Ultrasound-assisted emulsification-microextraction of emergent contaminants and pesticides in environmental waters

The analytical use of ultrasound-generated emulsions has recently found a growing interest to improve efficiency in liquid-liquid extraction since they increase the speed of the mass transfer between the two immiscible phases implied. Thus, dispersed droplets can act as efficient liquid-liquid microextractors in the continuous phase, and later they can be readily separated by centrifugation. A novel method based on ultrasound-assisted emulsification-microextraction (USAEME) and gas chromatography coupled to mass spectrometry (CC/MS) has been developed for the analysis of synthetic musk fragrances, phthalate esters and lindane in water samples. Extraction conditions were optimized using a multivariate approach. Compounds were extracted during 10 min in an acoustically emulsified media formed by 100 mu L chloroform and 10 mL sample (enrichment factor= 100). The method performance was studied in terms of accuracy (recovery = 78-114%), linearity (R-2 >= 0.9990) and repeatability (RSD <= 14%). Limits of detection (LODs) were at the pg mL(-1) level for most of compounds, and at the sub-ng mL(-1) level for the most ubiquitous phthalate esters. USAEME is proposed as an efficient, fast, simple and non-expensive alternative to other extraction techniques such as SPE, SPME and LPME for the analysis of environmental waters including bottled, tap, river, municipal swimming pool, sewage and seaport water samples. Since no matrix effect has been found for any of the water types analyzed, quantification could be carried out by using conventional external calibration, thus allowing a higher throughput of the analysis in comparison with other microextraction techniques based on equilibrium such as solid-phase microextraction. (C) 2008 Elsevier B.V. All rights reserved.