The Spectral Emission Characteristics of Laser Induced Plasma on Tea Samples

Abstract

Laser induced breakdown spectroscopy (LIBS) provides a useful technique for food security as well as determining nutrition contents. In this paper, optical emission studies of laser induced plasma on commercial tea samples were carried out. The spectral intensities of Mg, Mn, Ca, Al, C and CN vibration bands varying with laser energy and the detection delay time of an intensified charge coupled device were studied. In addition, the relative concentrations of six microelements, i.e., Mg, Mn, Ca, Al, Na and K, were analyzed semi-quantitatively as well as H, for four kinds of tea samples. Moreover, the plasma parameters were explored, including electron temperature and electron number density. The electron temperature and electron number density were around 11000 K and 10 17 cm −3 , respectively. The results show that it is reasonable to consider the LIBS technique as a new method for analyzing the compositions of tea leaf samples.

Automatic determination of optimal spectral peaks for classification of Chinese tea leaves using laser-induced breakdown spectroscopy

“…These tea leaves are popular and widely consumed in China. The physical properties of each sample, such as dryness, lapping uniformity, and density, have a great impact on spectral signal [16] . The samples were pretreated to improve the accuracy and stability of the results.…”

Classification of Chinese tea leaves using laser-induced breakdown spectroscopy combined with the discriminant analysis method

“…According to previous experimental experience, the physical proprieties of the samples, such as the dryness, lapping uniformity and density, have a great impact on the spectral signal. 17 To greatly reduce the inuence on the results, some necessary pretreatment of the tea leave samples need to be carried out before the determination step. At the outset, these six types of tea leaves were dried using an electric air blowing drying box for ve hours at 80 C and then ground using an agate mortar for one hour to obtain a uniform and ne powder.…”

Study on the spectra of Tieguanyin tea and ash by laser-induced breakdown spectroscopy

“…Wang et al [14] compared the effect for quantitative analysis of Pb in Pu 'er tea by external standard method, internal standard method, and multiple linear regression method and obtained the limit of detection of Pb as 47.2 ppm. Zheng et al [15] used LIBS technology to analyze the spectra of four different tea samples and carried out semi-quantitative analysis of the relative concentrations of six elements, including Mg, Mn, Ca, Al, Na, and K. At present, the application of LIBS technology in the identification and classification of elements in tea has been studied, but studies on LIBS spectra of tea ash have not been reported. In addition, more attention was paid to the total ash, water-soluble ash, acid-soluble ash, etc.…”