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چکیده
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Continuous sample drop flow-based microextraction (CSDF-ME) is an improved version of continuousflow microextraction (CFME) and a novel technique developed for extraction and preconcentration of benzene, toluene, ethyl benzene, m-xylene and o-xylene (BTEXs) from aqueous samples prior to gas chromatography–flame ionization detection (GC–FID). In this technique, a small amount (a few microliters) of organic solvent is transferred to the bottom of a conical bottom test tube and a few mL of aqueous solution is moved through the organic solvent at relatively slow flow rate. The aqueous solution transforms into fine droplets while passing through the organic solvent. After extraction, the enriched analyte in the extraction solvent is determined by GC–FID. The type of extraction solvent, its volume, needle diameter, and aqueous sample flow rate were investigated. The enrichment factor was 221–269 under optimum conditions and the recovery was 89–102%. The linear ranges and limits of detection for BTEXs were 2–500 and 1.4–3.1 mg L1, respectively. The relative standard deviations for 10 mg L1 of BTEXs in water were 1.8–6.2% (n¼5). The advantages of CSDF-ME are its low cost, relatively short sample preparation time, low solvent consumption, high recovery, and high enrichment factor
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