[Precipitation trapping with phenylfluorone and determination of trace gallium, germanium, molybdenum and indium by GFAAS].

The preconcentration of trace gallium, germanium, molybdenum and indium by trapping with precipitation of phenylfluorone (PF), and the determination of the elements by GFAAS were developed. The effects such as those of acidity, amounts of PF, aging time, volume of test solution, and the coexistent ions on the preconcentration of the trace elements were examined in detail. The optimum conditions of preconcentration for Ga(III) were pH approximately 2 test solution 500 mL with added 10.00 mg x mL(-1) PF (2.00 mL) and aging for 4 h, those for Ge(IV) were pH approximately 2 test solution 500 mL with added 10.00 mg x mL(-1) PF (4.00 mL) and aging for 10 h, those for Mo(V) were pH approximately 3 test solution 1 000 mL with added 10.00 mg x mL(-1) PF (3.00 mL) and aging for 6 h, and those for In(III) were pH approximately 5 test solution 100 mL with added 10.00 mg x mL(-1) PF (3.00 mL) and aging for 10 h. The experiment results showed that the main contribution to trapping trace gallium, germanium, molybdenum and indium with PF precipitation was post-precipitation instead of coprecipitation. The detection limits (3s) were 0.12 ng x mL(-1) for gallium, 0.30 ng x mL(-1) for germanium, 0.046 ng x mL(-1) for molybdenum and 2.7 ng x mL(-1) for indium. The developed methods were successfully applied to the determination of trace amount of the elements in water samples, geological standard reference materials, and zinc concentrate samples by graphite furnace atomic absorption spectrometry.