Quality Evaluation of Oils and Fats by the Thermogravimetry. VI.

Discriminatory and qualitative evaluation of natural waxes was made by thermogravimetry (TG) under a stream of air. A simple method for detecting paraffin wax adulterated in other waxes was also devised by the same means.1) The pattern of weight reduction on the TG curve differed according to the kind of natural wax. Weight reduction in waxes was initiated at 179°C and the lowest for Japan wax, and highest for carnauba wax at 252°C. The rate of weight reduction from the initial temperature to 300°C was highest for candelilla wax and bees wax of more than 20%. The rate of weight reduction from 300 to 350°C was highest for carnauba wax and bees wax, and the rate from 350450°C was higher for rice bran wax and Japan wax.2) According to TG analysis of components fractionated from the waxes by silica gel column chromatography, each component showed characteristic pyrolysis behavior. However, little difference was observed in the behavior of the same components from different waxes. This indicates that the pattern of weight reduction on TG curve of natural wax is dependent on composition and component content.3) The initial temperature of weight reduction on TG curve was closely correlated to the melting point for natural wax.4) Paraffin waxes adulterated to natural wax could be detected by the initial temperature of weight reduction on the TG curve when present at more than 5% in those with lower melting point and 20% in those with higher melting point. Paraffin wax with lower melting point could be also detected by the rate of weight reduction from the initial temperature to 300°C.