Amethod is described for the preconcentration and determination of the traceof Ag, Bi, Co, Cd, Cu, Fe, In, Mn, Ni, Pb, and Hg in sodiu血 perchlorate. The samples of 100 g of NaCIO4｡H20 were dissolved in 200mJ water and the solution was丘 1tered through a small 舳er paper coated with 50 mg of activated carbon, after the adlustment of pH to 6.0(the pH was n◎t adjusted for the Hg preconcentration). The trace metals of the concentration ranging from O.3to 200ppb and O.012 to 2.Oppb of Hg were quantitatively adsorbed◎n the activated carbon. The activated carbon(with exception for the procedure of Hg)was treated with l mZ of the concentrated nitric acid to liberate the adsorbed traces and the solution was evap◎rated to dryness. Then the residue was diss◎1ved in 3ml of 20%nitric acid and the trace metals were determined by the翌 ame atornic absorption spectrometry(AAS). The concentrations of Hg adsorbed on the activated carbon were deterrnined by the丑 ameless AAS, the activated carbon and the創 ter paper being together heated at 500◎C for 5 min and the mercury being atomized・The detection limits for the analysis of 100 g of NaCIO4｡H20 were O.012 pPb for Hg, 44ppb for Fe, and 0.3∼7 ppb for the other elements. When 0.016μ of mercury (II) chloride was dissolved into 200 ml of the distilled water in a beaker and stood for 24 h at 17°C, about 30% mercury was adsorbed on the glass wall. However, the adsorbed amounts of mercury decreased by the addition of sodium perchlorate and no appreciable adsorptions occurred in the sodium perchlorate solutions of the concentrations more than 0.14 mol-dm-3.
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