title: Development of liquid phase microextraction method based on solidification of floated organic drop for extraction and preconcentration of organochlorine pesticides in water samples.
abstract: A simple and efficient liquid-phase microextraction (LPME) in conjunction with gas chromatography-electron capture detector (GC-ECD) has been developed for extraction and determination of 11 organochlorine pesticides (OCPs) from water samples. In this technique a microdrop of 1-dodecanol containing pentachloronitrobenzene (internal standard) is delivered to the surface of an aqueous sample while being agitated by a stirring bar in the bulk of solution. Following completion of extraction, the sample vial was cooled by putting it into an ice bath for 5 min. Finally 2 muL of the drop was injected into the GC for analysis. Factors relevant to the extraction efficiency were studied and optimized. Under the optimized extraction conditions (extraction solvent: 1-dodecanol; extraction temperature: 65 degrees C; sodium chloride concentration: 0.25 M; microdrop and sample volumes: 8 muL and 20 mL respectively; the stirring rate: 750 rpm and the extraction time: 30 min), figures of merit of the proposed method were evaluated. The detection limits of the method were in the range of 7-19 ngL(-1) and the RSD% for analysis of 2 mugL(-1) of OCPs was below 7.2% (n=5). A good linearity (r(2)> or =0.993) and a relatively broad dynamic linear range (25-2000 ngL(-1)) were obtained. After 30 min of extraction, preconcentration factors were in the range of 708-1337 for different organochlorine pesticides and the relative errors ranged from -10.1 to 10.9%. Finally the proposed method was successfully utilized for preconcentration and determination of OCPs in different real samples.
authors.affiliation: Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.
authors.forename: Hadi
authors.initials: H
authors.lastname: Farahani
authors.forename: Yadollah
authors.initials: Y
authors.lastname: Yamini
authors.forename: Shahab
authors.initials: S
authors.lastname: Shariati
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Khalili-Zanjani
authors.forename: Saeed
authors.initials: S
authors.lastname: Mansour-Baghahi
mesh_terms: D005591:Chemical Fractionation; D002849:Chromatography, Gas; D007851:Dodecanol / Q000737:chemistry; D006843:Hydrocarbons, Chlorinated / Q000032:analysis* / Q000302:isolation & purification; D015999:Multivariate Analysis; D009578:Nitrobenzenes / Q000737:chemistry; D010575:Pesticides / Q000032:analysis* / Q000302:isolation & purification; D012044:Regression Analysis; D013696:Temperature; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000302:isolation & purification
chemical_list: D006843:Hydrocarbons, Chlorinated; D009578:Nitrobenzenes; D010575:Pesticides; D014874:Water Pollutants, Chemical; D014867:Water; D007851:Dodecanol; C005805:quintozene