A new approach to determine the homogeneity in hyperspectral imaging considering the particle size.

Determining homogeneity of a mixture using hyperspectral-imaging (HSI) techniques is at this moment an interesting research subject in pharmaceutical industry. A new methodology based in the macropixel analysis technique for the homogeneity assessment in powder blend mixtures has been developed. The appropriate selection of the macropixel size for evaluation of the homogeneity is a topic under discussion. We propose that the macropixel size selection would be based in a statistical criterion called "representative sample size" criterion. Moreover, it has been demonstrated that the macropixel size should be a function of the particle size and, thus, the particle size has been included in the formula to calculate the macropixel size. The proposed equations allow to accurately calculate the homogeneity index (H% Poole). By means of using simulated chemical images, a relationship between the H% Poole index and the controlled homogeneity was established. The method has been applied to determine the homogeneity of binary and ternary powder blends mixtures of different pharmaceuticals discriminating between homogeneous and non-homogeneous samples.