Powder particles were produced using a Buchi B-290 Mini Spray-Dryer (Buchi Labortechnik AG, Flawil, Switzerland) with a high performance cyclone in a closed-mode. Feed solutions of kanamycin (as sulphate) or/and rifampicin were prepared in a co-solvent system of ethanol and water (70:30, v/v). Rifampicin was first dissolved in ethanol; kanamycin was dissolved in water. The two solutions were then mixed (at rifampicin and kanamycin ratio of 40 and 60% w/w) and sonicated for 5 …show more content…
Powder samples were dispersed in saturated ethanol and bath sonicated for 15 s before transferring in to fraction cell. The refractive indices of kanamycin (1.67) (for kanamycin-only and kanamycin-rifampicin combination powder) and rifampicin (1.61) were used to automatically measure the particle volumetric diameters of the prepared powders by the built-in LA-950 Horiba software. The particle volumetric diameters were expressed as D10, D50 and D90, indicating the diameter under which 10%, 50% and 90% of the sample resided. Following equation was used to calculate the broadness (span) of size distribution. All measurements were done in triplicate for each