Communication. Technique for the introduction of dry atomic vapours for improved optimization and diagnostic studies of laser ablation inductively coupled plasma spectrometry

Abstract

An ETV technique is described for introducing internal standards (IS) into the sample carrier gas emanating from LA cells. Unlike ‘wet–dry’ dual flow systems, this method introduces the standards as a dry vapour prior to the spectrometer torch, thereby avoiding the polyatomic ion interference associated with wet plasmas and the need for specially designed dual flow torches and nebulizers. The IS elements behave similarly to ablated analyte elements and polyatomic Ar ions of similar mass under changing instrument conditions (lens settings and forward power). The technique offers improved dry plasma spectrometer optimization over previous methods, and the opportunity for separating and studying confounded LA and plasma phenomena such as the sources of signal noise and non-spectroscopic interferences. The system is easy to operate, and currently produces IS signal stability of ⩽1% RSD over 15 min and ⩽5% over 1 h. With further refinements in stability, internal standardization of spectrometer operation will also be possible.