Separating the lanthanide elements

It s been nearly impossible to separate these elements from one another due to the characteristics of their f orbitals and lanthanide contraction. Only recently has some of the chemistry been realized due to advances in separation techniques. 

The first popular method for separation was based on how they would stick to a substrate when passed over it, such as a large sieve in a chromatography column. Chromatography is well suited to separating molecules by exploiting slight and subtle differences in the binding affinity with the substrate. 

The ions that don t bind so well get eluted much faster because they wash through the column much easier. 

The material that s washed through the chromatography column is called the eluent. This is similar to how you might run water through cooked pasta to remove the excess starch, the starch is soluble in the water and is removed from the pasta substrate. This same technique is used to separate molecules because the properties of the solvent that you wash through the material alter the solubility of the materials you re trying to separate. 

There are several techniques used to separate the Ln elements, but most of them exploit the difference in solubility and complexing constants. The measure of how well the Ln cations bind with the complexing molecules is called the complexing constant the value is unique to each of the Ln atoms. 

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