INDUCED BREAKDOWN SPECTROSCOPY; MOLECULAR-EMISSION; LASER; AIR; SPECTROMETRY; CHLORINE
The determination of fluorine in solid samples using Laser Induced Breakdown Spectroscopy (LIBS) is a challenging task due to the low excitation efficiency of this element. Recently, the use of molecular CaF bands was demonstrated to improve the analytical capabilities of LIBS fluorine detection in Ca-containing samples. In this work, a novel approach has been developed to extend this methodology for fluorine quantification in calcium-free samples. In particular, the on-line nebulization of a Ca-containing solution on the surface of a fluorine containing sample has been successfully evaluated to obtain the desired CaF molecular emission. Nebulization parameters have been optimized in order to maximize the molecular emission. A linear relationship between the CaF molecular emission signal and the amount of F in the solid samples has been obtained. The calculated limit of detection for fluorine (about 50 mu g g(-1)) is in the same order of magnitude as that obtained for Ca-containing samples. This novel approach for fluorine quantification opens new ways for the analysis of halogens in solid samples.