Evaluation of a molecularly imprinted polymer as in‐line concentrator in capillary electrophoresis

Abstract

Molecularly imprinted polymers (MIPs) have been evaluated as sorbent for the construction of an in-line solid phase extraction concentrator in capillary electrophoresis to be applied in the monitoring of triazine herbicides: atrazine and its three metabolites, desethylatrazine, desisopropylatrazine and desethyldesisopropylatrazine. Initially, the electrophoretic separation of these compounds was optimized. The electrolyte consists of an aqueous solution of 75 mM phosphoric acid (H(3)PO(4)) adjusted to pH 2.1 and containing 0.7 mM cetyltrimethylammonium bromide. After the fabrication and assembly of the concentrator into the capillary, these optimal CE conditions were applied to evaluate the performance of this device. Efficiencies of 40 000-55 000 plates could be achieved and the separation time was around one hour. Different parameters affecting the in-line molecularly imprinted solid-phase extraction in capillary electrophoresis such as composition and volume of the elution plug were optimized. The method was evaluated in terms of linearity, precision and limits of detection and quantification. MIPs were compared with Oasis hydrophilic-lipophilic-balance (HLB) particles for the in-line coupling of solid-phase extraction and capillary electrophoresis. The superior selectivity of MIPs is demonstrated through direct injection of a urine sample spiked with 10 microg/mL atrazine, desethylatrazine, desisopropylatrazine and desethyldesisopropylatrazine. Recoveries were between 92 and 102% compared with an aqueous solution.

Different strategies for the preconcentration and separation of parabens by capillary electrophoresis

“…This material can be retained by means of two frits to prevent the sorbent particles from entering and blocking the CE capillary, or without frits, using sorbent particles with sizes larger than the internal diameter of the separation capillary. In general, the sorbents most commonly used to build the in‐line SPE‐CE systems have been C18, Oasis HLB, and Oasis MCX . One of the main advantages of the in‐line SPE‐CE system is that it allows the injection of a large volume of sample, since capillary volume is not a limitation in this case as it is for electrophoretic preconcentration, so the SEF achieved is high.…”

Applications of SPE-MIP in the Field of Food Analysis

“…The selectivity of the inline MI-SPE coupling to CE compared favorably to the analogous inline concentrator employing Oasis hydrophilic-lipophilic-balance particles. 16 More recently, a number of publications have appeared in literature where molecularly imprinted polymers are coupled to solid-phase microextraction (MI-SPME). Here, MIP monoliths are synthesized inside glass or CE capillaries fibers and are then used as SPME extraction fibers, prior to injection into a liquid or gas chromatograph for subsequent separation and detection of the adsorbed analytes.…”

Bubble cell for magnetic bead trapping in capillary electrophoresis

“…For example in the microchip field, bead chambers were developed by Oleschuk et al to pack the SPE sorbent [28]. In capillary electrophoresis, in-line systems integrating a concentrator having a larger diameter than the capillary diameter were proposed [29,30].…”