By Ivo Stassen, Centre for Surface Chemistry and Catalysis, KU Leuven.
Volumetric physisorption analysis is typically conducted using sample amounts of the order of milligrams to a few grams. For smaller sample quantities and for extremely low surface area samples, the number of non-adsorbed gas molecules at adsorption equilibrium can exceed the amount of molecules adsorbed on the sample, which will hamper the accurate measurement of gas uptake by the sample. Continue reading
Myke Scoggins | Senior Pharmaceutical Scientist | Micromeritics Instrument Corporation
In the pharmaceutical world, particle size analysis has traditionally been the method of choice to “characterize” raw materials. Beginning with sieve analyses all the way to more current technologies like laser light scattering, this physical characterization measurement has been used to set incoming raw material specifications, help determine which excipients will be used in a formulation, and troubleshoot product performance issues such as dissolution. While particle size analysis is, without a doubt, an important piece of the puzzle, it is exactly that – a piece. Other measurements can provide essential and useful information as well and, when paired with other techniques, assist the pharmaceutical scientist to more fully characterize their Active Pharmaceutical Ingredients (API) and excipient materials. Among these techniques is the measurement of surface area. Continue reading
Andrew D. D’Amico, part of the scientific services group specializing in characterization by physical and chemical adsorption, recently attended the spring 2013 meeting of the American Society for Testing and Materials (ASTM) catalyst committee (D32). For this meeting, Andrew prepared material for three topics of interest: static carbon monoxide (CO) chemisorption on supported platinum on alumina catalysts, dynamic carbon monoxide pulse chemisorption on supported platinum on alumina catalysts, and dynamic acid site characterization of zeolites by propylamines. Andrew also contributed to the discussion to keep and update the current standard of terminology relating to catalysts and catalysis (D3766).
Sarah Zellnitza, *, Jakob Dominik Redlinger-Pohnq, Nora Anne Urbanetza
aResearch Center Pharmaceutical Engineering GmbH, Graz/Austria
Dry Powder Inhalers (DPIs) are medical devices used for pulmonary drug delivery. The formulations used in DPIs typically consist of adhesive mixtures of the drug and a carrier. In order to reach the tiny airways of the deep lung the drug particles have to exhibit an aerodynamic diameter of 1 µm to 5 µm. Particles of this size are rather cohesive and show poor flow properties and thus poor dosing . That is why carrier based formulations, where the drug is attached to the surface of coarser carrier particles (50 µm – 200 µm) of adequate flowability, have been invented.