Determination of trace sodium and potassium in nickel-based superalloy by inductively coupled plasma mass spectrometry with graphite digestion
During the determination of Na and K by inductively coupled plasma mass spectrometry(ICP-MS),the sensitivity was relatively low due to the light mass number of Na and K.Moreover,the mass spectral interference of polyatomic ions and the easy contamination can cause high blank value.In experi-ments,the nickel-based superalloy sample was digested in a fully automatic graphite digestion instrument with 5 mL of hydrochloric acid,1 mL of nitric acid and 0.5 mL of hydrofluoric acid.23Na and 39K were se-lected as the isotopes to be measured.The mass spectral interference of polyatomic ions(7Li16O+and 38Ar1H+)and doubly charged ion(46Ti++)was overcome through the cold flame mode.Pure nickel was selected for matrix matching and Li was used as the internal standard to correct the matrix effect.A method for the determination of trace Na and K in nickel-based superalloys by ICP-MS was estab-lished.The measurement conditions were optimized:the radio-frequency power was 750 W and the sam-pling depth was 13.5 mm.Under the optimized experimental conditions,the linear correlation coefficients of calibration curves for Na and K were 0.999 9.The limits of detection for Na and K were 0.20 μg/g and 0.21 μg/g,and the limits of quantificaton were 0.66 μg/g and 0.69 μg/g,respectively.The established method was applied to determine Na and K in nickel-based superalloy samples,and the found results were in good agreement with those obtained by flame atomic absorption spectrometry.The relative standard de-viations(RSD,n=7)were less than 2.5％,and the spiked recoveries were 98％-102％and 95％-101％,re-spectively.
nickel-based superalloyinductively coupled plasma mass spectrometry(ICP-MS)graphite di-gestionpotassiumsodium
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