Laser-excited ionic fluorescence spectrometry of rare earth elements in the inductively coupled plasma
ABSTRACT A pulsed tunable dye laser pumped with an excimer laser is used to excite ionic fluorescence of the rare earth elements in the inductively-coupled plasma. Because several fluorescence lines were observed after laser excitation, it was possible to draw partial energy-level diagrams for most of the rare earths. Non-resonance fluorescence lines were used for all measurements in order to minimize spectral interferences. Detection limits at given excitation wavelengths are reported for each element. Laser-excited ionic fluorescence eliminates the problem of spectral interferences which has been associated with determination of the rare earths by atomic emission spectrometry in the inductively-coupled plasma.
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ABSTRACT: A diode laser based system for the detection of Li in an inductively coupled plasma (ICP) by diode laser induced fluorescence (DLIF-ICP) has been developed and successfully applied to the determination of lithium in several mineral waters and a thermal salt. The experimental setup is based on an unmodulated, continuous wave diode laser, emitting light at around 670 nm and exciting neutral Li atoms on their 2s 2S–2p 2P° transition, which was coupled to a commercial ICP atomic emission spectrometer. The spectrometer's monochromator, photomultiplier detector and built-in data acquisition software were utilized to collect background corrected fluorescence and emission signals. A simple, three-step measurement procedure was devised that corrected for the contribution of lithium thermal emission and scattered laser light in the analytical signals. Despite the facts that lithium was detected on its neutral atom, which accounts for less than 1% of the total concentration of Li in the ICP, and that only about 1–2% of all atoms could be excited by the laser light at any given time, the limit of detection (LOD) was still found to be as good as 8 μg/L. The LODs of the DLIF-ICP technique are therefore expected to be in the low ng/L range for elements that can be detected under more advantageous conditions. The linear dynamic range was found to be around three orders of magnitude.Spectrochimica Acta Part B Atomic Spectroscopy 01/2005; · 3.14 Impact Factor
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ABSTRACT: The determination of impurities in the concentration range down to about 0.1 mg/kg in rare earth compounds without chemical separation or preconcentration has been investigated by application of various multielement methods suitable for routine analysis. Mass spectrometry with a plasma ion source (ICP-MS) is most favourable for the determination of foreign rare earth elements (REE) and provides very low detection limits. It is also suitable for measuring a great number of non-REE. Atomic emission spectrometry in inductively coupled plasma (ICP-AES) is also applicable for many non-REE in the range of low concentrations, in particular for elements of low volatility. Flame atomic absorption spectrometry (FAAS) is preferable for alkali and alkaline earth elements, and voltammetry is well suited for the determination of low concentrations of Cu, Zn and Cd. X-ray fluorescence analysis (XRF) is applicable only in the range of concentrations higher than 1 to 10 mg/kg; it is well suited to give a survey of the presence of foreign elements in concentrations >10 mg/kg. Analytical data for 15 commercial REE compounds are presented and detection limits, selection of suitable analytical lines, advantages and disadvantages of the methods are discussed. The analytical data are compared with the specifications given by the suppliers.Fresenius Journal of Analytical Chemistry 09/1993; 346(10):896-904.