Methodological Approach to LIBS Elemental Analysis and Plasma Characterization of Quinoa and Amaranth Pseudocereals Using a TEA CO2 Laser

This study presents a methodological investigation of laser-induced breakdown spectroscopy (<i>LIBS</i>) for elemental analysis of quinoa and amaranth pseudocereals using a <i>TEA CO₂</i> laser. Solid samples were prepared as pressed pellets, and reference data were obtained by <i>ICP</i>-<i>OES</i>. Synthetic solid standards were developed for calibration of selected elements (Ca, Fe, Zn, and Mg). Laser parameters were optimized based on the signal-to-noise ratio of characteristic spectral lines and applied to both pseudocereal samples. Emission lines of Mg, Ca, Fe, K, P, Zn, Al, Sr, and Cu were identified, and limits of detection were determined. Quantitative analysis used calibration curves from analyte-to-internal standard line intensity ratios, showing good linearity and agreement with reference values. Plasma diagnostics under optimized conditions revealed an average temperature of ~11,000 K and electron number densities of ~5 × 10¹⁶ cm^-3 for both samples. Numerical plasma simulations confirmed the experimental results and provided additional insight into plasma composition and behavior. The developed <i>LIBS</i> methodology proved effective for multi-elemental analysis of pseudocereals and shows potential for application to other cereal and plant-based materials with similar composition. It should be noted that this methodology was demonstrated on pelletized samples prepared under controlled laboratory conditions; adaptation to rapid or field-based measurements would require alternative sample preparation strategies. This work provides a methodological framework and experimental validation for <i>LIBS</i> application in food compositional and nutritional analysis.