Development of Flow Injection and Continuous Flow System Using 1, 10-Phenanthroline Chemiluminescent Detection for Determina tion of Small Amounts of Rare Earth Metal Ions

Abstract

In order to determine small amounts of rare earth metal ions, a new flow injection and continuous flow system using 1, 10-phenanthroline (1, 10-Phen) chemiluminescent (CL) detection was developed. The proposed system is comprised of three flow lines at flow rate of 2.5 m //min each; the sodium hyroxide solution line, the surfactant and dye-sensitizer solutio n line and the hydrogen peroxide and/or sample solution line. Rare earth metal ion samples containing the mixed reagents of 1, 10-Phen and EDTA (H4edta) are analyzed by the flow injection method or by the continuous flow method. The 1, 10-Phen CL for the determination of rare earth metal ions is produced by a reaction of 1, 10-Phen and reactive oxygen species produced by a reaction of rare earth metal-edta complex and hydrogen peroxide in the alkaline solution, and enhanced by surfactant and dye-sensitizer. Typical europium 011Y s analytical characteristics for the proposed system are as follows. The lower detection limits are 2.0 x 10^-8 M (1 M=1 mol dm-3) in 20 ul injection volumes and 1.0 x 1 0^-8 M in 2.5 m i/min continuous sample flows. The magnitudes for the determination are 3.3 x 10^-7-1.0 x 10^-5 M by the flow injection method and 1.0 x 10^-8-1.0 x 10^-4 M by the continuous sample flow method. Analytical time required is Ca.12 s by the 20 al injection method. Relative standard deviations are 2.2% by the flow injection method and 1.7% by the continuous flow method in 5 repeated runs of the 3 x 10^-5 M euorpium solutions. Copper (II), the substance which may cause the largest interference to the europium CL intensity, did not interfer the intensity even by the 3 x 10^-7 M coexistence in the 3 x 10^-5 M europium solutions. The analytical properties for other rare earth metal ions such as samarium (III) showed the same tendency to those for europium. Coal fly ash was analyzed with the present system.