Abstract：A method for the determination of high content of bismuth in tin-bismuth solder was proposed. After the sample was dissolved by hydrochloric acid and nitric acid and fumed with perchloric acid, bismuth in the sample was separated from tin by converting tin to metastannic acid precipitate in nitric acid medium. Then, it was determined by EDTA titration. The influences of nitric acid dosage, the content of tin, and interference ions on determination results were investigated. It was found that, when the nitric acid dosage was 30 mL, bismuth could be completely separated from tin with the precipitation of tin and the hydrolysis of bismuth. Moreover, metastannic acid precipitate would produce absorption and encapsulation for bismuth, which could be reduced by controlling the sample weight. The coexistent ions of Cu2+, Fe3+, Sb, Te and In3+ interfered with the titration. Thereinto, the interference of Cu2+, Fe3+, Sb and Te could be eliminated by adding masking agent or controlling titration condition. The complexation of In3+ and EDTA raised the determination results. Such interference could be eliminated by deducting the indium content determined by atomic absorption spectrometry or inductively coupled plasma spectrometry from the determination results by titration. The method has been applied to the determination of bismuth in Sn20-Bi and Sn38-Bi tin-bismuth solder samples， the results were concordance with those obtained by hydrobromic acid volatilization-EDTA titration, and the relative standard deviations（RSDs, n=8）were less than or equal to 0.14%.
