Abstract: Sample solution (10 µL) of 10 mM Tb, -Ho or -Eu prepared from the corresponding chloride in 20 mM NaCl - 2 mM HCl (1:1; solution a) was injected into a steam of solution a which merged merged with a stream of 5 mM 4-(2-pyridylazo)resorcinol in 25 mM borax - 0.1 M NaOH buffer of pH 9.7. The mixture was passed through a PTFE T-piece connected to a knitted PTFE tube reactor (1 m x 0.3 mm) before its absorbance was measured at 515 nm. The calibration graph was rectilinear for 0.1 to ~10 µM-Tb, -Ho and -Eu; corresponding detection limits were 16.5, 15.9 and 15.2 ng mL-1, respectively. The results were comparable with those obtained by other techniques. A dual-line flow injection system is described for the spectrophotometric determination of terbium, holmium, and europium by complexation with 4-(2-pryidylazo)resorcinol (PAR). The first line contained a 1:1 mixture of 2 x 10^-2 M sodium chloride and 2 x 10^-2 M HCl, and the second line, the buffered PAR solution (10-4M, pH 9.7). 10 µL samples of Tb, Ho, and Eu were injected into the first line. Each lanthanide was made to react with the PAR solution at a teflon T-piece connected to a 1-m knitted teflon tube reactor (0.3 mm internal diameter). The PAR-Tb, -Ho, and -Eu complexes were detected at the output by a UV-visible spectrophotometer working at 515 nm. The linear detection range for each lanthanide extended from 10^-7 M to just above 10^-5M.

Abstract: Spectrophotometric determination of some heavy lanthanide ions by flow injection method is described. Xylenol Orange forms water soluble chelates with lanthanide ions in a tris[hydroxymethyl]-aminomethane-buffered medium having pH 8.3 and containing cetyltrimethylammonium bromide. The molar absorptivities of Ln(III)-XO complexes were increased by the ternary system with cetyltrimethylammonium bromide with the concomitant bathochromic shift of absorption maxium compared to those of the binary system without cetyltrimethylammonium bromide. The calibration curves are linear in the range 0.25-1.00 ppm for Gd(III), Dy(III), Er(III), Tm(III) and Yb(III) and the dynamic range are very wide. The detection limits (S/N=2) are from 2 ppb for Gd(III) to 30 ppb for Yb(III) and the relative standard deviations are from 1.2% for 0.5 ppm Gd(III) to 1.8% for 0.5 ppm Yb(III). The sample throughput was ~50 h-1.

Abstract: Using a flow injection ICP-MS method, yttrium and all the lanthanides in seawater were determined in the coastal/offshore mixing regime near Japan. Marked enrichments in the trivalent rare earth elements (REEs) in the surface waters are ascribed to the influence of coastal waters from Tokyo Bay in Mar. and perhaps somewhere else in Sept. and Oct. to this region. At less than half of the stations where the detailed vertical profiles were obtained throughout the water column, we found marked excess REE(III) concentrations. near the bottom. These bottom concentration. anomalies are probably caused by resuspension of underlying sediments. Excluding these surface and bottom anomalous concentrations., the distribution of REE(III)s in the midwater column are very similar to those of the open ocean and are highly correlated with each other (R2 > 0.95). This suggests that the boundary effects on the chemical fractionation of REE(III)s are small. We find no effect of the boundary scavenging known for 210Pb and 231Pa on the REE distribution, whereas there may be preferential release of light and middle REE(III)s over heavy REEs from slope sediments to the seawater much like 227Ac. From the shale-normalized REE patterns, we obtained up to 90% negative Ce and 10%positive Gd anomalies in the water column.