An efficient approach of Laser Induced Breakdown Spectroscopy (LIBS) and ICAP-AES to detect the elemental profile of Ocimum L. species

The present study is aimed to investigate the micro- and macro-element distribution in the leaves of four Ocimum species viz. Ocimum basilicum, Ocimum sanctum, Ocimum gratissimum and Ocimum americanum. For this, Laser Induced Breakdown Spectroscopy (LIBS) and Inductively Coupled Argon Plasma Atomic Emission Spectroscopy (ICAP-AES) were used. LIBS spectra of different Ocimum leaves (in the form of pellets) were recorded in the spectral range of 200–900 nm, which shows the atomic lines of potassium (K), sodium (Na), calcium (Ca), magnesium (Mg) and silicon (Si) along with lighter elements like carbon (C), hydrogen (H), oxygen (O) and nitrogen (N). Similarly, ICAP-AES also confirmed the presence of above mentioned elements as well as their patterns (except the lighter elements due to its identification limits). Results of both the techniques clearly revealed that Ca is the most abundant element in all the species followed by K, Mg and Na. Results further suggested that O. sanctum is a highly mineral rich species followed by the O. basilicum, O. gratissimum and O. americanum. Principal component analysis (PCA) was also used on data set of LIBS spectra of Ocimum species which revealed PC1 (72%) and PC2 (26%) data matrix explaining 100% variance in the data set. The PCA plots clearly classified the cultivated and wild species and separated them in the two clusters. Conclusively, the present work demonstrated the suitability of LIBS technique due to its rapid, nondestructive and eco-friendly approach and gives the comparative account of mineral availability in Ocimum spp.