title: In-syringe demulsified dispersive liquid-liquid microextraction and high performance liquid chromatography-mass spectrometry for the determination of trace fungicides in environmental water samples.
abstract: An in-syringe demulsified dispersive liquid-liquid microextraction (ISD-DLLME) technique was developed using low-density extraction solvents for the highly sensitive determination of the three trace fungicides (azoxystrobin, diethofencarb and pyrimethanil) in water samples by high performance liquid chromatography-mass spectrometry chromatography-diode array detector/electrospray ionisation mass spectrometry. In the proposed technique, a 5-mL syringe was used as an extraction, separation and preconcentration container. The emulsion was obtained after the mixture of toluene (extraction solvent) and methanol (dispersive solvent) was injected into the aqueous bulk of the syringe. The obtained emulsion cleared into two phases without centrifugation, when an aliquot of methanol was introduced as a demulsifier. The separated floating organic extraction solvent was impelled and collected into a pipette tip fitted to the tip of the syringe. Under the optimal conditions, the enrichment factors for azoxystrobin, diethofencarb and pyrimethanil were 239, 200, 195, respectively. The limits of detection, calculated as three times the signal-to-noise ratio (SN(-1)), were 0.026 μg L(-1) for azoxystrobin, 0.071 μg L(-1) for diethofencarb and 0.040 μg L(-1) for pyrimethanil. The repeatability study was carried out by extracting the spiked water samples at concentration levels of 0.02 μg mL(-1) for all the three fungicides. The relative standard deviations varied between 4.9 and 8.2% (n=5). The recoveries of all the three fungicides from tap, lake and rain water samples at spiking levels of 0.2, 1, 5 μg L(-1) were in the range of 90.0-105.0%, 86.0-114.0% and 88.6-110.0%, respectively. The proposed ISD-DLLME technique was demonstrated to be simple, practical and efficient for the determination of different kinds of fungicide residues in real water samples.
authors.affiliation: Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan, China.
authors.forename: Yating
authors.initials: Y
authors.lastname: Xia
authors.forename: Min
authors.initials: M
authors.lastname: Cheng
authors.forename: Feng
authors.initials: F
authors.lastname: Guo
authors.forename: Xiangfang
authors.initials: X
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Cheng
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004655:Emulsions; D004784:Environmental Monitoring; D005659:Fungicides, Industrial / Q000032:analysis*; D057230:Limit of Detection; D059627:Liquid Phase Microextraction / Q000379:methods*; D013058:Mass Spectrometry; D008689:Methacrylates / Q000032:analysis; D000432:Methanol / Q000737:chemistry; D010573:Pesticide Residues / Q000032:analysis*; D048448:Phenylcarbamates / Q000032:analysis; D011743:Pyrimidines / Q000032:analysis; D015203:Reproducibility of Results; D000073739:Strobilurins; D014050:Toluene / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D004655:Emulsions; D005659:Fungicides, Industrial; D008689:Methacrylates; D010573:Pesticide Residues; D048448:Phenylcarbamates; D011743:Pyrimidines; D000073739:Strobilurins; D014874:Water Pollutants, Chemical; D014050:Toluene; C070961:diethofencarb; C108337:pyrimethanil; C087670:azoxystrobin; D000432:Methanol