Chet Raj Bhatt

Iron measurement in water is important to ensure its quality. Although iron is essential for good health, when its level in water exceeds the permitted limit, it can cause health- and environmental-related issues. In this study, a spectroscopic methodology based on laser-induced breakdown spectroscopy (LIBS) has been developed for in-situ detection and quantification of iron in water. Wastewater from the foundation of a historic building at the National Energy Technology Laboratory (NETL) Morgantown site was collected for ten continual days and analyzed with the LIBS benchtop system and NETL’s LIBS probe. Spectral signatures of iron in the LIBS spectra were identified which demonstrated the significant presence of iron in the test samples. Machine learning tools, principal component analysis (PCA) and linear discriminant analysis (LDA), were used to distinguish the ten liquid samples. For quantitative study, univariate and multivariate analyses were performed. While two strong emission lines of iron, Fe I 371.9 nm and Fe I 373nm, were used to develop the calibration curve for univariate analysis, whole spectra in the selected wavelength range were utilized to plot the partial least square regression (PLS-R) curve. These calibration curves were then used to estimate the iron content in water samples, and the estimated values were compared to inductively coupled plasma-mass spectrometry (ICP-MS) measurements. The relative difference was found to be less than 15%, which shows that the iron content in liquid can be reliably detected and quantified by the LIBS-based spectroscopic technique.

Laser-induced breakdown spectroscopy (LIBS) was used to detect rare earth elements (REEs) in natural geological samples. Low and high intensity emission lines of Ce, La, Nd, Y, Pr, Sm, Eu, Gd, and Dy were identified in the spectra recorded from the samples to claim the presence of these REEs. Multivariate analysis was executed by developing partial least squares regression (PLS-R) models for the quantification of Ce, La, and Nd. Analysis of unknown samples indicated that the prediction results of these samples were found comparable to those obtained by inductively coupled plasma mass spectrometry analysis. Data support that LIBS has potential to quantify REEs in geological minerals/ores.

In this study, the laser-induced breakdown spectroscopy (LIBS) technique was used to identify and compare the presence of major nutrient elements in organic and conventional vegetables. Different parts of cauliflowers and broccolis were used as working samples. Laser-induced breakdown spectra from these samples were acquired at optimum values of laser energy, gate delay, and gate width. Both univariate and multivariate analyses were performed for the comparison of these organic and conventional vegetable flowers. Principal component analysis (PCA) was taken into account for multivariate analysis while for univariate analysis, the intensity of selected atomic lines of different elements and their intensity ratio with some reference lines of organic cauliflower and broccoli samples were compared with those of conventional ones. In addition, different parts of the cauliflower and broccoli were compared in terms of intensity and intensity ratio of elemental lines.