CHARACTERIZATION OF A MICROWAVE-INDUCED PLASMA-ATOMIC EMISSION-SPECTROMETRY SYSTEM USING A MODIFIED PLASMA TORCH COUPLED WITH PNEUMATIC ANDHYDRAULIC HIGH-PRESSURE NEBULIZATION

The analytical potential of a modified plasma torch was examined by th e determination of Cr, Fe and Mn in aqueous solutions. The microwave-i nduced plasma was sustained in a rectangular-type TE101 cavity with a power of 500 W. Argon was used as the plasma gas. Sample introduction was carried out by using a pneumatic nebulizer coupled with a cyclone spray chamber and also by using a hydraulic high-pressure nebulizer, A computer-controlled monochromator with background correction was used for detection of the emission lines of the analytes. The detection li mits of the analytes varied from 0.09 to 0.97 mu g ml(-1), The short-t erm stability and long-term precision were measured by monitoring the intensity of the Mn 279.482 nm line (n = 10) and were found to be 3 an d 4%, respectively, The excitation and gas temperatures of the microwa ve induced plasma were evaluated using Fe atoms and OH-radicals as the rmometric species, The temperatures obtained with Boltzmann plots were 4600 +/- 230 and 2500 +/- 60 K, respectively.