Welcome to the Biotage Flash Purification Blogs.

      How much DMF or DMSO can I inject on my reversed-phase flash chromatography column?

      June 13, 2019 at 5:05 PM / by Bob Bickler posted in Developments


      In a previous post I shared results of experiments where I evaluated selected organic solvents for sample dissolution and injection for reversed-phase flash purification.  I demonstrated that DMF and DMSO both are excellent solvents for this purpose and actually provide better chromatography than methanol, acetonitrile, and acetone.

      In this post I report some surprising results from follow-on work evaluating the impact of increased injection volume using DMF and DMSO as the sample diluent/injection solvent.

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      How do I Choose the Right Column Size for Purification by Flash Chromatography?

      June 13, 2019 at 4:59 PM / by Bob Bickler posted in Developments, Flash Theory


      In all my years of working with medicinal and organic chemists, I have found that choosing how many grams of silica to use for purification by flash chromatography is something frequently guessed at. Getting the size of the column right is awfully important because using too few grams of silica will doom your purification to failure and using more an optimal mass of the stationary phase means the purification  consumes excess silica, solvents, and a chemist's time. To determine the optimal amount of silica for a purification, I rely on a factor called ΔCV (delta Column Volume) to identify the best loading capacity on any cartridge. I have also found that ΔCV this is a better loading capacity predictor for flash purification than ΔRf.

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      Benefits of acetonitrile over methanol in normal-phase flash column chromatography

      June 13, 2019 at 4:57 PM / by Bob Bickler posted in Developments


      When it comes to the purification of polar organic compounds many chemists turn to normal-phase flash chromatography with dichloromethane and methanol as the mobile phase. This solvent system often can be challenging to optimize due to methanol’s high polarity and protic chemistry.

      I have found that acetonitrile can often replace methanol as the polar modifier in DCM-based solvent systems.  In this post I will show an example where this is true.

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      How to Optimize TLC to Enhance Purification by Flash Chromatography

      June 13, 2019 at 4:53 PM / by Bob Bickler posted in Flash Theory


      In this article I discuss the optimization of solvent ratios to generate ideal Rf (retention factor) values on TLC plates.  Then I show how maximizing efficiency of flash chromatography achieves higher loading with rapid and reliable isolation of compounds, reduced solvent use and improved separation.

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      How changing stationary phase chemistry can impact separation selectivity

      June 12, 2019 at 2:42 AM / by Bob Bickler posted in selectivity, stationary phase, impurity


      Challenging separations, we all have faced this vexing problem. You synthesized your compound, analyzed it, and know your molecule is in there, based on LC-MS or TLC. Then, you do some method development using a silica TLC plate and see a major spot with some minor, early-eluting impurities. You think that the purification will be easy only to find that your “purified” compound has some co-eluting impurities. Now what? Should you change solvents or change stationary phase?

      In this post, I will show how changing the column media but keeping the same solvents removed a co-eluting impurity in one of my reaction mixes.

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      Pesticide remediation of Cannabis oil - Myclobutanil removal by flash chromatography

      June 11, 2019 at 3:51 PM / by Brian Wagner posted in cannabis


      Welcome to a second installment of the Biotage Cannabis Application development flash blog.  The first post, dated August 20  2016, outlined an orthogonal approach to isolating cannabinoids from winterized extract.  Give it read if you have not seen it

      Today we investigate the “hot” topic of pesticide elimination from extract.  Specifically – Myclobutanil remediation.

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