Electroextraction and electromembrane extraction: Advances in hyphenation to analytical techniques

Abstract

Electroextraction (EE) and electromembrane extraction (EME) are sample preparation techniques that both require an electric field that is applied over a liquid‐liquid system, which enables the migration of charged analytes. Furthermore, both techniques are often used to pre‐concentrate analytes prior to analysis. In this review an overview is provided of the body of literature spanning April 2012–November 2015 concerning EE and EME, focused on hyphenation to analytical techniques. First, the theoretical aspects of concentration enhancement in EE and EME are discussed to explain extraction recovery and enrichment factor. Next, overviews are provided of the techniques based on their hyphenation to LC, GC, CE, and direct detection. These overviews cover the compounds and matrices, experimental aspects (i.e. donor volume, acceptor volume, extraction time, extraction voltage, and separation time) and the analytical aspects (i.e. limit of detection, enrichment factor, and extraction recovery). Techniques that were either hyphenated online to analytical techniques or show high potential with respect to online hyphenation are highlighted. Finally, the potential future directions of EE and EME are discussed.

Trends in sample preparation and separation methods for the analysis of very polar and ionic compounds in environmental water and biota samples

“…This approach is only applicable for the extraction of ionizable and ionic compounds from various liquid samples or extracts. High matrix tolerance and compatibility with common analytical techniques like LC, GC, and CE have already been demonstrated [64]. Selectivity regarding the polarity of compounds can be tuned with different membrane compositions.…”

Practical sample pretreatment techniques coupled with capillary electrophoresis for real samples in complex matrices

“…For more information regarding SPME, please refer to excellent recent papers by Pawliszyn et al [12,13,14]. Similarly, this section does not cover the electroextraction techniques, which were thoroughly reviewed by Oedit and Lindenburg [15] as well as Pedersen-Bjergaard et al [16]. We will focus on in-line LPME sample pretreatment techniques coupled with CE in an automatic manner with ease.…”

Electromembrane extraction–Recent trends and where to go

“…High specificity in the extraction step may reduce the costs and complexity of the final detection system. New SLMs have been addressed recently in several research papers, both using pure solvents [30] , [34] , [35] and solid additives in the SLM [12] , [36] , [37] , [38] . With respect to pure solvents, a range of alkylated phosphates and phosphites have been studied recently, and tributyl phosphate and bis(2-ethylhexyl) phosphite (DEHPi) were identified as new solvents providing efficient extraction of polar basic analytes [35] , [39] .…”

“…The publication frequency is positive and EME is an active research area. EME has been reviewed several times in recent years [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] . The literature comprises research articles on applications of EME, technical developments, and fundamental issues.…”