Ascorbic acid sensor based on molecularly imprinted polymer-modified hanging mercury drop electrode

Ascorbic acid sensor based on molecularly imprinted polymer (MIP) is reported for sensitive and selective analysis, without any cross-reactivity or matrix effect, in aqueous, blood serum and pharmaceutical samples. The sensor was developed by the direct coating of ascorbic acid-imprinted polymer, prepared from melamine and chloranil, on the surface of a hanging mercury drop electrode (HMDE) at +0.4 V (vs. Ag/AgCl). The molecular recognition of ascorbic acid was highly specific using non-covalent (hydrophobically driven hydrogen-bonding and electrostatic) interactions. The analyte was preconcentrated and oxidised instantaneously in the imprinted polymer layer giving voltammetric signal on cathodic stripping at optimised operational conditions: accumulation potential +0.4 V (vs. Ag/AgCl), polymer deposition time 120 s, template accumulation time 120 s, pH 7.0, scan rate 10 mV s(-1), pulse amplitude 25 mV. The proposed MIP sensor is able to enhance sensitivity substantially so as to detect serum ascorbic acid level as low as 0.26 ng mL(-1) (R.S.D. 0.5%, S/N 3) for the diagnosis of hypovitaminosis C (Vitamin C deficiency). (C) 2008 Elsevier B.V. All rights reserved.