Dispersive Solid Phase Extraction Clean-up and Gas Chromatography-Mass Spectrometry for Determination of Phthalate Esters in Soil Samples
A method was developed to determine phthalate esters in soil samples.The entire pre-treatment process involved microwave-assisted extraction,solvent conversion and clean-up of dispersive solid-phase extraction(DSPE).A total of 10 g soil sample was extracted by microwave mixed with 20 mL mixed-phase solvent of dichloromethane and acetone.And then the extract of mixed-phase was converted into the acetone-phase and then concentrated to 1.5 mL extract.The concentrated extract was shaken for 3 min that mixed with 0.2 g C18 absorbent,and centrifuged for 10 min(8000 r/min).The supernatant(1.0 mL) was quantitatively transferred and converted into n-hexane phase.The entire clean-up process was lower than 20 min.1.0 mL of the supernatant liquid was transferred into vial and then exchanged to hexane.Gas chromatography/mass spectrometry(GC/MS) was used for quantitative and confirmatory analysis of phthalate esters.The matrix effect of phthalate esters was compensated by matrix spiked calibration.The best removal efficiency of soil matrix was 72.65%.The method linearity range was 7.5-750 μg/kg(r0.998).The RSDs of the actual soil samples and the spiked samples were 5.5%-12.1% and 7.3%-19.4%,respectively.The average recovery of the spiked samples was 94.4%-114.6%,and the detection limit of the phthalate esters in soil samples was 1.2-4.3 μg/kg.