The most important factors to consider when selecting a flash chromatography cartridge

Finding the right flash chromatography cartridge for your application can be a tedious and confusing task. Read on to see how you can simplify the whole process by learning about important parameters for successful cartridge selection. Learn more about what modern tools are available to make the selection faster, more insightful and more enjoyable.

My nephew’s ninth birthday was a few weeks ago. I really wanted to get him something special, so I headed off to a toy store in the hopes of finding an original present. But once inside, it didn’t take long for me to feel completely lost in the labyrinth of aisles stuffed to the top with all kinds of toys. I also didn’t like any of the suggestions of the sales people I consulted with. So I went home empty-handed.

That night I decided to do some online shopping and there I had much better luck. I stumbled upon a toy store app with great filter criteria that made the whole selection process much easier. The important factors were age, if it needed to be gender-specific, what kind of a toy it should be and so on. I was relieved that it was fast and actually kind of fun to find the perfect gift.

So I had to smile a little when a few days later during a lunch break with my colleagues the topic of cartridge selection was brought up. It turns out that many chemists tend to feel overwhelmed by the sheer number of cartridges available out there. Navigating through a maze of cartridges was an experience I definitely could relate to, given my recent ordeal with the labyrinth of toys I had to go through.

To help you get to the most suitable cartridge for your chromatographic runs, I’d like to bring up some of the most important parameters of flash chromatography cartridges. As you might be aware, successful chromatography mainly depends on the cartridge used. The importance of picking the right equipment should not be underestimated. When selecting a cartridge, the focus should be on the sample and separation goals of your application.

Therefore, the main parameters that you should consider for cartridge selection are the stationary phase, the particle shape and size and the loading capacity.

Stationary phase – This parameter has a great impact on mass transfer kinetics and the selectivity of the purification. The choice of media chemistry dictates which mobile phase can be used with the cartridge. There is a wide range of stationary phases available from silica to amino, diol or alumina. Silica and alumina are the most commonly used stationary phases in flash chromatography.

Particle shape – This factor influences the efficiency of the separation. The particle shape can be either irregular or spherical. Spherical particles offer reduced backpressure, so that faster flow rates and steeper gradients can be used. This in turn speeds up the purification process and improves productivity. Spherical particles also tend to have greater mechanical stability, higher efficiency and better reproducibility (see graph below).

Graph showing differences in chromatograms when using irregular versus spherical particles in the flash cartridges

Particle size – This parameter impacts the efficiency and resolution of the chromatographic run. The particle size is chosen depending on the complexity of the sample. High efficiency columns with smaller particle sizes of up to 15 µm result in narrower, sharper peaks in the chromatograph (see graph below). Besides increasing the purity of the compound, a decrease in particle size also allows for higher loading capabilities. However, as discussed in a previous post, one must pay attention to how higher resolution can negatively impact run time. It might be a good idea to use particles smaller than 25 µm only with very low viscosity mobile phases or the flow rate would be very low.
The typical particle size of a silica gel is typically 40-60 µm.

Graph showing influence of particle size on peaks in chromatograph

Loading capacity – This factor enables selection based on sample size. A wide range of loading capacities enables purifications of any scale. This easy scalability helps chemists save money and resources by offering the option to either load more sample or to choose smaller cartridges.

Despite familiarizing yourself with the important parameters for cartridge selection, the traditional decision-making process when picking a cartridge could be quite dreary. Typically, scientists would refer to a catalogue or a website and spend valuable time on researching their options before settling on a cartridge.

Today, we have a tool that can help chromatographers navigate through the cartridge maze to quickly find the right cartridge for their application.

FlashPure Scout is a web app for easy cartridge selection. The tool breaks down the different steps you will need to consider when picking your column. FlashPure Scout then guides you to the most suitable cartridge based on a wide range of selection criteria. The tool also acts as a mini tutor, with expert advice on how to optimize each cartridge parameter, which can save you time from having to refer to other sources for additional information. If you already have a FlashPure cartridge, then you can rely on FlashPure Scout to gain comprehensive technical details on it. You can then use this information for method optimization in your lab. All in all, you can feel confident that you are using a fast track approach to more informed column choices.

Oh, and in case you are wondering, I got my nephew a magician set and he loved it.

Happy picking and until next time,

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