title: Optimization and application of SPME for the gas chromatographic determination of endosulfan and its major metabolites in the ng L(-1) range in aqueous solutions.
abstract: In the present study an analytical method was optimized for the determination of alpha-endosulfan, beta-endosulfan, endosulfan sulfate, endosulfan ether and endosulfan lactone in small volumes of environmental aqueous samples using solid-phase microextraction (SPME) and gas chromatography-electron capture detection (GC-ECD). A 100 micro m polydimethylsiloxane (PDMS) phase was used for the extraction. The limit of detection (LOD) for the analytes varied between 0.01 and 0.03 micro g L(-1) with a relative standard deviation of 3 to 11%. The influence of the ionic strength on the extraction efficiency was investigated for the individual compounds. alpha-Endosulfan, beta-endosulfan, endosulfan sulfate and endosulfan ether were extracted successfully without salt addition. The extraction efficiency of endosulfan lactone was improved with 30% NaCl content. A general decrease in extraction efficiency for alpha-endosulfan, beta-endosulfan, endosulfan sulfate and endosulfan ether with high NaCl content (20-30%) in the solution was observed due to glass surface adsorption. No effect of dissolved organic material (DOM) on the extraction efficiency was observed. The extraction coefficients changed between Log K=2.17 and 3.33. A sample from the Antarctic region was analyzed using the optimized GC-ECD/SPME method. To confirm the results obtained for the real sample a GC with a mass spectrometer (MS) was used. Endosulfan sulfate, the most toxic metabolite of endosulfan, was found in the sample at a concentration of 0.3 micro g L(-1).
authors.affiliation: Engler-Bunte-Institut, Bereich Wasserchemie, Universität Karlsruhe (TH), Engler-Bunte-Ring 1, Germany.
authors.forename: A B
authors.initials: AB
authors.lastname: Deger
authors.forename: T J
authors.initials: TJ
authors.lastname: Gremm
authors.forename: F H
authors.initials: FH
authors.lastname: Frimmel
authors.forename: L
authors.initials: L
authors.lastname: Mendez
mesh_terms: D000864:Antarctic Regions; D002849:Chromatography, Gas / Q000379:methods*; D004726:Endosulfan / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D006843:Hydrocarbons, Chlorinated; D007053:Ice; D007306:Insecticides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D009994:Osmolar Concentration; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D006843:Hydrocarbons, Chlorinated; D007053:Ice; D007306:Insecticides; D012996:Solutions; D004726:Endosulfan