Molecularly imprinted polymer-based solid-phase extraction combined with molecularly imprinted polymer-based sensor for detection of uric acid

The development of an easy-to-use, rapid, robust and inexpensive technique is required which can measure the basal concentration of uric acid (UA) lower than 1.0 x 10(-7) M (similar to 0.0 17 mg L-1) in biological samples to attend the problem of hypouricemia. In the present work an artificial receptor for UA, silica gel-bonded molecularly imprinted polymer (MIP), was used as a sorbent for molecularly imprinted solid-phase extraction (MISPE) in column chromatography. The use of a sensor based on a MIP-modified hanging mercury drop electrode (HMDE), as reported from our laboratory, could estimate UA with detection limit as low as 0.024 mg L-1 under the optimized conditions of differential pulse, cathodic stripping voltammetric (DPCSV) measurement. However, in the cur-rent investigation, with the use of the combination of MISPE followed by detection with a MIP-based HMDE sensor, the minimum detectable concentration could go down to 0.0008 mg L-1 (RSD = 0.63%, S/N = 3). The same MIP receptor for both MISPE and the corresponding sensor was able to enhance the preconcentration of analyte substantially so as to attain the desired level of sensitivity; and that to without any interference (cross-reactivity) from other structurally related analogues including the major interferent like ascorbic acid prevalent in the aqueous environment of biological samples. (c) 2007 Elsevier B.V. All rights reserved.