A reverse-phase UV-HPLC method was used to measure the amount of the degradation products of S-892216 in suspension. Subsequently, 50 µL of suspension was transferred to a volumetric flask, and acetonitrile/water (2:1) was added. The flask was sonicated for 1 minute. The solution volume was adjusted to 5 mL by adding acetonitrile/water (2:1), then filtered through a 0.45-µm membrane filter. The absorbance of the sample solution at a wavelength of 247 nm was measured using a UV-HPLC system (ACQUITY UPLC H-Class; Waters Corporation) equipped with a reverse-phase ODS column (ACQUITY UPLC BEH C18 1.7 µm, 2.1 × 100 mm; Waters Corporation). The column temperature was maintained at 40°C. The mobile phase consisted of 0.1% formic acid and acetonitrile/formic acid (2000:1). The separation was achieved in 60 min using the gradient program in Table . The flow rate was 0.4 mL/min throughout the run. The injection volume was 5 µL. The amount of degradation products was calculated as a percentage (%) of the total peak area of the chromatogram, which was set to 100%.