Joichi Ueda

Separation and concentration of beryllium by coprecipitation with hafnium hydroxide prior to determination by graphite furnace atomic absorption spectrometry

Hafnium hydroxide coprecipitates 0.01–0.2 µg of beryllium from 100–400 ml of sample solution at pH 6.0–10.5. The presence of hafnium quantitatively increases the atomic absorbance of beryllium by about 1.5 times, and the reproducibility of the measurement is improved. The calibration graph is linear for 0.4–8 ng ml–1 of beryllium. The interference induced by large amounts of aluminium can be eliminated by raising the pH of the solution to 13–13.5 with sodium hydroxide solution after the coprecipitation procedure has been carried out at about pH 9.5. Several other ions tested did not produce serious interference effects. This method is applicable to the determination of trace amounts of beryllium in water samples and in aluminium.

Determination of copper by electrothermal atomisation atomic absorption spectrometry following coprecipitation with hafnium hydroxide

Copper (0.1–10 µg) is coprecipitated quantitatively from solution (100–400 ml) with hafnium hydroxide at pH 6–11.7. The peak height of copper in the atomic absorbance measurements remains almost constant in the presence of 0.1–1.6 mg ml–1 of hafnium. A linear calibration graph was obtained in the range 4–400 ng ml–1 of copper. The 27 foreign ions investigated did not interfere with the determination in at least a 200-fold mass ratio to copper. The proposed method was successfully applied to the determination of trace amounts of copper in river water.