[Determination of norfloxacin, an active dissociation product of silver norfloxacin, in guinea pig plasma and tissue by high performance liquid chromatography with column-switching].

A column switching HPLC method was established for the determination of norfloxacin, and active dissociation product of silver norfloxacin, in guinea pig plasma and tissues. The pre-treating column (50 mm x 5 mm ID) and analytical column (150 mm x 5 mm ID) were packed with mu-Bondapak C18, 37-50 microns and YWG-C18, 10 microns, respectively. A mixture of CH3OH-0.008 mol/L phosphate buffer-0.05 mol/L tetrabutylammoniun bromide (25:75:4) was used as the analytical mobile phase with a flow rate of 1 ml/min. The pre-treating mobile phase was 0.008 mol/L phosphate buffer with a flow rate of 3 ml/min. UV detection was made at 280 nm. The results were linear within a range of 2-128 micrograms/ml norfloxacin for plasma. The lowest detection limit was 0.25 microgram/ml for plasma. The mean recovery of the method was 102% with a relative standard deviation of less than 7%.