Analysis of rare earth

Elderfield and Greaves [629] have described a method for the mass spectromet-ric isotope dilution analysis of rare earth elements in seawater. In this method, the rare earth elements are concentrated from seawater by coprecipitation with ferric hydroxide and separated from other elements and into groups for analysis by anion exchange [630-635] using mixed solvents. Results for synthetic mixtures and standards show that the method is accurate and precise to 1% and blanks are low (e.g., 1() 12 moles La and 10 14 moles Eu). The method has been applied to the determination of nine rare earth elements in a variety of oceanographic samples. Results for North Atlantic Ocean water below the mixed layer are (in 10 12 mol/kg) 13.0 La, 16.8 Ce, 12.8 Nd, 2.67 Sm, 0.644 Eu, 3.41 Gd, 4.78 Dy, 407 Er, and 3.55 Yb, with enrichment of rare earth elements in deep ocean water by a factor of 2 for the light rare earth elements, and a factor of 1.3 for the heavy rare earth elements. 

Balaram, V. (1996). Recent trends in the instrumental analysis of rare earth elements in geological and industrial materials. Trends in Analytical Chemistry 15 475 486. 

Cousin, H. and Magyar, B. (1994). Precision and accuracy of laser ablation-ICP-MS analysis of rare earth elements with external calibration. Mikrochimica Acta 113 313-323. 

B. S.R. Taylor, Trace element analysis of rare earth elements by spark source mass spectroscopy 359... 

C. R.J. Conzemius, Analysis of rare earth matrices by spark source mass spectrometry 377... 

Among the commonly observed spectral overlap problems due to molecular oxide and molecular hydroxide ions are those due to TiO+ (with 5 isotopes of Ti from mass 46 to 50) that result in overlaps with a minor isotope of nickel, 62Ni+ both isotopes of copper, 63Cu+ and 65Cu + and the two major isotopes of zinc, MZn+ and 66Zn+. Calcium oxide and hydroxide ions overlap with all five isotopes of nickel, both isotopes of zinc, and three of the four isotopes of iron. The analysis of rare earth elements is particularly complicated by molecular oxide and hydroxide ion spectral overlaps [141,142]. 

Spectrophotometric method of analysis of rare earth elements. 61... 

Methods based on precipitation reactions for the analysis of rare earths. 

TABLE 1.32 Polarographic methods of analysis of rare earths elements. ... 

Spectrophotometric analysis of rare earths with organic reagents. 

Some qualitative analytical reagents for the detection of rare earths elements are given in Tables 1.26 and 1.27. Gravimetric, volumetric, complexometric, precipitation and polarographic methods of analysis of rare earths are summarized in Tables 1.28 to 1.32. 

Alternating or direct current arcs and spark discharge are common methods of excitation for emission spectroscopic analysis of rare earth elements. Emission spectra of rare earth elements contain a large number of lines. The three arbitrary groups are (i) spectra of La, Eu, Yb, Lu and Y, (ii) more complicated spectra of Sm, Gd and Tm, (iii) even more complicated spectra of Ce, Nd, Pr, Tb, Dy and Er. Rare earths have been analyzed with spectrographs of high resolution and dispersion up to 2 A/mm. Some salient information is presented in Table 1.36. 

This is a classic method for the analysis of rare earths. L-spectra of the elements in the region 1500-2500 A show that for each element it is possible to select 2-5 lines for analysis. These analytical lines are given in Table 1.38. By this method rare earths in a complex mixture can be analyzed. The emission method has a sensitivity of 0.1 to 0.01 %. The time of analysis is 1.5-2.0 h. The method has been used in the analysis of minerals, alloys, etc. 

C. R.J. Conzemius, Analysis of rare earth matrices by spark source mass spectrometry 377 37D. E.L. DeKalb and V.A. Eassel, Optical atomic emission and absorption methods 405 37E. A.P. D Silva and V.A. Eassel, X-ray excited optical luminescence of the rare earths 441 37E. E.W.V. Boynton, Neutron activation analysis 457... 

In the analysis of geological samples, sample dissolution with respect to nebu-lization effects but also to ionization interferences is important [399], The analysis of rare earth minerals without [420] and with removal of the matrix has been reported. 

Broekaert J. A. C., Leis F. and Laqua K. (1979) Some aspects of matrix effects caused by sodium tetraborate in the analysis of rare earth minerals with the aid of inductively coupled plasma atomic emission spectrometry, Spectrochim Acta, Part B 34 167-175. 

Analysis of rare earth cations using sulfosalicylic acid to mask a large excess of alu-minum(lll) also proved quite successful. Linear calibration curves were obtained over at least 0.0.5 to 0.50 mM rare earth with 2.0 mM aluminum and 10 mM sulfosalicylic acid at pH 4.5. 

Karyakin, A. V. et al. Spectral Analysis of Rare Earth Oxides, Moscow, Nauka, 1974... 

III. R. J. Meyer and O. Hauser. Die Analyse der seltenen Erden and Erdsauren [Analysis of Rare Earths and Their Acids], Stuttgart, 1912, pp. 75-76 R. Bock. Angew. Chem. 62, 375... 

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