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)(3)(2+)/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 x 10(-10) to 1.59 x 10(-7) g/mL and the detection limit was 1.0 x 10(-10) g/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)(3)(2+)/DBAE system by phenolphthalein was also proposed. (C) 2011 Elsevier Ltd. All rights reserved.