Determination of Cyclophosphamide Related Substance A by Ion Chromatography-Suppressed Conductivity Detection

OBJECTIVE To establish ion exchange chromatography-suppressed conductivity detection for the determination of related substance A in cyclophosphamide. METHODS Using a Ionpac CS12A column (250 mm×4.0 mm Analytical), the mobile phase was 0.16% methane sulfonic acid, the flow rate was 1.0 mL·min^-1 with suppressed conductivity detector; the column temperature was 25 ℃; and the inject volume was 25 μL. RESULTS The detection and quantification limit was 0.54 and 1.8 μg·mL^-1, respectively. The linear range for the content of degradation impurity A was 1.8-24 μg·mL^-1(r>0.999), the average recoveries were in the range of 97.45%-99.81% with the relative standard deviation below 3%. CONCLUSION The method is simple, rapid, accurate and is suitable for the determination of cyclophosphamide degradation impurity A.