Determination of solubilities of energetic materials

Five methods to analyse liquid samples regarding to the concentration were compared to determine the solubility curve of RDX in different solvents. Spectroscopy and density measurements provided nearly the same values for all investigated systems. Refractometry and the gravimetric analysis differed in some cases up to 20 % from the other methods. These differences can be explained by an evaporation of solvent during analysis (e.g. tetrahydrofuran) or on the other hand by difficulties during drying the samples due to solvent inclusions in the crystals (low vapour pressure of the solvent like propylene carbonate). The HPLC analysis needs a very high dilution of the samples (otherwise the detector is blind) which can lead to falsification of the results. In conclusion, the best way of measuring the solubility of these systems is the density measurement. Further experiments with other energetic materials will be carried out to prepare a data pool. With this pool crystallization processes can be designed and the quality of the product can be controlled and improved.