[Determination of bisphenol A and 4-nonylphenol in rat tissues by high performance liquid chromatography with...

A simple and highly sensitive method has been developed for the determination of bisphenol A (BPA) and 4-nonylphenol (4-NP) in rat tissues by high performance liquid chromatography (HPLC) with fluorescence detection. The rat tissue samples were homogenized-with methanol-ammonium acetate buffer (2:8, v/v) by a high-speed homogenizer and then BPA and 4-NP were extracted by a mixed solvent of n-hexane and diethyl ether (7:3, v/v). The organic layer was evaporated with a stream of nitrogen, and the residue was dissolved in the mobile phase. The chromatographic operating conditions were a C18 column (250 mm x 4. 6 mm i.d., 5 microm), acetonitrile-ammonium acetate buffer (pH 4.5) (75:25, v/v) as mobile phase at a flow rate of 1 mL/min, fluorescence detection with the excitation and emission wavelengths at 227 nm and 313 nm, respectively. Average recoveries for rat tissues at three different levels were in the range of 82.0% -95.4% for BPA and 81.2% -96.5% for 4-NP. The relative standard deviations (RSDs) were 0. 37% - 5.28% and the detection limits were 4.0, 4.6, 3.2, 3.3 ng/g for BPA and 12.0, 15.6, 11.8, 13.8 ng/g for 4-NP in liver, kidney, heart and brain tissues, respectively. The intra-day precisions were 0.89% -4.50%, and the inter-day precisions were 3.10% - 12.40%. These results demonstrated that the proposed method is simple, sensitive, and reliable for the determination of BPA and 4-NP in animal tissues.