Build-a-bone: development of a matrix-matched reference material for quantitative analysis of bone with portable LIBS

Abstract

With the rising popularity of laser-induced breakdown spectroscopy (LIBS) for studying skeletal samples, the need for a matrix-matched reference material for quantitative analysis of bone has become a priority. Previous calibration materials used for laser-based sampling include glass standards, bone powders, carbonates, and hydroxyapatite standards, all of which fail to imitate both the physical and the chemical properties of the matrix of bone samples. This study focuses on the development, characterization, and application of matrix-matched reference material for bone. These materials are composed of a compact collagen scaffold that is embedded with elementally-enriched hydroxyapatite crystals. Physical characterization of the composites indicates a hydroxyapatite crystallinity and pore size that corresponds to bone. Molecular characterization confirms the presence of hydroxyapatite and collagen throughout the material, while elemental analysis reveals a profile nearly identical to that of bone. Calibration curves for strontium and barium were developed for portable LIBS (pLIBS) analysis, finding limits of detection and quantification values of 123 μg g⁻¹ and 140 μg g⁻¹ for strontium, and 29 μg g⁻¹ and 37 μg g⁻¹ for barium. Validation was performed on bone fragments for which pLIBS signal was used to determine the concentration of strontium and barium.