Liquid-liquid Microextraction Based on Solidification of Floating Organic Drops Coupled with Gas Chromatography for Analyzing Trace Benzene, Toluene and Xylene in Water Samples

A new liquid-liquid microextraction method based on the solidification of floating organic drops coupled with gas chromatography was developed for the determination of trace benzene, toluene and xylene（BTX） in water samples. In the microextraction procedure, a microdrop of n-decanol was delivered to the surface of the analytes’ solution, and stirred for a desired time. Following the absolute extraction, the sample vial was cooled in an ice bath for 10 min. The solidified n-decanol was then transferred into a plastic tube and melted naturally; and 1 μL of it was injected into gas chromatography for analysis. Factors relevant to the extraction efficiency were studied and optimized. The optimal experimental conditions were： 15 μL of n-decanol as extractive solvent, 30 mL of solution containing analytes, no salt, the stirring rate 400 r/min, the extraction temperature 30 °C, and the extraction time 30 min. Under those optimized conditions, the detection limit（LOD） of analytes was in a range of 0.05―0.10 ng/mL by the developed method. A good linearity（r0.99） in a calibration range of 0.01―100 μg/mL was obtained. The recoveries of the real samples at different spiked levels of BTX were in the range from 92.2% to 103.4%.

广东省工业企业危险废物环境风险评价研究

危险废物分级分类管理及风险管控的实现有赖于企业危险废物环境风险评价,通过风险评价将危废产生源进行分类分级,针对不同风险特征企业制定相应管理对策,才能在有限资源的前提下,实现危废高效管理。本研究针对广东省工业企业危险废物环境风险,根据企业危险废物环境风险系统的特征建立了涵盖风险源、控制机制、风险受体三大类评价因素,危险废物年产生量、危险废物危险特性等15项细化指标的评价指标体系,并提出了评价分级标准及评价方法。最后,运用建立的评价方法对珠海市3个工业企业危险废物环境风险水平进行了评价,确定了企业危险废物风险等级,并提出了各企业风险管控的侧重点。