HPLC analysis methodology
The mobile phase consisted of 60% methanol (A pump) and 40% pure water with 0.2% formic acid (B pump) with isocratic elution. Detection conditions were as follows: column temperature, 30 °C; autosampler injection volume, 20 μL; flow rate, 0.5 mL·min−1; and, detector wavelength, 240 nm. The major rivaroxaban metabolite (M1), was quantified from the rivaroxaban standards, for which the correlation coefficient was > 0.999. The quantitative method showed good sensitivity.