Colloidal Iron Suspensions

Colloidal iron suspensions are available commercially, and these may be found quite satisfactory. The working solution is usually given as an equal parts mixture of the suspension and 12% acetic acid.

For those who wish to make their own suspension, any of those below will be found suitable for use in Hale type procedures for the demonstration of acid mucopolysaccharides. Once made up, the suspensions are stable for several months, perhaps years, although proper control sections should always be used to ensure they are still suitable for use.

It should be noted that colloidal iron may also react with nuclear phosphate, so nuclear chromatin will often be stained.

 

Müller
Distilled water 250 mL Bring the water to a boil. Slowly add the ferric chloride while stirring. Continue boiling until the solution changes to clear, dark red. Cool.
Ferric chloride, 29% aqu. 4.4 mL
Working solution:– Stock colloidal iron 20 mL, Distilled water 15 mL, Glacial acetic acid 5 mL.

 

Krecke
Distilled water 250 mL Bring the water to a boil. Slowly add the ferric chloride while stirring. Continue boiling until the solution changes to clear, dark red. Cool. Dialyse against 2 litres distilled water, changing 3 times over 24 hours.
Ferric chloride, 29% aqu. 4.4 mL
Working solution:– Stock colloidal iron 10 mL, Distilled water 18 mL, Glacial acetic acid 12 mL.

 

Rhinehart & Abu'l Haj
Ferric chloride 75 g Dissolve the ferric chloride into 250 mL water. Add the glycerol, then slowly add the ammonia, stirring all the time. Place into dialysis tubing, allowing for quadrupling of the volume. Dialyse against distilled water for 72 hours, changing twice daily.
Glycerol 100 mL
Strong Ammonia 55 mL
Distilled water Litres
Working solution:– Stock colloidal iron 20 mL, 2M (12%) acetic acid 20 mL

 

Nito & Stokes
Ferric chloride 100 g Dissolve the ferric chloride in the water. Add the glycerol. To ¾ of the solution, while stirring, slowly add ammonia until pasty (±110 mL). Slowly add the other ¼ until clear, dark red-brown. Allowing for quadrupling of the volume, dialyse against distilled water, changed daily, until it reverts to the original volume (±2 weeks).
Glycerol 130 mL
Strong Ammonia 110 mL
Distilled water 230 mL
Working solution:– Stock colloidal iron 10 mL, Distilled water 10 mL, 2M (12%) acetic acid 20 mL.

Reference
Humason, G. L., (1967)
Animal tissue techniques, Ed. 2
W. H. Freeman and Company, San Francisco, Ca, USA

Culling C.F.A., (1974)
Handbook of histopathological and histochemical techniques Ed. 3
Butterworth, London, UK.

Lillie, R.D., (1954)
Histopathologic technique and practical histochemistry Ed.2
Blakiston, New York, USA.

 


 

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