DICP OpenIR
Subject Area分析化学
Investigation on hollow fiber based liquid-liquid-liquid micro-extraction with different driving forces
Wu Q(吴倩); Wu DP(吴大朋); Shen Z(沈铮); Guan YF(关亚风)
Source PublicationInvestigation on hollow fiber based liquid-liquid-liquid micro-extraction with different driving forces
Conference Name37th International symposium on High-Performance Liquid Phase Separations and Related Techniques
Conference Date2011-10-8
2011
Conference Place大连
Pages61-1
Publisher待补充
Publication Place待补充
Cooperation Status分会特邀报告
Department105
Funding Organization中国化学会色谱专业委员会和大连化学物理研究所
AbstractIn recent years, hollow fiber based liquid-liquid-liquid micro-extraction (HF-LLLME) [1] has been widely studied due to its higher enrichment factor, excellent ability of clean-up, and lower consumption of organic solvent. In HF-LLLME, the driving force for analytes transferring from donor phase through organic phase into acceptor phase is the essential factor for HF-LLLME to obtain fast extraction with a high enrichment factor. By far, the driving force most widely used for HF-LLLME is pH gradient between donor phase and acceptor phase [2-4]. Donor phase is adjusted to favor the deionization of analytes and distributing into organic phase, while the acceptor phase is adjusted to favor the analytes ionization and dissolving in acceptor. Actually, the ion strength gradient is also used as an auxiliary driving force when pH gradient is used [3]. The composition of organic phase is another critical factor that influences the selectivity and clean-up ability of HF-LLLME. The long extraction time to reach equilibrium and the low extraction recovery are the major disadvantages of HF-LLLME [2]. Recently the electrical potential difference is explored as the major driving force for analytes mass transfer in HF-LLLME, and this method is commonly called as electro-membrane extraction (EME) [5]. In EME, pH of the donor phase is adjusted to favor the ionization of analytes, and the target ions transfer from donor to acceptor under the electric field. This method takes much shorter time and owns higher selectivity, but by far the composition of organic phase for various compounds with different polarity to get enough recovery is still limited, especially for acidic compounds. In our study, HF-LLLME with above mentioned different driving forces have been developed to analyze endogenous gibberellins from complex plant extracts and have been compared with each other. With the same organic phase (n-octanol), it was found that EME favors the extraction of gibberellins with low polarity, but HF-LLLME with pH gradient has no such selectivity. In HF-LLLME with pH gradient as the major driving force and ion strength gradient as the auxiliary driving force, an interesting phenomenon has been observed: the water osmosis has been found from the acceptor to donor, and this process has been demonstrated theoretically and experimentally that it is helpful to reduce extraction time to reach equilibrium and improve the extraction recovery. Series of weak anion-exchange extractants has been added into organic phase for EME to selectively extract more polar acidic compounds (logP<0.5). The relationship between the molecular structure of organic solvent and the system selectivity has been found. Finally, another new auxiliary driving force, the temperature gradient, has been proposed to get even higher extraction efficiency. REFERENCES [1] S. Pedersen-Bjergaard, et al., Anal. Chem. 71 (1999) 2650 [2] S. Pedersenbjergaard, et al., J Chromatogr A 1184 (2008) 132 [3] G. Shen, et al., Anal. Chem. 74 (2001) 648 [4] J. Wu, et al., J. Chromatogr A 1082 (2005) 121 [5] S. Pedersen-Bjergaard, et al., J Chromatogr A 1109 (2006) 183; In recent years, hollow fiber based liquid-liquid-liquid micro-extraction (HF-LLLME) [1] has been widely studied due to its higher enrichment factor, excellent ability of clean-up, and lower consumption of organic solvent. In HF-LLLME, the driving force for analytes transferring from donor phase through organic phase into acceptor phase is the essential factor for HF-LLLME to obtain fast extraction with a high enrichment factor. By far, the driving force most widely used for HF-LLLME is pH gradient between donor phase and acceptor phase [2-4]. Donor phase is adjusted to favor the deionization of analytes and distributing into organic phase, while the acceptor phase is adjusted to favor the analytes ionization and dissolving in acceptor. Actually, the ion strength gradient is also used as an auxiliary driving force when pH gradient is used [3]. The composition of organic phase is another critical factor that influences the selectivity and clean-up ability of HF-LLLME. The long extraction time to reach equilibrium and the low extraction recovery are the major disadvantages of HF-LLLME [2]. Recently the electrical potential difference is explored as the major driving force for analytes mass transfer in HF-LLLME, and this method is commonly called as electro-membrane extraction (EME) [5]. In EME, pH of the donor phase is adjusted to favor the ionization of analytes, and the target ions transfer from donor to acceptor under the electric field. This method takes much shorter time and owns higher selectivity, but by far the composition of organic phase for various compounds with different polarity to get enough recovery is still limited, especially for acidic compounds. In our study, HF-LLLME with above mentioned different driving forces have been developed to analyze endogenous gibberellins from complex plant extracts and have been compared with each other. With the same organic phase (n-octanol), it was found that EME favors the extraction of gibberellins with low polarity, but HF-LLLME with pH gradient has no such selectivity. In HF-LLLME with pH gradient as the major driving force and ion strength gradient as the auxiliary driving force, an interesting phenomenon has been observed: the water osmosis has been found from the acceptor to donor, and this process has been demonstrated theoretically and experimentally that it is helpful to reduce extraction time to reach equilibrium and improve the extraction recovery. Series of weak anion-exchange extractants has been added into organic phase for EME to selectively extract more polar acidic compounds (logP<0.5). The relationship between the molecular structure of organic solvent and the system selectivity has been found. Finally, another new auxiliary driving force, the temperature gradient, has been proposed to get even higher extraction efficiency. REFERENCES [1] S. Pedersen-Bjergaard, et al., Anal. Chem. 71 (1999) 2650 [2] S. Pedersenbjergaard, et al., J Chromatogr A 1184 (2008) 132 [3] G. Shen, et al., Anal. Chem. 74 (2001) 648 [4] J. Wu, et al., J. Chromatogr A 1082 (2005) 121 [5] S. Pedersen-Bjergaard, et al., J Chromatogr A 1109 (2006) 183
Document Type会议论文
Identifierhttp://cas-ir.dicp.ac.cn/handle/321008/116114
Collection中国科学院大连化学物理研究所
Corresponding AuthorGuan YF(关亚风)
Recommended Citation
GB/T 7714
Wu Q,Wu DP,Shen Z,et al. Investigation on hollow fiber based liquid-liquid-liquid micro-extraction with different driving forces[C]. 待补充:待补充,2011:61-1.
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