Quantitative visualization of photosynthetic pigments in tea leaves based on Raman spectroscopy and calibration model transfer

Abstract

Background: Photosynthetic pigments participating in the absorption, transformation and transfer of light energy play a very important role in plant growth. While, the spatial distribution of foliar pigments is an important indicator of environmental stress, such as pests, diseases and heavy metal stress. Results: In this paper, in situ quantitative visualization of chlorophyll and carotenoid was realized by combining the Raman spectroscopy with calibration model transfer, and a laboratory Raman spectral model was successfully extended to a portable field spectral measurement. Firstly, a nondestructive and fast model for determination of chlorophyll and carotenoid in tea leaf was established based on confocal micro-Raman spectrometer in the laboratory. Then the spectral model was extended to a real-time foliar map scanning spectra of a field portable Raman spectrometer through calibration model transfer, and the spectral variation between the confocal micro-Raman spectrometer in the laboratory and the portable Raman spectrometer were effectively corrected by the direct standardization (DS) algorithm. The portable map scanning Raman spectra of the tea leaves after the model transfer were got into the established quantitative determination model to predict the concentration of photosynthetic pigments at each pixel of the tea leaves. The predicted photosynthetic pigments concentration of each pixel was imaged to illustrate the distribution map of foliar pigments. Statistical analysis showed that the predicted pigment contents were highly correlated with the real contents. Conclusions: It can be concluded that the Raman spectroscopy was applicable for in situ, non-destructive and rapid quantitative detecting and imaging of photosynthetic pigment concentration in tea leaves, and the spectral detection model established based on the laboratory Raman spectrometer can be applied to a portable field spectrometer for quantitatively imaging of the foliar pigments.

Fast quantification of diclofenac sodium content in commercially available tablets by transmission Raman spectroscopy with PLS

“…The established model is successfully applied to the API content determination of handmade tablets, but in order to apply the model to the quality control of DS in the production line, it is necessary to transform the model to be applicable to the determination of API in commercially available tablets. 35,36 The established model was used to predict the API content of three commercially available DS tablets (three tablets for each brand, nine pieces in total). The commercially available tablets used in the experiment were randomly selected, and they came from different manufacturers, which may have different excipients and proportions.…”

Application of SWSRA-DS Algorithm in Improving the Model Transfer for Near Infrared Analysis of Pulpwood Holocellulose

“…Among the currently proposed model transfer algorithms, they can be divided into two categories: with and without standardization [9]. Among them, the model transfer algorithms with standard samples include Slope/Bias (S/B) [10], Direct Standardization (DS) [11], and Piecewise Direct Standardization (PDS) [12]. The common model transfer methods without standard samples include wavelet transform (WT) [13], orthogonal signal correction (OSC), and linear model correction [14].…”