Feasibility of TXRF for Elemental Analysis of Fluid Inclusions in Galena Crystals

Abstract

In the present study the feasibility of total reflection X-ray fluorescence (TXRF) for elemental analysis of individual fluid inclusions (FIs) in galena crystals from the Madan Ore District, Bulgaria was evaluated. Method optimization using a multielement standard and synthetic FIs analogue (Synsol) focused on aliquot volume, dilution, carrier type, and excitation time. Optimal conditions (internal standard Ga with concentration 1 mg L^–1; 5 μL aliquots on acrylic carriers; 200–500 s excitation), enabled accurate quantification (±10%) of major FI elements such as K, Ca, Fe, Mn using their Kα lines. Among trace elements, Rb and Ba were reliably determined despite their lower sensitivity (L-lines), whereas Cu was systematically underestimated. Zn and Pb were overestimated, most likely as a result of contamination during sampling and sample preparation. At high dilutions, slight underestimation was observed for elements present at lower concentrations in Synsol (e.g., Cu, Rb) and for those quantified using less sensitive L-lines, such as Ba. Light elements were undetectable due to the instrument's limitations. Application to natural FIs confirmed TXRF as a rapid, sensitive, and minimally invasive method for μL-scale fluid inclusion analysis in ore systems, with accuracy influenced on element-specific chemistry and matrix effects.