Development and application of water-compatible molecularly imprinted polymers for the selective extraction of carbamazepine from environmental waters

Abstract

A molecularly imprinted polymer (MIP) was designed in order to allow the selective solid-phase extraction of carbamazepine (CBZ), an anticonvulsant and mood-stabilizing drug, at ultra-trace level from aqueous environmental samples. A structural analog of CBZ was selected as a dummy template and different synthesis conditions were screened. The selectivity of the resulting imprinted polymers was evaluated by studying the retention of CBZ in a solvent similar to the one used for the synthesis. The presence of imprinted cavities in the polymers was then demonstrated by comparing the elution profiles (obtained by using MIP and a non-imprinted polymer, NIP, as a control) of the template, of CBZ, and of a structural analog of CBZ. Then the extraction procedure was further optimized for the treatment of aqueous samples on the two most promising MIPs, with a special attention being paid to the volume and composition of the percolation and washing solutions. The best MIP provided a highly selective retention in tap water with 81 % extraction recovery for CBZ in the elution fraction of the MIP and only 14% for NIP. The repeatability of the extraction procedure was demonstrated for both tap and river waters (RSD below 4% in river water) for the drugs CBZ, oxcarbamazepine, and one metabolite (carbamazepine 10,11-epoxide). A MIP capacity of 1.15 µmol g-1 was determined. Finally, an analytical procedure involving the MIP was developed allowing the detection of CBZ at a concentration level of only a few ng L-1 in river water. The selectivity provided by the MIP resulted in a 3000-fold increase of the signal-to-noise ratio in LC/MS analysis as compared to the use of conventional sorbent.

Sample Preparation Using Molecularly Imprinted Polymers

“…In addition to this advantage, the dummy approach was also considered for an expensive or difficult-to-achieve template molecule. 29,55,[90][91][92][93] Towards green approaches…”

“…MIP-SPE was recently applied to the trace analysis of target analytes, mainly pesticides, industrial contaminants, and drugs, from real waters, 28,81,83,[90][91][92]131,132,134,136 soil and sediment extracts, 67,73 and food extracts or beverages. 38,54,60,72,82,87,123,124,129,130,133,137,138 It was also used to extract natural products from food or plants 39,[55][56][57]70,86,103,121,127,139 to control their occurrence, such as for toxins, or to purify them.…”

“…Therefore, the study in parallel of the extraction recoveries of the target analyte on the NIP must be done during the optimization of the extraction parameters, as it is often the case. 39,55,60,72,74,81,81,[90][91][92][93]110,124,135,136,140 These recoveries must be as low as possible on NIP to ensure that the retention on MIP is mainly due to the presence of specific cavities and then to ensure an optimal selectivity. A control molecule with a different structure from the target analytes(s) can also be studied on both sorbents.…”

Synthesis and Characterization of Molecularly Imprinted Polymers for the Selective Extraction of Carbamazepine and Analogs from Human Urine Samples

“…MIPs have been already developed for the selective extraction of CBZ [7][8][9][10][11][12][13][14][15][16][17][18] using systematically CBZ as template molecule except in one recent study from our group [18]. Indeed, as the synthesis process of the MIP requires the introduction of a large amount of template molecule, and regarding the targeted concentrations in samples, this choice was not considered as relevant.…”

“…Indeed, even after a careful washing of the polymer after its synthesis and a rigorous control of this step, the template molecule can still leak from the MIP during subsequent extraction procedures thus leading to false positives. This can be circumvented by selecting a CBZ analog, methoxycarbamazepine (MCBZ), that can be distinguish from CBZ by their different retention time in LC-MS analysis [18]. In most cases, methacrylic acid (MAA) was used as monomer in association with ethylene glycol dimethacrylate (EGDMA) [12,13,15,16], trimethylolpropane trimethacrylate (TRIM) [10,11] or with divinylbenzene (DVB) [7-9, 14, 18] as cross-linker and mainly in acetonitrile, toluene, chloroform and dichloromethane or in some mixtures of these solvents as porogen.…”