Chromatographic Techniques for Rare Earth Elements Analysis

Abstract

<jats:title>Abstract</jats:title><jats:p>The present capability of rare earth element (REE) analysis has been achieved by the development of two instrumental techniques. The efficiency of spectroscopic methods was extraordinarily improved for the detection and determination of REE traces in various materials. On the other hand, the determination of REEs very often depends on the preconcentration and separation of REEs, and chromatographic techniques are very powerful tools for the separation of REEs. By coupling with sensitive detectors, many ambitious analytical tasks can be fulfilled.</jats:p><jats:p>Liquid chromatography is the most widely used technique. Different combinations of stationary phases and mobile phases could be used in ion exchange chromatography, ion chromatography, ion-pair reverse-phase chromatography and some other techniques. The application of gas chromatography is limited because only volatile compounds of REEs can be separated. Thin-layer and paper chromatography are techniques that cannot be directly coupled with suitable detectors, which limit their applications. For special demands, separations can be performed by capillary electrophoresis, which has very high separation efficiency.</jats:p>

Separation of Rare Earth Elements (REE) by Ion Interaction Chromatography (IIC) Using Diglycolic Acid (ODA) as a Complexing Agent

“…It can be shown that making use of the Eqs. (1)(2)(3)(4)(5), this is equivalent to the formula: where: ′ LnL3 is bed distribution coefficient of the complex ion.…”

“…In the last decades, the problem of recovery of precious and rare metals from various forms of electronic wastes gained considerable attention and has been discussed in several papers and reviews [14][15][16]. Preliminary separation of REE from other elements is usually achieved by solvent extraction and/ or ion exchange [3][4][5].…”

“…Separation of REE is difficult because of similarity of their chemical properties and therefore only a few techniques like solvent extraction, ion exchange and various forms of chromatography have gained wider acceptance for technological and analytical purposes. Reviews dealing with the separation of REE were recently published [3][4][5]. Several carboxylic and aminocarboxylic acids have been employed for the column separation of REE by ion exchange chromatography (IEC) or ion interaction chromatography (IIC) in cation or anion exchange modes.…”

“…Several carboxylic and aminocarboxylic acids have been employed for the column separation of REE by ion exchange chromatography (IEC) or ion interaction chromatography (IIC) in cation or anion exchange modes. These reagents included: acetic acid, lactic acid, mandelic acid, α-hydroxyisobutyric acid (HIBA), tartaric acid, citric acid, oxalic acid, glycolic acid, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), trans-1,2diaminecyclohexane-N,N´tetraacetic acid (DCTA), and N-hydroxyethylenediaminetriacetic acid (HEDTA) [4,5]. Diglycolic acid (ODA) was rarely employed for REE separation.…”

“…Fig 4. The effect of changing the complexing agent concentration (C ODA ) at constant C TBAOH on retention factor of yttrium in the IIC system: Eternity C 18 -ODA/TBAOH mobile phase (at C TBAOH = 4 mM)…”