Ashok Kumar Pathak

Assessment of LIBS for Spectrochemical Analysis: A Review

Abstract This review assesses the applications of laser-induced breakdown spectroscopy (LIBS) for the analysis of a variety of samples, including biomaterials (teeth, nail, hair, gallstones, and kidney stones, etc.), food materials (fruits and vegetables, milk, salt, nutritional supplements, etc.), medicinal plants, industrial waste, liquid samples, etc. In addition, for the first time the identification of cholesterol and pigment stones was performed on the basis of atomic lines of different elements and molecular bands of C2 molecules present in the LIBS spectra of gallstones. Chemometric techniques such as principal component analysis (PCA) was also applied to LIBS data for rapid identification/classification of different gallstone samples. LIBS analysis of toxic/heavy elements present in vegetables (spinach, tomato) and rice is also presented in this review. It was observed that vegetables grown near industrial areas are rich in several toxic metals like Pb and Cr. The wastewater samples from different industries were also analyzed by recording their spectra using a liquid jet. These results clearly demonstrate the ability of LIBS technique as an instant monitoring device to detect heavy metals present in liquid samples. Finally, this review shows that LIBS is a versatile analytical technique with unlimited applications.

Laser-Induced Breakdown Spectroscopy: An Approach to Detect Adulteration in Turmeric

ABSTRACT In the present paper, four turmeric samples, A, B, C, and D, were analyzed using the laser-induced breakdown spectroscopic (LIBS) technique. Laser-induced breakdown spectra of A, B, and C give the spectral lines of elements such as carbon, sodium, potassium, magnesium, calcium, iron, and molecular bands of CN, whereas spectral signatures of the toxic elements lead and chromium are also present in sample D, demonstrating the adulteration in it. Principal component analysis of the LIBS data of the turmeric samples has been used for instant discrimination. The plots and principal components provide clusters belonging to two groups, enabling laser-induced breakdown spectroscopic data along with principal component analysis to be used as an instant monitoring tool.

Effect of Analyte Concentration on the Laser-Induced Plasma Temperature and Electron Density in Liquid Matrix

ABSTRACT In the present work, we report spectroscopic studies of laser-induced plasmas produced by focusing the second harmonic (532 nm) of a Nd:YAG laser onto the laminar flow of a liquid containing chromium. The plasma temperature is determined from the coupled Saha–Boltzmann plot and the electron density is evaluated from the Stark broadening of an ionic line of chromium [Cr(II)] at 267.7 nm. Our results reveal a decrease in plasma temperature with an increase in Cr concentration up to a certain concentration level; after that, it becomes approximately constant, while the electron density increases with an increase in analyte (Cr) concentration in liquid matrix.

An Approach of Laser-Induced Breakdown Spectroscopy to Detect Toxic Metals in Crushed Ice Ball

This paper deals the application of laser-induced breakdown spectroscopy (LIBS) to toxic metals used as pigment in crushed ice-ball samples. The present work highlights the advantages of LIBS as in situ, real-time analytical tool for rapid detection of toxic or heavy metals like lead (Pb) and chromium (Cr) and non toxic elements like carbon (C), nitrogen (N), magnesium (Mg), calcium (Ca), sodium (Na), and potassium (K) in crushed ice-ball of different colors (red, green, yellow, pale yellow, and orange) collected from five different areas, with minimal sample preparation. For rapid surveillance of toxic metals we have used multivariate analysis, that is, principal component analysis (PCA) with the LIBS spectral data of ice-ball samples. This study suggests that LIBS coupled with PCA may be an instant diagnostic tool for identification and classification of adulterated and nonadulterated samples.