Analysis of sediment-associated insecticides using ultrasound assisted microwave extraction and gas chromatography-mass spectrometry

An ultrasound assisted microwave extraction (UAME) method was developed to simultaneously extract five organophosphate (OP) and eight pyrethroid insecticides from sediment The optimized UAME conditions were to use 100 ml of a mixture of hexane and acetone (1 1 v/v) solution as the extraction solvents and extraction time microwave and ultrasonic power settings of 6 min 100 W and 50W respectively Extracts were cleaned using solid phase extraction and analyzed by gas chromatography-mass spectrometry in negative chemical ionization mode and quantification was based on matrix-matched standard solutions along with internal standard calibration At the spiked concentrations of 1 5 and 20 ng/g dry weight (dw) recoveries of OPs were 776-122% 65 2-128% and 756-141% with relative standard deviations (RSDs) of 10 6-181% 3 1-125% and 8 0-35 3% respectively while recoveries of pyrethroids were 780-101% 764-104% and 71 0-99 5% with RSDs of 10 3-23 5% 4 7-17 6% and 8 8-18 7% respectively Method detection limits ranged from 031 to 045 ng/g dw for the OP insecticides and from 027 to 0 70 ng/g dw for the pyrethroid insecticides The newly developed UAME method was validated by comparing it to Soxhlet and sonication extraction methods Better recoveries were achieved for most OPs by the novel UAME method whereas there was no significant difference in recoveries for most of I he pyrethroids Finally the UAME method was used to quantify the target insecticides in field-contaminated sediment samples which were collected in Guangzhou China (C) 2010 Elsevier B V All rights reserved