Voltammetric Detection of Lead(II) Using Amide‐Cyclam‐ Functionalized Silica‐Modified Carbon Paste Electrodes

Abstract

[2][3][4]8,4,8,acetamide (TETAM) derivatives bearing 1, 2, or 4 silylated arms have been synthesized and grafted to the surface of silica gel and ordered mesoporous silica samples. The resulting organic-inorganic hybrids have been incorporated into carbon paste electrodes and applied to the preconcentration electroanalysis of Pb(II). The attractive recognition properties of these cyclam derivatives functionalized with amide pendent groups toward Pb(II) species and the highly porous structure of the adsorbents can be exploited for the selective and sensitive detection of the target analyte. Various parameters affecting the preconcentration and detection steps have been discussed with respect to the composition and pH of both accumulation and detection media, the nature of the adsorbent (number of silylated groups linking the macrocycle to silica, texture of materials), the accumulation time, and the presence of interfering cations. Under optimal conditions and for 2 min accumulation at open-circuit, the voltammetric response increased linearly with the Pb(II) concentration in a range extending from 2 Â 10 À7 to 10 À5 M, while a longer accumulation time of 15 min afforded a linear calibration curve between 10 À8 and 10 À7 M with a detection limit of 2.7 Â 10 À9 M which is well below the European regulatory limit of lead in consumption water.

Fast and simultaneous determination of Pb2+ and Cu2+ in water samples using a solid paraffin-based carbon paste electrode chemically modified with 2-aminothiazole-silica-gel

“…2+ and Cu 2+ are close to those reported in literature using other electroanalytical methods. 12,22,23,26,27,30 The main positive aspects of the proposed method are the very short accumulation time and the use of a silica commercially available at relatively low cost. In addition, solid paraffin is an inexpensive binder agent able to produce robust electrodes in a very simple and fast way.…”

“…Nanostructured [22][23][24] and mesoporous [25][26][27][28][29][30] silica have been widely used to prepare chemically modified electrodes for quantification of several metallic ions. Conventional silica (amorphous and silica gel) have also been used and it has allowed the reliable and low level quantification of Cu 2+ and Ni 2+ in ethanol fuel samples, [31][32][33] Hg 2+ and Cd 2+ in natural waters, 34,35 etc.…”

Electrode Materials (Bulk Materials and Modification)

“…734 Other examples are mesoporous silica functionalized with aminopropyl, 712,735 carbamoylphosphonic acid, 724,736 2-benzothiazolethiol, 737 5-mercapto-1-methyltetrazole, 738 propylsulfonic acid, 721 thiomorpholine, 739 carnosine, 720 acetylacetone, 740 2-acetylpyridine, 741 thiourea derivatives, 742 or cyclam. 618,619 More recently, ordered mesoporous carbon electrodes have been developed with great promise in electroanalysis, 44 these materials being most often deposited as particulate films onto solid electrodes but an example of OMC-modified CPEs has been also described. 743 The second category of "nano" additives to CPEs concerns the nanoparticles (NPs) for which the physicochemical properties can differ from the bulk materials.…”

Recent advances of mesoporous materials in sample preparation

“…Various technologies have been developed for the determination of hazardous metals in polluted area, such as the spectrophotometry [25], electrochemical analysis [26], atomic adsorption spectrometry (AAS) [27], electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) [28], inductively coupled plasma optical emission spectrometry/mass spectrometry (ICP-OES/MS) [29,30], and inductively coupled plasma atomic emission spectrometer (ICP-AES) [31]. However, due to the complexity of sample matrix and the trace level of target metal ion in sample, it is often difficult to determine metal ions by these techniques directly.…”

“…Ordered mesoporous Al 2 O 3 materials or mesoporous titanium film have also been used as capillary microextraction coating for the preconcentration of trace metal ions. Table 2 summarizes the preconcentration of metal ions by various functionalized mesoporous materials [26,30,[32][33][34][35][36][37][38].…”