Welcome to the Biotage Flash Purification Blogs.

      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.

      But, if you have only one flash system available, can you, should you, and how do you efficiently switch from non-polar, normal-phase solvents to polar, reversed-phase solvents – and back again without issues? In this post I'll attempt to shed some light on the topic.

       

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      Minor Cannabinoid Separation by Reversed-phase Flash Chromatography

      May 17, 2019 at 8:30 PM / by Bob Bickler posted in hemp, purify, cannabinoid, isolate

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      Previously, I have posted on a normal-phase flash chromatography method to separate and isolate CBG from a CBD-rich hemp distillate. CBG is just one of many naturally occurring minor cannabinoids of interest in this fast-growing market.

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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, loading capacity

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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 efficiency, purity, speed

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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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      Determining solvent strength in flash column chromatography

      May 7, 2019 at 5:23 PM / by Bob Bickler posted in Developments, selectivity, solvent strength

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      Recently, one of our readers wrote and asked how to determine solvent strength in normal-phase flash chromatography. This is an excellent question because solvent strength is one of several factors impacting flash chromatography performance.

      In this post I will explain how solvent strength can easily be determined.

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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 flash column, Flash column chromatography, loading capacity

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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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      Greener flash chromatography tips

      April 30, 2019 at 10:18 PM / by Bob Bickler posted in solvent, greener flash purification, particle size, surface area

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      In our more environmentally aware climate, chemical and pharmaceutical companies now prioritize reducing organic solvent use in chemistry labs. Employees and shareholders alike are pushing their companies to become greener which impacts how chemistry, both synthesis and purification, is performed.

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      Isolation of some minor cannabinoids using flash chromatography

      April 16, 2019 at 11:02 PM / by Bob Bickler posted in cannabis, CBD, CBG, purify

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      Cannabis entrepreneurs continually seek to differentiate themselves from others in the market. Some focus on THC while others focus on CBD. What I have seen recently after attending some cannabis-specific conferences is a growing interest in isolating/purifying some of the minor, naturally occurring phytocannabinoids such as CBG and CBDV.

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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 Developments, efficiency, linear gradient, step-gradient

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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.

      What is the best starting strong solvent %?   What is the ending strong solvent %?  Should the mobile phase concentrations vary gradually in a linear manner or should they vary step-wise or something else altogether?  Most separations are performed once, occasionally a handful of times.  Because of this, spending effort optimizing a gradient is just not very productive unless there are aids in choosing the gradient profile that provides an effective purification with minimum effort.

      Software in flash chromatography instruments, makes it simple to create a gradient.  Now, what should that gradient look like?

      In this post I compare isocratic, step, and linear gradients and provide some sage advice on choosing among them.

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      Is there an easy way to purify organic amines?

      April 11, 2019 at 9:35 AM / by Bob Bickler posted in Amine, base, dichloromethane, heterocyclic

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      If you synthesize organic amine compounds, especially heterocyclic, secondary, or tertiary amines, you likely have encountered problems with their chromatography using silica columns. With the amine groups being basic and silica being acidic, there is a natural attraction between the two. This sometimes strong attraction often requires the use of a competing amine in the solvent system. Modification of the mobile phase with the addition of a solvent like triethyl amine can provide a successful purification. Often times the use of an amine-modified stationary phase can provide the needed conditions to avoid the acid-base interaction that can interfere with a successful flash chromatography purification.

      In this post I will discuss how amine-functionalized silica can simplify organic amine purification and your life (at least in the lab).

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      So, what exactly is a column volume in flash column chromatography and how is it determined?

      April 10, 2019 at 6:36 PM / by Bob Bickler posted in column, volume

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      In many of my previous posts I have used the term column volume, typically abbreviated as CV, as a value used to help determine separation quality and loading capacity.  However, I recently was asked a question about this topic from a chemist who understands the column volume concept but wanted to better understand its definition and how it is determined.

      In this post I will explain what a column volume is and how it is determined empirically.

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      Does methanol really dissolve silica during flash column chromatography?

      April 9, 2019 at 11:23 PM / by Bob Bickler posted in Developments, methanol, dichloromethane, dissolve

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      This is an age-old question that has been around a long time, perhaps as long as me (and I have been around a while) –  “Does silica dissolve in methanol?”

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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 equilibration, heat, speed, media

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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.

      In this post, I examine the role of equilibration speed and duration to show its impact, or lack there of, on purification performance.

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      Why is reversed-phase flash chromatography use increasing?

      April 3, 2019 at 4:18 AM / by Bob Bickler posted in co-elution, Mass Detection, normal phase, reversed-phase

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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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      Are so-called “high performance” flash columns worth their higher prices?

      March 19, 2019 at 10:05 PM / by Bob Bickler posted in resolution, particle size, surface area

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      Most flash column manufacturers now offer “high performance” flash chromatography columns with the promise of higher loading, increased purity, and even reduced solvent consumption. Working for Biotage, I have made those valid claims for our products as well.

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      Webinar: A Roadmap to Successful Chromatography

      March 19, 2019 at 10:00 PM / by Bob Bickler posted in Flash column chromatography, flash purification, column chromatography lab, webinar

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      On July 26th, 2018, Bob Bickler, Senior Technical Specialist, recorded a webinar on A Roadmap to Successful Flash Chromatography. To learn more, read the description below as well as watch the recording!

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