Tirmann Schmelzer
Turnbull's Blue for Ferrous Iron

Iron deposits in the body are usually ferric compounds such as hemosiderin. Occasionally ferrous iron deposits are encountered, sometimes from mining activity or foreign bodies. These iron deposits may be demonstrated with Tirmann Schmelzers's Turnbull's blue. The method is very similar to Perls' Prussian blue, but uses potassium ferricyanide instead of ferrocyanide. The ferrous iron reacts with the potassium ferricyanide to form ferrous ferricyanide. This is an insoluble, blue compound known as Turnbull's blue. The intensity of the colour gives some indication as to amount, but it is qualitative only.

Solutions

Neutral red

Stock solution A
Potassium ferricyanide	20	g
Distilled water	100	mL

Stock solution B
Hydrochloric acid, conc.	1	mL
Distilled water	100	mL

Working solution
Stock solution A	1	volume
Stock solution B	1	volume

Tissue sample
5µ paraffin sections of neutral buffered formalin fixed tissue are suitable. Avoid iron containing materials and jars while fixing as these may contaminate the tissue. Acid containing fixatives may remove some of the iron deposits, but apart from that most are satisfactory.

Method

1. Bring sections to distilled water with xylene and ethanol.
2. Place into the working solution for 15 minutes.
3. Rinse with distilled water.
4. Wash well with tap water.
5. Stain with neutral red for one minute.
6. Rinse well with tap water.
7. Dehydrate with ethanol.
8. Clear with xylene.

Expected results

• Ferrous iron  –  blue
• Nuclei  –  red

Notes

1. The working solution should be made immediately before use.
2. Avoid washing with tap water before placing into the working solution, as rust in the water or tap fixtures could cause false positive staining.
3. Wash well at step 3, as traces of iron will form a granular red deposit with neutral red.

 

Reference

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

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