Ion Microprobe Determination of Rare Earth Elements in Perovskite from Kimberlites and Alnöites

1988 ◽  
Vol 52 (366) ◽  
pp. 331-339 ◽  
Author(s):  
Roger H. Mitchell ◽  
Stephen J. B. Reed
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Accurate Determination ◽  
Parental Magma ◽  
Molecular Ions ◽  
Crustal Material ◽  
Ion Microprobe ◽  
Smooth Curves ◽  
Ion Probe

AbstractIon microprobe analysis ofperovskite from kimberlites and alnöites permits the accurate determination of La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Er and Yb at the part per million level. Other rare earth elements (REE) are subject to interferences in the mass spectrum caused by matrix-derived molecular ions and cannot easily be determined with comparable precision. Chondrite-normalized plots of the ion probe REE data are smooth curves, confirming the superiority of this technique over electron microprobe methods at the levels of REE abundance found in these perovskites. The perovskites analysed contain between 2.8 and 7.1 wt. % REE oxides and are highly enriched in the light REE, having La/Yb ratios of 577–3229. These La/Yb ratios are not representative of the parental magmas but result from REE fractionation during crystallization of the perovskite. Parental magma La/Yb ratios are estimated to be of the order of 120–650. The lower La/Yb ratios (80–200) found for whole-rock kimberlites are considered to result from contamination by relatively heavy REE-enriched crustal material.

A Rapid and Accurate X-Ray Determination of the Rare Earths Elements in Solid or Liquid Materials using the Double Dilution Method

1968 ◽  
Vol 12 ◽  
pp. 546-562
Author(s):  
R. Tertian
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Accurate Determination ◽  
Fluorescence Analysis ◽  
Dilution Method ◽  
Practical Advantage ◽  
X Ray ◽  
The Matrix

AbstractThe double dilution method has many important advantages. For any element to be determined, let us say A, It enables us to control or calculate the matrix factor (sum of the absorption end enhancement effects) for the sample being Investigated towards A radiation, and it furnishes corrected Intensities which are strictly proportional to A concentration. Thus the results are exact, whatever the general composition of the sample, their accuracy depending only on the quality of measurement and preparation. Another major practical advantage is that the method does not require systematic calibration but only a few permanent standards consisting of a pure compound or of an accurately known sample.The procedure has been tested successfully for accurate determination of rare earth elements using, for solid materials such as ores and oxide mixtures, the borax fusion technique. It also can be readily applied to liquids. All the rare earth elements can be titrated by that method, as well as yttrium, thorium and, if necessary, all the elements relevant to X-ray fluorescence analysis. The concentration range considered for solids is of one comprised between 0.5 and 100 % and, with a lesser accuracy, between 0.1 and 0-5 % Examples are given relative to the analysis of various ores. Finally it rcust be pointed out that the method is universal and applies to the analysis of every solid, especially ores, provided that they can be converted to solid or liquid solutions. It appears that most industrial analyses can be worked on In this way.

The fluorimetric determination of cerium and terbium

1989 ◽  
Vol 54 (3) ◽  
pp. 616-621 ◽  
Author(s):  
Záviš Holzbecher
Keyword(s):  
Rare Earth ◽  
Detection Limit ◽  
Rare Earth Elements ◽  
Fluorimetric Determination ◽  
Fluorescence Maximum ◽  
Relative Standard ◽  
And Shifts ◽  
Hcl Medium ◽  
Fold Excess

It has been found that phosphoric acid decreases the first excitation maximum of Ce(III) at 256 nm, increases the second excitation maximum at 297 nm and shifts the fluorescence maximum from 350 to 346 nm. Under optimum conditions, with λexc = 297 nm and λem = 346 nm, Ce(III) can be determined fluorimetrically with a detection limit of 1.2 ng ml-1 in 12M-H3PO4 medium. No interference was observed from a 20-200 fold excess of HCl, H2SO4, Na, K, NH4+, Al and the rare earth elements. HNO3 interferes and Ce(IV) and Fe(III) interfere strongly. It follows from the stereofluorograms of Ce and Tb that the spectra of the two elements are practically independent. The detection limit for Tb(III) in 0.02-2.5M-H2SO4 medium for λexc = 222 nm and λem = 494 nm is 33 ng ml-1. No interference was observed from a 5-20 fold excess of Al3+ and the other rare earth elements. The determination is slightly less sensitive in H3PO4 or HCl medium. The relative standard deviation of the measurement for 10 ng ml-1 Ce(III) or 50 ng ml-1 Tb(III) is about 3%.

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