Welcome to the Biotage Flash Purification Blogs.

    Can I use TLC for reversed-phase flash column chromatography method development?

    January 7, 2020 at 8:49 PM / by Bob Bickler posted in Reversed-phase, TLC, method development

    2 Comments

    I am often asked why reversed-phase TLC data does not translate well to reversed-phase flash column chromatography.  There are several reasons for this and in this post I will attempt to explain the challenges associated with reverse-phase TLC as a method development tool for reversed-phase flash chromatography.

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    How do I decide between normal- or reversed-phase flash column chromatography?

    December 30, 2019 at 4:49 PM / by Bob Bickler posted in Normal phase, Reversed-phase

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    Choosing a good purification strategy is an important for successful crude compound purification. A major factor in your strategy is choosing between normal-phase or reversed-phase chromatography.  How do you choose?

    In this post, I will provide some simple guidance on helping determine which route to take.

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    Are reversed-phase flash chromatography columns designed for aqueous solvents necessary?

    December 30, 2019 at 3:54 PM / by Bob Bickler posted in Reversed-phase, Water, Aqueous

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    When it comes to the purification of polar, water-soluble compounds reversed-phase chromatography is the most commonly used approach. However, because of strong stationary phase – mobile phase repulsion forces, the use of highly aqueous (90-100% water) solvent systems has been shown to provide less retention than needed.  This issue has led to the development of “aqueous compatible” reversed-phase media.

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    Purifying ionic compounds by flash column chromatography

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

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    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.

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    Prep HPLC vs. reversed-phase flash chromatography: How to choose?

    October 15, 2019 at 5:02 PM / by Bob Bickler posted in HPLC, Normal phase, Reversed-phase

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    This question is one that is increasing in frequency. Over the past 10 or so years reversed-phase flash chromatography use has increased dramatically. Likewise, reversed-phase preparative HPLC (RP pHPLC) use has also increased. Chemists need to know when to choose between the speed and low solvent use of flash column chromatography and the ultimate purification of RP pHPLC. With this as the backdrop, let me give you my thoughts on how to choose between flash chromatography and when it is best to use RP pHPLC.

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    How does solvent choice impact reversed-phase flash chromatography separations?

    October 4, 2019 at 6:30 PM / by Bob Bickler posted in Reversed-phase, Solvents

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    I have recently posted on how solvent choice influences the separation of hard to resolve compounds using normal-phase flash chromatography. As a chemist with an inquiring mind, I thought I would expand my research beyond normal-phase and see what happens in reversed-phase.

    In this post, I share my results. 

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    How do I choose between Normal- or Reversed-phase flash column chromatography for my compound purification?

    October 4, 2019 at 6:25 PM / by Bob Bickler posted in Normal phase, Reversed-phase, Solvents

    4 Comments

    How to choose between normal- and reversed-phase flash column chromatography is an excellent question and one that my readers often ask.  Those who use column chromatography know that as long as the reaction products or compounds are fairly non-polar and near neutral pH they will have successful purifications.  However, when your mixture's chemical characteristics are more challenging (polar, non-polar, basic, acidic) there are other options that are available to successfully separate pure compounds.

    In this post, I will discuss the criteria you can use to guide your choice between normal- or reversed-phase flash chromatography.

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    Which injection solvents should I use for reversed-phase flash purification?

    September 20, 2019 at 8:21 PM / by Bob Bickler posted in Reversed-phase, Solvents

    6 Comments

    In previous posts I have touched upon various sample loading options and how they impact flash chromatographic performance, primarily in normal-phase flash purification. As the use of reversed-phase flash chromatography has steadily increased over the past few years I thought it would be a good idea to discuss one of the most important factors impacting its success.

    In this post I discuss the results of some of my original research studying the impact of injection solvent choice on reversed-phase flash separations.

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    What are good reversed-phase dry load options?

    July 23, 2019 at 2:40 PM / by Bob Bickler posted in Reversed-phase, Sfär, Loading method

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    Using a “dry” loading technique with flash chromatography typically improves compound purity and overall separation quality compared to liquid loading. The reasons for this I have prophesized previously and include:

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    How can I perform normal-phase and reversed-phase column chromatography on one flash system?

    May 20, 2019 at 2:21 PM / by Bob Bickler posted in Normal phase, Reversed-phase

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    For chemists, flash chromatography is part of their everyday synthesis workflow. For most syntheses, crude reaction mixtures are purified by normal-phase (aka adsorption) chromatography.  There are times, however, where the crude mixture’s complexity and polarity make normal-phase chromatography very challenging.  For these situations, reversed-phase (aka partition) chromatography may be a preferred option.

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    Can reversed-phase flash chromatography purify better than normal-phase?

    May 9, 2019 at 4:44 PM / by Bob Bickler posted in Normal phase, Reversed-phase, Media

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    The answer to this question is yes, reversed-phase can sometimes provide a better separation and thus better purification than normal-phase.  When is reversed-phase likely to be the better choice is a different, and likely better, question.

    In this post I will try to demonstrate when reversed-phase is likely the better purification mode.

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    Why is reversed-phase flash chromatography use increasing?

    April 3, 2019 at 4:18 AM / by Bob Bickler posted in Normal phase, Optimization, Reversed-phase, Mass-directed purification

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    Reversed-phase flash chromatography usage is increasing rapidly. In fact, over the past 10 or so years, reversed-phase flash chromatography use has increased a dramatic 650%! This is amazing growth despite the fact that reversed-phase flash columns are considerably more expensive than silica columns and you need to evaporate water from your fractions. So, what’s driving this change in chemists’ modus operandi?

    In this post, I will explain why chemists are increasingly using reversed-phase flash chromatography for routine, intermediate, and final compound purification and provide and example as well.

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