Mastersizer 2000 laser diffraction particle size analyser

Two model liquid cores (aqueous active suspension or solution) were prepared for use in the syringe based liquid dispenser: a. Dipyridamole suspension was initially prepared by subjecting aqueous dipyridamole suspension (1.5 g/ 30 mL) to size reduction via application to T8.01 Ultra Turrax Homogeniser (IKA, Germany) at 25,000 rpm. This was carried out for 1 h at 15 min interval with 5 min cooling time between the intervals. Methocel E4 was added to the suspension to reach a polymer concentration 0.5% w/v before probe sonicating using Sonics Vira cell (USA) at 15 min interval in an ice bath for additional 4 h using an amplitude of 70%. The final suspension was diluted with Methocel E4 (0.5% w/v in water) to achieve a drug concentration of 1.5% w/v. The size distribution of dipyridamole particles in the suspension was confirmed by a Mastersizer 2000 laser diffraction particle size analyser (Malvern Instruments, UK). b. Theophylline solution was prepared by adding 15 g of citric acid and 1.5 g of Tween 80 to a 4% w/v theophylline aqueous suspension (50 mL). This was heated to 65 o C and stirred until a complete solution is formed. Methocel E4 was then added to achieve a cellulosic solution concentration of 0.25% w/v before cooling in an ice bath.

The particle size distribution was assessed using a Mastersizer 2000 laser diffraction particle size analyser (Malvern Instruments, Orsay, France) equipped with Hydro2000S as sample dispersion unit (A) mod using the Mie light scatteringtheory. The refractive indices used were 1.305 for the PFOB and 1.333 for the dispersant (water). Several drops of the emulsion were added with a stirring of 500 rpm to the sample dispersion unit. The Mie theory was used to determine the volume weighted mean diameter D [4,3] and the polydispersity was calculated as d90/d10. d90 is the diameter at which 90% of the sample's volume is comprised of droplets with a diameter less than this value. d10 is the diameter at which 10% of the sample's volume is comprised of droplets with a diameter less than this value. The size distribution histogram is shown in Figure 1b.