Long path atomic/ionic absorption spectrometry in an inductively coupled plasma

Abstract

A novel approach was taken to increase the atomic/ionic absorption path length in an inductively coupled plasma (ICP) by using a water-cooled quartz "T-shaped" bonnet. Atomic and ionic absorption spectrometry was performed utilizing a continuum source and line sources. Absorption spectra of synthetic multielement solutions were collected with a photodiode array. Sample introduction into the ICP was accomplished with an ultrasonic nebulizer. To prevent the bonnet from cracking, low radio frequency powers were utilized (i.e., 400-600 W). Plasma diagnostics were performed to study the plasma temperature and electron number density within the "T-shaped" bonnet. Analytical figures of merit were found to be better than those obtained from previous work attempted with inductively coupled plasma atomic absorption spectroscopy and approaching that of flame atomic absorption spectroscopy.

Exploration of Microwave Plasma Source Cavity Ring-Down Spectroscopy for Elemental Measurements

“…Therefore, subsequent research on ICP-AAS has mainly focused on fundamental studies and plasma diagnostics. [8][9][10] Although cavity ring-down spectroscopy (CRDS) has rapidly gained popularity in the molecular spectroscopy community, there are few reports exploring atomic absorption with CRDS. [11][12][13][14] So far, the only published papers used an inductively coupled plasma as an atomization cell for CRDS measurement.…”

“…The following reasons were identified: (1) the high plasma gas flow rate required for maintaining the ICP dilutes the concentration of analyte atoms, resulting in a short residence time of analyte in the plasma; (2) the absorption path length in an ICP is relatively short and thus is not beneficial for AAS measurement; and (3) the high temperatures in the ICP source favor the production of excited and ionized species while AAS needs ground-level populations. Therefore, subsequent research on ICP-AAS has mainly focused on fundamental studies and plasma diagnostics. − …”