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چكيده انگليسي :

Application of dispersive liquid liquid microextraction for determination of phenylurea herbicides in water samples by high performance liquid chromatography Neda Tansazan neda 10@ch iut ac ir March 1 2009 Department of Chemistry Isfahan University of Technologhy Isfahan 84156 83111 IranDegree M sc Language FarsiSupervisor Assist Prof Mohammad Saraji saraji@cc iut ac ir AbstractRecently a new technique so called dispersive liquid liquid microextraction has been extensively used forthe extraction of organic and inorganic compounds from environmental samples Phenylureas PhUs arethe type of herbicides more widely used in pre and post emergence Consequently they can give rise toresidues in crops soils and surface waters The widespread agricultural use toxicity and possiblecarcinogenicity of the PhU herbicides have stimulated the development of methods for their detection The potential toxicity of these compounds is regulated in the European Community allowing a maximumof 0 1 g L of any single pesticide in drinking waters In this work dispersive liquid liquid microextraction coupled with Reversed Phase high performanceliquid chromatography diode array detector RP HPLC DAD was applied for the extraction anddetermination of phenylurea herbicides PUHs from water samples For the extraction 2150 0 Ldispersive solution containing 2000 L dispersive solvent acetone and 150 L extraction solvent carbondisulfide toluene was injected rapidly into a glass tube with conical bottom containing aqueous solution ofPUHs by a 5000 L syringe Gastight Hamilton This injection led to a cloudy water solution caused bythe fine droplets dispersion of the immiscible extraction solvent carbon disolfide in the aqueous sample The result of this phenomenon was the generation of a high contact area between the aqueous phase and theextraction solvent The final step of the microextraction procedure was centrifugation 4 min at 3500 rpm to collect the dispersed tinny disolphid carbon droplets in the bottom of the conical test tube Aftercentrifugation the sedimented phase was complectely transferred to another tube with conical bottom usinga 250 0 L HPLC syringe The volume of the sedimented phase was about 145 0 5 L Then the organicsolvent was evaporated by a slow flow of nitrogen gas and the residue was redissolved in 25 0 L mixtureof methanol water 50 50 and 20 0 L of the solution was injected into the HPLC The compounds oftebuthiuron thidiazuron fluometuron diuron propanil siduron linuron and diflubenzuron were studied Inorder to obtain optimum condition of the extraction eight parameters affecting on the extraction such as extraction solvent type dispersive solvent type extraction and dispersive solvent volume salt addition co solvent type fraction of co solvent and effect of NaCl in present of co solvent were studied Underoptimum condition namely extracting solvent carbon disulfide dispersive solvent acetone extractingsolvent volume 160 0 L volume of dispersive solvent 2 00 mL without salt addition and 30 toluene asco solvent The method was evaluated with respect to the LODs according to Environmental ProtectionAgency EPA Method 532 Enrichment factors and limits of detections LODs were ranged 11 3 117 8and 0 01 0 5 g L respectively The relative standard deviations R S D s for analysis of 5 g L of eachPUHs in water samples were in the range of 3 0 7 7 n 5 Good linearity was obtained in the range of0 2 200 g L for the most compounds and correlation coffieients ranged from 0 9925 0 9995 Also R S D sfor spiked water solutions at level of 5 g L of each PUHs were ranged between 1 0 and 12 7 n 5 As aresult the proposed method was used for analysis of rael samples such as tap water well water zayandehrood Esfahan river water and 3000 tonekabon river water Keywords Dispersive liquid liquid microextraction HPLC DAD Phenylureaherbicides Co solvent

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كاربرد ريز استخراج مايع - مايع پخشي براي اندازه گيري علف كش هاي فنيل اوره در نمونه هاي آب توسط كروماتوگرافي مايع با كارايي بالا

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