Using high-performance liquid chromatography it has been possible to separate 14 lanthanide elements in less than 40 min by elution with an ahydroxyisobutyric acid concentration gradient. LiChrosorb KAT cation exchanger (10 pm) is used as the packing material and the eluted lanthanides are detected with an ultraviolet detector after complexation with Arsenazo 111. The detection limit is about 0.1 pg.Determinations of the rare-earth composition in monazite sand and .rareearth impurities in high-purity lanthanum(III), cerium(IV), samarium(II1) and yttrium(II1) oxides were carried out. The proposed method is more convenient than others, and the separation of major components is not necessary in analyses of high-purity rare earths; the elution time is only about 1 h.
The mixture of metal ions [Bi(III), Fe(III), Fe(II), Cu(II), Zn(II), Ni(II), Co(II), Pb(II), Cd(II), Mn(II)] were separated in the bonded‐phase strong cation exchange column (Vydac‐401 SA) and monitored at 540 nm after a postcolumn reaction with 4‐(2‐pyridylazo)‐resorcinol (PAR). Citrate, tartrate, lactate and α‐hydroxyisobutyrate buffer were used as eluent and it has been found that the elution order of some metal ions were changed with different eluents. The detection limits and the calibration curves of metal ions were also studied.
The determination of trace iron(II) is' usually interfered by the presence of iron(Ill) when ortho-phenanthroline colorimetric method is used. In this report a chromogenic reagent which contain'S onho-pbenantnroline-Blj'I'A mixture has been developed to decrease the interference of ferric ion after adjusting the acidity of sample at 0.1 N by adding the sulfuric acid. .The procedure -is also simplified by introducing sulfamate buffer solution (pH == I.S) without adjusting the acidity of sample with 'Sulfuric acid. If iron(I1l) is not present in the sample. this method is also applicable. The comparative results are exhibited for the present method and the conventional o-phenanthroline method.
A simple on‐line flow injection analysis pre‐concentration technique has been developed. The flow injection system consisted of a 4‐channel peristaltic pump, two 6‐way rotary injection valves containing a microcolumn of Chelex‐100 resin, and a flame atomic absorption spectrometer, allowing the determination of lead at a concentration as low as ppb. The degree of pre‐concentration depended on the injected sample volume. Lead contained in NBS 1634b and other heavy oil samples was determined using the system. Samples were ashed directly in a furnace at 550°C for two hours, dissolved with perchloric acid and then injected into the system. The sampling frequency also depended on the injected sample volume.
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