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1、enbuchibestLaboratory Scale Spray Drying of Lactose: A R Information Bulletin Number 57/2010 LactoseDry Powder Inhalationbestbuchi 57/ 2010 enThe adjustable spray drying process parameters: inlet and outlet temperature, sample feed rate, drying gas flow rate and spray gas flowIn the presented resear
2、ch studies (see Table 4), the inlet air temperatures ranged Author: Dr. Cordin Arpagaus, Dr. Nina Schafroth and Marco MeuriIntroduction Spray drying is a commonly practiced method to prepare inhalable powders. This study reviews recently published scientific work in the field of lactose spray drying
3、 for inhalable applications using BCHI laboratory scale spray dryers. The generations of the Mini Spray Dryer; B-190, B-191 and B-290 models and the new Nano Spray Dryer B-90 are illustrated in Figure 1.Laboratory Scale Spray Drying of Lactose: A Reviewfrom 90 C to 210 C depending on the application
4、, the feed rate was set between 2 mL/min to 15 mL/min, the drying gas flow rate was set typically to 40 m/h and the spray gas was 300-700 L/h. Mainly aqueous solutions were prepared by dissolving an active ingredient (drug, nanoparticles) and excipient (lactose and others) in water at different soli
5、d concentrations. In some studies ethanol was added to the solution to enhance evaporation 3, 5, 7, 8. The sample volume varied between 50 and 450 mL. The resultant spray dried powder was separated by a cyclone and collected in a vessel. The exhaust gas was extracted from the cyclone and filtered.In
6、 contrast, the new Nano Spray Dryer B-90 is based on a new spray drying concept, as illustrated in Figure 3. A comparison with the traditional Mini Spray Dryer B-290 is given in Table 1.The drying gas enters the apparatus from the top where it is heated to the set inlet temperature, flows then throu
7、gh the drying chamber, and exits the spray dryer Figure 1: Generations of BCHI laboratory scale spray dryers with the Mini Spray Dryer; B-190, B-191 and B-290 models and the new Nano Spray Dryer B-90Figure 2: Process diagram of the Mini Spray Dryer B-190, B-191 and B-290 models with process paramete
8、rs1997 - 1994 Mini Spray Dryer B-1901994 - 2003 Mini Spray Dryer B-1912009 - ongoing Nano Spray Dryer B-902003 - ongoing Mini Spray Dryer B-2902009 - ongoing Mini Spray Dryer B-290bestbuchi 57/ 2010 envia a peristaltic pump in a circulation mode. The generation of droplets is based on a piezoelectri
9、c driven actuator, vibrating a thin, perforated, stainless steel membrane in a small spray cap. The membrane (spray mesh) features an at the bottom outlet. The gas is addition- ally fine filtered before leaving the instru- ment. The inlet temperature and outlet temperature are measured just after th
10、e heater and before the fine filter. The liquid sample is fed to the spray nozzle array of precise, micron-sized holes (4.0, 5.5 or 7.0 m). The actuator is driven at around 60 kHz, causing the membrane to vibrate, ejecting millions of precisely sized droplets per second with a very narrow distributi
11、on. These extremely fine droplets are dried into solid particles and collected by electrostatic charging and subsequent deflection to the collecting electrode. Finally the resulting powder is collected using a rubber spatula. Typical operating conditions for ex- periments are: inlet air temperature
12、120 C, outlet temperature around 45-56 C, feed rates range from 3 to 25 mL/h (depending on the solution viscosity, composition, spray rate), the drying gas flow rate 130 L/min and 4.0 m spray mesh. Commonly applied analytical methods to characterize the powders after spray drying are: SEM particle m
13、orphology and size Laser Diffraction particle size Anderson Impactor fine particle fraction X-Ray Diffraction amorphous/crystalline state DSC glass transitions temperature Gas adsorption mass specific surface area Karl Fisher moisture contentSpray drying is a commonly practiced method to prepare inh
14、alable powders and has been applied to a variety of substances, such as peptides, Nano Spray Dryer B-90Mini Spray Dryer B-290Main benefitfor small quantities, finest particles, highest yieldsfor traditional spray drying, established process Max. inlet temperature120 C220 CWater evaporationmax. 0.2 k
15、g/h1.0 kg/h, higher for solventsNozzle typepiezoelectric driven vibrating meshtwo-fluid nozzleParticle size300 nm 5 m2 25 mParticle separationelectrostatic particle collectorcycloneTypical yieldup to 90%typically around 60%Min. sample volume1 mL30 mLMax. sample viscosity10 cps (diluted samples)300 cps (viscous samples and juices possible)Scale-uplimited by spray head and electrical particle collectorpossible to scale-up to kg- and tons-scaleTable 1: Comparison of main features and benefits between Mini Spray Dryer B-290 and Nano Spray Dryer B-90Figure 3: Process diagram of the
