Welcome to the Biotage Flash Purification Blogs.

    How does gradient slope impact flash chromatography loading capacity?

    February 9, 2021 at 1:40 PM / by Bob Bickler posted in Chromatography Fundamentals, Reversed-phase, Troubleshooting and Optimization, Scale-Up

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    For many synthetic chemists the primary purification goal is to isolate as much synthetic product as possible with a minimum of 80% purity. The go-to technique for product isolation is flash purification (flash chromatography), especially for intermediates.

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    Detecting the undetectable in flash column chromatography, part 2

    December 1, 2020 at 2:19 PM / by Bob Bickler posted in Chromatography Fundamentals, Troubleshooting and Optimization, Detector

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    Compound detection challenges are, for many chemists, a part of life. In a previous post I discussed how wavelength focusing can help your flash system detect and fractionate compounds with poor chromophores. However, compounds naked to UV-Vis light,  such as carbohydrates, are impossible to detect by UV when separating by liquid chromatography.

    There are some alternatives, however, and in this post I will discuss the application of evaporative light scattering detection (ELSD) to flash purification.

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    How does media pore size impact small-molecule flash column chromatography?

    October 30, 2020 at 6:40 PM / by Bob Bickler posted in Chromatography Fundamentals, Troubleshooting and Optimization, purification

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    For most chemists, flash purification is a means to an end. In other words, it is a tool needed to purify and isolate one compound from a mixture of compounds so that the next reaction can occur with reduced by-product formation. Other than choosing between normal- or reversed-phase, there typically is not much thought put into cartridge selection, especially not related to stationary phase media porosity.

    For most small molecules, this approach makes sense, but for larger molecules and very lipophilic compounds, factoring for media porosity should be included.  In this post, I will discuss the impact media porosity can have on chromatographic performance.

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    How do I remove an annoying MS TIC background?

    April 10, 2020 at 2:52 PM / by Bob Bickler posted in Chromatography Fundamentals, Troubleshooting and Optimization, Sfär, Detector, Normal Phase, V-10, Isolera

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    Have you ever run flash column chromatography with mass detection (Flash-MS) and observed the total ion current or TIC increase during the purification only to find that there was no discernible compound contributing to the effect?

    In this post I discuss how I came across this issue and the solution I found to work.

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    What do I do if a 2-solvent gradient will not separate my sample?

    February 11, 2020 at 3:12 PM / by Bob Bickler posted in Chromatography Fundamentals, Solvents, Troubleshooting and Optimization, Normal Phase, Isolera

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    Usually, a 2-solvent or binary gradient will separate your desired compound from the by-products and impurities. Sometimes though, you can encounter a mixture in which some compounds co-elute and are not separable with any binary gradient you try.

    I encountered this situation recently while trying to purify a lavender essential oil and have dedicated this post to how I solved the problem. 

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    Why do I see more peaks than I expect with flash column chromatography?

    January 8, 2020 at 3:23 PM / by Bob Bickler posted in Chromatography Fundamentals, Solvents, Troubleshooting and Optimization, Normal Phase, Isolera

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    Are you observing more chromatographic peaks than you expect compared to TLC or other assessment data?  Well, it could be that your method is separating some isomers or, it could be that there is an actual method issue.

    In this post I will discuss what could cause a method issue and suggest some ideas as to how to fix it.

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

    January 7, 2020 at 8:49 PM / by Bob Bickler posted in Chromatography Fundamentals, Reversed-phase, Troubleshooting and Optimization, Media and Resin, HPLC

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    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 purify ionizable organic amine compounds using flash column chromatography?

    November 21, 2019 at 3:59 PM / by Bob Bickler posted in Amine, Chromatography Fundamentals, Solvents, Troubleshooting and Optimization, Green, Media and Resin

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    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.

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    Why can’t I reproduce my TLC separation using flash column chromatography?

    November 21, 2019 at 3:48 PM / by Bob Bickler posted in Chromatography Fundamentals, Troubleshooting and Optimization, Normal Phase

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    You have performed your synthesis and now it is time to purify the reaction mix. You have used thin-layer chromatography (TLC) and see a separation but when you try to purify with flash column chromatography, you can’t get the target compound separated from an impurity. So, what is happening (or isn’t happening)?

    In this post I will give some input on why some separations are not transferable from TLC.

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    How to prevent compound precipitation during flash column chromatography

    November 1, 2019 at 9:34 PM / by Bob Bickler posted in Reversed-phase, Solvents, Troubleshooting and Optimization, Selekt, Loading Techniques, Normal Phase, Isolera

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    Compounds precipitating during flash chromatography is at best an inconvenience when working up your crude reaction mixture.  Precipitation during purification typically happens in the column or in the tubing exiting the column.

    In this post, I will propose a strategy that can minimize and perhaps prevent this issue from occurring.

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    Why are my flash column chromatography peaks splitting?

    November 1, 2019 at 9:19 PM / by Bob Bickler posted in Troubleshooting and Optimization, Normal Phase

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    Split peaks? Multiple peaks? Are they really a problem? What causes the issue?

    In this post I will discuss what split peaks are and what to do to fix the problem.

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    Purifying ionic compounds by flash column chromatography

    October 18, 2019 at 10:00 PM / by Bob Bickler posted in Reversed-phase, Troubleshooting and Optimization, Sfär, Selekt, Media and Resin

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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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    How do I purify my high boiling solvent reaction mixture using silica flash chromatography?

    October 18, 2019 at 9:48 PM / by Bob Bickler posted in Solvents, Troubleshooting and Optimization, Synthesis, V-10, Isolera, Initiator

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    Many chemists today find they need to synthesize molecules at higher temperatures in order to force difficult reactions to proceed. Solvents such as DMF, DMSO, and NMP are commonly used in these reactions as they facilitate the use of the high reaction temperatures.  However, the same attributes that make these chemicals attractive as reaction solvents make compound recovery from them very difficult, including flash column chromatography.  These high boiling solvents are typically polar and pose a challenge if purification is to be accomplished with normal-phase silica.

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    How to minimize particulate build-up in flash chromatography systems

    July 9, 2019 at 3:23 PM / by Bob Bickler posted in Chromatography Fundamentals, Troubleshooting and Optimization, Normal Phase

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    In order to perform flash chromatography consistently, the equipment you use must be properly maintained by following some “best practices”. These best practices include using clean solvents (I typically use ACS grade), volatile organic modifiers, and quality columns.

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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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    Webinar: A Roadmap to Successful Chromatography

    March 19, 2019 at 10:00 PM / by Bob Bickler posted in Chromatography Fundamentals, Reversed-phase, Troubleshooting and Optimization, Webinar, Loading Techniques

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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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