Analysis of endocrine disrupting alkylphenols, chlorophenols and bisphenol-A using hollow fiber-protected liquid-phase microextraction coupled with injection port-derivatization gas chromatography-mass spectrometry.

Liquid-phase microextraction (LPME) coupled with gas chromatography-mass spectrometry were used to determine alkylphenols (APs), chlorophenols (CPs) and bisphenol-A (BPA) in aqueous samples. APs, CPs and BPA are highly polar compounds and need to be derivatized before analysis by GC-MS. In this work, they were derivatized in the GC injection port with bis(trimethylsilyl)trifluoroacetamide (BSTFA). The analytes were extracted directly from 5 ml of sample solution using 5 microl of organic solvent though a porous polypropylene hollow fiber. The hollow fiber, filled with an immiscible organic solvent (ca. 5 microl), was immersed in the sample solution which was stirred during the 30-min extraction. An aliquot (2 microl) of the extract and 2 microl of BSTFA were then consecutively injected into the GC injection port. Extraction parameters such as extraction time, pH of sample, concentration of salt added, and stirring rate were optimised. The proposed LPME provided a good average enrichment factor of up to 162-fold, reproducibility ranging from 5.9 to 13.9% (n = 4), and good linearity (r2 = 0.995) for spiked water samples. The limits of detection (LODs) ranged between 0.005 and 0.015 microgl(-1) (S/N = 3) using GC-MS with selective ion monitoring and limits of quantification were in the range of 0.012-0.026 microg l(-1). A comparative study was performed between LPME, headspace solid-phase microextraction (HS-SPME) and liquid-liquid extraction (LLE). The results obtained suggested that hollow fiber LPME was a rapid, simple and efficient technique for APs, CPs and BPA, and provided a good alternative to SPME and LLE. Finally, the proposed method was applied to monitor Singapore coastal water samples.