Micromeritics has introduced two instruments that provide skeletal and envelope volume measurements to determine the total pore volume and the porosity percentage.
The company's Accupyc II 1340 gas pycnometer provides skeletal volume and density measurements on a variety of materials with volumes from 0.01cm3 to 350cm3.
Micromeritics' Geopyc 1360 pycnometer determines the envelope volume and the density of monolithic samples as well as the bulk volume and density of powdered materials.
Both instruments are based on Archimedes' displacement principle.
The Accupyc is a fully automated instrument that utilises a gaseous displacement medium, typically helium.
The pressures observed upon filling the sample chamber, then discharging the displaced gas into a second empty chamber, allow computation of the sample solid phase volume.
The Geopyc uses a quasi-fluid displacement medium composed of microspheres having a high degree of flowability that do not wet the sample or fill its external or internal pores.
A range of sample chambers is available to accommodate various sample sizes.
Many of the physical, mechanical and pharmacokinetics properties of tablets are influenced by the basic settings of a tablet press.
Using the Accupyc coupled with the Geopyc, scientists can determine the skeletal density, envelope density, total pore volume, porosity percentage and closed-cell pore volume of tablets produced with varying press settings.
The two instruments have also been used to determine a variety of pharmaceutical ribbon physical properties.
Using the Accupyc, the skeletal or true density of the blend of materials making up the ribbon can be measured.
When the skeletal density is included in the setup parameters for the envelope density, the Geopyc will calculate and report the percentage porosity and total pore volume of the ribbon.
This information is useful for controlling the mechanical properties of the material, the compression force settings on the roller compactor and the subsequent tablet press settings.
