What is the smallest amount I can purify using flash chromatography?
January 19, 2023 at 2:07 PM / by Bob Bickler posted in sensitivity, detection
Why is Solvent Evaluation by TLC Important for Good Flash Chromatography Results?
November 22, 2022 at 3:27 PM / by Bob Bickler
Organic chemistry can be messy with not only the desired compound created but also myriad by-products. As synthetic chemists, our goal is to make these desired compounds in sufficient yield and purity to either create another compound or submit for evaluation by other departments. To purify these reaction mixtures, flash chromatography is the primary technique.
How does a flash system’s internal volume affect gradients?
November 8, 2022 at 9:21 PM / by Bob Bickler
For many years I have been publishing a blog on flash chromatography, especially related to its theory and application. It dawned on me today that one area I have not yet addressed is the impact of the flash system’s internal plumbing volume on a programmed gradient, so, here it is.
How does an acidic pH affect reversed-phase chromatography separations?
November 1, 2022 at 2:19 PM / by Bob Bickler
Chromatography is as much an art as it is a science. Between synthetic reaction products and natural products, the range of compounds requiring separation, purification, and isolation is broad and diverse creating challenges from time to time. Because of this diversity, not all chromatographic separations can be performed with a “neutral” solvent system – one without added pH modifiers or buffers.
Flash chromatography gradients need to provide as good of a separation between the target compound at its closest eluting by-products as possible in order to maximize product purity and load. Many chemists create methods based on a history with a compound class, knowing what has worked in the past. If no history with a synthetic compound class exists, then methods need developing.
What is a step gradient and why should I use it?
September 27, 2022 at 2:07 PM / by Bob Bickler
Most chemists I meet utilizing flash chromatography use linear gradients. These gradients are either very generic (X% to Y% over a certain time or volume) or can be complex with multiple slope changes and even isocratic holds. These complex gradients are often created during a purification to get the desired separation because the generic gradient does not provide enough separation for the target compound needing purification.
How does acid concentration impact reversed-phase flash chromatography?
August 24, 2022 at 2:55 AM / by Bob Bickler
Reversed-phase flash chromatography is extremely useful when purifying all types of compounds. Compounds that are charged or ionizable, however, typically need either a pH modifier (acid or base) or a buffer to better control compound retention, peak shape, and selectivity.
How important is flow rate in flash chromatography?
August 9, 2022 at 1:54 PM / by Bob Bickler
I often get questions from customers about the influence of flow rate on their flash chromatography. Typically, the questions are…
Which solvents are best for terpene flash chromatography?
July 6, 2022 at 2:59 PM / by Bob Bickler
Well, it’s spring as I write this, my favorite time of year, and the foliage is in various stages of bloom. I like the rebirth of nature and the floral aromas that emanate from the blooms. These botanical aromas are the result of the various terpenes and terpenoids in the plant which can be very different between species.
How to maximize UV detection sensitivity in flash chromatography
June 21, 2022 at 4:11 PM / by Bob Bickler
Automated flash chromatography has become an integral component of the workflows of both synthetic organic chemistry and natural product research. The most utilized chromatographic technique is normal-phase, which uses a polar stationary phase filled column (i.e. silica) and a mix of non-polar and moderately polar solvents, i.e. hexane or heptane and ethyl acetate (EtOAc), resp.
How to isolate impurities from a reaction product
June 7, 2022 at 5:57 PM / by Bob Bickler
Ensuring that the product of a reaction is pure is critical to that compound’s viability as a marketable entity. Impurities often require characterization if they are in excess of regulated limits. The isolation of these compounds can be quite challenging.
How to avoid sample blowback when liquid loading
May 24, 2022 at 2:19 PM / by Bob Bickler
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.
Do It Yourself: Flash Chromatography Test Mix
May 12, 2022 at 7:19 PM / by Charles Parsons
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.
When do I need to use an ELSD with flash chromatography?
May 11, 2022 at 2:16 PM / by Bob Bickler
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.
Is reversed-phase flash chromatography less expensive than normal-phase?
April 26, 2022 at 2:41 PM / by Bob Bickler
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?
What is the maximum flash column sample load volume?
April 12, 2022 at 9:40 PM / by Bob Bickler