Selective liquid chromatographic separation of yttrium from heavier rare earth elements using acetic acid as a novel eluent

• HPLC method for selective separation of Y from heavier REEs is proposed.
• Acetic acid is used as novel eluent.
• Selectivity relies on weaker stability of Y-AcO complex compared to heavier REE analogs.
• The traditional elution position of Y is shifted from amongst the heavier REEs to the lighter REEs.
• The method is successfully used to separate REE sample containing 80% of Y and 20% heavier REEs.

One of the major difficulties in the rare earth elements separation is purification of yttrium from heavy rare earth elements. Thus, an HPLC method using acetic acid as novel eluent was explored for selective separation of yttrium form the heavy rare earth elements. When acetic acid is used as a mobile phase yttrium eluted with the lighter lanthanides. This is contrary to its relative position amongst heavier lanthanides when eluents commonly used for separation of rare earth elements were employed. The shift in elution position of yttrium with acetic acid as eluent may reflect a relatively lower stability constant of the yttrium-AcOH complex (in the same order as for the lighter lanthanides) compared to the corresponding AcOH complexes with heavy lanthanides, enabling selective separation of yttrium from the latter. The method was successfully used for selective separation of yttrium in mixed rare earth sample containing about 80% of yttrium and about 20% of heavy rare earth oxides. Thus, the use of AcOH as eluent is an effective approach for separating and determining the trace amounts of heavy rare earth elements in large amounts of yttrium matrix. Separation was performed on C18 column by running appropriate elution programs. The effluent from the column was monitored with diode array detector at absorbance wavelength of 658 nm after post column derivatization with Arsenazo III.