Spectroscopic diagnostics of eggshells plasma using LIBS with self-absorption correction in conjunction with WDXRF, EDS and FTIR techniques

Precise determination of heavy metals and trace elements in eggshells from conventional and organic poultry production systems is carried out using a two distinct CF-LIBS techniques, namely one-line calibration-free (OLCF) and self-calibration (SC) LIBS, coupled with XRD, WD-XRF, EDS and FTIR. A Q-switched Nd:YAG laser with a wavelength of 1064 nm, pulse duration of 9 ns and pulse energy of 126 mJ was used to generate plasma. Spectral analysis revealed Ca, Mg, S, Fe, Mn, Cr, Sr, Al, Cu, Ni, Na, and Li in both organic (OE) and regular (FE) chicken eggshells, whereas a heavy element Ba was only detected in OE emission spectra. A mean value of plasma temperature was calculated as 7500 ± 750 K using a Boltzmann plot in addition to Saha-Boltzmann plot approach with self-absorption corrections and used for calcium quantification, whereas electron number density value was calculated as 5.68 × 10¹⁶ cm⁻³. The concentration of major constituent Ca in OE versus FE determined by CF-LIBS techniques along with XRF and EDS was found as: OLCF-LIBS = 99.23% versus 99.11%, SC-LIBS = 99.78% versus 99.73%, XRF = 99.81% versus 99.76%, and EDS = 99.83% versus 99.89%. The results showed that SC-LIBS method is more accurate for precise compositional analysis and findings were close to that determined by XRF and EDS methods. The results further demonstrated LIBS capability to identify heavy metals and trace elements within eggshell samples accurately and hence, contributing to and advancing our understanding of the utilization of LIBS technique in this field.

Graphical abstract

Spectroscopic diagnostics of eggshells plasma using LIBS