Methanol

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

Wikipedia has an article about methanol.

PropertyData
ChemicalMethanol
SynonymsMethyl alcohol
Methyl hydrate
FormulaCH3OH
StateColourless fluid
ConcentrationAbsolute
Fixation timeSeveral hours
AdditiveNo
CoagulantYes
HardensYes
Acid dyesNeutral
Basic dyesNeutral
AftertreatmentNone

Methanol is the simplest of the alcohols and the fixative traditionally used for blood smears to be stained with Romanowsky stains. It has also been recommended as a substitute for ethanol in Carnoy's fluid, which is then called "methacarn". Other than that it is not usually used as a fixative for tissues to be examined by light microscopy.

How it fixes
The fixation obtained with methanol is very similar to that of ethanol. It is a non-additive precipitant fixative. It fixes proteins by dehydration and precipitation. Mixtures incorporating it are usually water free.

Carbohydrates
These are not specifically fixed but may be precipitated along with proteins.

Lipids
Lipids are not preserved and some may be dissolved.

Morphology
Nuclear preservation is satisfactory, but cytoplasmic preservation is only fair as some constituents are destroyed. There may be considerable shrinkage overall.

Time
Several hours for a 3 mm thick piece of tissue should be satisfactory. Thinner tissues such as fine needle biopsies will be fixed within an hour or two.

Simple solution
Methanol is rarely used alone as a fixative for tissue, but it is the most common fixative for blood and bone marrow aspirate smears.

Aftertreatment
No particular aftertreatment is needed. Since it is a dehydrant, tissues are appropriately transferred to a clearing agent directly or to absolute ethanol if dehydration is not complete.

Reference
Kiernan. J.A., (1999)
Histological and histochemical methods: Theory and practice, 3rd ed.
Butterworth Heinemann, Oxford, UK. pp. 14 - 15

 


 

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