DLLME in Pesticide Residue Analysis Reporter:Yuhong Qin Parterners:Xiaoning Li,Yongna Li Supervisors:Canping Pan Yuxia Hou,YaJia Liu

Contents 1.History 2.Introduction 3.Applications 4.Comparison 5. References

History Dispersive liquid–liquid microextraction (DLLME) as a novel liquid-phase microextraction technique was developed by Mohammad Rezaee in It is based on ternary component solvent system such as Homogeneous liquid–liquid extraction(HLLE) and Cloud-point extraction(CPE). The performance of DLLME is illustrated with the determination of polycyclic aromatic hydrocarbons (PAHs) in water samples by using GC-FID.

History Also, the ability of DLLME technique in the extraction of other organic compounds such as organochlorine pesticides (OCPs),organophosphorus pesticides (OPPs) and benzene, toluene,ethyl benzene and xylenes (BTEX), carbamate pesticides from water samples was studied.

Introduction

Applications

PAHs:A 5.00mL of bidistilled water was placed in a 10mL screw cap glass test tube with conic bottom and spiked at the level of 2μg/L of PAHs and biphenyl (as internal standard). 1.00mL of acetone (as disperser solvent) containing 8.0μL C 2 Cl 4 (as extraction solvent). GC-FID

Applications

Applications(ultrasound-assisted solvent extraction followed by DLLME) by) Ops:Analytical portions of 1.00 g homogenised sample spiked or not with pesticides was exactly weighted into a 10-ml screw cap centrifuge tube and 5.0 ml of acetone (as extractant) and 10.0 μL of 5.0 mg/L triphenyl phosphate in methanol as internal standard were added and extracted in an ultrasonic bath for 35 min. After this step 60.0 μL of chlorobenzene, which is a microextraction solvent in DLLME, was added to screw cap centrifuge tube.GC-MS

Applications

Applications(Ionic liquid based DLLME) One gram of homogenized bananas (1 kg) was weighed into the 50mL centrifuge tube and spiked with a small volume of an appropriate standard mixture solution. Samples and standards were carefully mixed (with the help of ultrasounds) and left at room temperature for at least 30 min before the extraction procedure. Then, 5mL of ACN were added and the tube was closed and shaken vigorously by hand for 1min. To induce phase separation and pesticide partitioning, a buffer-salt mixture (consisting of 2g of anhydrous magnesium sulfate, 0.5g of sodium chloride, 0.5 g of sodium citrate tribasic dehydrate and 0.25 g of sodium hydrogencitrate sesquihydrate) was added. The tube was closed and immediately shaken vigorously on a Vortex mixer for 1min. Then, the mixture was sonicated for 5min and centrifuged at 4000rpm for 10 min. The supernatant was filtered through a 0.45μm filter. And evaporated at 40 ◦ C and 205 mbar, The residue was dissolved with 10mL of Milli-Q water at pH 2.7 (adjusted with 1.0M HCl) containing 28.9% NaCl (w/v) and subjected to DLLME.

Applications(Ionic liquid based DLLME) Multiple pesticides ： A mixture of 88mg of 1-hexyl- 3-methylimidazolium hexafluorophosphate [C6MIM][PF6] (extraction solvent) and 714μL of methanol (disperser solvent) was immediately injected into the sample solution in order to induce the formation of a cloudy solution, which consisted in fine droplets of IL dispersed in the aqueous sample. HPLC-DAD

Applications(Ionic liquid based DLLME)

Comparison Advantages:simplicity of operation, rapidity, low-cost, high-recovery and high-enrichment factor, offering potential for ultra-trace analysis.

References 1. Zhi Mei Liu et al. Novel method for the determination of five carbamate pesticides in water samples by dispersive liquid–liquid microextraction combined with high performance liquid chromatography. Chinese Chemical Letters 20 (2009) 213– S.C. Cunha et al. Fast analysis of multiple pesticide residues in apple juice using dispersive liquid–liquid microextraction and multidimensional gas chromatography–mass spectrometry. Journal of Chromatography A, 1216 (2009) 8835– Lidia M. Ravelo-Pérez et al. Ionic liquid based dispersive liquid–liquid microextraction for the extraction of pesticides from bananas. Journal of Chromatography A, 1216 (2009) 7336– Mohammad Rezaee et al. Determination of organic compounds in water using dispersive liquid–liquid microextraction. Journal of Chromatography A, 1116 (2006) Kristof Demeestere et al. Sample preparation for the analysis of volatile organic compounds in air and water matrices. Journal of Chromatography A, 1153 (2007) 130–144

References 6. Carol Cortada et al. Determination of organochlorine pesticides in water samples by dispersive liquid–liquid microextraction coupled to gas chromatography–mass spectrometry. Analytica Chimica Acta 649 (2009) 218– Araz Bidari et al. Sample preparation method for the analysis of some organophosphorus pesticides residues in tomato by ultrasound-assisted solvent extraction followed by dispersive liquid–liquid microextraction. Food Chemistry 126 (2011) 1840–1844

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