Elemental Analysis of Adhatoda Vasica by Multi-Element Saha-Boltzmann Plot (ME-SBP) Calibration Free-Laser-Induced Breakdown Spectroscopy (CF-LIBS)

This is the authors' abstract. We don't add key points for this paper.

Adhatoda vasica, an herbal bronchodilator used for treating respiratory ailments, requires accurate nutrient profiling to support health benefits. In this work, the optical emission spectra from laser-generated plasma of Adhatoda vasica leaves confirmed the presence of Ca, K, Mg, Na, Fe, Al, Si, Sr, Zn, Rb, and Mn. The application of an external electric field across the laser-produced plasma not only significantly enhanced the intensities of the detected lines but also resulted in the appearance of additional lines of trace elements with a good signal-to-noise ratio. To improve the accuracy of elemental quantification in the sample, an integrated approach was employed by coupling the multi-element Saha-Boltzmann plot (ME-SBP) with calibration-free laser-induced breakdown spectroscopy (CF-LIBS). The key aspect of this approach is that the electron temperature calculated from the ME-SBP method can be effectively used for slope fixation of the Boltzmann plot in CF-LIBS, ensuring correct intercept estimation. The intercept is highly sensitive to the slope of the Boltzmann plot, as even minor changes in the spectral intensity can alter the slope, causing a shift in the intercept. This shift can result in temperature error and inaccuracy in the calculation of elemental composition. Incorporating ME-SBP, which involves multi-element correction terms and also reduces the reliance on intensity error, resulted in a more reliable determination of the electron temperature with a mean relative error of 3% and improved R2 of 0.992, leading to a more precise elemental quantitative analysis.