Autopore 4 9510

Mercury porosimetry runs were undertaken using an Autopore IV 9510 (Micromeritics, Madrid, Spain) porosimeter with a 3 cm³ penetrometer. An adequate number of tablets per tested formulation was used in order to obtain a stem volume between 25% and 90% of the penetrometer capacity. Working pressures covered the range 0.1–60,000 psi. Total porosity and pore size distribution of tablets were determined before and after the drug release study in duplicate and for each tested batch.
In the case of leached tablets, the porosity results have been normalized by subtracting the initial mercury intrusion, in order to perform a clearer comparison of the structure of the pore network inside these systems.

The MICP technique can effectively determine connected porosity and pore-throat size distribution, using a mercury intrusion porosimeter (AutoPore IV 9510; Micromeritics Corporation)⁵ . The cubic sample with a linear dimension of 10 mm was dried at 60 °C for at least 48 hours to remove moisture, and cooled to room temperature (~23 °C) in a desiccator with relative humidity less than 10%. Then, low- (5 to 30 psi; 0.034 to 0.21 MPa) and high-pressure (30 to 60000 psi; 0.21 to 413 MPa) analyses were initiated by progressively increasing the intrusion pressure while monitoring the volume change of mercury at a detection limit of <0.1 μL. Pore-throat size distributions from MICP tests were obtained using the Washburn equation^{43 (link)}, with the confinement correction of contact angle and surface tension of mercury in shale nanopores^{27 (link)}. The corrected pore-throat diameters cover a measurement range of 50 μm to 2.8 nm for the experimental conditions (e.g., using a penetrometers with a filling pressure of 5 psi) suitable for shale samples with porosities commonly less than 5%. Pore structure parameters (such as pore-throat size distribution, median pore-throat size, pore volume, pore area, and porosity) can be obtained for multiple connected pore networks at nm-μm spectrum^{8 (link)}.