Welcome to the Biotage Flash Purification Blogs.

    How do I purify ionizable organic amine compounds using flash column chromatography?

    November 21, 2019 at 3:59 PM / by Bob Bickler posted in Amine, Chromatography, Gradient, Normal phase, Optimization, Polar, Solvents, Troubleshooting, TLC

    4 Comments

    For most organic reaction mixture purifications the process is fairly straightforward. Use hexane/ethyl acetate or, for polar compounds, DCM/MeOH.  But what do you do if this doesn't work and your compounds are basic organic amines?

    In this post, I re-examine the options available to achieve an acceptable organic amine purification when typical separation methods are insufficient.

    Read More

    How does mobile phase organic solvent choice impact reversed-phase flash column chromatography?

    November 21, 2019 at 3:45 PM / by Bob Bickler posted in Gradient, Optimization, Polar, Solvents, TLC

    3 Comments

    Organic and medicinal chemists frequently utilize flash chromatography to purify their reaction mixtures. Normal-phase flash chromatography is most often used but may not the best methodology, especially when the compounds are quite polar and/or ionizable.

    For these molecules, reversed-phase flash chromatography is preferred but often is not used due to an uncertainty regarding the best solvent choices and the reversed-phase mechanism.  In this post, I will discuss how organic solvent choice in reversed-phase chromatography can influence the chromatographic separation.

    Read More

    How many times can I reuse my flash chromatography column?

    November 21, 2019 at 3:40 PM / by Bob Bickler posted in Gradient, Normal phase, Optimization, Polar, Solvents, Troubleshooting

    4 Comments

    Flash chromatography – a purification tool for both organic chemists and natural product researchers.  This tool is essential when you need to remove impurities from your targeted product, or products, in order to get them pure.  To reduce the costs associated with flash chromatography, some chemists try reusing the same column over and over, not always with success.

    Read More

    Purifying ionic compounds by flash column chromatography

    October 18, 2019 at 10:00 PM / by Bob Bickler posted in Polar, Reversed-phase, Solvents

    2 Comments

    One of the more challenging purifications is that of water-soluble, ionizable compounds. Typically, normal-phase with silica is not used because of the probable non-reversible interactions, especially between the ionized amines interacting and the ionizable silanols.  With normal-phase out of the purification solution that leaves ion exchange and reversed-phase as chromatographic options.

    In this post I will discuss the use of reversed-phase and the influence pH and buffers have on the chromatography of some ionic, water soluble compounds.

    Read More

    When should I use dry loading instead of liquid loading with flash column chromatography?

    October 4, 2019 at 6:17 PM / by Bob Bickler posted in Chromatography, Small Molecule, Polar, Samplet(R), Synthesis, Workflow, Media, Loading method

    0 Comments

    Many microwave assisted organic synthesis (MAOS) reactions use polar solvents such as alcohols, DMF, DMSO, because they absorb and transfer microwave energy very efficiently.  However, the downside of using polar, microwave absorbing solvents is that they can interfere with normal-phase flash chromatography.

    In this post, I discuss why dry loading can be advantageous when purifying polar-solvated reaction mixtures.

    Read More

    Very polar compound purification using aqueous normal-phase flash column chromatography

    September 20, 2019 at 2:49 PM / by Bob Bickler posted in Normal phase, Polar, Solvents

    2 Comments

    Purifying polar organic compounds can be very challenging. In a previous post I have discussed using reversed-phase flash chromatography to retain and purify ionizable and ionic compounds.  My colleague, Dr. Elizabeth Denton, has also posted a blog on purifying very polar peptides as well.  Sometimes, however, despite all your efforts with reversed-phase, success is elusive. When this happens, what do you do?

    Read More