemistry
  for rationale and instructions. PVP was used as a plasma
  substitute. Perhaps the less successful uses or "complete
  cases" led to the need for a method to show where it ended up.

    PVP is also a very good as an aqueous mounting medium; another
    of Pearse's achievements, I think. It's cheap, dissolves quite
    quickly, and tolerates such additives as buffers and anti-fade
    compounds. This last paragraph is just a little plug for the
    polymer. Nothing to do with iodine!

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1