| As a kind of separation technique and method, chromatography has become awidely used analytical method after a century of development. And GC is a rathermature and widely used technique in the separation and analyses of complex mixture.Gas chromatography usually suffers from its own drawbacks and also low detectionlevel is required. So sample preparation is very important in order to extract, isolateand concentrate the target analytes from these complicated matrices to obtain samplescompatible for instrumental analysis. Traditional preconcentration techniques needlarge amounts of toxic organic solvents, which are environmentally hazardous andcould harm analysts.More recently, a novel LPME technique named dispersive liquid-liquidmicroextraction （DLLME） was proposed by Assadi and Coworkers, it is based onternary component solvent system such as Homogenous liquid-liquid extraction（HLLE） and Cloud point extraction （CPE）. DLLME has the advantages of ease ofoperation, very short extraction time, low cost and high enrichment factors and isenvironmentally friendly. It has been widely applied for the determination of phthalateesters, herbicides, emerging contaminants and metal ions and so on. This paper isfocused on the application of dispersive liquid-liquid microextraction coupled withgas chromatography in the research of milk, teas and fruit juices.1.A novel extraction method termed surfactant-assisted dispersive liquid-liquidmicroextraction （SA-DLLME） prior to gas chromatography-flame ionizationdetection （GC-FID） was developed for extraction and determination of four phthalateesters （PEs） in milk samples. Some parameters that affect the extraction efficiency were investigated and optimized in this developed technique, such as the type andvolume of extraction solvent, the type and concentration of surfactant, the salt addedand pH value. Under the optimal conditions, the linear range of DMP, DEP, DBP andDEHP obtained was in the range of20500μg L-1, the linear range of DCHP was50500μg L-1with the correlation coefficients （R2） ranging from0.9955to0.9999, thelimits of detection （LODs） were7.314.0μg L-1, the relative standard deviations（RSDs）（n=5） varied from2.4%to6.9%, the enrichment factors （EFs） were19.925.8.The recoveries of PEs from milk samples were ranged from81.5%to129.3%. Theproposed method was demonstrated to be simple, low-cost and practical in thedetermination of PEs in milk samples.2. In this present work, a novel dispersive liquid-liquid microextraction based onsolidification of floating organic droplet （DLLME-SFO） method followed by gaschromatography was applied for determination of organophosphorus pesticides （OPPs）in teas. In this proposed method, a serious of important experimental parameters thataffect extraction efficiency were optimized, such as the type and volume of extractionand dispersive solvents, the amount of salt-addition. Under optimized conditions, thelinear range for methyl parathion and fenthion were0.060.8and0.040.8μg mL-1with the correlation coefficients （R2） ranging from0.9890to0.9982, the limits ofdetection （LODs） were0.051and0.027μg mL-1, and relative standard deviations（RSDs） fell in the range of1.06.5%, and the enrichment factors （EFs） varied from71.5to136.7. The recoveries of the target analytes were between64.9%and134.1%.3. A traditional dispersive liquid-liquid microextraction combined with gaschromatography was developed for the determination of OPPs in fruit juices. Someimportant environmental parameters were investigated such as the kind and volume ofextraction and dispersive solvents and salt effect. Under optical conditions, the linearranges of phorate, methyl parathion and fenthion were0.0240.4,0.040.5and0.0240.4μg mL-1with the correlation coefficients varying from0.9811to0.9962, theLODs for phorate, methyl parathion and fenthion were0.021,0.024and0.018μgmL-1respectively, and the method precision varied from7.2%to15.7%, and high EFswere achieved in the range of143226. The recoveries of the analytes from fruitjuices were in the range of51.8128.9%. |
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