Determination of fluorine content in rocks using laser-induced breakdown spectroscopy assisted with radical synthesis

In the atmosphere, fluorine element in rocks is hard to detect using fluorine atomic emission spectrum in laser-induced breakdown spectroscopy. In this study, a novel radical synthesis method based on laser ablation was proposed, by which strontium-fluorine (SrF) radical spectrum was collected to quantify fluorine element in rocks instead of fluorine atom spectrum. A pure strontium carbonate was placed orthogonally to the sample, and ablated by an additional laser to provide sufficient strontium atoms for promoting SrF radical formation. The fluorine content in rocks was sensitively and accurately determined by SrF radical emission signal. The coefficient of determination, average relative standard deviation, root mean square error, limit of detection, and limit of qualification were 0.996, 4.68%, 0.0068 wt%, 6.36 μg g^-1, and 21.2 μg g^-1, respectively. This work proved that this novel method provides a new way to promote radical synthesis and has considerable potential for detecting fluorine in rocks in geological exploration.