衍生-超临界流体CO_2萃取固体基质中的铅(Ⅱ)

Dithizone chelating-supercritical fluid CO_2 extraction of lead (Ⅱ) in solid samples

采用双硫腙 (H2 Dz)作衍生剂、超临界流体CO2 为萃取剂 ,螯合萃取固载在硅胶上的铅 (Ⅱ )。研究了影响萃取率的各种因素 ,包括温度、压力、超临界流体CO2 流速及用量、衍生剂用量、改性剂等。结果表明 ,在压力2 5MPa、温度 6 0℃、SF -CO2 流速 0 .6mL/min、SF -CO2 用量 9mL条件下 ,采用 10 % (v/v)二氯甲烷作改性剂 ,固载在硅胶上的铅 (Ⅱ )可得到完全萃取。用该方法萃取标准土样 (GSS - 2 )及河底污泥中的铅 (Ⅱ ) ,回收率为 79.5 %～ 92 .3% ,结果令人满意。

A method using dithizone (H_2Dz) as chelating agent and supercritical fluid CO_2 as extractant to extract lead (Ⅱ) in silica gel and standard reference soil samples was studied. Various factors influencing extraction efficiency were investigated, including temperature, pressure, flow rate and volume of CO_2, quantity of chelating agent and type of modifier. It is shown that lead (Ⅱ) in silica gel can be extracted completely using methylene chloride as modifier, when the pressure is 25MPa, temperature is 60℃, and flow rate and volume of SF-CO_2 are 0.6 mL/min and 9mL, respectively. The recoveries are 79.5%～92.3% for extrating lead (Ⅱ) in standard soil samples and river sludge.