DETERMINATION OF TRACE AMOUNTS OF CADMIUM IN ZIRCONIUM AND ITS ALLOYS BY GRAPHITE-FURNACE AAS

Trace amount of cadmium in zirconium and its alloys was determined by grapite furnace atomic absorption spectrometry (GF-AAS) after ion exchange separation. A 2 g chip sample was decomposed with 20 ml of hydrofluoric acid (1 + 9) and a few drops of nitric acid. A trace amount of cadmium was separated from zirconium by strongly acidic cation-exchange resin (MCI GEL CK 08P) using 50 ml of hydrochloric acid as an eluent. The solution was gently evaporated to dryness on an electric hot plate heater and under an infrared lamp. The residue was dissolved in 1 ml of nitric acid (I + 14) and diluted to 10 ml in a volumetric glass flask with distilled water. Ten microliters of this solution was injected into a graphite furnace and then atomized at 2200-degrees-C for 4 s in argon at a flow rate of 3.0 1/min. Acids used in the analytical procedure were purified by azeotropic distillation and cation-exchange resin. The limit of determination (3sigma(BK)) for cadmium was 0.5 ngCd/g and the relative standard deviation (RSD) at 1 ngCd/g level was less than 20% for the GF-AAS. The accuracy of this technique was confirmed by NIST SRM 1643b (trace elements in water).