Evaluation of laser-induced breakdown spectroscopy for nutritional and trace elemental mapping in Otostegia limbata...

Medicinal plants have been an essential source of indigenous medicines and continue to play a vital role in pharmaceutical industries. Comprehensive knowledge of their elemental composition is crucial, as these elements significantly influence metabolic and physiological processes. The current investigation focuses on the compositional analysis of the Otostegia limbata (OL-MP), a medicinal plant, using the fast and efficient Laser-Induced Breakdown Spectroscopy (LIBS) technique. Four major parts of the plant, root, bark, leaves, and flowers, along with surrounding soil samples, were analyzed. Twelve elements, including Ca, Mg, Al, K, Sr, Ba, Fe, Ti, Cr, Mn, Li, and Na, were detected with varying concentrations across the samples. Plasma temperature and electron number density were estimated using the Boltzmann plot method and Stark broadening parameter, yielding values of approximately (10,000 ± 1000 K) and (1.31 ± 1.00 × 10¹⁷ cm^-3), respectively. Compositional analysis was conducted using Calibration-Free LIBS (CF-LIBS), which revealed high concentrations of silicon (22.8 %) and calcium (13.5 %) in the soil. In plant tissues, calcium was predominant, with roots containing 34.7 % calcium and 18.5 % iron; bark exhibiting elevated calcium (24.11 %), potassium (19.38 %), and iron (16.38 %); leaves rich in calcium (30.6 %) and barium (20.3 %); and flowers showing the highest calcium content at 34.9 %, highlighting its key role in reproductive structures. The accuracy of the proposed method was comparable to that of advanced laboratory equipment, with detected elemental concentrations found to be below toxic thresholds. This comprehensive, non-destructive analytical approach demonstrates potential for direct toxicity monitoring and quality assurance in homeopathic and pharmaceutical applications.