Investigation and Comparison of Nutritional Supplements (Elements and Compounds) in Various Tea Leaves using Spectroscopic Techniques

Abstract

Qualitative and quantitative analyses of nutritional supplements and adulteration/toxic elements present in various tea leaves have been performed and compared. Rapid identification of inorganic (i.e., Ca, K, Na, Mg, Ba, Al, Sr, Mn) and organic (C, N, O, H) elements have been done using laser-induced breakdown (LIB) spectra of tea leaves. The electronic bands of the metal oxides (CaO, BaO, SrO, and AlO) are also identified. Molecular bands of CN and C₂ molecules in the LIB spectra show the presence of organic compounds in the tea samples. The concentration of the constituents of the tea samples has been determined using the calibration free (CF-LIBS) technique and results are further compared with results obtained by energy-dispersive X-ray (EDX) technique. The toxicity of the various tea leaves has been discussed based on the contents of Ba, Al, and Sr in each sample. The quantitative analysis of Na, K, and Mg may be helpful to control hypertension and chronic kidney disease. Principal component analysis (PCA) classifies the different samples based on their elemental constituents. In all tea leaves samples, the presence of amino acids, enzymes, pigments, carbohydrates, caffeine and nicotine has been established via photoacoustic spectroscopy (PAS). Further, the confirmation of the molecular bands of the tea leaves is done with (Fourier Transform Infrared) FTIR spectroscopic technique.