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28 Pharmaceutical Technology LABORATORY BEST PRACTICES 2018 P h a r mTe c h . c o m JUL AND/STOCK.ADOBE.COM Sample Preparation S a mple prepa rat ion is one of t he most crit ica l steps during particle size analysis, especially when trying to maximize accuracy and precision. A common device used during sample preparation is the vortex mixer, and of ten, the importance of the vortex mixer is overlooked. Vortex mixers generally are used to mix solutions or disperse sample material when more shear is required than is possible by hand shaking, but when less shear is required than that generated by an ultrasonic probe. When making sample suspensions and dispersing using a vor- tex mixer, there is potential for too much energy to be put into the sample, which can cause the particle size and morphology to change. For this study, the applied shear to sample suspensions from several vortex mixers was compared. The vortex mixers were then used to disperse various ibuprofen morphologies to observe the effects of applied shear on the particle size distribution. Vortex mixers, which apply shear to a suspension to disperse the particles, are a common component in the laboratory. When using vortexers to apply shear to a dispersion, an undesired breakage of particles—commonly referred to as attrition (1)—may occur. The applied shear from a specific vortex mixer is almost never determined in the laboratory. Due to this, various model and age vortex mixers that may not be equivalent may be used to disperse a given suspension. This has the potential to impact various results depending on the sample vulnerability to shear, also referred to as a material's relative hardness as defined by the International Union of Pure and Applied Chemists (IUPAC) (2). The Impact of Vortexing on the Particle-Size Distribution of Pharmaceuticals If a vortex mixer produces too much energy during sample preparation for particle size analysis, the size and morphology of particles can change. A study compares the applied shear to sample suspensions of ibuprofen to observe the effects of applied shear on the particle size distribution. Greg Maj is a scientist; Jeff Driscoll is an associate group leader; Eric Olson is a senior research scientist; Jonathon Salsbury is an associate director, all at PPD GMP Lab, Middleton, WI. Greg Maj, Jeff Driscoll, Eric Olson, and Jonathon Salsbury