Welcome to the Biotage Flash Purification Blogs.

    When should I use an amine-bonded silica for flash chromatography?

    May 8, 2020 at 8:30 PM / by Bob Bickler posted in Amine, Chromatography Fundamentals, Sfär, Media and Resin, Normal Phase

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    Flash chromatography is a standard part of an organic chemist’s workflow. It is utilized after most reaction steps in order to remove most of the generated by-products and excess reagents.

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    5 Steps to successful flash chromatography

    April 20, 2020 at 10:15 AM / by Bob Bickler posted in Amine, Chromatography Fundamentals, Reversed-phase, Solvents, Media and Resin, Loading Techniques, Normal Phase, Pillar Page

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    The bane of organic synthesis for most chemists is purification rather than synthesis. Synthetic reaction mixtures are rarely devoid of impurities so some type of purification is necessary.  Most often flash chromatography is used but for many chemists, it is less well understood than their chemical reaction and provides some level of anxiety.

    In this post, I will summarize the five most important steps to creating a successful flash chromatography method and thus the anxiety associated with it.

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    Does a longer flash column really provide better purification?

    April 17, 2020 at 9:30 PM / by Bob Bickler posted in Chromatography Fundamentals, Sfär, Scale-Up, Cost, Normal Phase

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    This is an interesting question that I am asked from time to time. There does seem to be two camps in which chemists reside – one believing longer and thinner columns provide better separations and the other preferring shorter and fatter columns to do the same chromatography.

    Which is right? That is a question I will try to answer based on my own data.

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    Understanding silica – why matching TLC and flash silica is important for good flash column chromatography

    April 15, 2020 at 12:00 PM / by Bob Bickler posted in Chromatography Fundamentals, Solvents, Sfär, Media and Resin, Normal Phase

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    Recently, I posted an article explaining why high performance TLC plates are not needed for method development for high-performance flash chromatography.  Based on some excellent feedback, I see a need to discuss silica chemistry and its impact on chromatography.

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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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    How does an alkaline pH affect normal-phase flash chromatography separations?

    April 7, 2020 at 6:25 PM / by Bob Bickler posted in Amine, Chromatography Fundamentals, Solvents, Sfär, Normal Phase, Isolera

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    The products of organic synthesis are designed with specific functional groups in order to possess desired properties. Depending on the compound’s functionality, it can be neutral, acidic, or basic as determined by a compound measurement called pKa or acid dissociation constant. Compounds with low pKa are typically acidic while those with high pKa tend to be basic. Compounds with a pKa near 7 are deemed neutral.

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    What is the Chemistry Behind Normal-Phase Flash Chromatography?

    February 11, 2020 at 3:44 PM / by Bob Bickler posted in Chromatography Fundamentals, Normal Phase

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    Our clientele at Biotage have interesting and diverse backgrounds from highly skilled synthetic chemists, to experts in natural product chemistry, to those who are just beginning they journey with chemistry. What I have learned over my 40+ year career in the “art” of chromatography is that for many of these fine folks there is a lack of understanding about chromatographic principles. This lack of understanding, I believe, is only due to their core study curriculum where separation science is used as a tool during lab work but the principles behind why a mixture’s components separate (or do not separate) perhaps are not effectively explained, understood, or studied.

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    How can I modify my flash chromatography method to separate chemically similar compounds?

    February 11, 2020 at 3:13 PM / by Bob Bickler posted in Chromatography Fundamentals, Reversed-phase, Solvents, Sfär, Selekt, Media and Resin, Normal Phase

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    The challenges organic, medicinal, and natural product chemists face are many: from designing reactions, to optimizing synthesis, work-up / extraction, and purification / isolation of the desired compound or compounds. Among those issues related to purification / isolation is the common problem of separating compounds with similar chemistry that either co-elute or separate poorly.

    In this post I will discuss some tips on how to "resolve" this issue (yes, pun intended).

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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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    Does Size Really Matter in Flash Chromatography? Part 2

    January 7, 2020 at 8:46 PM / by Bob Bickler posted in Chromatography Fundamentals, Sfär, Scale-Up, Normal Phase

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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 Chromatography Fundamentals, Normal Phase

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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 Reversed-phase, Detector, Normal Phase

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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 Chromatography Fundamentals, Reversed-phase, Green, Normal Phase, Isolera, HPLC

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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 Chromatography Fundamentals, Normal Phase

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    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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    Pushing flash column chromatography loading limits

    December 30, 2019 at 3:39 PM / by Bob Bickler posted in Chromatography Fundamentals, Green, Sfär, Loading Techniques, Cost, Normal Phase, Pillar Page

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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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