Compensation of Ca and Na interference effects in axially and radially viewed inductively coupled plasmas

The linear relationship between Ca and Na interferences and energy potentials for a wide range of atomic and ionic lines is used to compensate for variable intensity suppression in robust axially and radially viewed inductively coupled plasmas (ICPs). In the axial configuration, intensity attenuation varied from 0 to 40% in the presence of 0.5% Ca and Na. In the radially viewed ICP, interferences were smaller, varying from 5 to 15% for 0.5% Na and from 10 to 30% for 0.5% Ca. Signal attenuation was broadly a linear function of the energies of the spectral lines. These linear functions were estimated by using spectral lines covering the energy range from Sb I 206.833 (5.98 eV), Y II 371.209 and Sc II 361.384 (9.9 eV), Sc II 255.237 (11.42 eV), and Be II 313.042 (13.28 eV) nm. These functions were then used as variable internal standards to compensate for Ca, Na, and mixed Ca-Na matrix effects. Whereas analyte recoveries without compensation varied from about 40 to 90%, they varied mostly from 100 +/- 5% when these functions were used. In the presence of Ca and Na, the Mg II 280.270/Mg I 285.213 nm intensity ratio decreased from about 12 for an aqueous solution to 9 at 1.5 kW. Such values confirm that the radially and axially viewed ICPs were robust, (C) 1999 Academic Press.