Zinc Chloride

Please read this explanation about safe working with zinc chloride and cleanup of spills.

Wikipedia has an article about zinc chloride.

PropertyData
ChemicalZinc chloride
FormulaZnCl2
StateWhite powder
ConcentrationVaries, perhaps 2-5%
Fixation timeone or more hours
AdditiveYes
CoagulantYes
HardensYes
Acid dyesSome improvement
Basic dyesSome improvement
AftertreatmentNone

How it fixes
Fixation with zinc chloride is probably similar to that with mercuric chloride, They are both group 12 elements in the periodic table, along with cadmium, but the mechanism does not appear to have been commented on apart from that.

It had been recommended long ago as a fixing agent, but was not popular. Most likely this was because it is inferior to mercuric chloride and microscopists preferred the results from using that. Recently, however, as mercuric chloride began to be criticised as a fixing agent because of its toxicity and the effect of disposal on the environment, a search for possible substitutes led to zinc chloride which, it was claimed at first, was as good as the former and a lot less toxic. It is true that it is a lot less toxic, but it does not live up to the claims initially made in its favour. It is a good fixing agent but it falls short of what has been claimed for it. What is needed is a thorough, objective evaluation of its fixation characteristics so that some definitive information is available.

Morphology
The preservation is good, although inferior to mercuric chloride. Staining is not quite as bright and clear, although quite acceptable.

Time
Anecdotal statements are that solutions containing zinc chloride as a substitute for mercuric chloride require approximately 50% longer for the same degree of fixation. There does not appear to be any objective information.

Simple solution
It is not used alone, but usually as a substitute for mercuric chloride in mixtures.

Aftertreatment
None particular.

 

Reference
Kiernan, J.A., (1999)
Histological and histochemical methods, theory and practice. Ed. 3,
Butterworth, Heinemann, Oxford, UK.

 


 

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