Comparative evaluation of three α-hydroxycarboxylic acids for the separation of lanthanides by dynamically modified reversed-phase high-performance liquid chromatography

The resolution for the three homologues of α-hydroxycarboxylic acids viz. lactic acid, α-hydroxyisobutyric acid (α-HIBA) and α-hydroxy-α-methylbutyric acid (α-H-α-MBA), was compared for the individual separation of 14 lanthanide elements under identical experimental conditions. α-HIBA was found to be the best for separation of heavier lanthanides (Tb to Lu) while α-H-α-MBA led to a better separation for lighter lanthanides (La to Eu). All the 14 lanthanides were separated by gradient HPLC employing both α-HIBA and α-H-α-MBA so that there was reasonable resolution among all the peaks and the separation was completed in a short time.