Determination of eight pharmaceuticals in an aqueous sample using automated derivatization solid-phase microextraction combined with gas chromatography–mass spectrometry

• An automated SPME-GC/MS method was proposed for the determination of pharmaceuticals.
• In-aqueous derivatization method was employed and optimized.
• Excellent sensitivity was achieved under the optimized conditions.
• The method was applied to analysis of sea water samples.

An automated aqueous derivatization solid-phase microextraction (SPME) coupled with a gas chromatography/mass spectrometry (GC/MS) method was developed for simultaneous determination of eight pharmaceuticals in water samples. Dimethyl sulfate and tetrabutylammonium hydrogen sulfate were selected as derivatization and activation reagents for the esterification reaction. An experimental design approach, central composition design (CCD), was employed to investigate and optimize the operative factors influencing the extraction efficiency, including extraction time, extraction temperature and ionic strength. The other parameters such as type of fiber coating, pH and derivatization conditions were also evaluated. SPME was finally carried out in headspace mode at 80 °C for 60 min with the presence of 3.00 g Na2SO4, using a home-made 44 μm PDMS fiber. Wide linear ranges and low limits of detection (0.06–1.24 ng L−1) were obtained under the optimized conditions. The relative standard deviations (RSDs) and recoveries ranged from 0.5% to 12.3% and 85% to 110%, respectively. The proposed method was successfully applied to the analysis of the real surface water samples from the Pearl River Estuary.

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