title: Dispersive liquid-liquid microextraction coupled with programmed temperature vaporization-large volume injection-gas chromatography-tandem mass spectrometry for multiclass pesticides in water.
abstract: A simple solvent-less procedure for the determination of seventeen pesticides and related compounds in environmental water and wastewater using dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry in tandem (GC-MS/MS) with large-volume injection, having a programmed temperature vaporizer (PTV-LVI), is described. The parameters affecting the extraction efficiency of the target analytes from water samples were systematically investigated. A response surface Doehlert design was used. The best extraction conditions involved a rapid injection of a mixture of 1.9 mL of acetonitrile (as a dispersant) and 178 μL of trichloroethane (as an extractant) into 10 mL of water placed in a conical bottom glass tube. After manually shaken for 3.0 min and centrifugation at 3600 rpm (5 min), 50 μL of the sedimented phase was directly injected into the PTV-LVI-GC-MS/MS system. The limits of quantitation (LOQs) ranged from 0.5 to 18 ng L⁻¹ for all pesticides, except empentrin (132 ng L⁻¹). The relative standard deviations (RSDs) for the analytes ranged between 0.8 and 14.6% for both intraday and interday precision. Accuracy, expressed as the mean extraction recovery, was between 70 and 130%. Using the internal standard method and surrogate deuterated standards, the total concentration of pesticides was in the range from 2.7 to 440 ng L⁻¹ in seawater, river water and sewage water.
authors: Dpto. de Química Analítica, Nutrición y Bromatología, Facultad de Química, Universidad de Santiago de Compostela, Avda. de las Ciencias, s/n 15782 Santiago de Compostela, Spain. tuchi.carro@usc.es
authors: A M
authors: AM
authors: Carro
authors: S
authors: S
authors: Fernández
authors: I
authors: I
authors: Racamonde
authors: D
authors: D
authors: García-Rodríguez
authors: P
authors: P
authors: González
authors: R A
authors: RA
authors: Lorenzo
mesh_terms: D000704:Analysis of Variance; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D059627:Liquid Phase Microextraction / Q000379:methods*; D009994:Osmolar Concentration; D010575:Pesticides / Q000032:analysis* / Q000302:isolation & purification*; D012044:Regression Analysis; D015203:Reproducibility of Results; D012623:Seawater / Q000737:chemistry; D012680:Sensitivity and Specificity; D012722:Sewage / Q000737:chemistry; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000302:isolation & purification*
chemical_list: D010575:Pesticides; D012722:Sewage; D014874:Water Pollutants, Chemical