Zhu Gang-Tian, Liu Fei, He Sheng, He Xiao-Mei, Zhu Shu-Kui, Feng Yu-Qi
Key Laboratory of Tectonics and Petroleum Resources (Ministry of Education), China University of Geosciences Wuhan 430074 P. R. China
Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University Wuhan 430072 P. R. China.
RSC Adv. 2018 May 29;8(35):19486-19493. doi: 10.1039/c8ra02262c. eCollection 2018 May 25.
Magnetic aqueous ammonia (MAA) was prepared as a magnetic extractant for dispersive microextraction of petroleum acids (PAs). The amount of extractant in MAA was custom-made by a simple approach. In the MAA composed of an aqueous ammonia coating and FeO@SiO core, the coating is a base extractant that can selectively extract acids, while the magnetic core serves as a support to achieve dispersion as well as rapid magnetic retrieval of the extractant during the extraction processes. This is the first use of reusable, stable and modifiable FeO@SiO as a support instead of bare FeO in a magnetic particle assisted dispersive liquid-liquid microextraction technique. The parameters that affect extraction efficiency were investigated. The sampling step as well as the desorption step can be completed in 2 min. The linear ranges are 5-5000 ng g, while the limits of quantification range from 2.5 to 6.2 ng g. The recoveries in spiked crude oil samples are in the range of 79.1% to 112.1% with relative standard deviations less than 11.3% (intra-day) and 13.4% (inter-day). Finally, the proposed method was applied to the analysis of PAs in diluted crude oils with different maturities. In comparison to the existing methods for extraction of PAs, the proposed method provides superior performances including high throughput (12-well plate), high degree of sample clean-up, and low consumption of separation material, solvent and time.
磁性氨水（MAA）被制备成用于分散微萃取石油酸（PAs）的磁性萃取剂。通过一种简单的方法定制了MAA中萃取剂的用量。在由氨水溶液涂层和FeO@SiO核组成的MAA中，涂层是一种碱性萃取剂，能够选择性地萃取酸，而磁性核作为载体，在萃取过程中实现萃取剂的分散以及快速磁回收。这是首次在磁性粒子辅助分散液液微萃取技术中使用可重复使用、稳定且可改性的FeO@SiO作为载体，而非裸露的FeO。研究了影响萃取效率的参数。采样步骤和解吸步骤均可在2分钟内完成。线性范围为5 - 5000 ng/g，而定量限在2.5至6.2 ng/g之间。加标原油样品的回收率在79.1%至112.1%范围内，日内相对标准偏差小于11.3%，日间相对标准偏差小于13.4%。最后，将所提出的方法应用于分析不同成熟度的稀释原油中的石油酸。与现有的石油酸萃取方法相比，所提出的方法具有卓越的性能，包括高通量（12孔板）、高度的样品净化、分离材料、溶剂和时间的低消耗。
