Determination of Lead, Bismuth, and Selenium Elements in Nickel Based High Temperature Alloys by Graphite Furnace Atomic Absorption Spectrometry

0.100 0 g of nickel based high temperature alloy sample was taken and placed in a 100 mL-polytetrafluoroethylene beaker. 2.0 mL of hydrochloric acid, 1.0 mL of nitric acid, and 0.5 mL of hydrofluoric acid were added. The beaker was covered with a plastic surface dish and the mixture was heated at 90 ℃ water bath for about 60 min until the sample was completely dissolved. The solution was cooled and transferred to a 100 mL-plastic volumetric flask. 10 mL of nitric acid was added, and the solution was made its volume up to 100 mL with water and mixed well. Lead, bismuth, and selenium elements in the solution were determined by graphite furnace atomic absorption spectrometry, and 3 μL of 250 g·L^-1 ammonium dihydrogen phosphate solution, 5 μL of 250 g·L^-1 thiourea solution, and 8 μL of 1 000 μg·L^-1 Pd(NO₃)₂ and 500 μg·L^-1 Mg(NO₃)₂ solution were sequentially added as matrix modifiers for the determination of lead, bismuth, and selenium elements by the automatic sampler. The determined results were corrected by alternating longitudinal Zeeman background and standard curves were drawn with the matrix matching mixed standard solutions. As shown by the results, linear relationships between values of the corresponding absorbance and mass concentration of lead, bismuth, and selenium elements were kept in definite ranges, with detection limits (3s/k) in the range of 0.01-0.03 μg·L^-1. This method was used to analyze the nickel based high temperature alloy reference materials, and most of the determined values were within the uncertainty range of the certified values, with RSDs (n=6) of the determined values not more than 25%. This method was used to analyze 3 actual nickel based high temperature alloy samples, and the determined values were basically consistent with those obtained by glow discharge mass spectrometry.