A study of some techniques for direct solids sampling in plasma spectrometry

Abstract

The capabilities and limitations of three techniques for direct solids sampling in atomic spectrometry are discussed and results obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES) for the analysis of real samples reported. First, the use of electroerosion with a medium-voltage spark at high repetition rate combined to ICP-AES for the direct analysis of metals is described. Detection limits are down to the smg g level and matrix effects are low, as is shown by the example of aluminium. Both are explained from an investigation of the produced analyte vapor by electron probe microanalysis. As a second technique, direct insertion of the sample into the plasma is studied. It is used for the direct determination of volatile elements but also of Ti in Al 3O 3. A suitable sample preparation technique and volatilization studies including the use of thermochemical aids are reported. Direct sample insertion also can be used for metal analyses, provided the trace elements to be determined are separated from the matrix. In aluminium, trace elements at the sub- μg g level have been determined after sorption of the elements on cellulose collectors. As a third technique, the use of slurry atomization for the analysis of powders of a small grain size has been investigated. The optimization of a Babington nebulizer and capabilities of the technique are illustrated by initial results for TiO 2 and Al 2O 3 powders.