Tartrazine: physical, thermal and biophysical properties of the most widely employed synthetic yellow food-colouring azo dye

• Published in: Journal of thermal analysis and calorimetry Vol. 134; no. 1; pp. 209 - 231
• Main Authors: Leulescu, Marian, Rotaru, Andrei, Pălărie, Ion, Moanţă, Anca, Cioateră, Nicoleta, Popescu, Mariana, Morîntale, Emilian, Bubulică, Maria Viorica, Florian, Gabriel, Hărăbor, Ana, Rotaru, Petre
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.10.2018; Springer; Springer Nature B.V
• Subjects: Analysis; Analytical Chemistry; Antioxidants; Azo compounds; Biological activity; Chemical bonds; Chemistry; Chemistry and Materials Science; Coloring; Crystals; Diffraction; Dyes; Electron transitions; Fluorescence; Food; Gallic acid; Identification methods; Inorganic Chemistry; Measurement Science and Instrumentation; Optical properties; Organic chemistry; Physical Chemistry; Phytotoxicity; Polymer Sciences; Proteins; Pyrazole; Refractivity; Scanning electron microscopy; Stability analysis; Structure; Thermal analysis; Thermal stability; Wheat; X-ray diffraction; X-rays; Biophysical activity; Tartrazine; Physical properties; Azo dye; Thermal stability; Yellow food-colouring
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-018-7663-3

The food-colouring dye tartrazine is a significant additive and in the same time a biologically active material. Thermal behaviour of trisodium (4E)-5-oxo-1-(4-sulphonatophenyl)-4-[(4-sulphonatophenyl)hydrazono]-3-pyrazole carboxylate, tartrazine or E102 as it is also known, was studied in relation with the physical, chemical, thermal and biophysical (interaction with proteins, antioxidant and phytotoxicity) properties. Tartrazine structure and microstructure have been determined by X-ray diffraction and scanning electron microscopy investigations. Tartrazine has a monoclinic crystalline structure (space group C 2/ c ). Electronic transitions and atomic bonds behaviour in molecules and fluorescent excitation of the compound have been identified by spectroscopic methods: Fourier-transformed infrared, UV–Vis, atomic fluorescence and Raman spectroscopies. Tartrazine absorbs in the visible region at 436.36 nm and shows laser fluorescence of all its elements. Chemical (acidity) and optical properties (refractive index and electric susceptibility) were determined for different concentrations on a sensitive range of temperatures. Thermal analysis measurements of tartrazine revealed thermal stability until 200 °C in air, while in the inert environment (argon) the stability is increased to 300 °C. Biological and biophysical activities and properties of tartrazine have been evidenced through its interaction with animal proteins, comparison with the standard gallic acid and phytotoxicity towards wheat strains/roots, when several concentrations of tartrazine solutions were used. Tartrazine has moderate biological activity when interacting with proteins, obtained antioxidant activity above a threshold concentration of 0.25% and presents plant growth phytotoxicity.