Can flash chromatography be green? Part 1

The term “Green Chemistry” has become a major part of the science community’s lexicon. When I think about green chemistry and its relationship to flash column chromatography I think of two specific areas where it applies…

1. Replacing chlorinated solvents with those considered more environmentally friendly

2. Reducing solvent use and waste generation with more thoughtfully applied chromatography principals

In this post I will discuss alternatives to chlorinated solvent-based flash column purification.  In the future, look for a post on reducing solvent use (and its waste).

Continue reading Can flash chromatography be green? Part 1

Scaling-up flash purification – as easy as 1, 2, 3, 4

For many chemists performing bench-scale organic synthesis flash column chromatography is the primary purification technique.  When your synthesis needs scaling to multi-gram levels, so does the flash purification. The logical approach is to just increase the flash cartridge or column size, but this is only part of the solution.

In this post I discuss the process of simplified flash purification scale-up.

Continue reading Scaling-up flash purification – as easy as 1, 2, 3, 4

How do I choose between Normal- or Reversed-phase flash column chromatography for my compound purification?

How to choose between normal- and reversed-phase flash column chromatography is an excellent question and one that my readers often ask.  Those who use column chromatography know that as long as the reaction products or compounds are fairly non-polar and near neutral pH they will have successful purifications.  However, when your mixture’s chemical characteristics are more challenging (polar, non-polar, basic, acidic) there are other options that are available to successfully separate pure compounds.

In this posting I will discuss the criteria you can use to guide your choice between normal- or reversed-phase flash chromatography.

Continue reading How do I choose between Normal- or Reversed-phase flash column chromatography for my compound purification?

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

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.

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

Which injection solvents should I use for reversed-phase flash purification?

In previous posts I have touched upon various sample loading options and how they impact flash chromatographic performance, primarily in normal-phase flash purification. As the use of reversed-phase flash chromatography has steadily increased over the past few years I thought it would be a good idea to discuss one of the most important factors impacting its success.

In this post I discuss the results of some of my original research studying the impact of injection solvent choice on reversed-phase flash separations. Continue reading Which injection solvents should I use for reversed-phase flash purification?

Which loading method should I use for purification by flash chromatography?

Getting the most benefit from your crude sample purification with column chromatography or flash chromatography involves optimizing many variables.  In previous posts I have talked about selecting the best solvents, their ratios, and maximizing load based on TLC Rf data. These are all important chromatography-generated variables but now I would like to share some tips on actual technique differences and their impact on purification performance.

In particular in this post I will focus on the benefits and drawbacks of liquid loading and dry loading.  Both have their place in liquid chromatography but when should one technique be used over another?

Continue reading Which loading method should I use for purification by flash chromatography?

Different ways to load flash columns

Here is a video post that is somewhat of the commercial nature but I think it could be interesting for you to see some different loading options one can use with Biotage® ZIP and SNAP Ultra flash chromatography columns.

Dr. Greg Saunders goes through techniques for loading your Biotage flash purification columns. The versatile Biotage® SNAP Ultra cartridges gives you the possibility to load your sample in up to seven different ways. Read more about our flash consumables at biotage.com/product-group/flash-cartridges

Feel free to share the video and write me a comment of what you think about it here below.

Six key factors that impact flash chromatography

In this post I will delve into six key factors that impact your purification success in flash column chromatography.

Previously, I have discussed the use of TLC for solvent scouting and method development and optimization. I have have also talked about cartridge size, particle size, and surface area and their impact on flash purification.  Here I integrate that information into the six factors below.

Continue reading Six key factors that impact flash chromatography

Does Size Really Matter in Flash Chromatography? Part 2

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.

But there are other chromatographic aspects where size can impact performance. In this post I will focus on some areas where size does matter – media particle size and media surface area.

Continue reading Does Size Really Matter in Flash Chromatography? Part 2

Does size really matter in flash chromatography? Part 1

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.

Continue reading Does size really matter in flash chromatography? Part 1