Determination of Micronutrients and Toxic Elements in Moringa Oleifera Leaves by Calibration Free Laser-Induced Breakdown Spectroscopy (LIBS)

Abstract

The Moringa oleifera tree, including the leaves, flowers, pods, and seeds, is highly nutritious and useful for the prevention and control of various diseases. Here we have probed the micronutrients in Moringa oleifera leaves using laser-induced breakdown spectroscopy (LIBS). The time-resolved and time-integrated LIBS data reveal the presence of Ca, Mg, K, C, Si, Fe, Al, Ti, Sr, Na, H, O, and Li. The plasma temperature and electron number density required for the elemental composition analysis were estimated to be (6375 ± 500) K from the Saha-Boltzmann plot and (1.0 ± 0.2) $\times$ 10¹⁷ cm⁻³ from the Stark broadened H_α line, respectively. Elemental analysis of the samples was performed using one-line calibration free LIBS (CF-LIBS). The results reveal that C is the major element together with Ca, Mg, K, Fe Na, Al, Ti, Sr, and Li as micronutrients. The concentrations of the micronutrients determined by CF-LIBS were validated by inductively coupled plasma – optical emission spectrometry (ICP-OES). LIBS has been demonstrated to be a practical candidate for the detection of potentially toxic elements (Li, Al, Si, and Sr) as well as for the compositional analysis.

Keywords:

• Calibration-free laser-induced breakdown spectroscopy (CF-LIBS)
• inductively coupled plasma – optical emission spectrometry (ICP-OES)
• Moringa oleifera Leaves
• plasma parameters
• time-integrated and time-resolved laser-induced breakdown spectroscopy (LIBS)

Acknowledgments

MAB is thankful to MMMF, Jakarta, for facilitating the experimental work.

Additional information

Funding

We are thankful to the Pakistan Academy of Sciences (PAS) and the National Center for Physics for their financial support. Muliadi Ramli and Alion Mangasi Marpaung wish to express their sincerest thanks to the Indonesia Ministry of Research and Higher Education for financial support under contract number 109/UN11.1/PP/SP3/2019.