Chromatographic separation of magnesium isotopes by monoazacrown bonded Merrifield peptide resins

Magnesium isotope separation was investigated by chemical ion exchange with the 1-aza-12-crown-4 (I) and the 1-aza-18-crown-6 (II) bonded Merrifield peptide resin using an elution chromatographic technique. The capacities of each novel monoazacrown ion exchanger were 1.0 meq/g for (I) and 2.3 meq/g for (II) bonded Merrifield peptide resins, respectively. The single stage separation factor was determined according to the method of Glueckauf from the elution curves and isotopic assays. The separation factors of magnesium isotope pairs, ²⁴Mg²⁺–²⁵Mg²⁺, ²⁴Mg²⁺–²⁶Mg²⁺ and ²⁵Mg²⁺–²⁶Mg²⁺ were 1.015, 1.029, and 1.014 for (I) and 1.012, 1.024, and 1.009 for (II) bonded Merrifield peptide resins, respectively.