Extraction Discharge Source for Enhancing Analyte Line Intensities in Inductively Coupled Plasma Atomic Emission Spectrometry

Abstract

A supplementary electrical discharge is generated by extraction of the axial channel of an Ar inductively coupled plasma (ICP) into a small vacuum chamber. The spectral background levels and background noise emitted by this discharge are similar to those from the ICP alone. The discharge enhances the intensities of ion lines by factors of up to 13 relative to intensities observed from the ICP alone. Neutral atom lines from elements with high ionization energies (≤9 eV) are also enhanced but by less than ion lines; neutral atom lines from easily ionized elements are suppressed by the discharge. Metal oxides in the ICP can be seen to dissociate into atomic species as they enter the discharge. These effects are attributed to more efficient atomization, excitation, and ionization in the discharge and to the tendency of analyte species to be constricted or concentrated closer to the central axis of the ICP as they flow into the discharge. Under the same operating conditions a 40-MHz plasma generates a more intense discharge and yields higher intensity enhancements than does a 27-MHz plasma.

Elemental matrix effects in ICP-AES

“…The emitted radiation is measured from this discharge and an enhancement in the signal is observed for some lines. 129 A general signal depression is produced in the presence of 1000 and 5000 mg ml 21 . In summary, it can be stated that the matrix effects were more pronounced with this device than with a normally observed ICP.…”

Inductively coupled plasma-mass spectrometry: insights through computer modeling

“…Several groups also investigated the plasma region itself, [9][10][11][12][13][14][15][16][17] but without comparison of plasma characteristics in the presence of the interface to the same characteristics in the absence of the interface. On the other hand, a detailed comparison of the plasma characteristics with and without sampling interface was performed by the groups of Houk, 18,19 Farnsworth 20 and Hieftje. 21 Ma et al 20 used laser induced fluorescence (LIF) to investigate the effect of the sampling interface on the analyte atom and ion distributions in the ICP, while Lehn et al 21 reported that the presence of the sampling interface causes changes in the fundamental plasma characteristics, such as electron number density and gas temperature.…”

“…Figure18. Total Cu sample evaporation rate, integrated over the entire torch, as a function of the injector gas flow rate.…”

Occurrence of gas flow rotational motion inside the ICP torch: a computational and experimental study

“…Therefore optimization of its analytical performance is crucial. A number of studies have been performed for the effect of the presence of a mass spectrometer interface on ICPMS, [1][2][3][4][5][6][7][8] as well as for the effect of the ICP geometrical parameters (i.e., position and diameter of the sampler orice, as well as gas inlet diameter) on the plasma characteristics. [9][10][11][12][13][14][15][16] These observations all suggest that the use of an interface with different orice sizes signicantly affects the plasma characteristics.…”