Analysis of total phenolic compounds and caffeine in teas using variable selection approach with two-dimensional fluorescence and infrared spectroscopy

Recent Developments in Plasmonic Sensors of Phenol and Its Derivatives

“…As a normal type of optical sensor, fluorescence techniques have been extensively applied in many fields, such as fast detection of phenolic substances [22], bioimaging [74], detection of aniline [75], determination of peroxynitrite products [76], analysis of total phenolic substances in teas [21], quantification of bisphenol A and its derivatives [77], determination of phenolics [78], and aptamer-labeled fluorescent detection of bisphenol A [79]. Plasmonic resonance-based fluorescence method has been used predominantly, because of its excellent plasmonic resonance mechanism.…”

“…Recently, various optical sensor techniques have been developed, such as colorimetric [19,20], fluorescence [21,22], LSPR phenomenon [23,24], and plasmon-enhanced surface enhanced Raman scattering (SERS) [25][26][27]. Among these techniques, the SERS method based on plasmonic resonance nanomaterials is promising because of its high specific, selective, and sensitive detection capability.…”

A disposable electrochemical caffeine sensor based on a screen-printed electrode modified with a copper-metal organic framework and functionalized multi-walled carbon nanotube nanocomposite

“…The current methods of CAF analysis, such as fluorescence, 5 UV spectrophotometry, 6 and high-performance liquid chromatography, 7 present limitations that include difficult procedures, expensive machinery, prolonged analysis times, and low sensitivity. Less complicated electrochemical methods are gaining favor over more traditional techniques because of their simplicity, rapidity, sensitivity and selectivity.…”

First ATR-FTIR Characterization of Black, Green and White Teas (Camellia sinensis) from European Tea Gardens: A PCA Analysis to Differentiate Leaves from the In-Cup Infusion

“…Several studies have reported the ability of near infrared (NIR) spectroscopy which works in the spectral range 13000–4000 cm −1 , to predict, with the help of multivariate calibration methods, the presence of different bioactive compounds in tea such as catechins, caffeine, free amino acids and theaflavins [ 10 , 11 , 12 , 13 , 14 , 15 ]; this technique has been also used to discriminate different tea varieties, also in relation with the geographical origins, and to identify tea grades and tea processing degree [ 10 , 16 , 17 , 18 ]. Conversely, to the best of our knowledge, only a few studies can be found in the literature regarding the use of FTIR spectroscopy in the MIR region (spectral range 4000–400 cm −1 ) to investigate tea leaves and tea brews and to highlight differences due to processing, cultivation site and extraction methods [ 4 , 16 , 18 , 19 , 20 , 21 , 22 ]. One advantage of FT-MIR spectroscopy is its ability to provide with one single acquisition the real chemical fingerprint of the analysed material, since it is very sensitive to the chemical composition of the sample as it contains the fundamental vibrations of almost all the functional groups [ 23 ].…”