Study of the Thermal Stability Properties of Pyridoxine Using Thermogravimetric Analysis

• Published in: Analytical Letters Vol. 45; no. 11; pp. 1519 - 1525
• Main Authors: Juhász, Márta, Kitahara, Yuki, Takahashi, Seiji, Fujii, Toshihiro
• Format: Journal Article
• Language: English; Japanese
• Published: Philadelphia, PA Taylor & Francis Group 15.07.2012; Informa UK Limited; Taylor & Francis
• Subjects: Analytical chemistry; Atmosphere; Chemical and thermal methods; Chemistry; Decomposition kinetics; Exact sciences and technology; Ozawa method; Pyridoxine; Shelf life; TGA; Data analysis; Oxygen; Decomposition kinetics; Thermal decomposition; Thermogravimetry; Kinetic method; Pyridoxine; Time; Shelf life; Air; Nitrogen; Thermal stability; TGA; Ozawa method; Atmosphere; Chemical decomposition; Thermal analysis; Kinetics; Activation energy
• ISSN: 0003-2719; 1532-236X
• DOI: 10.1080/00032719.2012.675491

The thermal decomposition behavior and kinetics of pyridoxine in nitrogen-only and air atmospheres were studied using thermogravimetry analysis (TGA). Kinetic interpretation of thermal analysis data for pyridoxine decomposition was carried out using Ozawa and ASTM E698 isoconversional methods. The activation energy of the decomposition process varied with the degree of decomposition and was different in the nitrogen and air atmospheres. At a 5% decomposition level, the activation energy and the pre-exponential factor were found to be 28.3 kcal mol −1 and 1.2 × 10 14  min −1 , respectively, in the nitrogen-only atmosphere. Thermal stability was determined by calculating the time for 5% of the pyridoxine vitamer to decompose at 25°C. The calculated shelf life for the pyridoxine vitamer obtained via TGA was surprisingly smaller in nitrogen (0.9 years) than in air (1.5 years). This is speculated to be the result of a more complex decomposition mechanism in air, involving thermo-oxidative decomposition in the presence of oxygen.