Study on the paper substrate room temperature phosphorescence of theobromine, caffeine and theophylline and analytical application

Analytical methods applied for the characterization and the determination of bioactive compounds in coffee

“…Other methods used for the determination of caffeine in coffee include UV spectrometry [54,64,65], voltammetry [44,66], gravimetric analysis [54] and paper substrate phosphorescence [67]. As direct measurement of caffeine UV absorbance in water extract of coffee is impossible because of high matrix effects, Balay et al [64] proposed usage of dichloromethane for its extraction before UV measurement.…”

“…However, the method was not selective, as each of the three methylxanthines had analytical signal at the same region of wavelengths. Therefore, caffeine was determined as main constituent in coffee and tea, theobromine in chocolate and theophylline in tablets containing this active pharmaceutical ingredient [67].…”

Methylxanthines for halogen bonded cocrystals with 1,4-diiodotetrafluorobenzene: green synthesis, structure, photophysics and DFT studies

“…17 In the particular case of cocrystals, progressive advances have been reported following the preparation of halogen bonded cocrystals. [18][19][20][21][22][23][24][25][26] Concerning the PL properties of methylxanthines, little information has been found in the literature; while some references to phosphorescence in solution have been reported in the past, [27][28][29][30][31][32][33][34] solid state studies are very scarce 34 and specific for caffeine or theobromine derivatives. 35,36 On the other hand, the use of DITFB as a coformer in combination with fluorescent organic compounds or aromatic model systems has afforded new cocrystals with luminescence features (fluorescence and phosphorescence) in the solid state.…”