HPLC analysis of the quantity of PG490 in PG27. The chromatogram of PG27 with PG490 is presented, showing the retention time of 13.4 min. PG490 calibration graphs were constructed in the range of 12.5 μg/mL to 1.6 mg/mL. The regression equations of these curves and their correlation coefficients were calculated to be y = 46682x + 82.221 (r2 = 1, top-right corner). The peak area ratios show a linear relationship with the concentration of PG490. When the sample solution was analyzed by HPLC, the PG490 peak was confirmed by comparison to the retention time standards. The PG490 content in PG27 was determined to be 1.27 ± 0.06%.