Tristar 2 analyzer

X-ray diffraction (XRD) patterns were recorded using a Rigaku Ultima IV X-ray diffractometer (Japan) with Cu Kα radiation (λ = 1.5418 Å) operating at 40 kV and 60 mA. While, SEM analysis was performed via SEM (Hitachi SU 8000 Type II) connected with energy-dispersive X-ray spectroscopy (EDX). In addition, BET surface area and BJH pore size distribution analyses were conducted by a Tristar II analyzer (Micromeritics, Japan). In addition, TEM analysis was carried out via JEM-2100F (JEOL, Japan). Moreover, Raman analysis was performed on a JASCO NRS-3100 micro-spectrometer with excitation radiation.

Specific surface area of each API lot was obtained from analyzing low-temperature nitrogen adsorption-desorption isotherms (at 77 K) collected using a TriStar II analyzer (Micromeritics Instrument Corp., Norcross, GA, USA). Each material was loaded into a sample tube and degassed under nitrogen at 35 °C for 1 h before analysis. After cooling to room temperature, the tube was weighed and placed into the adsorption port of the instrument. A static adsorption mode was used including full equilibration after each adsorbate load. The adsorption isotherms were measured over a relative pressure, p/p_o, range of 0.001–0.995. Desorption isotherms were measured over a relative pressure range of 0.995–0.015. Surface area was calculated via the Brunauer–Emmett–Teller (BET) method using the relative pressure range from 0.1 to 0.30 [28 (link)].