A highly selective molecularly imprinted sorbent for extraction of 2-aminothiazoline-4-carboxylic acid - Synthesis, characterization and application in post-mortem whole blood analysis

In this paper, the optimized synthesis and detailed characterization of novel imprinted material for selective extraction of 2-aminothiazoline-4-carboxylic acid (ATCA) were described. The prepolymeric system contained 1-allyl-2-thiourea and ethylene glycol dimethacrylate in methanol, tetrahydrofuran and dimethyl sulfoxide porogenic mixture and 2-aminothiazole-4-carboxylic acid which was used as the template for ATCA. This structural analog of the target analyte was found to provide the imprinted polymer with sufficient binding capacity (60.7 ± 0.9 μg g−1) and high selectivity (imprinting factor equal to 18.4) toward ATCA. The adsorption of ATCA was analyzed by the Langmuir model. The heterogeneous population of binding sites on the imprinted polymer was characterized by dissociation constants equal to 3.72 μg L−1 and 435 μg L−1 for high and low affinity binding sites, respectively. The morphology of the polymer was studied employing SEM and BET analyses and the composition was confirmed by EDS and 13C CP/MAS NMR analyses. Adsorption of amino acids on the imprinted material was tested to analyze the impact of the sample components. The superiority of the imprinted sorbent was proved in a novel dispersive solid phase extraction procedure of ATCA from post-mortem whole blood with respect to the extraction efficacy on the commercial ion-exchange sorbents. The limit of quantification and limit of detection of ATCA in the new analytical method were 12 μg L−1 and 3.5 μg L−1, respectively. The recovery of ATCA was in the range of 81-89% and the precision of the method ranged from 1.5 to 2.7%.