Ultrasound-assisted emulsification-microextraction of phenolic preservatives in water.

Simultaneous ultrasound-assisted emulsification-microextraction (USAEME) and derivatization combined with gas chromatography-tandem mass spectrometry (GC-MS/MS) is proposed for the first time for the analysis of parabens, triclosan and related phenols in water samples. In situ acetylation was successfully applied for the derivatization of target compounds with high efficiency using non-expensive reagents. The proposed method exhibits many advantages such as simplicity, efficiency, low cost, and minimum solvent consumption. In addition, the whole analytical process, including sample preparation and determination, is performed in only 20 min. A multifactorial experimental design was employed to study and optimize the main variables potentially affecting the microextraction and derivatization processes (extraction solvent, phase ratio, sodium chloride concentration, extraction time, and acetic anhydride volume). The performance of the method was studied in terms of accuracy, linearity, precision, and enrichment factor. Quantitative recoveries (>or=85%) were obtained for all target compounds, and method precision was also satisfactory (RSD<or=13%) even for complex samples. Enrichment factors ranging from 100 to 200 were obtained, allowing achieving limits of detection at the low picogram per millilitre for most of the target compounds. Several real samples, including wastewaters, river waters and swimming pool water, were analyzed. Since matrix effects were not observed, quantification can easily be performed using external calibration with acetylated standards, allowing a high sample throughput.