Abstract: The detection of species that are slightly soluble in water is possible by using an appropriate organized medium in flow injection analysis. Triton X-100 (I) was used to give stable aqueous solution of 1-(2-pyridylazo)-2-naphthol, which were used to determine rare-earth metals, with detection at 560 nm. Detection limits for La, Pr, Nd, Er, Tm and Y ranged from 0.16 to 0.56 µM. The effect of pH on signals was studied. I was also used to stabilize strongly acidic solution (3.6 M HCl) of arsenazo III, which were used for determination of U and Th, with detection at 665 nm.

Abstract: The applicability of FI-ICP-MS combined with microwave sample digestion for the simultaneous determination of trace amounts of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in iron and steel samples was studied. The use of hydrofluoric acid in the sample dissolution process produced nearly invisible insoluble particles with the REEs, leading to erroneous quantification of these elements. The addition of boric acid, complexing HF, solved this problem. By monitoring the transient signals produced by the FI microsampling system, it was possible to evaluate the effectiveness of the sample dissolution procedure. Severe depressive matrix effects caused by the sample matrix were encountered when the signals were compared with those from HNO3 solutions; in contrast, no effects were observed with the addition of boric acid. A highly alloyed steel, stainless steel certified reference material JK 37 (Sandvik Steel), was used to evaluate the effectiveness of the dissolution procedure and to develop the method. The limits of quantification (LOQ) calculated from 10.sqroot.s ranged between 0.008 µg g-1 for Lu and 0.040 µg g-1 for Nd. The relative standard deviation for all the analytes was better than 3% (n=4) for concentrations >10 times the LOQ.

Abstract: Flow-injection analysis-inductively coupled plasma-atomic emission spectrometric (FIA-ICP-AES) method for the determination of 14 rare earth impurities in high-purity yttrium oxide was developed. The effects of some factors including length of transportation tube, volume of sample, exposure time, ICP working parameters, acidity and matrix concentration. were investigated. The dispersion ratio of FIA-ICP-AES method for the given condition was calculated from experimental results. Under optimum conditions the detection limits of different impurities in the method proposed are from 0.25 to 12.5 to mg/g and relative standard deviation in the range of 1.0-2.9%. This method was used for the determination of trace amounts of rare earth impurities in 99-99.99% of yttrium oxide, and their results are in good agreement with those obtained by continuous pneumatic nebulization (CPN)-ICP-AES method. In comparison with the CPN-ICP-AES method, the FIA-ICP-AES is superior in efficiency, precision, influence of acidity and matrix effect, atmosphere of sample used, and permissible concentration of salt. The sensitivity loss in FIA-ICP-AES can be compensated by increasing matrix concentration. in solution This method can be applied to the routine analysis in the rare earth industry. (SFS)