Comparative Quantitative Analysis of Inorganic Mineral Fractions and Organic Matrix Components in Layer Chicken Eggshells Using FTIR, XRD, and CHNS Techniques

Abstract

Eggshells represent a highly ordered biomineral composite with significant applications in materials science, nutrition, and biomineralization research. This study comprehensively evaluated inorganic and organic constituents of Gallus gallus (layer chicken) eggshells using Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and Carbon-Hydrogen-Nitrogen-Sulfur (CHNS) elemental analysis to provide a coordinated quantitative profile. FTIR spectra revealed characteristic carbonate vibrational bands (e.g., ~1410–1450 cm⁻¹ and ~873 cm⁻¹) attributable to calcium carbonate (CaCO₃) alongside weaker protein-associated bands indicating the presence of the organic matrix. XRD analysis confirmed calcite, the trigonal polymorph of CaCO₃, as the predominant crystalline phase of the eggshell in agreement with previous studies. CHNS analysis enabled separation of mineral-derived carbon from organic nitrogen and sulfur signatures, revealing the relative proportions of inorganic and organic components. Correlating results showed that the dominant inorganic fraction (≈95 % CaCO₃) coexists with a minor but functionally significant organic matrix (~3–5 %), comprising proteins, glycoproteins, and proteoglycans that guide mineral phase formation and structural organization. The integrated multi-technique approach provides a robust framework for quantifying eggshell constituents and understanding their structural relationships, with implications for valorizing eggshell waste and improving applications in biomaterials and feed supplementation.