The aim of this work was to investigate the influence of different levels of microwave irradiation on the structure and particle
size characteristics of α-lactose monohydrate. The structural study of the samples was carried out by XRD, the presence of
lactose polymorphs in the test samples was determined by DSC and the particle size distribution was measured by laser diffraction.
The samples subjected to microwave irradiation retained their original X-ray patterns. No significant differences in thermal
transition characteristics and particle size were observed. Hence, neither the occurrence of crystalline-amorphous transition
resulted by microwave irradiation nor the presence of lactose polymorphs in the test samples can be assumed. The unmodified
properties can be attributed to the fact that the water of crystallization is very difficult to remove from the crystal structure
and is not free to move during microwave treatment, which results in stability to microwaves.
Our results allow the conclusion that microwave processing of α-lactose monohydrate has no influence on further pharmaceutical
technological properties, which are related to the structure and the particle size distribution of this substance.