What is turning my methanol yellow/orange??

[Trishia]

The methanol in my lab gradually turns yellow/orange in the bottles (glass or plastic) and after it has completely evaporated, orange-brown crystals (or perhaps colourless if they were to be washed?) can be found at the bottom.

This has occurred with two different types of methanol, and I can't figure out why (furthermore, I think it causes some issues within my SFC systems!). A MS of the original MeOH did not show anything...


Thanks,

Trishia.

[unmgvar]

reading this I am less concern of the MeOH bottle
if this stuff is in the air it means you are breathing it too

what does show an MS of the MeOH while it is yellow/orange?

[bhuvfe]

The methanol in my lab gradually turns yellow/orange in the bottles (glass or plastic) and after it has completely evaporated, orange-brown crystals (or perhaps colourless if they were to be washed?) can be found at the bottom.

This has occurred with two different types of methanol, and I can't figure out why (furthermore, I think it causes some issues within my SFC systems!). A MS of the original MeOH did not show anything...


Thanks,

Trishia.

How long does it take to have a visible discoloration? Days, weeks?

[nellermann]

This has happened to me too. I just thought it had been contaminated by others in my lab.

[Trishia]

Hi there,

It takes a few weeks/months. I didn't try to inject a solution of the crystals on my GC-MS since I didn't know what they were and didn't want to cause any damage. I've looked extensively on the web to see if I could figure out what was happening but never found anything that seemed relevant.

It's driving me completely nuts and I'm pretty sure it's been causing issues by clogging my SFC's.

(As for safety concerns, our lab is well-ventilated (the bottles I'm speaking of are wash or modifier bottles)).


Trishia.

[HW Mueller]

Sabotage?

[unmgvar]

all you do is open the bottle, use the solvent,close the bottle?
and until next time it stay there?
and the bottle is closed air tight correct?
and you are the only one using the MeOH, or others do too?

by the way a well ventilated lab only means that the air is moving very much and very well
this does not indicate anything on the quality of the air in the lab

it would not be the first time I see a well ventilated lab of HPLCs that had a construction site next to them and the systems get all clogged up because the dust quantity simply rise up so much in the lab and is very well ventilated inside the lab

[Trishia]

No, the bottle is not airtight (it's a modifier bottle so tubing comes in the top (like HPLC)). By "well-ventilated", I mean that we have Alsident extractor arms.

Same thing is happening is the solvent wash bottle we have of methanol in one of the fumehoods.

I am the only one using them and I'm pretty sure no one comes into my lab to pee in my bottles .


Trishia.

[unmgvar]

how do you wash those bottles?
if in a washing machine, then what else goes there?

[Equisraya]

can you do an ir spectrum of the cristals???

[bhuvfe]

Maybe try to dissolve your crystals in CHCl3 or CHCl2 and inject the solution into your GC-MS.
It's extremely unlikely you can damage it.

[Trishia]

I think I got an MS spectra (will see if I can get access to an IR as well next week).

I posted the result here; http://tinypic.com/r/2dam55i/7


Trishia.

[Equisraya]

if you can get access to a perkin elmer ir spectrometer, maybe i can compare the unknow spectrum with my spectral library (if you post the sp file).

regards!

[bhuvfe]

Same thing is happening is the solvent wash bottle we have of methanol in one of the fumehoods.

Trishia.

Does this happen to the methanol of the original bottle (e.g; the one you got from the supplier)?

Do you use for your instruments brown colored bottles or transparent ones?


About the MS spectrum. Is it a very intense peak that you see on your GC-MS (million counts)?

[southp]

The mass spectrum looks like that of iodomethane.