Matrix Effect Studies in the Inductively Coupled Plasma with Monodisperse Droplets. Part I: The Influence of Matrix on the Vertical Analyte Emission Profile

Abstract

The effects of different matrices on the analyte vertical emission profile in the inductively coupled plasma were evaluated with use of a monodisperse droplet sample introduction system in combination with a pneumatic nebulizer. The influence of matrix in the gas phase was separated from influences in the desolvation and volatilization steps. The results suggest that vertical shifts in the analyte emission profiles occur primarily during droplet desolvation and vaporization. The vertical shifts can be correlated to the size of the desolvated particles; larger particles produce emission profiles closer to the load coil. Possible effects of radiative heat transfer were also studied. Strongly absorbing species can increase the evaporation rate of the solvent and produce vertical shifts toward the load coil.

Toward a Fuller Understanding of Analytical Atomic Spectrometry

“…It has been suggested that this earlier volatilization might be the consequence simply of the higher sample concentration displacing some of the solvent in each droplet of a given size. 39 Availability of images for the various plasma features also enables likely mechanisms of atomic or ionic excitation to be identified. Each such mechanism is assumed to be kinetically controlled but to be in steady state at any given location in the plasma.…”

Comparison of matrix effects in inductively coupled plasma using laser ablation and solution nebulization for dry and wet plasma conditions

“…Plasma-related non-spectroscopic matrix effects from easily ionizable elements (such as K, Na) and other matrices (such as HNO 3 , H 2 SO 4 ) cause analyte signal suppression or enhancement in inductively coupled plasma-atomic emission spectrometry (ICP-AES) [1][2][3][4][5][6][7][8][9][10][11][12]. Matrix effects remain an important yet not fully understood phenomenon in plasma emission spectrometry [12][13][14][15].…”

“…Matrix effects remain an important yet not fully understood phenomenon in plasma emission spectrometry [12][13][14][15]. Different mechanisms have been proposed for the plasma-related non-spectroscopic matrix interferences in ICP-AES including increased collisional excitation [1][2][3][4][5], ambipolar diffusion [1], shift in analyte-ionization equilibrium [1][2][3], ion-electron recombination [5][6][7], lateral diffusion [2][3][8][9], change in energy distribution of species that collide with and excite the analyte [10] and change in excitation conditions of the plasma [11]. So far there is no agreement on the dominant mechanism [12][13][14][15].…”

“…So far there is no agreement on the dominant mechanism [12][13][14][15]. A possible reason for the lack of a general theory on matrix effects is that most of the reports on matrix effects in ICP-AES used direct solution nebulization or solution nebulization followed by desolvation [1][2][3][4][5][6][7][8][9][10][11]. The aerosol is not completely dry even with desolvation, and water remains a major component among the injected species [16].…”

“…Most of the matrix effects studies in the literature were based on solution sample introduction [1][2][3][4][5][6][7][8][9][10][11][18][19][20], in which the central channel gas flow rate was typically 1 L/min. The flow rate used in our previous study using laser ablation sampling was 0.4 L/min.…”