I want to fix some samples. what are the advantages and disadvantages of each of them?
Dear @Mohadese Shahriari,
Both ethanol and acetone [ and even 'technical' iso-propanol ] work for ‚washing‘, rinsing, [cleaning surfaces] or dehydration. For the latter purpose, because miscibility with (cellular, tissue) water is high.
There might be issues regarding not only their chemical properties (properties as a solvent) but their different boiling points: Acetone bp= 57°C, Ethanol bp = 79°C (as compared to Isopropanol bp = 83°C, which also is a solvent used in dehydration). A lower boiling point means that evaporation (i. e. drying out of substrate, like tissue sections) takes place more easier or easily / rapidly than a solvent with higher bp.
You might consult also: http://www.brainstuffshow.com/blogs/good-question-what-is-the-difference-between-alcohol-ethanol-denatured-alcohol-rubbing-alcohol-methanol-and-isopropyl-alcohol.htm (If you are not able to link to that technical info page for any reason, let me know and I shall send a copy&paste-document).
Acetone has a greatly enhanced solvent power (as compared to ethanol), so – for animal / human tissues in histological processing – it can be expected that degreasing or elution of fat/lipids might pose an effect which is not intended for the task (especially if you decrease steps of increasing acetone concentration / dilution series, e. g. instead of 30%, 50%, 70%, 80%, 90%, 96%, 100% as usually used for EtOH only say 70% [sometimes omitting also 90%], and 100% acetone).
Regarding „solubility“ or solvent properties:
QUOTE: „Polarity is a widely discussed and quoted property of a solvent but it is used loosely to cover a number of different effects, including those covered by dielectric constant and dipole. ….“ End of quote (citation from: https://www.researchgate.net/post/What_is_the_polarity_order_of_solvents_such_as_acetone_ethanol_and_methanol/1, for an explanation see especially Re# 004 by YOGESH CHANDRA TRIPATHI).
For delicate dehydration purposes (single cells, cell cultures, ultrastructural studies) IMHO (undenatured) ethanol is for sure a good option (despite more expensive), admitting that globally there are hundreds of labs which most ssucessfully dehydrate with (dilutions of – and ) acetone without problems.
As other commenters rightly have pointed out: the use of such chemicals / the right/respective chemical/solvent depends always on the method used, the task to be achieved and the specific experimental setting.
Last but not least I would like to mention also the principle of „rapid dehydration of tissue fragments“. This is an old/ancient/ancillary method in specimen preparation for TEM=transmission electron microscopy used not very frequently or standardized and starts with „incubation/ placing“ of small tissue pieces into an organic solvent 2,2-di-methoxypropane.
The clear fluid 2,2-DMP (which principally would be insoluble in „water“ or hydrous milieu) immediately before use has to be acidified with some drop of concentrated HCl (therefore called „acidified 2,2-DMP“). The reaction mechanism is reported that a (one) molecule water cleaves acidified 2,2-DMP immediately and in place into methanol and acetone…. So the dehydration (esp. when supported by agitation of the tissue piece by shaking or by a specimen rotator) is expected to be very rapid (1-2 changes into fresh acidified 2,2-DMP might be of benefit) and specimens up to 1-2 mm³ have been reported to be completely dehydrated within only „seconds“. Dealing with delicate (LM & EM) diagnostic specimens, my own practical experience over more than 25 years has shown (documented by TEM examination and micrographs) that there are - comparing Ethanol vs. acidified 2,2-DMP dehydration - slight differences in morphological appearance in ultrathin sections of these diagnostic specimens (especially regarding appearance / content of lipids / fat).
Ethanol is mild - used for Cells
Acetone preferred for tissues - more robust.
The main difference is acetone requires no permeabilization step whereas, ethanol do.
what kind of samples? I think with a more detailled question you will get more reliable answers.
Dear @Mohadese Shahriari,
Both ethanol and acetone [ and even 'technical' iso-propanol ] work for ‚washing‘, rinsing, [cleaning surfaces] or dehydration. For the latter purpose, because miscibility with (cellular, tissue) water is high.
There might be issues regarding not only their chemical properties (properties as a solvent) but their different boiling points: Acetone bp= 57°C, Ethanol bp = 79°C (as compared to Isopropanol bp = 83°C, which also is a solvent used in dehydration). A lower boiling point means that evaporation (i. e. drying out of substrate, like tissue sections) takes place more easier or easily / rapidly than a solvent with higher bp.
You might consult also: http://www.brainstuffshow.com/blogs/good-question-what-is-the-difference-between-alcohol-ethanol-denatured-alcohol-rubbing-alcohol-methanol-and-isopropyl-alcohol.htm (If you are not able to link to that technical info page for any reason, let me know and I shall send a copy&paste-document).
Acetone has a greatly enhanced solvent power (as compared to ethanol), so – for animal / human tissues in histological processing – it can be expected that degreasing or elution of fat/lipids might pose an effect which is not intended for the task (especially if you decrease steps of increasing acetone concentration / dilution series, e. g. instead of 30%, 50%, 70%, 80%, 90%, 96%, 100% as usually used for EtOH only say 70% [sometimes omitting also 90%], and 100% acetone).
Regarding „solubility“ or solvent properties:
QUOTE: „Polarity is a widely discussed and quoted property of a solvent but it is used loosely to cover a number of different effects, including those covered by dielectric constant and dipole. ….“ End of quote (citation from: https://www.researchgate.net/post/What_is_the_polarity_order_of_solvents_such_as_acetone_ethanol_and_methanol/1, for an explanation see especially Re# 004 by YOGESH CHANDRA TRIPATHI).
For delicate dehydration purposes (single cells, cell cultures, ultrastructural studies) IMHO (undenatured) ethanol is for sure a good option (despite more expensive), admitting that globally there are hundreds of labs which most ssucessfully dehydrate with (dilutions of – and ) acetone without problems.
As other commenters rightly have pointed out: the use of such chemicals / the right/respective chemical/solvent depends always on the method used, the task to be achieved and the specific experimental setting.
Last but not least I would like to mention also the principle of „rapid dehydration of tissue fragments“. This is an old/ancient/ancillary method in specimen preparation for TEM=transmission electron microscopy used not very frequently or standardized and starts with „incubation/ placing“ of small tissue pieces into an organic solvent 2,2-di-methoxypropane.
The clear fluid 2,2-DMP (which principally would be insoluble in „water“ or hydrous milieu) immediately before use has to be acidified with some drop of concentrated HCl (therefore called „acidified 2,2-DMP“). The reaction mechanism is reported that a (one) molecule water cleaves acidified 2,2-DMP immediately and in place into methanol and acetone…. So the dehydration (esp. when supported by agitation of the tissue piece by shaking or by a specimen rotator) is expected to be very rapid (1-2 changes into fresh acidified 2,2-DMP might be of benefit) and specimens up to 1-2 mm³ have been reported to be completely dehydrated within only „seconds“. Dealing with delicate (LM & EM) diagnostic specimens, my own practical experience over more than 25 years has shown (documented by TEM examination and micrographs) that there are - comparing Ethanol vs. acidified 2,2-DMP dehydration - slight differences in morphological appearance in ultrathin sections of these diagnostic specimens (especially regarding appearance / content of lipids / fat).
Dear Mohadese Shahriari,
No doubts this is an interesting topic. I work with plant anatomy and I am facing several problems to prepare my samples to SEM. Sometimes I use acetone series (30,50, 70, 90,100%), but it seems very dangerous for delicate samples. On the other hand, If i use ethanol, sometimes I have problems after the CO2 Critical Point.
Dr. Wolfgang Muss shaded light on different aspects of the solvents. You can easily find this tips.
Thanks and good luck!
João
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