By Jean-Philippe Lambert on Thursday, June 6, 2002 - 07:26 am:
Hi,
I recently did a synthesis and my product was pure except for a single impurity absorbing only in very high wavelength. I believe the impurity to be Diethly amine. Does anybody knows the UV cutoff for DEA or does any body have a link to an UV cutoff table??
Greatly appreciated
By John B on Friday, June 7, 2002 - 04:35 am:
CRC handbook has a section for common liquids but DEA was not listed.
By Anonymous on Friday, June 7, 2002 - 05:50 am:
Jean-Philippe,
According to Snyder et. al. (Practical HPLC Method Development) the cutoff for TEA (yes I know it's not DEA but should have the same cutoff) they used a 10 mM TEA*HCl TEA mix down to 200 nm. Your impuritty is probably not DEA if it is absorbing at anything over about 220 nm.
Regards,
Mark
By Cindy on Friday, June 7, 2002 - 07:01 am:
Jean,
Check out here:
http://home.planet.nl/~skok/techniques/hplc/eluotropic_series_extended.html
Cindy
By Jean-Philippe Lambert on Friday, June 7, 2002 - 09:40 am:
Thanks for all your quick answers, very appreciated.
By Chris Pohl on Monday, June 10, 2002 - 08:45 am:
DEA doesn't absorb in the ultraviolet but hydroxide anion does. Perhaps this is the source of your absorbance.
By Benjamin on Monday, June 10, 2002 - 01:41 pm:
Jean;
I have no experience with DEA, but I can tell you the following about TEA. It does absorb strongly below 240nm in Water and in Hexane solutions. The cutoff of a 0.1M solution in H20 is 230NM.
I believe some of the comments above refer to HCl salts rather than the free bases.
Benjamin esquivel
By Chris Pohl on Monday, June 10, 2002 - 02:28 pm:
TEA doesn't absorb in the UV either. The cutoff mentioned above is likely due to the presence of oxidized impurities (manifested by a yellow-orange color), chloride ion (although this couldn't be responsible for a cutoff as high as 230 nm) or hydroxide anion (relevant only in the freebase form).
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