Laser diffractometry of nanoparticles: frequent pitfalls & overlooked opportunities

Laser diffraction is a frequently applied technique for the size analysis of particles. The method possesses many advantages but also disadvantages or pitfalls. If these pitfalls are overlooked or not considered appropriately, size analysis by laser diffraction can lead to false and/or meaningless results. As shown in previous studies, this is especially true for the size analysis of nanoparticles. In this study further possible pitfalls for the size analysis of nanosized formulations were investigated. This included both, influences related to the sampling and influences related to the instrument setup. The results revealed that sampling position, the type of sampling device, the stirring speed in the instrument and/or the use of ultrasound can lead to tremendous changes in the size result. However, the data also showed that these often overlooked pitfalls, if understood, represent a great opportunity to gain more detailed information about the properties of the nanosized formulations.