Development of liquid phase microextraction method based on solidification of floated organic drop for extraction and preconcentration of organochlorine pesticides in water samples

Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.
Analytica chimica acta (Impact Factor: 4.52). 10/2008; 626(2):166-73. DOI: 10.1016/j.aca.2008.08.001
Source: PubMed

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.

  • Source
    Pesticides - Strategies for Pesticides Analysis, 01/2011; , ISBN: 978-953-307-460-3
  • [Show abstract] [Hide abstract]
    ABSTRACT: The study presents the possibility of multi-criteria decision analysis (MCDA) application when choosing analytical procedures with low environmental impact. A type of MCDA, Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE), was chosen as versatile tool that meets all the analytical chemists - decision makers requirements. Twenty five analytical procedures for aldrin determination in water samples (as an example) were selected as input alternatives to MCDA analysis. Nine different criteria describing the alternatives were chosen from different groups - metrological, economical and the most importantly - environmental impact. The weights for each criterion were obtained from questionnaires that were sent to experts, giving three different scenarios for MCDA results. The results of analysis show that PROMETHEE is very promising tool to choose the analytical procedure with respect to its greenness. The rankings for all three scenarios placed solid phase microextraction and liquid phase microextraction - based procedures high, while liquid-liquid extraction, solid phase extraction and stir bar sorptive extraction - based procedures were placed low in the ranking. The results show that although some of the experts do not intentionally choose green analytical chemistry procedures, their MCDA choice is in accordance with green chemistry principles. The PROMETHEE ranking results were compared with more widely accepted green analytical chemistry tools - NEMI and Eco-Scale. As PROMETHEE involved more different factors than NEMI, the assessment results were only weakly correlated. Oppositely, the results of Eco-Scale assessment were well-correlated as both methodologies involved similar criteria of assessment. Copyright © 2015 Elsevier B.V. All rights reserved.
    Journal of Chromatography A 02/2015; 1387:116-122. DOI:10.1016/j.chroma.2015.02.009 · 4.26 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A simple, rapid and inexpensive solidified floating organic drop microextraction (SFODME) and flow injection flame atomic absorption spectrometric determination (FI-FAAS) method for copper were developed. 3-amino-7-dimethylamino-2-methylphenazine (Neutral red, NR) was used as the complexing agent. Several factors affecting the microextraction efficiency, such as, pH, NR and sodium dodecylbenzenesulfonate (SDBS) concentration, extraction time, stirring rate, and temperature were investigated and optimized. Under optimized experimental conditions an enrichment factor of 541 was obtained for 100mL of sample solution. The calibration graph was linear in the range of 0.5–20.0ngmL−1 and the limit of detection (3s) was 0.18ngmL−1, the limit of quantification (10s) was 0.58ngmL−1. The relative standard deviation (RSD) for 10 replicate measurements of 10ngmL−1 copper was 2.7%. The developed method was successfully applied to the extraction and determination of copper in different certified reference materials (Estuarine water, Slew 3 and fortified water, TM 23.2) and real water samples and satisfactory results were obtained.
    Microchemical Journal 07/2011; 98(2):215-219. DOI:10.1016/j.microc.2011.02.001 · 3.58 Impact Factor