Welcome to the Biotage Flash Purification Blogs.

    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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    When should I choose APCI or ESI for my flash column chromatography?

    February 11, 2020 at 3:16 PM / by Bob Bickler posted in Detector, Isolera

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    Mass spectrometers today are typically available with either Electrospray Ionization (ESI) or APCI (Atmospheric Pressure Chemical Ionization) sources.  That’s really nice but, how do you know which source will work best when purifying your sample?

    In this post I attempt to provide some guidance to selecting the ionization source best suited to your sample types.

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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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    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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    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 Chromatography Fundamentals, Media and Resin, Normal Phase, Isolera

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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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    How does mobile phase organic solvent choice impact reversed-phase flash column chromatography?

    November 21, 2019 at 3:45 PM / by Bob Bickler posted in Chromatography Fundamentals, Reversed-phase, Solvents, Normal Phase, Isolera

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    Organic and medicinal chemists frequently utilize flash chromatography to purify their reaction mixtures. Normal-phase flash chromatography is most often used but may not the best methodology, especially when the compounds are quite polar and/or ionizable.

    For these molecules, reversed-phase flash chromatography is preferred but often is not used due to an uncertainty regarding the best solvent choices and the reversed-phase mechanism.  In this post, I will discuss how organic solvent choice in reversed-phase chromatography can influence the chromatographic separation.

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    The Step Gradient Explained

    November 1, 2019 at 9:37 PM / by Greg Saunders posted in Chromatography Fundamentals, Solvents, Green, Cost, Normal Phase, Isolera

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    Up to six compounds can be easily separated with an automated step-gradient optimizer embedded in modern flash chromatography systems.

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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

    4 Comments

    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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    Biotage vs Biotage, and the winner is...

    October 23, 2019 at 9:28 AM / by Panagiotis Ioannidis posted in Sfär, Selekt, Cost, Isolera

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    When Isolera™ was launched, the maximum system pressure that could be reached was 10 bars, but reaching that pressure was a challenge since most of the Flash columns could not withstand the higher pressures. The maximum pressure rating for the Biotage® SNAP columns, for example, is limited to five or seven bars, depending on the size, and columns from most of manufacturers have the same limitation.

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    How Sfär Impacted Column use at the University of North Carolina Chapel Hill

    October 22, 2019 at 2:42 PM / by Sarah Moran posted in Sfär, Customer case, Isolera

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    On a beautiful sunny day in Chapel Hill, North Carolina, I travelled to the University of North Carolina campus where I spoke with Dr. Alfredo Picado about how using our new Sfär columns has impacted his time, output, and overall efficiency in his lab.

    Dr. Picado works within the Structural Genomics Consortium (SGC), housed under the Eshelman School of Pharmacy at the University of North Carolina. Their team consists of chemists and biologists who all work under the SGC. We were able to discuss Dr. Picado’s most recent project at SGC and why Biotage’s columns made such an impact.

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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 does solvent choice impact flash column chromatography performance?

    October 18, 2019 at 9:44 PM / by Bob Bickler posted in Chromatography Fundamentals, Reversed-phase, Solvents, Normal Phase, Isolera

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    Selectivity and solvent strength are the most important factors that determine success or failure of a chromatographic separation. These two independent dynamics apply to both normal- and reversed-phase chromatography and should be optimized, especially when high fraction purity is needed.

    In this post I will discuss the impact that elution solvent choice has on both normal- and reversed-phase purification.

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    Detecting the undetectable in flash column chromatography using wavelength focusing

    October 2, 2019 at 5:52 PM / by Bob Bickler posted in Chromatography Fundamentals, Selekt, Detector, Isolera

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    Sometimes it feels as if organic chemistry and chromatography are a mixture of art and science.  Maybe its because of the necessary creativity needed to address the variety of challenges that we face almost daily.  Frankly, its what I find most interesting about this world.

    One of the bigger challenges facing chemists is the ability to detect and collect compounds with little or no UV absorption during flash purification.  In this post I will talk about a technique that I have found to be quite useful when trying to purify mixtures containing one or more poor absorbers.

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    How do I Create an Efficient Gradient Flash Chromatography Method?

    September 20, 2019 at 2:58 PM / by Bob Bickler posted in Chromatography Fundamentals, Solvents, Normal Phase, Isolera

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    For most organic and medicinal chemists flash chromatography is just another step in the synthesis work flow - react, analyze, purify, react, analyze, purify... until the final product is made. The desired product of each reaction, and the mixture of other species present are, of course, different with each cycle.  Separating the desired compound efficiently without a lot of hassle is something I have written about in this post as well as in others in this series.

    In this post, I've written about how that TLC (thin layer chromatography) plate you use for monitoring your reaction can be used to create reliable, efficient, effective gradients.

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