CORRECTION OF MATRIX EFFECTS IN QUANTITATIVE ELEMENTAL ANALYSIS WITH LASER-ABLATION OPTICAL-EMISSION SPECTROMETRY

A new approach to the quantification of the optical emission signals f rom a laser produced plasma in air at atmospheric pressure is describe d, It is based on a simple analytical model giving intensity of the em ission lines as a function of the vaporized mass and the plasma excita tion temperature, Under the hypothesis of a stoichiometric ablation pr ocess, these two parameters are presumed to be responsible for the mat rix effects observed when the composition of the sample is changed. Un der the experimental conditions chosen it is demonstrated that the aco ustic signal emitted by the plasma is proportional to the vaporized ma ss and that the excitation plasma temperature can be controlled using the line ratio of a given element chosen as a 'temperature sensor'. No rmalization of the emission signals by these two parameters allows for an efficient correction of the matrix effects, Results obtained on a series of aluminium alloys, steel and brass samples demonstrate, for t he first time, the possibility of matrix independent analysis with LA- OES with an accuracy of a few percent.