Elemental Chromatography Modeling Using CADET?

Hi CADET Community,

I am a PhD student in isotope geochemistry/geochronology trying to simulate elution curves for separating specific elements (Pb, Th, and U) using anion-exchange resins (e.g., AG1X8 and Uteva). There are rumors within the isotope geochemistry world that there might be a chromatography code to model elution curves and that brought me to CADET. Most of the papers that I have found about CADET have been focused on biological applications so I thought I would reach out to this community to see if it is possible to use CADET for my application.

Thanks in advance!


Hello Christine and welcome to the CADET forum,

while the main application of our software indeed comes from biotechnological research, it can definitely be used for other applications.

In CADET, we have implemented several chromatographic column models which include different effects (e.g. dispersive effects, transport limitations, surface diffusion). These models can be combined with different adsorption behavior (linear, Langmuir, …) and even chemical reactions. Moreover, it’s possible to combine different unit operations in a larger system, in case multiple columns are used or extra column effects have to be considered.

So the first step would be to find a suitable model for your system and then determine the values of the parameters.

For an in depth introduction to the features of CADET, I recommend registering for the upcoming workshop in October. Moreover, we’re currently working on a new documentation and introductory examples so you can expect more content in future.

Follow-up question: I’m playing around with the web interface for CADET and I’m trying to figure out what is the particle porosity. When you hover your mouse over “particle porosity”, it says “column porosity.”

In a packed column, there are several contributions to the total porosity \epsilon_{total} of the bed. First, the bed itself has free volume because there is space between particles. We call this the column porosity or bed porosity \epsilon_{column}. Moreover, the particles themselves have pores (this is, in fact, where usually all adsorption processes take place). This is the particle porosity \epsilon_{particle}
The overall or total porosity is then defined as:

\epsilon_{total} = \epsilon_{column} + (1- \epsilon_{column}) \cdot \epsilon_{particle}

Depending on the model, you either have to specify both the bed/column porosity AND the particle porosity or just a total porosity (in case of the lumped rate model without pores).

Also, in the interface, it should also return “particle porosity” when you hover over it. @w.heymann, could you maybe update this in the interface?

Hope that helps.

Dear Christine (and dear Johannes),

In order to judge the applicability of CADET to your problem, the retention mechanism behind your separation should be known. If you could say something about the type of interaction behind your separation, we could potentially recommend one of the adsorption (binding) models in CADET to be used.
Since you mention that you separate Pb, Th and U by anion exchange, I am not fully sure about this. Aren’t these cations, and shouldn’t one use a cation exchanger here? Or are they neutral?



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Hi Malte,

You are correct, typo on my part, they are indeed a cation-exchange. We typically use the partition coefficients to determine the retention mechanism so I haven’t really figured out how to integrate CADET into my experiments. Do you think CADET is not applicable for my experiments?


Dear Christine,

Sorry for not answering for such a long time! I hope the fellow colleagues could help you in the meantime!

However, my balated answer to your last message. I actually expect that binding models like SMA (steric mass action law) in CADET should fully fit your needs. As far as I understand your case includes only small ions (“classical ion exchange”). This is a “simple” base case of the SMA (which was originally established for describing ion exchange for large molecules where e.g. steric effects have to be accounted for).

So I actually think your application should be relatively easy to implement by “reducing” the SMA model to the classical small ions. Since, yet, I am more experienced in chromatography than in CADET, some colleagues may give you suggestions on the actual implementation.

Note: An important aspect will be the salt concentration you use during injection and elution.