The result of the reference method (26.67%) was satisfactorily obtained in the rapid mode at 95–110°C and also at 105°C and 110°C in the gentle and the standard modes. The determination time decreases with higher temperature and from the gentle to the rapid mode. During the drying process a crust is formed at the surface of the sample which might prevent included water from evaporation, whereas, on the other hand, decomposition reactions with formation of volatile matter might have taken place. To obtain the result of the reference method, these two errors must compensate each other. This effect seems to be achieved for this product in the rapid programme.
In a further experiment the sample mass was increased from 1 g to 2 and 4 g at 105°C using the same programmes. The results are shown in Table 2.