title: [Near infrared determination of the content of caffeine in tea polyphenol].
abstract: In the present paper the caffeine in the tea polyphenol was analysed spectrally and quantitatively by using near infrared spectroscopy. From the original absorbance of caffeine in the tea polyphenol an obvious and strong peak can be viewed. By using second derivative, MSC (multiple scatter correction) and correlation analysis the spectral characteristics of caffeine in the near infrared region can be seen very clearly, thus the robust calibration model can be set up easily. The result obtained shows that through this technique the absorptive characteristic of those primary fundamentals of caffeine can be looked through easily, meanwhile, calibration test was performed to quantitatively measure the weight percent of caffeine in the tea polyphenol, and fine precision of the result was obtained in a comparatively very large range of concentration. The SEC(standard error of calibration) is 0.49%, and the correlation coefficient r is 0.993. The result shows that NIR is feasible and superior in analyzing the content of caffeine in tea polyphenol.
authors.affiliation: State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130022, China.
authors.forename: Yong-jun
authors.initials: YJ
authors.lastname: Lu
authors.forename: Hua-cai
authors.initials: HC
authors.lastname: Chen
authors.forename: Jin
authors.initials: J
authors.lastname: Lü
authors.forename: Xing-dan
authors.initials: XD
authors.lastname: Chen
mesh_terms: D002110:Caffeine / Q000032:analysis* / Q000737:chemistry / Q000592:standards; D005240:Feasibility Studies; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry; D015394:Molecular Structure; D010636:Phenols / Q000032:analysis* / Q000737:chemistry; D059808:Polyphenols; D012015:Reference Standards; D015203:Reproducibility of Results; D019265:Spectroscopy, Near-Infrared; D013662:Tea / Q000737:chemistry*
chemical_list: D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D013662:Tea; D002110:Caffeine