ANALYSIS OF MONO-ATOMIC IONS IN INDIVIDUAL FLUID INCLUSIONS BY LASER-PRODUCED PLASMA EMISSION-SPECTROSCOPY

The analysis of mono-atomic ions in individual fluid inclusions was investigated using emission spectroscopy of a laser-produced plasma. The first step was the application of this technique to the analysis of major cations (Ca++, Mg++, Na+, and K+) contained in macroscopic electrolyte solutions before applying the method to synthetic individual fluid inclusions. A ND-YAG laser beam focused on the surface of the sample produces plasma which is used as a photon source for emission spectrometry. The plasma extends over several millimeters above the sample and its image is focused on the entrance slit of the one-stage monochromator. The spectral range from 270 to 570 nm is recorded with a multichannel detector (spectral window width of 13 nm) with a spectral resolution of 0.1 nm for a 25-mu-m entrance slit width. The emission line spectra for calcium and magnesium were investigated using macroscopic solutions (concentration: 0.05 to 1 molal). The determination of the best spectral range and the calibration curve were performed using Ca and Mg solutions. The study of macroscopic standard solutions demonstrated that the plasma production as well as the emission process are representative of the analysed material. The good analytical results obtained on Mg and Ca lines for synthetic fluid inclusions are consistent with the data related to macroscopic solutions.