Mercury Porosimetry of Mannitol Tablets: Effect of Scanning Speed and Moisture

Abstract

Purpose of the work was to study the effect of the scanning speed of mercury porosimetry and moisture content of the sample on the mercury porosimetry result for mannitol tablets. Tablets were compressed at three different compression pressures from nonhygroscopic mannitol powder and granules. Pore structure of tablets was determined with three different scanning speeds of a high-pressure mercury porosimeter after storage in three different moisture conditions. With low scanning speed, smallest pores of tablets were determined more accurately. Small amounts of moisture, even as low as 1%, before evacuation in nonhygroscopic mannitol tablets decrease the porosity. Decrease in porosity was observed at a pore diameter range of 50–1000 nm, not at the smallest determined pores. Thus, the role of water in pharmaceutical samples appears to be complicated. Reasonably slow scanning is recommended in high-pressure mercury porosimetry. If total pore volume is the only parameter of interest, fast scanning can be used. Pretreatment of the samples by proper drying before mercury porosimetry is important.

Keywords:

• Mannitol
• Mercury porosimetry
• Moisture
• Pore structure
• Scanning speed
• Tablet