The new crystal form was however not stable. By PXRD data collected over 10 days, we found that a series of phase transformation events had occurred. The final phase-stable spherulite is a mixture of the new GSF crystal form and a few other GSF polymorphs, as some peaks in the PXRD pattern (at 10, 15 and 23 2θ, in particular) related strongly to peaks of GSF Form I (Figure and). To gain a more accurate understanding of the phases present in the GSF/PEG melt crystallisation product, we applied the high-throughput 3D ED method.