Direct determination of bisphenol A and nonylphenol in river water by column-switching semi-microcolumn liquid chromatography/electrospray mass spectrometry

A rapid and sensitive analytical method based on column-switching semi-micr ocolumn high-performance liquid chromatography (HPLC) with electrospray mas s spectrometry was developed for determining trace levels of bisphenol A (2 ,2-bis(4-hydroxyphenyl)propane) and nonylphenol (4-nonylphenol) in river wa ter, An aliquot of sample solution was directly injected into the precolumn packed with Capcellpak MF-Ph for sample cleanup and enrichment, The compou nds of interest were then transferred to a C-18 analytical column for main separation through a change in flow path by a programmed su itching valve. Bisphenol A, nonylphenol, and interfering substances were satisfactorily se parated with a simple gradient elution complete within 35 min. Detection of their deprotonated molecules was conducted in negative ion mode. A reduced flow rate (100 mu L/min) optimized for the narrow bore column was found ad vantageous in obtaining a high degree of sensitivity during electrospray de tection. The influence of carrier additives on sensitivity was also examine d. This method produced detection limits of 0.5 ng/mL for bisphenol A and 1 0 ng/mL for nonylphenol (signal-to-noise ratio 3), Calibration curves were observed in the range of 2.5-50 ng/mL (r(2) = 0.999) for bisphenol A and 50 -500 ng/mL (r(2) = 0.998) for nonylphenol, Recoveries of the compounds from spiked distilled water and river water were 99.7-138.5% with a relative st andard deviation (RSD) ranging from 2.2-9.7%. Copyright (C) 1999 John Wiley & Sons, Ltd.