Why is methanol so popular in SPE washing and eluting?

Discussions about sample preparation: extraction, cleanup, derivatization, etc.

4 posts Page 1 of 1
hi everyone,

most SPE protocols use some percentage of methanol:water for washing, and 100% methanol for eluting in the end.

Arent there advantages of using acetone, ethanol, ethyl actetate, acetonitrile, propanol and others has washing solvents instead of methanol or methanol mixs?

thank you all for you time!

may the gods of science be with you
Methanol is considered the best solvent for both washing and elution due to the consistency of the interactions between both sorbent bed and analyte during elution.

In regards to elution, general rule of thumb is that polar target compounds will elute best with polar solvents; methanol > acetonitrile> ethylacetate>acetone> THF
pumpedupchemist wrote:
Methanol is considered the best solvent for both washing and elution due to the consistency of the interactions between both sorbent bed and analyte during elution.

In regards to elution, general rule of thumb is that polar target compounds will elute best with polar solvents; methanol > acetonitrile> ethyl acetate>acetone> THF


thanks for your reply.

is there any relation between efficiency and price when it comes to methanol?

is it possible that so many protocols based on methanol because simply is there a lot of experience and easily available?

i have a protocol that washes with methanol, but elutes with ethyl acetate. im curiosed to try to wash with solvents between methanol and acetate ethyl strength (like acetonitrile.. acetone.. ethanol..). wondering if original protocol didnt do it because it was good enough.. or if there are other reasons for not to use such solvents (like price.. efficiency..)
Depends on the analyte, sorbent and interference you are trying to remove.

Of all the methods I use I only have one that requires any methanol as a wash and that one only uses 150ul to wash before drying the sorbent, which is then eluted with 10% methanol in methylene chloride.

At the beginning of an extraction the cartridges are normally washed with the elution solvent (ethyl acetate or methylene chloride for most of my procedures) then washed with methanol to remove residual solvent which is not water miscible then washed with DI water to prepare the sorbent to accept the aqueous sample. Methanol is used here because the initial wash solvent and the water are both miscible with it and it works as a transition between the two. After extraction the cartridges are air dried so to remove the water without the need for a methanol intermediate wash, which could take some of the target analytes with it. If methanol is strong enough to elute the targets from the sorbent then you could use it as the final solvent, if not best to keep it out of the final solvent.

In the one method I use that requires 10% methanol in methylene chloride it is used to adjust the polarity to better remove the target analyte from the sorbent.
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