Qingyun Chang

Publications (2)7.23 Total impact

• Article: Analysis of eight pyrethroids in water samples by liquid–liquid microextraction based on solidification of floating organic droplet combined with gas chromatography

  Qingyun Chang, Tao Feng, Shuangju Song, Xin Zhou, Chun Wang, Zhi Wang
  [show abstract] [hide abstract]
  ABSTRACT: A novel method was developed for the determination of eight pyrethroids in water samples by liquid–liquid microextraction based on solidification of floating organic droplets followed by gas chromatography with electron capture detection. The type and volume of the extraction solvents, extraction time, sample solution temperature, stirring rate and ionic strength were studied and optimized. Under the optimum conditions, enrichment factors ranged from 824 to 1,432, and the limit of detection range from 2.0 to 50ng∙L−1. The calibration graph is linear from 0.15 to 80μg∙L−1 for cyfluthrin, fenvalerate, fluvalinate and deltamethrin, 0.09 to 80μg∙L−1 for fenpropathrin, 0.006 to 80μg∙L−1 for lambda-cyhalothrin, 0.026 to 80μg∙L−1 for permethrin, 0.01 to 80μg∙L−1 for cypermethrin. The correlation coefficients (r) varied from 0.9961 to 0.9988. The method was successfully applied to the determination of pyrethroid pesticide residues in tap water, well water, reservoir water, and river water. Recoveries ranged from 79.0% to 113.6%, and relative standard deviations are between 4.1% and 8.7%. KeywordsPyrethroids-GC-ECD-Water samples-Liquid–liquid microextraction based on solidification of floating organic droplet
  Microchimica Acta 04/2012; 171(3):241-247. · 3.03 Impact Factor
• Article: Ultrasound-assisted surfactant-enhanced emulsification microextraction for the determination of carbamate pesticides in water samples by high performance liquid chromatography.

  Qiuhua Wu, Qingyun Chang, Chunxia Wu, Huan Rao, Xin Zeng, Chun Wang, Zhi Wang
  [show abstract] [hide abstract]
  ABSTRACT: A novel ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) coupled with high performance liquid chromatography-diode array detection has been developed for the extraction and determination of six carbamate pesticides (metolcarb, carbofuran, carbaryl, pirimicarb, isoprocarb and diethofencarb) in water samples. In the UASEME technique, Tween 20 was used as emulsifier, and chlorobenzene and chloroform were used as dual extraction solvent without using any organic dispersive solvent that is normally required in the previously described common dispersive liquid-liquid microextraction method. Parameters that affect the extraction efficiency, such as the kind and volume of the extraction solvent, the type and concentration of the surfactant, ultrasound emulsification time and salt addition, were investigated and optimized for the method. Under the optimum conditions, the enrichment factors were in the range between 170 and 246. The limits of detection of the method were 0.1-0.3 ng mL(-1) and the limits of quantification were between 0.3 and 0.9 ng mL(-1), depending on the compounds. The linearity of the method was obtained in the range of 0.3-200 ng mL(-1) for metolcarb, carbaryl, pirimicarb, and diethofencarb, 0.6-200 ng mL(-1) for carbofuran, and 0.9-200 ng mL(-1) for isoprocarb, with the correlation coefficients (r) ranging from 0.9982 to 0.9998. The relative standard deviations varied from 3.2 to 4.8% (n=5). The recoveries of the method for the six carbamates from water samples at spiking levels of 1.0, 10.0, 50.0 and 100.0 ng mL(-1) were ranged from 81.0 to 97.5%. The proposed UASEME technique has demonstrated to be simple, practical and environmentally friendly for the determination of carbamates residues in river, reservoir and well water samples.
  Journal of chromatography. A 01/2010; 1217(11):1773-8. · 4.19 Impact Factor