A sensitive and specific high performance liquid chromatography method was established for measuring cefazolin sodium level in rabbit synovial fluid. Acetonitrile was used to precipitate proteins and antipyrine was used as internal standard. Samples were analyzed on a Dionex Ultimate U3000 HPLC system equipped with Phenomenex Luna C18 column （150 mmx4.60 mm, 5 Bm, 100 A）. The mobile phase consisted of acetonitrile and 0.1% formic acid in water. The flow rate was 1 mL/min. The detection wavelength was set at 272 nm. The column temperature was maintained at 25 ℃. The calibration curve was linear in the range of 1.0-100.0 μg/mL （r2 = 0.9999）. The limit of detection （LOD, S/N - 3） was 0.07 μg/mL. The limit of quantitation （LOD, S/N = 10） was 0.22 pg/mL. The recovery of cefazolin sodium （low, medium and high） was 124.6%, 117.8%, and 100.6% （RSD% - 1.9%, 4.0%, 1.1%, n = 5）, respectively. The intra-day and inter-day precision values were in the range of 0.5%-2.7%. The method was simple, sensitive and reliable. It can be used for the quantitative determination of cefazolin sodium in rabbit synovial fluid.
