Welcome to the Biotage Flash Purification Blogs.

    Flash column equilibration – is it a waste of time or necessary step?

    November 1, 2019 at 9:30 PM / by Bob Bickler posted in Optimization, Media, Theory


    slash column chromatography has been practiced by chemists since the 1970s. That practice requires the silica in the column be properly wetted to remove trapped gasses and ensure uniform flow (remember those days of not letting air into the column?). Today, with automated flash chromatography systems and pre-packed columns as the norm, chemists ask me – do I really need to pre-equilibrate my column?

    In this post I explore the impact on chromatography that equilibration, and lack thereof, has on separation performance.

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    How does solvent choice impact flash column chromatography performance?

    October 18, 2019 at 9:44 PM / by Bob Bickler posted in Troubleshooting, Theory


    Selectivity and solvent strength are the most important factors that determine success or failure of a chromatographic separation. These two independent dynamics apply to both normal- and reversed-phase chromatography and should be optimized, especially when high fraction purity is needed.

    In this post I will discuss the impact that elution solvent choice has on both normal- and reversed-phase purification.

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    Using TLC to Scout Flash Chromatography Solvents

    September 20, 2019 at 3:06 PM / by Bob Bickler posted in Optimization, Solvents, TLC, Theory


    TLC is the tool most used for normal-phase flash chromatography method development. For many chemists, a solvent system of hexane (or heptane) + ethyl acetate is the first, and sometimes only, solvent system evaluated. Though often useful, ethyl acetate may not always provide the optimal purification conditions.

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    How do I determine loading capacity in reverse phase flash column chromatography?

    July 10, 2019 at 3:01 PM / by Bob Bickler posted in Theory


    As the popularity of prep-scale, reversed-phase flash chromatography increases, so does the frequency that I get asked this question, "How do I determine loading capacity in reversed-phase flash chromatography?"

    In the world of HPLC, loading capacity isn’t normally a concern as it is primarily an analytical technique.  In the synthetic organic chemistry world, most purification is performed with silica gel where flash column purification methods are developed and loading capacity estimated from TLC data.  However, when normal-phase flash does not work and reversed-phase flash is needed, the question of how to determine reversed-phase loading capacity comes up.

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    How do I Choose the Right Column Size for Purification by Flash Chromatography?

    June 13, 2019 at 4:59 PM / by Bob Bickler posted in Theory


    In all my years of working with medicinal and organic chemists, I have found that choosing how many grams of silica to use for purification by flash chromatography is something frequently guessed at. Getting the size of the column right is awfully important because using too few grams of silica will doom your purification to failure and using more an optimal mass of the stationary phase means the purification consumes excess silica, solvents, and a chemist's time.

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    How to Optimize TLC to Enhance Purification by Flash Chromatography

    June 13, 2019 at 4:53 PM / by Bob Bickler posted in Theory


    In this article I discuss the optimization of solvent ratios to generate ideal Rf (retention factor) values on TLC plates.  Then I show how maximizing efficiency of flash chromatography achieves higher loading with rapid and reliable isolation of compounds, reduced solvent use and improved separation.

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