Fundamental studies of matrix effects in the inductively coupled plasma by spatially resolved emission and fluorescence spectroscopy

Changes in analyte intensity in the presence of easily ionizable (EIE), non-easily ionizable (non-EIE), and HCl matrices were investigated in the inductively coupled plasma by time-integrated, spatially resolved emission and laser-induced, saturated fluorescence. The presence of matrix affected both the fraction of atoms (ions) that were excited and the number of atoms (ions) that were in the observation zone. Changes in the number of atoms (ions) that were in the observation zone were monitored via fluorescence spectroscopy, while the ratio of emission to fluorescence intensity was used to measure variations in the fraction of the atoms (ions) that were excited. The instrumental system that was used to measure spatially resolved emission and laser-induced, saturated fluorescence at multiple radial positions simultaneously is described.;The change, or lack of change, in laterally resolved analyte emission intensity in the presence of matrix is the result of often offsetting on-axis and off-axis radially resolved emission changes. For equimolar amounts of matrix, EIE matrices have the largest effect on the plasma, although non-EIE and HCl matrices also cause significant changes. The presence of EIE matrices produced shifts in the relative numbers of atoms and ions and enhanced excitation. Sample introduction and diffusional processes also appeared to be affected by the presence of matrix, although mechanism(s) could not be assigned. Changes that are caused by a combination of EIE matrices with HCl were not additive.;Preliminary evidence is presented for the need of spatially resolved emission and fluorescence measurements on the millisecond to microsecond time scale. On this time scale the presence of droplets in the plasma affect local conditions greatly. Results from such measurements may show that the effect of matrix is much different in the presence, than in the absence, of droplets.