title: Thermal stability of vitamin C: thermogravimetric analysis and use of total ion monitoring chromatograms.
abstract: The thermal decomposition kinetics and shelf life of vitamin C in nitrogen or air were studied by using thermogravimetric analysis (TGA) and evolved-gas analysis-lithium-ion attachment mass spectrometry (EGA-Li⁺IAMS). Arrhenius parameters obtained via TGA were reported for thermal decomposition. For vitamin C in a nitrogen atmosphere, the activation energy (E(a)) was 25.1 kcal/mol and the pre-exponential factor (A) was 2.5 × 10¹¹ min⁻¹. The kinetic parameters estimated via TGA agreed with values estimated from a pyrogram when the weight loss observed by TGA was shown to be due to gas evolution as a result of decomposition of the compound. Thermal stability was expressed by calculating the time for 10% of the vitamin C to decompose at 25 °C (t(90%,25 °C)). The t(90%,25 °C) for vitamin C obtained via TGA or EGA-Li⁺IAMS was higher in nitrogen (2.0 and 2.0 years, respectively) than in air (1.3 and 1.6 years, respectively). This indicates that the type of atmosphere influences vitamin C stability.
authors.affiliation: Department of Chemistry, Faculty of Sciences and Engineering, Meisei University, Hodokubo 2-1-1, Hino, Tokyo 191-8506, Japan.
authors.forename: Márta
authors.initials: M
authors.lastname: Juhász
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kitahara
authors.forename: Seiji
authors.initials: S
authors.lastname: Takahashi
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Fujii
mesh_terms: D001205:Ascorbic Acid / Q000032:analysis* / Q000592:standards; D004355:Drug Stability; D004356:Drug Storage; D006358:Hot Temperature; D007700:Kinetics; D013058:Mass Spectrometry / Q000379:methods*; D013818:Thermogravimetry
chemical_list: D001205:Ascorbic Acid