[A high performance liquid chromatographic method for the determination of teniposide in brain tissue using...

A reversed-phase HPLC method for the determination of teniposide in brain tissue is described. Teniposide can be separated on a Hypersil ODS column with a mobile phase of methyl alcohol-water-acetic acid (56:41:3, V/V) and flow rate of 0.8 mL/min (10 MPa). Column temperature was 35 degrees C and operating potentials for electrochemical detection was 0.70 V. To 50 mg brain tissue were 1 mL 50% ammonium sulfate and 4 mL ethyl acetate. The sample was vortexed for 5 min and ultrasonically agitated for 15 min, then centrifuged at 3000 r/min for 15 min. The upper (organic) layer was collected and the lower layer reextracted with 4 mL of ethyl acetate by vigorously vortexing, then centrifuged at 3000 r/min for 15 min. The organic layer was combined with the previously collected ethyl acetate layer. This organic extract was dried under a gentle nitrogen stream, and the residue was reconstituted with 1 mL internal standard of guaifenesinum before HPLC analysis. The linear range was 0.1-10.0 mg/L, and the detection limit 0.1 mg/L. Intra-day and inter-day RSD for assaying brain tissue sample were 0.87% and 1.41%, respectively. The average recovery was 92.87% with coefficient of variation of 2.35%.