1987 Volume 36 Issue 5 Pages 293-296
Preconcentration/AAS determination of trace Mn(II) and Pb(II) was inverstigated with xanthate immobilized silica gels (Silyl Xanthate: SX) as the chelating functional groups. Xanthate groups are chemically bonded directly to the surface-OH of four kinds of silica gels which differ in particle diameter, specific surface area, pore volume and pore diameter. Preconcentration procedure were made for small glass columns packed with 500 mg of SX. The glass columns were about 10 cm long and 0.5 cm inside diameter. The sample solutions flowed through the small columns with the aid of a peristaltic pump to maintain a constant flow rate. After washing with 20 ml of pure water, the metal ions were eluted from the SX columns with 25 ml of 0.1 M hydrochloric acid solution. The pH dependence of a preconcentration is considerably similar in the optimum pH region that is at pH 5.0 to 6.0 for Mn(II) and at pH 5.2 to 5.8 for Pb(II). At pH 5.5 of sample solutions, the maximum capacity per 1.0 g of SX is about 0.11 mmol for Mn(II) and 0.12 mmol for Pb(II). The presence of a 15-fold amount of chloride ion interferes in the preconcentration efficiency of Mn(II), and almost equal amounts of Mg(II), Ni(II), Co(II), Cu(II) and Fe(II or III) gives a poorer efficiency. This method was applied to natural waters where known amounts of Mn(II) or Pb(II) were added, and was performed to determine those metal ions in seawater and river water where very low concentrations cannot be determined directly with AAS method, except for Mn(II) in seawater.
