Welcome to the Biotage Flash Purification Blogs.

    Flash system UV detectors – similarities and differences

    January 14, 2020 at 9:41 PM / by Bob Bickler posted in UV, sensitivity, fiber optic

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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, Gradient, Normal phase, Solvents, Troubleshooting

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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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    So, how does an ELSD work?

    January 7, 2020 at 9:06 PM / by Bob Bickler posted in ELSD, Nebulize

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    Evaporative Light-Scattering Detection, or ELSD for short, is a technology used with liquid chromatography to see UV-transparent (and UV-absorbing) compounds. In a previous post I talked about some applications where ELSD is not only useful, but required.

    In this post, I will explain how an ELSD is configured and functions.

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    5 Tips on extending reversed-phase flash chromatography cartridge life

    January 7, 2020 at 8:51 PM / by Bob Bickler posted in dry loading column, Clean-up, Extraction

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    With reversed-phase flash column chromatography becoming increasingly popular for routine purification, understanding how to make the cartridges last (since they cost more) is important to know. 

    In this post I will mention a few tips to prolong reversed-phase cartridge life.

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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 Reversed-phase, TLC, method development

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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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    Does Size Really Matter in Flash Chromatography? Part 2

    January 7, 2020 at 8:46 PM / by Bob Bickler posted in Media, Load, surface area, particle size

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    In a previous post I talked about column size, specifically long-thin versus short-fat and the impact of the cartridge’s dimensions on purification performance. With that comparison I showed that in preparative chromatography, purification efficiency is more about the amount of silica than column dimensions. Cartridges of different dimensions containing the same amount of the same media will provide the same separation efficiency.

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    Does size really matter in flash chromatography? Part 1

    January 7, 2020 at 8:43 PM / by Bob Bickler posted in Load, throughput, column

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    Yes, the title is a bit salacious but it got your attention, didn’t it? I believe this is a topic worthy of discussion as it relates to flash chromatography for purification because many chemists believe longer but thinner columns perform better than short, wide columns.  The facts of the matter may surprise you.

    In this post I discuss the impact that cartridge dimensions have on purification performed using flash purification.

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    So, which detector should I use for flash column chromatography?

    January 3, 2020 at 3:38 PM / by Bob Bickler posted in UV, Detector

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    In my role as senior technical specialist at Biotage I am often asked about compound detection options. For most flash chromatography methods, UV is the default detection tool since many compounds do absorb some UV light.

    Diode array UV detectors provide chemists choices in wavelength selection providing the ability to widen or narrow the wavelength range needed to detect specific compounds and enhance their sensitivity.

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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 there advantages to stacking flash chromatography columns?

    December 30, 2019 at 4:38 PM / by Bob Bickler posted in column, stacking, performance

    3 Comments

    When it comes to isolating a compound from a mixture at maximum purity there are many options available through flash column chromatography. In previous posts I have addressed using smaller particle media, higher surface area media, and step gradients to achieve this goal.

    In this post I will discuss how stacking columns in series may help improve separation quality.

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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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    Pushing flash column chromatography loading limits

    December 30, 2019 at 3:39 PM / by Bob Bickler posted in step gradient, Load

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    A question I hear a lot from chemists is “how much can I load”. The answer is always “it depends on your separation quality”.  At that point I begin asking about the TLC data and purification goals. Purification goal setting should be your first step and the question to answer is – what do I need this purification to achieve? Is the goal high purity, high yield, or some combination.  Remember, you will typically sacrifice purity for high yield and yield for high purity so optimization is an important consideration.

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    Green Flash Chromatography Webinar

    November 26, 2019 at 9:03 PM / by Bob Bickler posted in Chromatography, Webinar

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    Over the past several decades, the chemical industry has implemented process changes and updated practices in R&D and manufacturing in an effort to reduce liquid and solid lab waste. The pharmaceutical industry in particular has taken steps within their drug discovery labs to reduce solvent use by requiring their chemists to find and implement measures that achieve the corporate environmental goals without curtailing their productivity – quite the challenge.

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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, Gradient, Normal phase, Optimization, Polar, Solvents, Troubleshooting, TLC

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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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    Does particle shape and/or particle size impact flash column chromatography load limits?

    November 21, 2019 at 3:51 PM / by Bob Bickler posted in Media

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    There are many factors which influence successful flash column chromatography. One of those factors is sample load, which itself is influenced by things like selectivity, efficiency, dissolution solvent, and load technique. Several of these factors I have addressed in previous posts. Of these, selectivity and efficiency are specific to a media's physical and chemical characteristics.

    In this post I will show if particle size and/or particle shape can influence loading capacity.  Additionally, I will show the positive impact that surface area has on flash column chromatography purification.

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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 Optimization, TLC

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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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