Determination of Trace Silver in Nickel-base Super Alloys by GF-AAS Combined with Microwave Digestion

Graphite furnace atomic absorption spectrometry combined with microwave digestion was applied for the determination of trace silver in nickel-base super alloys. The sample was digested by microwave in a mixture of nitric acid-hydrofluoric acid-water (5+1+5). A mixed solution of palladium nitrate and magnesium nitrate was used as matrix modifier. The ashing temperature was 1 000 ℃ and the atomization temperature was 1 850 ℃. Background interference was deducted by Zeeman correction technique. The detection limit (3s/k) was 2.3 pg. The recovery rates measured by standard addition method were in the range of 98.3%-104%. The proposed method was used to determining trace silver in nickel-base super alloys,giving results consistent with that obtained by ICP-MS.