title: Comparison of air-agitated liquid-liquid microextraction technique and conventional dispersive liquid-liquid micro-extraction for determination of triazole pesticides in aqueous samples by gas chromatography with flame ionization detection.
abstract: Two micro-extraction methods, air-agitated liquid-liquid microextraction (AALLME) and dispersive liquid-liquid microextraction (DLLME), have been compared with each other by applying them for the analysis of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole and triticonazole) in aqueous samples by gas chromatography with flame ionization detection (GC-FID). In the AALLME method, which excludes any disperser solvent, much less volume of organic solvent is used. In order to form fine and dispersed organic droplets in the aqueous phase, the mixture of aqueous sample solution and extraction solvent is repeatedly aspirated and dispensed with a syringe. In the DLLME method, an appropriate mixture of extraction solvent and disperser solvent is rapidly injected by a syringe into the aqueous sample. Effect of the pertinent experimental factors on DLLME (i.e. identity and volume of the extraction and disperser solvents and ionic strength) and on AALLME (identity and volume of the extraction solvent, number of agitations, and ionic strength) were investigated. Under optimal conditions, limits of detection for the five target pesticides obtained by AALLME-GC-FID and DLLME-GC-FID ranged from 0.20 to 1.1ngmL(-1) and 1.9 to 5.9ngmL(-1), respectively. The relative standard deviations (RSDs, n=5) were in the range of 1-4% and 3-5% with the enrichment factors of 449-504 and 79-143 for AALLME-GC-FID and DLLME-GC-FID, respectively. Both of the compared methods are simple, fast, efficient, inexpensive and can be applied to the analysis of the five pesticides in different aqueous samples in which penconazole and hexaconazole were found. For spiked samples, the recoveries were in the ranges of 92-105%, and 92-104% for AALLME and DLLME, respectively.
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran. mafarajzadeh@yahoo.com
authors.forename: Mir Ali
authors.initials: MA
authors.lastname: Farajzadeh
authors.forename: Mohammad Reza Afshar
authors.initials: MR
authors.lastname: Mogaddam
authors.forename: Abdollah Abdollahi
authors.initials: AA
authors.lastname: Aghdam
mesh_terms: D001628:Beverages / Q000032:analysis*; D002498:Centrifugation; D015946:Ethylene Dibromide; D005410:Flame Ionization / Q000379:methods*; D005618:Fresh Water / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D059627:Liquid Phase Microextraction / Q000379:methods*; D018551:Solanum lycopersicum / Q000737:chemistry; D000432:Methanol / Q000737:chemistry; D010573:Pesticide Residues / Q000032:analysis* / Q000302:isolation & purification; D015203:Reproducibility of Results; D012965:Sodium Chloride / Q000737:chemistry; D014230:Triazoles / Q000032:analysis* / Q000302:isolation & purification; D027843:Vitis / Q000737:chemistry
chemical_list: D010573:Pesticide Residues; D014230:Triazoles; D015946:Ethylene Dibromide; D012965:Sodium Chloride; D000432:Methanol
keywords: Air-agitated liquid–liquid micro-extraction; Dispersive liquid–liquid micro-extraction; Gas chromatography; Triazole pesticides