High-performance liquid and ion chromatography: Separation and quantification analytical techniques for rare earth elements

High-performance liquid chromatography (HPLC) and ion chromatography (HPIC) have been widely used as cheap, relatively rapid, precise and accurate separation and quantification analytical techniques for the rare earth elements (REE). In this "Back to Basics" review, a general description of the basic components of instrumentation and the most common detectors is presented, with special attention to separation conditions and chromatographic quality parameters for the REEs. Also included is a brief survey of the literature on the use of HPLC and HPIC in the determination of REEs in synthetic solutions as well as other matrices such as nuclear fuels and geochemical reference materials. For a proper evaluation of HPLC and HPIC applications, and use of these techniques by other researchers it is recommended that parameters such as the amount and uncertainty estimates of an element injected, eluents and post-column reagents and information on linear or complex gradients and detector system set-up, should always be reported or relevant literature references provided. Finally, a brief account is also presented on state-of-the-art liquid chromatography known as ultra high- or extremely high-performance liquid chromatography, which has high potential for a diversity of applications in all scientific and engineering fields including the Earth Sciences.