Electromembrane Extraction Using Sacrificial Electrodes

Abstract

In this paper, we report the first example of employing a sacrificial electrode in the acceptor solution during electromembrane extraction (EME). The electrode was based on a silver wire with a layer of silver chloride electroplated onto the surface. During EME, the electrode effectively inhibited electrolysis of water in the acceptor compartment, by accepting the charge transfer across the SLM, which enabled the application of 500 μA current without suffering gas formation or pH changes from electrolysis of water. The electroplating strategy was optimized with a design-of-experiments (DOE) methodology that provided optimal conditions of electroplating. With an optimized electrode, 1 cm of the electrode in contact with the acceptor solution inhibited electrolysis of water for approximately 30 min at 500 μA current (redox capacity). Further, the redox capacity of the electrode was found to increase through multiple uses. The advantage of the electrode was demonstrated by extracting polar analytes at high-current conditions in a standard EME system comprising 2-nitrophenyl octyl ether (NPOE) as SLM and 10 mM HCl as sample/acceptor solutions. Application of high current enabled significantly higher recoveries than could otherwise be obtained at 100 μA. Sacrificial electrodes were also tested in μ-EME and were found beneficial by eliminating detrimental bubble formation. Thus, the sacrificial electrodes improved the stability of μ-EME systems. The findings of this paper are important for development of stable and robust systems for EME operated at high voltage/current and for EME performed in narrow channels/tubing where bubble formation is critical.

Kinetıc analysıs of Cr(VI) transport wıth electromembrane processes

“…28 However, with exceeding the optimum voltage applied during the extraction, EME transport efficiency may decrease with higher system current throughout SLM/EME and an increased probability of electrolysis in the electrodes can occur at the pH changes in both phases, and this phenomenon is resulted with unstable SLM. 29,30 As it can be seen from Table 1 and Fig. 1, there was a decrease in the kinetic results after the optimum current (0.3 A) and electrical potential value (50 V).…”

Selectivity and efficiency of electromembrane extraction of polar bases with different liquid membranes—Link to analyte properties

“…This SLM extracted even the model analytes of highest polarity, due to relatively low intrinsic hydrophobicity. It is, however, known from previous literature [14–15, 23] that extraction performance of polar bases may be severely affected by complex samples. Extractions were, therefore, also performed from spiked samples of human plasma and urine.…”

“…EME was performed in laboratory‐built 96‐well format that has been described previously [23]. Photos of the equipment are given in Supporting information 1.…”

Electromembrane Extraction and Mass Spectrometry for Liver Organoid Drug Metabolism Studies

“…The stepped voltage was used to ensure that the extraction current was kept below 50 μA per well, which was considered a safe limit for robust operation. 40 …”