Determination of priority pollutants in aqueous samples by dispersive liquid-liquid microextraction

A dispersive liquid-liquid microextraction (DLLME) method followed by high-performance liquid chromatography-triple quadrupole mass spectrometry has been developed for the simultaneous determination of linear alkylbenzene sulfonates (LAS C10, C11, C12, and C13), nonylphenol (NP), nonylphenol mono- and diethoxylates (NP1EO and NP2EO), and di-(2-ethylhexyl)phthalate (DEHP). The applicability of the method has been tested by the determination of the above mentioned organic pollutants in tap water and wastewater. Several parameters affecting DLLME, such as, the type and volume of the extraction and disperser solvents, sample pH, ionic strength and number of extractions, have been evaluated. Methanol (1.5 mL) was selected among the six disperser solvent tested. Dichlorobenzene (50 μL) was selected among the four extraction solvent tested. Enrichment factor achieved was 80. Linear ranges in samples were 0.01-3.42 μg L(-1) for LAS C10-13 and NP2EO, 0.09-5.17 μg L(-1) for NP1EO, 0.17-9.19 μg L(-1) for NP and 0.40-17.9 μg L(-1) for DEHP. Coefficients of correlation were higher than 0.997. Limits of quantitation in tap water and wastewater were in the ranges 0.009-0.019 μg L(-1) for LAS, 0.009-0.091 μg L(-1) for NP, NP1EO and NP2EO and 0.201-0.224 μg L(-1) for DEHP. Extraction recoveries were in the range from 57 to 80%, except for LAS C10 (30-36%). The method was successfully applied to the determination of these pollutants in tap water and effluent wastewater from Seville (South of Spain). The DLLME method developed is fast, easy to perform, requires low solvent volumes and allows the determination of the priority hazardous substances NP and DEHP (Directive 2008/105/EC).