Papers by Author: Wei Liu

Abstract: A novel method for determination of organochlorine pesticides residuals (2,4-DDT and 4,4-DDT) in water samples through hollow fiber membrane-liquid phase microextraction using ionic liquid material as extractant coupled with high performance liquid chromatography has been developed. The effect of extraction parameters including pH of the feed solution, stirring rate and extraction time was investigated. The proposed method provided enrichment efficiency of 323 and 289 for 2,4-DDT and 4,4-DDT respectively. The method had good linear range of 0.5-50 μg /L and the limits of detection of the pesticides were 0.1 μg /L.

Abstract: Supported emulsion liquid membrane using copper(Ⅱ) N-dodecyl-(L)- hydroxyproline as a chiral carrier was used as a novel technique to extract L-theanine. The effects of initial concentration of L-theanine in the feed phase, chiral carrier concentration in the membrane phase and salt concentration in receiving phase on extraction performance were studied and some optimum conditions were achieved.

Abstract: This paper deals with the partittion-diffusion model of transport and enantioseparation of phenylalanine across hollow fiber supported liquid membranes. Observed partition coefficient between the feed phase and the membrane phase, the stripping phase and the membrane phase, mass transfer resistance of boundary layer in strip phase inside the hollow fibers, boundary layer in feed phase and the diffusion in the membrane phase are taken into account in the model equations.

Abstract: Extraction of amygdalin by ethanol refluxing from waste loquat kernel was performed successfully. Amygdalin concentrations were determined by using ultraviolet spectrophotometry with ethanol as solvent at 210 nm. And the influences of various factors on extraction process were discussed. The result shows that the concentration of ethanol is the most influencing factor in this process, and then the solid-liquid volume ratio, the extraction temperature and the extraction time. Optimum conditions for this extraction process are: the solid-liquid volume ratio is 1/10, the concentration of ethanol is 65%, the extraction temperature is 60°C and the extraction time is 45min.

Abstract: In this work, the effect of split ratio and the column flow in determination of OCPs in Traditional Chinese medicines are discussed in the name of heptachlor. When the split ratio is 60:1, the measured concentration is close to the actual concentration; on the contrary, they lead the measured concentration lower than the actual concentration. The column flow has not obviously effect on result. The split ratio is considered in OCPs analysis.