Determination of bisphenol A in human serum by high-performance liquid chromatography with multi-electrode electrochemical detection

A simple and sensitive method using high-performance liquid chromatography with multi-electrode electrochemical detection (HPLC-ED) including a coulom etric array of four electrochemical sensors has been developed for the dete rmination of bisphenol A in water and human serum. For good separation and detection of bisphenol A, a CAPCELL PAK UG 120 C-18 reversed-phase column a nd a mobile phase consisting of 0.3% phosphoric acid-acetonitrile (60:40) w ere used. The detection Limit obtained by the HPLC-ED method was 0.01 ng/ml (0.5 pg), which was more than 3000-times higher than the detection limit o btained by the ultraviolet (UV) method, and more than 200-times higher than the detection limit obtained by the fluorescence (FL) method. Bisphenol A in water and serum samples was pretreated by solid-phase extraction (SPE) a fter removing possible contamination derived from a plastic SPE cartridges and water used for the pretreatment. A trace amount (ND similar to0.013 ng/ ml) of bisphenol A was detected from the parts of cartridges (filtration co lumn, sorbent bed and frits) by extraction with methanol, and it was comple tely removed by washing with at least 15 mi of methanol in the operation pr ocess. The concentrations of bisphenol A in tap water and Milli-Q-purified water were found to be 0.01 and 0.02 ng/ml, respectively. For that reason, bisphenol A-free water was made to trap bisphenol A in water using an Empor e disk. In every pretreatment, SPE methods using bisphenol A-free water and washing with 15 mi of methanol were done in water and serum samples. The y ields obtained from the recovery tests using water to which 0.5 or 0.05 ng/ ml of bisphenol A was added were 83.8 to 98.2%, and the RSDs were 3.4 to 6. 1%, respectively. The yields obtained from the recovery tests by OASIS HLB using serum to which 1.0 ng/ml or 0.1 ng/ml of bisphenol A was added were 7 9.0% and 87.3%, and the RSDs were 5.1% and 13.5%, respectively. The limits of quantification in water and serum sample were 0.01 ng/ml and 0.05 ng/ml, respectively. The method was applied to the determination of bisphenol A i n healthy human serum sample, and the obtained detection was 0.32 ng/ml. Fr om these results, the HPLC-ED method should be the most useful in the deter mination of bisphenol A at low concentration levels in water and biological samples. (C) 2000 Elsevier Science B.V. All rights reserved.