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Pharmaceutical Technology LABORATORY BEST PRACTICES 2018 35 What was observed was the vortexer level was indeed non-linear and instead of the expected plot of vortexer setting vs. particle size having the gen- eral shape of an exponential decay, ae -bx , the plot appeared quadratic, ax 2 -bx+c, with a minimum at the vortexer level midpoint. This suggests that even though the rotational velocity of the vortexer may increase with a higher setting, the shear imparted on the particles decreases after a certain point. This is counter-intuitive, but one possible hypothe- sis is at some rotational velocity, the dispersion will move from laminar to turbulent f low (8–10). This will cause air to become entrained in the disper- sion, thus decreasing the effective viscosity, which will decrease the amount of applied shear. It was hypothesized before conducting the analy- ses that the longer the duration of applied shear, the greater the particle size reduction effect. Though the vortexer duration was statistically significant in at least one interaction, vortexer level*vortexer duration, on the D[v,0.9], no main effect was ob- served for any of the three responses. This again is counter-intuitive. One possible hypothesis is the sample dispersion was not vortexed long enough to be a significant main effect with respect to any of the responses. Table VI: Effect tests, D[v,0.1]. Source Nparm DF Sum of Squares F Ratio Prob > F Vortexer Level(3,7) 1 1 0.0146 0.0132 0.9088 Vortexer Duration (s)(0,60) 1 1 5.7609 5.2076 0.0254 Vortexer 1 1 4.5606 4.1226 0.0460 Morphology 1 1 3882.9865 3510.0927 <.0001 Vortexer Level*Vortexer Duration (s) 1 1 5.8365 5.2760 0.0245 Vortexer Level*Vortexer 1 1 4.3737 3.9537 0.0506 Vortexer Duration (s)*Vortexer 1 1 1.1846 1.0708 0.3042 Vortexer Level*Morphology 1 1 4.6161 4.1728 0.0447 Vortexer Duration (s)*Morphology 1 1 4.9863 4.5074 0.0372 Vortexer*Morphology 1 1 11.1757 10.1025 0.0022 Vortexer Level*Vortexer Level 1 1 6.8138 6.1594 0.0154 Table VII: Effect tests, D[v,0.5]. Source Nparm DF Sum of Squares F Ratio Prob > F Vortexer Level(3,7) 1 1 76.1252 6.9482 0.0103 Vortexer Duration (s)(0,60) 1 1 0.0205 0.0019 0.9656 Vortexer 1 1 58.4987 5.3394 0.0237 Morphology 1 1 7747.9333 707.1826 <0.0001 Vortexer Level*Vortexer Duration (s) 1 1 14.5436 1.3274 0.2531 Vortexer Level*Vortexer 1 1 173.3290 15.8204 0.0002 Vortexer Duration (s)*Vortexer 1 1 10.2478 0.9354 0.3367 Vortexer Level*Morphology 1 1 65.5054 5.9789 0.0169 Vortexer Duration (s)*Morphology 1 1 0.4324 0.0395 0.8431 Vortexer*Morphology 1 1 70.0085 6.3899 0.0137 Vortexer Level*Vortexer Level 1 1 181.3360 16.5512 0.0001