硒连续化学提取技术中的若干问题讨论

硒的生物可利用性、毒性、环境行为和生物效应等不仅仅与硒的总量有关,更取决于硒的形态。硒的连续化学提取技术是硒形态研究的一个重要手段。在硒七步连续提取方案的基础上,重点探讨了有机结合态、元素态、硫化物/硒化物结合态硒的提取技术细节,讨论了不同液固比和提取剂对硒提取的影响,并对不同结合态硒提取中存在的问题进行了相应讨论。研究结果表明:在硒的连续化学提取过程中,液固比为20:1到50:1时能够满足不同结合态硒提取的要求;在水浴加热条件下,NaOH浓度0.1～0.5mol/L时能有效提取有机结合态硒;1mol/LNa2SO3溶液是元素硒的较好提取剂;而对于硫化物/硒化物结合态硒,600～700ml/min的载气气流能保证其还原所产生HSe气体的完全吸收。

The Discussion of Several Issues on Selenium Sequential Chemical Extraction for Environmental Samples

The bioavailability,toxicity,mobility and biological effect of selenium are more controlled by chemical speciation than total selenium in the environment.Sequential chemical extraction technology is one of the practical tools for selenium speciation analysis.Base soluble,elemental,sulfide/selenide selenium are stressly discussed based on seven-steps sequential chemical extraction protocol.The influence of solution/solid ratio and extracted reagents on extraction is studied,and other fractionations are also discussed.The results showed that appropriate solution/solid ratios range from 20 to 50 in extraction procedure.0.1～0.5 M NaOH can effectively extract base solution selenium under heated water bath.1 M Na_2SO_3 is a better reagent for elemental selenium extraction.600～700 mL/min airflow flux ensures that H_2Se reducted by sulfide/selenide selenium is fully sorbed.