Considered as being one of the building blocks of the purification schemes used in industrial applications, melt crystallization is an accurate, energy saving, and a reproducible approach to the purification of materials. The separation between two mixed materials, lutrol and ibuprofen, is achievable here through tightly optimizing the highly versatile crystallization conditions. The so called, phase separation, is the end result of a melt crystallization process and its applicability on the molten drop scale is further discussed in detail. Analysis in the form of light microscopy and ultra-violet spectrometry are also introduced to quantify the final phase separation in the drops and to compare the results. The advantage of using lutrol seeding to control the separation within the molten drops is demonstrated through producing successful phase separation at the drop scale. Together with changing the cooling temperatures, seeding is also proven a successful method to produce a better phase separation and hence lower levels of impurities in the outer layer. Crystallizing the molten drops on lutrol or starch coated surfaces also enhances the quality of the phase separation by a different method, but significantly since it alters the final solidified drops geometry along with changing the cooling conditions. Finding an explanation to the different separation qualities founded on a theoretical basis for a full understanding of the process and giving the basis of a possible future optimization. (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B. V. and The Society of Powder Technology Japan. All rights reserved.