THE INFLUENCE OF INCOMPLETELY DESOLVATED DROPLETS AND VAPORIZING PARTICLES ON CHEMICAL MATRIX EFFECTS IN INDUCTIVELY-COUPLED PLASMA SPECTROMETRY - TIME-GATED OPTICAL-EMISSION AND LASER-INDUCED FLUORESCENCE MEASUREMENTS

The effects of high concentrations of NaCl on analyte (Sr) atom and io n number densities (measured by laser-induced fluorescence), ionizatio n (assessed from ion to atom fluorescence intensity ratios) and excita tion (determined from emission to fluorescence intensity ratios) were investigated near and away from incompletely desolvated droplets and v aporizing particles. Matrix effects on analyte ion number densities, i onization and excitation were more severe near droplets or particles. This is expected, considering that local temperatures are more than 10 00 K cooler near an incompletely desolvated droplet or vaporizing part icle. However, offsetting spatial effects (on and off axis radially) a nd ion number density vs ion excitation effects resulted in almost ide ntical matrix-induced changes in Sr ion emission intensities near and away from an incompletely desolvated droplet at 14 mm above the load c oil. Line-of-sight Sr ion emission intensities were unaffected by high concentrations of NaCl at 14 mm above the load coil both near and far from desolvating droplets. Sr ion emission intensities at 22 mm above the load coil were depressed in the presence of NaCl in the sample by similar magnitudes near and away from vaporizing particles. (C) 1997 Elsevier Science B.V.