Welcome to the Biotage Flash Purification Blogs.

    Six key factors that impact flash chromatography

    October 18, 2019 at 9:54 PM / by Bob Bickler posted in Chromatography Fundamentals, Solvents, Sfär, Media and Resin, Automation, Cost

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    In this post I will delve into six key factors that impact your purification success in flash column chromatography.

    Previously, I have discussed the use of TLC for solvent scouting and method development and optimization. I have have also talked about cartridge size, particle size, and surface area and their impact on flash purification.  Here I integrate that information into the six factors below.

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    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 Fundamentals, Reversed-phase, Synthesis, Workflow, Media and Resin, Loading Techniques

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    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.

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

    September 20, 2019 at 2:49 PM / by Bob Bickler posted in Chromatography Fundamentals, Reversed-phase, Sfär, Selekt, Media and Resin, Normal Phase

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    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?

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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 Chromatography Fundamentals, Reversed-phase, Media and Resin, Loading Techniques

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    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 much DMF or DMSO can I inject on my reversed-phase flash chromatography column?

    June 13, 2019 at 5:05 PM / by Bob Bickler posted in Chromatography Fundamentals, Reversed-phase, Solvents, Media and Resin, Loading Techniques

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    In a previous post I shared results of experiments where I evaluated selected organic solvents for sample dissolution and injection for reversed-phase flash purification.  I demonstrated that DMF and DMSO both are excellent solvents for this purpose and actually provide better chromatography than methanol, acetonitrile, and acetone.

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    How changing stationary phase chemistry can impact separation selectivity

    June 12, 2019 at 2:42 AM / by Bob Bickler posted in Chromatography Fundamentals, Solvents, Sfär, Media and Resin

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    Challenging separations, we all have faced this vexing problem. You synthesized your compound, analyzed it, and know your molecule is in there, based on LC-MS or TLC. Then, you do some method development using a silica TLC plate and see a major spot with some minor, early-eluting impurities. You think that the purification will be easy only to find that your “purified” compound has some co-eluting impurities. Now what? Should you change solvents or change stationary phase?

    In this post, I will show how changing the column media but keeping the same solvents removed a co-eluting impurity in one of my reaction mixes.

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    Dry loading media options – diatomaceous earth

    May 28, 2019 at 10:47 PM / by Bob Bickler posted in Sfär, Media and Resin, Loading Techniques

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    Various flash chromatography sample loading options are available including liquid and dry loading. Choosing the right technique is important because your sample loading choices (sample solvent and dry load sorbent), can have a major impact on the results.

    In this post, I compare the two techniques and show the benefits dry loading with a form of diatomaceous earth can bring to your purification.

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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 Chromatography Fundamentals, Reversed-phase, Solvents, Sfär, Selekt, Media and Resin, Cost, Normal Phase, HPLC

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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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    How can I reduce flash column purification time and cost?

    May 8, 2019 at 2:57 PM / by Bob Bickler posted in Chromatography Fundamentals, Reversed-phase, Solvents, Troubleshooting and Optimization, Green, Sfär, Selekt, Media and Resin, Cost, Normal Phase

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    This is a question being asked of my colleagues and me more and more frequently, especially in pharma accounts.  Why?  Well, you are familiar with the adage – Time is Money, right.  Well this really applies to them. A new molecular entity (NME) created as a pharmaceutical can take up to a decade and a billion dollars to bring to market.  Granted, the biggest costs are in the clinical trials but the synthetic route and the time to discover and make the compound – and purify it – plays a major role within drug discovery and development. This timeline is not helped by the ever increasingly difficult-to-synthesize compounds being investigated as drug candidates today.

    With that in mind, this post focuses on ways to speed the purification process without sacrificing purity and yield.

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    How do particle size and flow rate affect normal-phase flash column chromatography

    May 7, 2019 at 5:19 PM / by Bob Bickler posted in Chromatography Fundamentals, Media and Resin, Normal Phase

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    Media particle size and solvent flow rate play major roles in chromatographic separations including flash purification.  This is true in both reversed-phase chromatography (aka partition chromatography) as well as normal-phase chromatography. The roles played are related to the overall compound mass-transfer kinetics and diffusion/dispersion as they migrate through the column.  Smaller particles reduce sample dilution by reducing interstitial volume, while flow rate impacts the ability of molecules to efficiently pass through the porous particles. In this post, I will show how both particle size and flow rate impact flash chromatography.

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    How to Choose Between Linear Gradients and Step Gradients for Flash Chromatography

    April 12, 2019 at 12:51 PM / by Bob Bickler posted in Chromatography Fundamentals, Green, Media and Resin

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    Varying the concentrations of mobile phase solvents during  flash purification chromatography enhances the ability of the technique to effectively isolate the desired compound from reaction by-products and unconsumed reagents.  Choosing how these concentrations will be varied over time has a significant effect on the purity and recovery of desired compounds.

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    Flash column chromatography equilibration speed – how fast can you go?

    April 9, 2019 at 11:22 PM / by Bob Bickler posted in Chromatography Fundamentals, Sfär, Selekt, Media and Resin

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    Equilibrating silica flash chromatography columns is something I always do.  There are chemists who see this as an unnecessary, time-and-solvent-wasting step.  However, because getting consistent, predictable results is a priority for me, I equilibrate to remove the variability that can be caused by heat generated as solvent initially contacts the silica. Consistency is really important when running flash column chromatography because re-runs are time consuming and may put your compound at risk.

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    Which dry load sorbent should I use for flash column chromatography?

    February 19, 2019 at 10:55 PM / by Bob Bickler posted in Sfär, Selekt, Media and Resin, Loading Techniques

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    This is an interesting question that does not have a straightforward answer. In fact, there are many materials that are potentially useful sorbents for dry loading crude mixtures. Some of the more popular are silica, diatomaceous earth (e.g. ISOLUTE® HM-N, Celite®), alumina, and Florisil®. The sorbent choice can influence your purification results because each of the available media have different chemistry and capacity. In most cases, sample/sorbent reactivity really is not a major concern, though it can occur. What is important is the sorbent’s capacity to adsorb/absorb all of your sample and the ratio of your crude sample to the amount of dry load sorbent.

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    Does your crude sample/sorbent dry load ratio impact flash column chromatography results?

    February 5, 2019 at 8:10 PM / by Bob Bickler posted in Chromatography Fundamentals, Sfär, Selekt, Media and Resin, Loading Techniques, Isolera

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    Dry loading crude samples for flash purification typically works better than liquid loading, especially for challenging purifications. In this post, I discuss how the ratio of crude sample to dry load sorbent impacts purification performance.

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    Dry loading vs. liquid loading, which provides better flash column chromatography results?

    January 23, 2019 at 2:15 PM / by Bob Bickler posted in Chromatography Fundamentals, Media and Resin, Loading Techniques

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    When it comes time to purify your reaction mixture or natural product extract, you have a choice to make. Should you simply load your dissolved sample onto your flash column or take the extra step to adsorb your mix onto a sorbent and dry it before loading? The choice can have a major impact on your results.

    In this post, I will share results of work I conducted in my lab, comparing liquid and dry loading a reaction mixture that containing eight major components.

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    Biotage® Sfär

    October 1, 2018 at 1:17 PM / by Raffaella Bombarda posted in Chromatography Fundamentals, Green, Sfär, Media and Resin, Scale-Up

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    Sfär Stands for Spherical, Biotage® Stands for Quality 

    Biotage developed and introduced pre-packed columns for flash purification in 1994. Today our broad selection of columns enables professionals to choose the solution which best suits their purification needs.

    Sfär is the Swedish word for "sphere", and the name of our columns reflects the fact that we have made spherical silica a standard due to its higher surface area and higher loading capacity. Reliable and flexible, Biotage® Sfär columns deliver larger loading capacities, tighter elution bands and purer fractions than traditional flash columns.
    Biotage® Sfär is a complete portfolio of flash columns, available in a large variety of sizes from 5g to 350 g and in a range of media types, so you can purify milligrams to multi-grams of your valuable compounds quickly and easily.

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