Mercury porosimetry of pharmaceutical powders and granules

Effect of scanning speed and moisture content of the sample on the result o f mercury porosimetry analysis of mannitol and microcrystalline cellulose ( Emcocel(R) 50M) powders and granules produced by wet granulation were studi ed. In high-pressure porosimetry analysis, the smallest pores (diameter < 2 0 nm) of the powders and granules could not be detected accurately when hig h scanning speeds were used. If the total pore volume is the only parameter of interest, fast scanning speed can be used, because the scanning speed d oes not affect this value. In high-pressure porosimetry analysis, the volum e of the smallest pores (diameter < 40 nm) of mannitol and microcrystalline cellulose granules increased with increasing water content. For powders, n o effect of moisture on the volume of the smallest pores was observed. Thus , the increase in the volume of the smallest pores of granules with increas ing moisture is related to the structure of the granules. Measurement of th e water content of the samples together with proper drying of the samples b efore the porosity measurement is extremely important.