Molecularly Imprinted Solid-phase Extraction Protocol Research Articles

A highly sensitive electrochemiluminescence method combined with molecularly imprinted solid phase extraction for the determination of phenolphthalein in drug, slimming food and human plasma

An electrochemiluminescence (ECL) inhibition method combined with molecularly imprinted solid phase extraction (MISPE) was developed for quantitative determination of phenolphthalein in drug, slimming food and human plasma. Phenolphthalein could strongly inhibit the ECL signal of Ru(bpy)32+/2-(dibutylamino)ethanol (DBAE) system that was used as the basis of the analysis. Molecularly imprinted polymers (MIPs) were synthesized as solid phase extraction (SPE) sorbents, and MISPE protocol was developed for the selective extraction and purification of phenolphthalein. Under the optimized conditions, quenched ECL intensity versus the logarithm of the concentration of phenolphthalein was in good linear relationship over a concentration range from 3.18×10−10 to 1.59×10−7g/mL and the detection limit was 1.0×10−10g/mL. High affinity and selectivity of MISPE enabled the successful application of this method to determine phenolphthalein in drug, slimming food and human plasma. Further, a possible mechanism for the quenching effects of Ru(bpy)32+/DBAE system by phenolphthalein was also proposed.

Synthesis by precipitation polymerisation of molecularly imprinted polymer microspheres for the selective extraction of carbamazepine and oxcarbazepine from human urine

Two molecularly imprinted polymers (MIPs), in the physical form of well-defined polymer microspheres, were synthesised via precipitation polymerisation (PP) using an antiepileptic drug, carbamazepine (CBZ), as template molecule, methacrylic acid as functional monomer and either divinylbenzene 80 (DVB-80) or a mixture of DVB-80 and ethylene glycol dimethacrylate (EGDMA) as crosslinking agents. The MIP obtained using DVB-80 alone as crosslinking agent (MIP A) had a narrow particle size distribution (9.5 ± 0.5 μm) and a well-developed permanent pore structure (specific surface area in the dry state = 758 m 2 g −1), whereas when a mixture of DVB-80 and EGDMA (MIP B) were used as crosslinking agents, the polymer obtained had a broader particle size distribution (6.4 ± 1.8 μm) and a relatively low specific surface area (23 m 2 g −1). The molecular recognition character of both polymers was evaluated by means of LC and then a molecularly imprinted solid-phase extraction (MISPE) protocol; CBZ was recognised by both polymers, and useful cross-selectivity for oxcarbazepine (OCBZ), which is the main metabolite of CBZ, also observed. In a detailed bioanalytical study, MIP A was selected in preference to MIP B since MIP A enabled a high volume of sample to be extracted such that lower limits of detection were achievable using this polymer. High recoveries of CBZ and OCBZ were obtained in a MISPE protocol when 50 mL of human urine spiked at 0.2 mg L −1 were percolated through MIP A (90% and 83%, respectively).