According to Qiagen
> Since imidazole absorbs UV radiation at 280 nm, an elution profile > measured at 280 nm while purifying a 6xHis tagged protein by FPLC will > show an increase in absorbance above the background signal allowing > quantitation of your protein. The absorbance of imidazole can vary > depending on its source and purity, but elution buffer containing 250 > mM imidazole usually has an A280 of 0.2–0.4. Cheers, Ed. On Wed, 2013-08-21 at 11:25 -0400, Edward A. Berry wrote: > Would you happen to know what the A280 of a 1M (or .1 M) solution is? > I wonder if this absorbance is really due to impurities or is the tail of a > weak absorbance band of imidazole itself. I > notice A280 is not one of the properties sigma lists for its imidazole. > > Jan wrote: > > Hi Bernhard, > > this one works for us: > > Sigma BioUltra imidazole, >99.5% by GC, 56749 > > > > Cheers, > > Jan > > -- > > Jan Abendroth > > Emerald BioStructures > > Seattle / Bainbridge Island WA, USA > > home: Jan.Abendroth_at_gmail.com > > work: JAbendroth_at_embios.com > > http://www.emeraldbiostructures.com > > > > On Aug 21, 2013, at 7:33 AM, Bernhard Rupp <hofkristall...@gmail.com > > <mailto:hofkristall...@gmail.com>> wrote: > > > >> Hi Fellows, > >> could someone please point me towards the source of a known high purity > >> imidazole > >> with low absorbance at 280 nm? I am facing the problem of detecting a low > >> absorption protein > >> in high imidazole background after IMAC gradient elution. In the UV > >> spectra of the > >> 2 imidazoles I checked there is some contaminant that absorbs at 280… > >> Thx, BR > >> ---------------------------------------------------------------------------------------- > >> Bernhard Rupp > >> Marie Curie Incoming International Fellow > >> Innsbruck Medical University > >> Schöpfstrasse 41 > >> A 6020 Innsbruck – Austria > >> +43 (676) 571-0536 > >> bernhard.r...@i-med.ac.at <mailto:bernhard.r...@i-med.ac.at> > >> ---------------------------------------------------------------------------------------- > >> Dept. of Forensic Crystallography > >> k.-k. Hofkristallamt > >> Vista, CA 92084 > >> 001 (925) 209-7429 > >> b...@ruppweb.org <mailto:b...@ruppweb.org> > >> b...@hofkristallamt.org <mailto:b...@hofkristallamt.org> > >> http://www.ruppweb.org/ > >> ----------------------------------------------------------------------- > > -- Edwin Pozharski, PhD, Assistant Professor University of Maryland, Baltimore ---------------------------------------------- When the Way is forgotten duty and justice appear; Then knowledge and wisdom are born along with hypocrisy. When harmonious relationships dissolve then respect and devotion arise; When a nation falls to chaos then loyalty and patriotism are born. ------------------------------ / Lao Tse /
