Sensing System Integrating Lanthanum Hydroxide Nanowires with Copper(II) Ion for Uracil and its Application

Abstract

A sensing system for uracil was constituted by using lanthanum hydroxide nanowires (LNW) as a modifier to obtain LNW modified carbon paste electrode (LNW/CPE) and by introducing copper(II) ion into supporting electrolyte to transform electroinactive uracil to electroactive uracil-Cu(II) complex. The voltammetric behaviors of uracil in the presence of Cu(II) ion at LNW/CPE were investigated. A reduction peak of the uracil-Cu(II) complex at 20.18 V was the two-electron reduction of Cu(II) ion in the uracil-Cu(II) complex; while a new oxidation peak at 0.22 V was the one-electron oxidation of the uracil-Cu(I) complex. Additionally, the voltammetric responses of all the complexes at LNW/CPE were more sensitive than that at carbon and multiwall carbon nanotube paste electrodes, which resulted from both the large surface effect of LNW and the chemical coordination of uracil with La(III) ion in LNW. With the sensitive oxidation peak of the uracil-Cu(I) complex at LNW/CPE, a linear range of 4.0 Â 10 29 2 3.0 Â 10 28 mol/l for uracil was obtained along with a detection limit of 2.0 Â 10 210 mol/l. The proposed system was evaluated by the determination of uracil derivatives, anticancer drug 5-flurouracil, in pharmaceutical preparations.

Ultratrace analysis of uracil and 5‐fluorouracil by molecularly imprinted polymer brushes grafted to silylated solid‐phase microextraction fiber in combination with complementary molecularly imprinted polymer‐based sensor

“…As for as solid-phase extraction method (Salvador et al, 2006) is concerned, Ura and 5FU were reportedly coeluted with other endogenous substances of plasma. Whereas HPLC/ UV (Maring et al, 2005;Deporte et al, 2006), HPLC/fluorescence (Yoshida et al, 1986;Kindberg et al, 1989), GC/MS (Shin et al, 1998;Mashiyama et al, 2008) and voltammetric methods (Mirceski et al, 2000;Liu et al, 2007) showed impressive Ura and 5FU sensitivity, integration with advanced technology such as LC/MS (Jiang et al, 2002;Salvador et al, 2006) required costly and sophisticated instrumentation. To the best of our knowledge, no work related to direct SPME for Ura and 5FU analysis in biological fluids has hitherto been reported barring a few SPME analyses of substituted Ura herbicides (Beltran et al, 2000;Krutz et al, 2003).…”