Polymorphic behaviour of chloroquine diphosphate

Abstract

The crystalline structure of two different batches of chloroquine diphosphate was studied. Differential thermal analysis showed the existence of two polymorphic modifications in one of the batches, whilst spectral analysis did not reveal any differences. This discrepancy is attributed to the fact that the second modification is formed during the transition phase when analysed by differential thermal analysis. This recrystallization process is initiated by the presence of seed material. The ratio of transition heat of both modifications is dependent on particle size and heating rate during analysis.