Study On Precipitation Trapping With Phenyl Fluorone And Determination Of Trace Gallium Germanium Molybdenum And Indium By Graphite Furnace Atomic Absorption Spectrometry

On the basis of a review of the application and progress in precipitation and co-precipitation method in separation of trace element, according to the merits of organic reagent and the new characteristic that organic reagent can be applied to acid solution and trap trace elements without carriers, this thesis would attempt to develop phenyl fluorone to be a new organic precipitant. The following aspects were investigated in the thesis:1 The conditions of trapping trace gallium by precipitation with phenyl fluorone were optimized. The influences of gallium during the ash and atomization stage were compared using Ni and Mg as matrix modifiers. Using Ni as matrix modifiers, sensitivity was increased and matrix interferences were overcome effectively. The method can be used to trap trace gallium in water samples, zinc concentrate and artificial zinc samples. The detection limit was 0.027ng/mL; the precision was between 3.1~4.0%. The enrichment multiple was from 20 to 6 102. Measured values of gallium in national standard reference samples GBW07405 and GBW07107 by the above-mentioned method were in good agreement with certified values.2 A method of trapping trace germanium by precipitation with phenyl fluorone was studied. The conditions of enrichment and measurement were optimized. With specially-made graphite tube coated with W, and La as matrix modifiers, sensitivity was increased and matrix interferences were effectively eliminated. The method can be used to trap trace germanium in water samples, artificial zinc samples and spirulina. The detection limit was0.03ng/mL and the precision was between 4.9-5.9%. The enrichment multiple was from 20 to 6 103. Measured values of gallium in national standard reference samples GBW07405 and GBW07107 by our established method were in good agreement with certified values.3 A method of trapping trace molybdenum by precipitation with phenyl fluorone was studied. The conditions of enrichment and measurement were optimized. The enhancement effect of Ni, NaF, CaF2, CaCl2, EDTA in the determination of molybdenum was studied. The mechanism of CaF2 sensitivity enhancement when it is used as matrix modifiers is discussed. The method can be used to trap trace molybdenum in water samples and copper concentrate. The detection limit was 0.046ng/mL and the precision was between 3.1~4.0%. The enrichment multiple was from 40 to 4 X 102. Measured values of molybdenum in national standard reference samples GBW07405 and GBW07103 by our established method were in good agreement with certified values.4 A method of trapping trace indium by precipitation with phenyl fluorone was studied. Ag was tested as matrix modifier and found to be effective in eliminating the matrix interferences. The method can be used to trap trace indium in water samples and zinc concentrate. The detection limit was 2.5ng/mL.The enrichment multiple was from 4 to 2 103.5 The sensitivity-enhancing effect and precipitation mechanism of phenyl fluorone in the process of trapping gallium, germanium, molybdenum and indium were studied. The results showed that the phenyl fluorone which had been precipitated and aged had more distinct sensitivity-enhancing effect; the precipitation process was mainly post-precipitation, with partial co-precipitation of gallium and molybdenum.