Quantification of low levels of amorphous content in sucrose by hyperDSC

Abstract

A method was developed for the quantification of low levels of amorphous content in sucrose with hyperDSC. The method was based on the fact that the change of specific heat at the glass transition is linearly proportional to the amorphous content. It was found out that as annealing time increased, the glass transition temperature moved to a higher temperature and the change of specific heat increased. Δ C p for annealed totally amorphous sucrose was 0.761 ± 0.012 J g −1 °C −1. Synthetic mixtures with various proportions of crystalline and amorphous sucrose were prepared. The following linear regression between Δ C p and amorphous content was obtained: Δ C p = 0.0075 x − 0.00484 ( R = 0.999). The limit of detection (LOD) and the limit of quantification (LOQ) values were 0.062 and 0.207%, respectively. The effect of grinding time on the amorphous content of crystalline sucrose was studied and a correlation between grinding time and amorphous content of sucrose was found. It was also found that the amorphous content could only attain a value of about 80–90% by grinding in the way used in this study.