Direct derivation of the crystalline fraction of highly potent active pharmaceutical ingredients by X-ray powder diffraction

Direct derivation (DD) is a novel Powder X-ray diffraction quantification method based on intensity–composition equation, which can determine the weight fraction of individual phases in a mixture of components by chemical formulas . The DD method was applied to determine crystallinity degree of binary mixtures containing amorphous hydroxypropyl methylcellulose and crystalline monohydrate α-lactose in weight percentage ≤ 15% w/w. Three different scenarios were considered: a) the unit cell parameters of the crystalline phases are available b) the unit cell parameters are unknown but the patterns of pure crystalline and amorphous references are available and c) only the mixtures’ patterns are available. Relative errors in scenarios a and b were comparable and reasonable (