HPLC-UV determination of related substances of cefazolin sodium according to the Ph. Eur. Monograph on an ARION® Polar C18 3 µm column, 125 mm × 4.0 mm, part number ARI-5721-IJ40. Mobile phase A is a solution containing 14.54 g/L of disodium hydrogen phosphate dodecahydrate R and 3.53 g/L of potassium dihydrogen phosphate R; mobile phase B is acetonitrile R. Gradient elution (time interval / A% / B%): 0–2 / 98 / 2, 2–4 / 98 → 85 / 2 → 15, 4–10 / 85 → 60 / 15 → 40, 10–11.5 / 60 → 35 / 40 → 65, 11.5–12 / 35 / 65, 12–15 / 35 → 98 / 65 → 2, 15–21 / 98 / 2. Flow rate 1.2 mL/min, column temperature 45 °C, injection volume 5 µL, UV detection at 254 nm. Analytes as numbered in the note: 1. impurity J, 2. impurity E, 3. impurity H, 4. impurity C, 5. impurity G, 6. impurity D, 7. impurity…