By Anonymous on Wednesday, March 24, 2004 - 09:42 am:

We are having trouble with Fisher (UK) HPLC grade methanol seeming to not meet UV absorbtion specifications as listed on the bottle, particularly in the 240- 200 nm region.

Upon contacting the Fisher QA department we were told that they purge their solvents with nitrogen for 5 minutes at a flow rate of 500 ml/min prior to checking the UV absorbance spectrum.

For obvious reasons we would choose not purge our HPLC solvents with nitrogen, prefering to degas with either helium or by filtration followed by ultrasonication so I am incredulous as to why they use nitrogen to degas their solvents for QA purposes.

My question is: does anyone have any clues why they might use N2 instead of helium (incidently when we followed their degassing procedure we still obtained UV absorbances well outside quoted specifications).

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By Anonymous on Wednesday, March 24, 2004 - 01:11 pm:

Anon,
We had trouble with the US Fisher methanol several years ago during qualification of a MS system. The tech was trying to use methyl stearate I believe and could not get good results. The bottom line was that the bottle of methanol came with a methyl stearate background, probably from a detergent residue. This wouild have some absorption in the low UV range you are checking. Might be worth doing a quick GC run to look for residual FAMES in the methanol.

Regards,
Mark

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By Tom Mizukam on Wednesday, March 24, 2004 - 01:39 pm:

Oxygen has a max uv absoption at about 220 nm. In HPLC we use helium to sparge because helium has a low solubility in our mobile phases and will remove disolved gasses. Fisher isn't worried about outgassing, they just want to get rid of the oxygen, thus no need to use the more expensive helium.

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By Anonymous on Thursday, March 25, 2004 - 07:30 am:

Cheers for that advice, I will check the methanol on the GC.

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By HW Mueller on Tuesday, April 6, 2004 - 12:07 am:

It seems that I started a chain, some time ago, on reactivity (on column) of methanol from Lab-Scan. We concurred that it must have been due to formate content. GC didn´t show it, so it will be particularily interesting to know what you see in GC.
Incidentally, contacting the manufacturer did not yield any info on this to date.

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By Anonymous on Tuesday, April 6, 2004 - 11:16 am:

a while ago i had a problem with hplc-grade methanol from rathburn. we use it for a gradient sepration and a single lot of methanol gave a huge hump in the end of the chromatogram. it was the only lot of methanol that gave this problem and the suplier offerd to take all the botles back and replace them with an other lot (offcourse he said we where the only lab reporting this problem but i have heard thatone before). never seen the problem since. maybe this solution will work for you?

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By Chemist on Tuesday, June 1, 2004 - 04:54 am:

I also had a problem with Lab-Scan MeOH, running HPLC gradient analysis. A lot of strange peaks appeared. All of them were sourced back to Lab-Scan MeOH. Talking with Lab-Scan representative haven't yielded anything. They blamed Thailand manufacturing plant. So I decided to dump them as my supplier and started purchasing more expensive MeOH from Merck. Never looked back.
By the way, I am still purchasing ACN from Lab-Scan, which I am finding a good value for money.