A new method for the determination of trace non-rare earth elements in high purity rare earth oxides by ICP-AES with preconcentration on an active carbon-silica gel microcolumn in a flow injection system is described ...A new method for the determination of trace non-rare earth elements in high purity rare earth oxides by ICP-AES with preconcentration on an active carbon-silica gel microcolumn in a flow injection system is described in this paper. Experimental parameters such as pH, flow rate,reagent concentration,length of reaction coil,eluent acidity,etc. were optimized. In the buffer solution of NH3. H2O/NH4Cl at pH 4. 6,Al,Cr,Cu,Fe, Pb, V and Zn can be preconcentrated and then eluted with 4. 5 mol/L nitric acid utilizing stop-flow technique. The enrichment factors were in range of 8. 1￣12. 6 with detection limits of μg/m level ,and the RSD with metals at μg/g level were 2. 3￣5. 0% (n= 7). The method proposed can reduce the matrix interference effectively , and has been applied to the determination of non-rare earth metals atμg/g level in high purity Eu2O3 with satisfactory results.展开更多
The adsorption isotherms of phenylalanine from aqueous solution on active carbon and silica gel at varying pH,and the influence of inorganic salt upon the ad rption have been studied (at 25℃).The adsorption amount of...The adsorption isotherms of phenylalanine from aqueous solution on active carbon and silica gel at varying pH,and the influence of inorganic salt upon the ad rption have been studied (at 25℃).The adsorption amount of phcnylalanine on the silica gel is very low due to the strong ad- sorption of water by silica gel.The results on the active carbon show:(1)The adsorption is found to be pH-dependent,within pH 4.1—5.1 it increases with pH,within pH 5.1—11.8 it decreases with pH,at pH 5.1 the adsorption reaches its maximum;(2)The phenylalanine is adsorbed mainly in the form of zwitterion;(3)A certain amount of cations and anions of phenylalanine are also adsorbed with van der Waals interaction;(4)After adding NaCl,the adsorption of phenylalanine increases markedly.展开更多
文摘A new method for the determination of trace non-rare earth elements in high purity rare earth oxides by ICP-AES with preconcentration on an active carbon-silica gel microcolumn in a flow injection system is described in this paper. Experimental parameters such as pH, flow rate,reagent concentration,length of reaction coil,eluent acidity,etc. were optimized. In the buffer solution of NH3. H2O/NH4Cl at pH 4. 6,Al,Cr,Cu,Fe, Pb, V and Zn can be preconcentrated and then eluted with 4. 5 mol/L nitric acid utilizing stop-flow technique. The enrichment factors were in range of 8. 1￣12. 6 with detection limits of μg/m level ,and the RSD with metals at μg/g level were 2. 3￣5. 0% (n= 7). The method proposed can reduce the matrix interference effectively , and has been applied to the determination of non-rare earth metals atμg/g level in high purity Eu2O3 with satisfactory results.
文摘The adsorption isotherms of phenylalanine from aqueous solution on active carbon and silica gel at varying pH,and the influence of inorganic salt upon the ad rption have been studied (at 25℃).The adsorption amount of phcnylalanine on the silica gel is very low due to the strong ad- sorption of water by silica gel.The results on the active carbon show:(1)The adsorption is found to be pH-dependent,within pH 4.1—5.1 it increases with pH,within pH 5.1—11.8 it decreases with pH,at pH 5.1 the adsorption reaches its maximum;(2)The phenylalanine is adsorbed mainly in the form of zwitterion;(3)A certain amount of cations and anions of phenylalanine are also adsorbed with van der Waals interaction;(4)After adding NaCl,the adsorption of phenylalanine increases markedly.
