Mixing effectiveness of a new pneumatic PTS-Batchmixer® with an in-line sampling device

The aim of this paper is to define the range of utilisation of a new pneumatic pilot plant mixer. We report the validation of the mixing performances and efficiency for a binary mixture of cohesive powders, lactose monohydrate as excipient and salicylic acid as tracer. We studied the effect of the fill levels (25%, 50% and 90%) and tracer concentrations (0.01%, 0.1%, 1% and 10% w/w) obtained without pre-blending on the blend homogeneity (relative standard deviation) and the mixing time. We also investigated the effect of the sampling size (30 g vs 1 g) on the stochastic homogeneity of 2% (w/w) salicylic acid blends with an automatic sampling device.The fill level has only a slight effect on the mixing performances of the mixer with 30 g samples. Moreover the different target concentrations were obtained in a single blending step in less than 6 min. Most of the related RSD were beneath 7%. A smaller sample size of 1 g showed a greater variation in the limits of ±10% of the target value.This mixer is a good alternative to most batch mixers used at the time in the pharmaceutical industry. Nevertheless, as assumed, we confirmed the crucial impact of the scale of scrutiny.

Figure optionsDownload as PowerPoint slideHighlights
► New pneumatic pilot plant mixer of 100 L with an automatic in-line sampling device.
► Mixing lactose monohydrate and salicylic acid.
► Tracer concentrations investigated for 0.01%, 0.1%, 1% and 10% w/w.
► Mixing trials in a single blending step using 25%, 50% and 90% of the load capacity.
► Comparison of automatic in-line sampling device with 30 g vs 1 g.