TECHNIQUE FOR THE INTRODUCTION OF DRY ATOMIC VAPORS FOR IMPROVED OPTIMIZATION AND DIAGNOSTIC STUDIES OF LASER-ABLATION INDUCTIVELY-COUPLED PLASMA SPECTROMETRY

An ETV technique is described for introducing internal standards (IS) into the sample carrier gas emanating from LA cells. Unlike 'wet-dry' dual how systems, this method introduces the standards as a dry vapour prior to the spectrometer torch, thereby avoiding the polyatomic ion interferences associated with wet plasmas and the need for specially d esigned dual flow torches and nebulizers, The IS elements behave simil arly to ablated analyte elements and polyatomic Ar ions of similar mas s under changing instrument conditions (lens settings and forward powe r), The technique offers improved dry plasma spectrometer optimization over previous methods, and the opportunity for separating and studyin g confounded LA and plasma phenomena such as the sources of signal noi se and non-spectroscopic interferences, The system is easy to operate, and currently produces IS signal stability of less than or equal to 1 % RSD over 15 min and less than or equal to 5% over 1 h, With further refinements in stability, internal standardization of spectrometer ope ration mill also be possible.