Spectral analysis of mint (pudina) using laser-induced breakdown spectroscopy and inductively coupled plasma/atomic emission spectroscopy

In the current study, pulsed Nd:YAG laser-induced breakdown spectroscopy (LIBS) was successfully applied, at 532 nm with a suitable detector, for the spectral analysis of mint (domestic mint and wild mint) available in Pakistan. From the spectral emissions of the mint plasmas recorded with the spectrometer (LIBS2000+, Ocean Optics, Inc.), 17 elements were identified in the domestic mint whereas the wild mint was observed to have 18 different elements, comprising both nutritional elements and toxic metals. Prior to recording the spectral emissions, the sensitivity of our LIBS detection was enhanced by optimizing various LIBS parameters. Under ambient environments, a laser pulse irradiance of about 2.0 × 1011 W cm−2 was employed for the generation of the plasmas on the surfaces of the target samples. The quantitative analyses were performed via calibration curves drawn for all the elements through standard samples prepared in a known concentration in the mint matrix, as well as by a weight percentage method under the assumptions of local thermodynamic equilibrium and optically thin plasma. The electron temperature and number density were determined through the Boltzmann plot method and stark broadened line profile method, respectively, using Ca-I spectral lines. Furthermore, to verify the precision of our LIBS findings, the abundance of each element in the mint samples was also estimated by means of a standard analytical tool, such as inductively coupled plasma/atomic emission spectroscopy (ICP/AES). The outcomes of the LIBS system were found to be in good agreement with the results of ICP/AES statistically, which guarantees that the method is reliable in the illustration and detection of both nutritional and toxic chemical differences in the mint samples, and is hence a step forward in securing human health through environmental and agricultural development.