Direct extraction of double-stranded DNA into ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate and its quantification
Jian-Hua Wang* ,De-Hong Cheng,Xu-Wei Chen,Zhuo Du,and Zhao-Lun Fang
Research Center for Analytical Sciences, Box332, Northeastern University, Shenyang 110004 China
Abstract： Ionic liquid 1 - butyl - 3 - methylimidazolium hexafluorophosphate ( BmimPF6 ) , as a green solvent , was successfully used for the direct extraction of dsDNA. The extraction efficiency and the distribution coefGcient values indicated that trace amounts of DNA at the levels of less than or equal 5ng L-1 facilitate quantitative fast extraction，while proteins and metal species do not interfere. A total of 30% of the DNA in ionic liquid at[ similar to ] 20ng L-1 was back extracted into aqueous phase in phosphate -citrate bufifer with a single-stage extraction. The extraction is demonstrated to be endothermic with an enthalpy of 34. 3 kJ • mol-1. The extraction mechanisms were proposed and verified by 31P-NMR and FT-IR spectra. Interactions between cationic 1 -butyI-3-methylimidazolium (Bmim+) and P-O bonds of phosphate groups in the DNA strands take place both in the dissolved BmimPF6 in aqueous phase and at the interface of the two phases. This interaction consequently led to the transformation of DNA confbrmations，along with a reduction of ethidium resonance light scattering at 510nm,and a procedure for DNA quantification in ionic liquid was developed based on this observation.
(该文发表在 Analytical Chemistry,2007,Vol. 79,No. 2；此摘要被 Ei Compendex 收录)
中文译文：
摘要：离子液体1-丁基-3-甲基咪唑六氣磷酸盐作为一种绿色溶剂被成功地用于直接萃取双链DNA。测得的萃取效率和分配系数表明，当浓度低于5ng - L-1时痕量DNA可快速地被萃取进入离子液体相，而共存的蛋白质和金属组分不影响其萃取。离子液体相中20ng • L-1DNA可用磷酸盐-拧檬酸盐缓冲溶液反萃取，单次反萃取率约为30%。研究表明，DNA的萃取是一个吸热过程，其焓变为34. 3kJ . mor-1。用31P-NMR和FT-IR谱证实了萃取的相关机理，即在水相中及两相介面上存在1-丁基-3-甲基咪唑阳离子与DNA链中P-O键的相互作用，这种作用力驱使DNA转入离子液体相并发生构型改变，同时导致溴化乙锭在510nm处的共振光散射强度降低。本文依据此现象提出了一种在离子液体相中直接定量测定DNA的方法。
