Gas Chromatographic-Mass Spectrometric Determination of Bisphenol-A in Water at Nanogram Per Liter Concentrations

A GC-MS method for the determination of bisphenol-A (BPA) in water has been developed and validated for a concentration range of 5.0−514.8 ng/L. In contrast to hitherto published methods we report validation data in detail for the entire applicable concentration range of the developed method. The method employs liquid/liquid extraction for analyte and internal standard isolation and concentration. The D₈-BPA analog is used as surrogate standard to increase method accuracy and precision. The identity confirmation of BPA is performed using the ion intensity ratios of the molecular ion and the M-15 fragment. Trifluoroacetylation of BPA and D₈-BPA is employed in order to obtain less polar derivatives. As a result of the derivatization narrow and symmetrical gas chromatographic peaks are obtained which allow the quantification of very small amounts of BPA. The relative recoveries of BPA are greater than ninety percent over the entire validated concentration range. The method quantification limit is 5.0 ng/L BPA, which is the lowest validated concentration. The impact of suspended particulate matter frequently present in surface water samples on the quantification results could be demonstrated. It was shown that false positive results can be obtained due to losses of the surrogate standard by adsorption on the particulates present.