Anthropology and bioarchaeology rely heavily on field instruments to minimize disruption to the site. Elemental analysis by optical emission using Laser-Induced Breakdown Spectroscopy (LIBS) is seen as a complement to X-Ray Fluorescence thanks to its sensitivity to light elements – all the way down to hydrogen. Nonetheless, being a laser-based technique, LIBS is highly sensitive to matrix properties. Osseous materials, such as bones and teeth, have a unique matrix of inorganic and organic components. The hydroxyapatite and collagen matrix, along with the variable nature of bone porosity and hardness, contributes to both chemical and physical matrix effects that can interfere in the spectroscopic analysis. There are currently no commercially available matrix-matched standards for osseous materials to correct, as they are time-consuming to produce. As an alternative, one should consider a calibration-free approach. Assuming ideal plasma conditions and equilibrium atomic excitation, quantitative elemental profiles can be extracted from the spectral data. This method enables quantitative analysis of osseous samples without the need for matrix-matched standards.<br/>A calibration-free approach has already been successfully applied to LIBS in laboratory conditions. However, as mentioned above, field analysis is increasingly required for the analysis of bone. As a result, it is more practical to use a portable, handheld LIBS (hhLIBS) instrument to analyze these materials. This study establishes whether the calibration-free method can be applied to hhLIBS data to successfully measure the elemental concentrations of osseous samples. Demonstrating the ability of calibration-free hhLIBS to serve as an accurate quantitative technique will decrease the need for matrix-matched standards and will broaden the range of analytical applications in fieldwork, especially in anthropological contexts.

Quantitative handheld LIBS for the field using a calibration-free approach

ACS Spring 2022

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