Extraction of bisphenol-A and 17β-estradiol from water samples via solid-phase extraction (SPE)

Abstract

Solid-phase extraction (SPE) is one of the most commonly applied methods for extracting endocrinedisrupting compounds (EDCs) from aqueous samples prior to chemical analysis. Here, we critically review the application of SPE to two particular EDCs, namely bisphenol-A (BPA) and 17β-estradiol (E2). These two EDCs were selected because of their frequent occurrence, their environmental significance, and their chemical similarity to other important EDCs (e.g., steroids and alkylphenols). The review of previous literature considers factors such as which solid phase is best suited for extraction of the target analytes from an aqueous sample, which eluent should be employed for eluting the target analytes from the solid phase, and how the target analytes should be derivatized prior to analysis by gas chromatography and mass spectrometry (GC/MS). We also conducted original experiments in order to: (1) compare two types of SPE cartridges; (2) compare two common derivatization agents [N-methylN-(trimethylsilyl)-trifluoroacetamide (MSTFA) and N,Obis(trimethylsilyl)-trifluoroacetamide (BSTFA)] identified during the critical review; and (3) assess the extent to which the range of linearity of GC/MS calibration curves can be extended by varying the sample volume applied during SPE prior to GC/MS analysis. Results of the experiments indicate that: (1) under the conditions tested, there was no significant difference in analyte recovery between C18 and poly(divinylbenzene-co-N-vinylpyrrolidone) SPE cartridges; (2) MSTFA and BSTFA perform almost identically as silylation agents for BPA and E2 under the conditions tested; and (3) by varying the applied aqueous sample volume from 20 ml to 4000 ml, it is possible to obtain linear GC/MS calibration curves over a concentration range of 0.01 μg/l–100 μg/l for both BPA and E2.