Liquid-Phase Microextraction LPME

More recently, a miniaturised version of liquid-liquid extraction has been developed, known as liquid-phase microextraction (LPME). Two main forms of this... 

S. Myung, S. Yoon and M. Kim, Analysis of benzene ethylamine derivatives in urine using the programmable dynamic liquid-phase microextraction (LPME) device. Analyst, 2003,128(12), 1443-1446. 

S. Pedersen-Bjergaard, T. S. Ho and K. E. Rasmussen, Fundamental studies on selectivity in 3-phase liquid-phase microextraction (LPME) of basic drugs. Journal of Separation... 

S. M. Richoll and I. Colon, Liquid-phase Microextraction (LPME) A Novel Approach to the Isolation and Quantitation of Low Level Impurities in Pharmaceutical Applications. Abstracts of Pittcon 2004. 

The analysis of ILs may afford considerable insight into the physicochemical properties underlying the rich potential interaction chemistries of ILs [14] and suggest possibilities for future applications. Simultaneously, the unique features of ILs provide some intriguing new possibilities in the area of separations that have yet to be realized. Hence, topics to be covered in this chapter include analysis of ILs by LC, applications of ILs in liquid-phase microextraction (LPME), in high-performance LC (HPLC) as mobile-phase additives, and in capillary electrophoresis (CE) as buffer additives as well as applications of surface-confined ILs (SCIL) as novel stationary phases for LC. 

To enhance extraction efficiency in the SME system (also called single-drop microextraction [SDME]), He and Lee developed a procedure termed liquid-phase microextraction (LPME),89 which, in its static mode, resembles the SME system. 

Bardstu, K.F., Ho, T.S., Rasmussen, K.E., Pedersen-Bjergaard, S. and Jonsson, J.A. (2007) Supported liquid membranes in hollow fiber liquid-phase microextraction (LPME) — Practical considerations in the three-phase mode. Journal of Separation Science, 30, 1364. 

Fig.l Headspace analysis and microextraction methods (here only the headspace mode is shown) used for the determination of fuel oxygenates, (a) Headspace analysis, (b) headspace solid-phase microextraction (HS-SPME) redrawn after [60], (c) solid-phase dynamic extraction (SPDE) redrawn after [61] and (d) liquid-phase microextraction (LPME) redrawn after [62]... 

Single drop extraction (SDE) or liquid-phase microextraction (LPME) is a recently developed microscale extraction method. In this method a single liquid drop is used as a collection phase. Small volumes of organic solvent (from 0.5 pi to 2.5 pi) are used. The collection phase must have a sufficiently high surface tension to form a drop which can be exposed to the analyte solution." When the extraction is finished, the single drop is injected into the GC. A scheme of such a device is shown in Eigure 2.8. 

Recently, Psillakis et al. " have developed a liquid phase microextraction (LPME) technique using a hollow fiber membrane in conjunction with GC-MS for the extraction and analysis of phthalates. The resulting method was validated and compared with SPME. Both techniques showed comparable performance and were considered suitable for trace analysis of phthalates in water. 

Pedersen-Bjergaard S, Rasmussen KE, Jonsson jA. Liquid-phase microextraction (LPME) utilizing porous hollow fibers. In Pawhszyn J, Lord H, eds. Handbook of Sample Preparation. Hoboken, NJ John Whey Sons 2010 pp. 125-148. 

Bardstu KF, Ho TS, Rasmussen KE, Pedersen-Bjergaard S, Jonsson jA. Supported hquid membranes in hollow fiber liquid-phase microextraction (LPME). Practical considerations in the 3-phase mode. J Sep Sci 2007 30 1364-1370. 

In liquid-phase microextraction (LPME), a liquid membrane is used to enrich and isolate analytes from a complex sample. The liquid membrane, which is immiscible with water and the sample matrix, is immobilized in the pores of a porous hollow fiber. Such a liquid membrane is referred to as a supported liquid membrane (S LM). Immobilization of the SLM is achieved by simply dipping the hollow fiber in an organic solvent allowing the pores to be filled. Figure 9.11 shows a schematic representation of LPME. 

Liquid-phase microextraction (LPME) as a sample preparation technique for chromatography and electrophoresis is one of the recently developing techniques. In LPME, the principles of LLE and the miniaturized nature of SPME are combined to realize the advantages of both techniques. 

LLLME, (Hou and Lee 2003), liquid phase microextraction, LPME, (Tao et al. 2009), LLE-SPE tandem extraction (Alaejos et al. 2008) and headspace single-drop microextraction, HS-SDME, (Zhou and Ye 2008), have been reported for the extraction of aromatic amines from environmental water samples. 

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