A technique of ultrasound-assisted low density solvent based dispersive liquid-liquid microextraction was developed for the determination of four phthalate esters, including dimethyl phthalate（DMP）, diethyl phthalat...A technique of ultrasound-assisted low density solvent based dispersive liquid-liquid microextraction was developed for the determination of four phthalate esters, including dimethyl phthalate（DMP）, diethyl phthalate（DEP）, di-n-butyl phthalate（DnBP） and di（2-ethylhexyl） phthalate（DEHP） in bottled water samples. A low density solvent, toluene, was selected as extraction solvent. In the extraction process, a mixture of 15 μL of toluene（extraction solvent） and 100 μL of methanol（disperser solvent） was rapidly injected into 1.0 mL of water samples. A cloudy solution was formed after ultrasounded for 5 min, and then centrifuged at 5000 r/min for 5 min. The enriched analytes in the floa- ting phase were determined by means of gas chromatograph. Under the optimum conditions, the enrichment factors were found to be in a range of 29--67, and the recoveries were ranged from 81.2% to 103.9%. The limits of the detection were in a range of 3.8--5.6 μg/L. The proposed method was applied to the extraction and determination of phthalate esters in bottled water samples, and the concentrations of phthalate esters found in the water samples were below the allowable levels.展开更多
文摘A technique of ultrasound-assisted low density solvent based dispersive liquid-liquid microextraction was developed for the determination of four phthalate esters, including dimethyl phthalate（DMP）, diethyl phthalate（DEP）, di-n-butyl phthalate（DnBP） and di（2-ethylhexyl） phthalate（DEHP） in bottled water samples. A low density solvent, toluene, was selected as extraction solvent. In the extraction process, a mixture of 15 μL of toluene（extraction solvent） and 100 μL of methanol（disperser solvent） was rapidly injected into 1.0 mL of water samples. A cloudy solution was formed after ultrasounded for 5 min, and then centrifuged at 5000 r/min for 5 min. The enriched analytes in the floa- ting phase were determined by means of gas chromatograph. Under the optimum conditions, the enrichment factors were found to be in a range of 29--67, and the recoveries were ranged from 81.2% to 103.9%. The limits of the detection were in a range of 3.8--5.6 μg/L. The proposed method was applied to the extraction and determination of phthalate esters in bottled water samples, and the concentrations of phthalate esters found in the water samples were below the allowable levels.
文摘在单因素试验基础上,采用Plackett-Burman设计和中心组合设计试验筛选和优化了提取剂用量、超声时间和超声温度等条件对超声辅助提取PM_(2.5)中Pb的影响.实验结果表明:在最佳提取条件下,即提取温度95℃,提取时间45 min,提取剂用量14.53 m L时,铅提取率最大.方法的加标回收率为84.0%~106%,相对标准偏差(RSD)在4.5%~6.1%之间,检出限为1.4μg·L^(-1).t检验结果表明超声提取法与加热板消解法及微波消解法(行业标准)之间不存在显著性差异,但超声提取法更为简便、快速、温和、安全.本方法应用于测定锦州市渤海大学(1~#)、解放路(2~#)、中央大街(3~#)、世博园(4~#)四个代表性采样点的PM_(2.5)中Pb的含量,其中2~#和3~#采样点的Pb污染最严重,分别为0.33μg·m^(-3)和0.41μg·m^(-3).虽然四个采样点Pb含量均未超过Pb浓度限值(0.5μg·m^(-3)),但Pb富集因子很高(>100),表明Pb在大气颗粒物中富集明显,受人类活动影响较大.
