Interference Effects of Easily Ionizable Elements in ICP-AES and Flame AAS: Characterization in Terms of the Collisional Radiative Recombination Activation Energy

Departure from local thermal equilibrium during ICP-AES and FAES: Characterization in terms of collisional radiative recombination activation energy

“…If it is assumed that electronic collisions with heavy particles can occur before or after thermal equilibration, then the electron should experience different activation energies depending on whether collisions leading to the observed interference effects occurred before or after thermal equilibration. In a recent paper [57], we proposed a simplified rate model for the interference effects of EIEs in FAAS and ICP-AES, which showed that when the analyte signal is determined in the absence and presence of the interferent, the change in the activation energy for collisional radiative recombination, ΔE a , is zero when the system conforms to LTE, and proceeded to show that when CaI, Ca(II), and Mg(II) are determined in the absence and presence of excess Li interferent, this condition was not met, while the results obtained suggested pre-LTE collisions for electrons from the ionization of the analyte and Ar. In this paper we report the results of a study carried out to characterize the interference effects of (a) excess K and Li on Mg(II), Sr(II), and Ca(II) line emission intensity in the ICP, and (b) excess K and Na on Mg and K atom line, respectively, in the air-acetylene flame, in terms of the activation energies involved when the determination is done in the absence and presence of the interferent, with the view to confirm our previous findings, and to assess the effect of ionization potential of both the analyte and interferent on ΔE a .…”

“…In this paper we report the results of a study carried out to characterize the interference effects of (a) excess K and Li on Mg(II), Sr(II), and Ca(II) line emission intensity in the ICP, and (b) excess K and Na on Mg and K atom line, respectively, in the air-acetylene flame, in terms of the activation energies involved when the determination is done in the absence and presence of the interferent, with the view to confirm our previous findings, and to assess the effect of ionization potential of both the analyte and interferent on ΔE a . The rate model presented by Zaranyika et al [57] was derived for FAAS conditions, then extended to ICP conditions by assuming the I'/I = A'/A, where I and A denote emission and absorbance signals, respectively. Because the composition of the plasma in the ICP differs greatly from that of flame systems, in the Theoretical section we give a generalized derivation of the rate model taking into account the composition of the plasma in the ICP.…”

Plasma Diagnostics through Kinetic Modelling: Characterization of Matrix Effects during ICP and Flame Atomic Spectrometry in terms of Collisional Radiative Recombination Activation Energy?A Review

“…The degree of ionization for analytes and interferents are based on the Saha equation [61], otherwise literature values are used [1,[62][63][64]. Table 2 shows typical number density values obtained for ICP and flame experiments involving Group II analytes and I interferents [58,59].…”

“…To tackle the problem of the non-involvement of Ar species in collisional processes leading to the observed emission signal enhancement, Zaranyika et al [58][59][60] invoked ambipolar diffusion as the possible source of the discrepancy. Ambipolar diffusion is common plasmas [5], and is defined as the state of charge separation balance in which ions and electrons diffuse with the same velocity.…”

“…11 should yield a linear graph of a slope from which the change in activation energy can be calculated, and compared to theoretical values as predicted by Limiting Cases IA to IC in Table 3. Table 4 shows the regression data and the experimental ∆E a values obtained when various analyte/interference systems were studied in the ICP [58,59] as well as the air-acetylene flame [60].…”