A Desolvation Unit for Introducing Microliter Volumes of a Dry Aerosol to an Atomic Spectrometric System

Abstract

Recent communications from this laboratory describe an impaction-electrothermal atomization atomic absorption spectrometric (I-ETAAS) system for direct and near-real-time determination of metallic compounds in the atmosphere. Calibration was achieved by introducing aqueous standards by a pipet or by using a pneumatic nebulization aerosol deposition technique. This assumes that the transport and final atomization processes are identical for a sample introduced as an ion in solution or as a dry particle from the atmosphere. A more accurate and comparable calibration would be achieved if the standard could be introduced to the I-ETAAS system as a dry aerosol. The introduction of a dry aerosol to an atomic spectrometric system has been achieved with the use of a graphite furnace, although the major advantage of this method of sample introduction was the use of micro-volumes, minimizing sample preconcentration, and reducing interferences. The cost and availability may prevent the widespread use of the graphite furnace for sample introduction of dry aerosol. A dry aerosol has been achieved for laser-enhanced ionization spectrometry using a microcondenser with a heated injection port for introduction of sample, but only a few details of the system have been given. Browner and Boorn have recently reviewed sample introduction techniques for atomic spectrometry, pointing out that pneumatic nebulization for flames and plasmas is the preferred, most widely used, and most readily available approach in the majority of situations. Sample introduction to an electrothermal atomizer using a pneumatic nebulization aerosol deposition technique has been described. The use of pneumatic nebulization is unlikely to change in the near future despite concern over poor transport efficiency.