Temporal emission and absorption characteristics of silver, lead and manganese in furnace atomization plasma excitation spectrometry

Abstract

The temporal behaviour of the signal measured for Ag, Pb and Mn in furnace atomization plasma excitation spectrometry was studied using atomic emission and atomic absorption spectrometry. Analyte was deposited both on the wall and on the r.f. electrode with and without the r.f. power applied. Analyte condensation on the r.f. electrode is observed when no plasma is formed. When the plasma is formed inside the furnace it heats the electrode such that, for Ag and Pb, condensation is not observed except for large amounts of analyte. For Ag and Mn, the appearance temperatures and peak temperatures are not significantly affected by the plasma relative to the response obtained using a graphite furnace. For Pb, appearance and peak temperatures are shifted significantly earlier. For Pb, atom formation may be effected by the presence of CO in the gas phase generated from oxidation of the graphite furnace wall and electrode. The role of carbon in atom formation was studied by depositing the sample on both tungsten and graphite electrodes.

Analyte ionization in the furnace atomization plasma excitation spectrometry source ? spatial and temporal observations

“…1 is a schematic diagram of the FAPES source. Compared with the source previously used in our laboratory, 10,11,15,22,23 the new HGA-500 based source has reduced void volume that allows more efficient and uniform cooling of the graphite tube. This source has a faster heating rate (about 1500 ‡C s 21 ) allowing the atomic population to build up rapidly, thereby creating a high instantaneous atomic concentration in the atomizer volume and increasing analytical sensitivity.…”

Iridium as a permanent modifier for determination of cadmium and lead in sediment and biological samples by furnace atomization plasma emission spectrometry

“…3,13,15,23 However, it was verified that only the first such peak responded to changes in analyte concentration, whereas the second peak remained constant. The identity of the second peak was never verified, but it likely arises as a consequence of the presence of matrix components rather than second surface vaporization phenomena 23 involving analyte being released from the cooler center electrode. This effect is less likely to occur in the presence of a sample matrix because the latter increases the appearance time (cf.…”

“…Double peaks frequently occur in FAPES as a result of re-distribution of analyte from the wall to the cooler center electrode. 3,13,15,23 However, it was verified that only the first such peak responded to changes in analyte concentration, whereas the second peak remained constant. The identity of the second peak was never verified, but it likely arises as a consequence of the presence of matrix components rather than second surface vaporization phenomena 23 involving analyte being released from the cooler center electrode.…”

Atomic Absorption, Atomic Emission, and Flame Emission Spectrometry

“…The reason He plasmas are easier to ignite than Ar plasmas was explained by a higher electron ionization rate in He. The temporal behavior of the signals for Ag, Pb, and Mn were studied (341). In particular the characteristic times were compared with conventional AA signals in the same furnace (i.e., without the radio frequency plasma).…”