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How to avoid sample blowback when liquid loading

May 24, 2022 at 2:19 PM / by Bob Bickler

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Ever experience the problem where you load your dissolved sample into a flash column via a syringe only to encounter either resistance or “blowback”? Blowback is a term describing the situation where your sample does not stay in the column but flows back out of the column’s cap after the loading syringe is removed.

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Do It Yourself: Flash Chromatography Test Mix

May 12, 2022 at 7:19 PM / by Charles Parsons

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In today’s post I’d like to discuss how you can check your Biotage flash system to ensure it is running smoothly and still performing at the high level and capability that is expected of all Biotage products. I’ll go over how to set up and run the Sfär-TM1 parabens test, what to look for as indicators of the “health” of the system, and what you can do if anything looks amiss.

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When do I need to use an ELSD with flash chromatography?

May 11, 2022 at 2:16 PM / by Bob Bickler

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Flash chromatography can be complex. Solvent choice, column size, stationary phase, loading technique, gradient method, flow rate, and detection parameters are all variables which factor into flash chromatography and your success with this purification technique. Of these variables, detection parameters, i.e. the type of detector, can really impact your flash chromatography results.

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Is reversed-phase flash chromatography less expensive than normal-phase?

April 26, 2022 at 2:41 PM / by Bob Bickler

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For many labs on a tight budget, keeping expenses at a minimum is crucial. Many of these same labs are also required to become more sustainable, or greener, by reducing the amount of organic solvent they use. Reducing solvent also reduces expenses, but what is the impact on lab productivity?

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What is the maximum flash column sample load volume?

April 12, 2022 at 9:40 PM / by Bob Bickler

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A fairly common question I receive is "how much of my reaction mixture can I load on my flash chromatography column?". To this question there is not a cut and dry answer because of a number of variables which influence the outcome. To help illustrate this, I will show in this post the results of a study I performed in my lab with one of my reaction mixtures.

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When is Gradient Elution Better than Isocratic Elution?

March 30, 2022 at 2:00 PM / by Bob Bickler

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Gradient or isocratic elution, that is the question. Within flash chromatography these are the options afforded to separate reaction mixtures and natural product extracts and is the focus of this post.

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How should normal-phase gradient solvents be chosen?

March 14, 2022 at 1:43 PM / by Bob Bickler

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Normal-phase flash chromatography is an integral component of the organic synthesis workflow. Since reactions rarely generate 100% pure product, they need purification and flash chromatography is the most utilized tool for that task.

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How many times can I reuse my reversed-phase flash column?

February 22, 2022 at 2:41 PM / by Bob Bickler

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Reversed-phase flash chromatography use continues to increase for a variety of reasons. Unlike silica normal-phase flash columns, which typically are used only once, reversed-phase flash columns can be cleaned, stored, and reused. How many times can a column be reused is a frequent question I receive. In this post, I will do my best to answer this question.

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How does reagent concentration impact synthesis?

February 8, 2022 at 6:00 PM / by Bob Bickler

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As you know, reaction chemistry involves determining and selecting the right conditions for optimal product yield and purity. There are actually six variables, that I know of, needing consideration including…

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When Should I Replace My Flash C18 Column?

January 25, 2022 at 3:36 PM / by Bob Bickler

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Knowing when it is time to replace your reversed-phase flash column is a question I am asked frequently along with…

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How Scalable is Flash Chromatography?

January 11, 2022 at 2:08 PM / by Bob Bickler

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Flash chromatography is the most commonly used purification tool for organic and medicinal chemists whose reaction scales typically range from milligrams to grams. The column size to be used for the purification of these reaction mixtures is selected either by using the 1% rule which states that for many reaction mixtures, a crude reaction mixture load equaling 1% of the column’s media weight often will provide the needed purity, assuming the right elution method is selected. While this strategy can work, often chemists either overload or underload the selected column resulting in low product purity which requires re-purification. In both situations, the chemists wastes time, solvent, and the cost of the column.

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How does reaction time impact synthetic product purity and yield?

November 30, 2021 at 4:59 PM / by Bob Bickler

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For my purification blog I often will synthesize compounds so I can show representative, real-world reaction product purification. In doing so, I decided I would also post on the impact of various synthesis variable. This post looks at the impact of reaction temperature time on an amide synthesis.

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Can Reaction Temperature Impact Synthetic Product Yield and Purity?

November 17, 2021 at 7:01 PM / by Bob Bickler

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Though this is a purification blog I do, from time to time, like to address synthetic chemistry experimentation findings in the desire to assist you with your reactions, as this is the front-end of your synthesis workflow. So, in this post, I report on some findings of the effect of reaction temperature on the synthesis of an amide, 2-amino-N-benzylbenzamide, a potential antibacterial compound[1].

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Does reagent and reaction solvent order impact product yield and purity?

October 19, 2021 at 6:00 PM / by Bob Bickler

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This is a question I asked myself while I have been studying synthesis variables to see what, if any, impact each variable has on reaction product yield and purity. For this post, I evaluated the order in which I added reactants and solvent.

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Can maximizing product yield and purity from messy reaction mixture be green?

October 5, 2021 at 8:42 PM / by Bob Bickler

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Chemical reactions gone wrong, I’m sure we all have experienced this issue, I know I have. You add your reagents in the proper amounts with a suitable solvent and perform your reaction only to find your by-product yield was greater than your product; by a lot. So, what do you do to isolate what little product you created with maximum yield and purity without breaking the proverbial bank on a big flash column and the solvent required for the purification?

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Can water be used as an organic synthesis solvent?

September 23, 2021 at 2:28 PM / by Bob Bickler

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