Diffusion ordered NMR spectroscopy measurements as screening method of potential reactions of API and excipients in drug formulations.

•Screening mixtures based on diffusion coefficient offers the possibility to verify and separate the containing substances.•Differentiation of signals within in a DOSY spectrum can be done despite of overlapping or much smaller signals next to larger ones.•Potential of different processing methods in analyzing DOSY spectra: detection of hidden signals by fragmented examination of signals.