Detecting the undetectable in flash column chromatography using wavelength focusing

Sometimes it feels as if organic chemistry and chromatography are a mixture of art and science.  Maybe its because of the necessary creativity needed to address the variety of challenges that we face almost daily.  Frankly, its what I find most interesting about this world.

One of the bigger challenges facing chemists is the ability to detect and collect compounds with little or no UV absorption during flash purification.  In this post I will talk about a technique that I have found to be quite useful when trying to purify mixtures containing one or more poor absorbers.

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Published by

Bob Bickler

Technical Specialist, Biotage

4 thoughts on “Detecting the undetectable in flash column chromatography using wavelength focusing”

  1. We have the baseline correction feature with our Isoleras, so we will give it a try with some other solvents.

  2. Hi Bob, we will definitely give this a try. However, I’m not sure how well this strategy will work when separating low-polarity compounds and using e.g. ethyl acetate/hexanes, where presumably the absorbance of ethyl acetate will complicate the detection of low absorbance materials. Have you used any solvents other than methanol? Presumably ether/hexanes would be fine.

    1. Hi Chris,

      You need to have a flash system with all wavelength detection and baseline correction to implement this technique. The key, of course, is the baseline correction capability which eliminates absorbance due to your gradient solvents. But even in my examples with methanol, which absorbs UV up to about 220 nm, it was the baseline correction which made compound detection possible.


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