Electropolymerized surface ion imprinting films on a gold nanoparticles/single-wall carbon nanotube nanohybrids modified glassy carbon electrode for electrochemical detection of trace mercury(II) in water.

Electrochemical detection of Hg(II) using a electropolymerized ion imprinting poly(2-mercaptobenzothiazole) films at the surface of gold nanoparticles/single-walled carbon nanotube nanohybrids modified glassy carbon electrode (PMBT/AuNPs/SWCNTs/GCE) is described for the first time. The Hg(II)-imprinted PMBT/AuNPs/SWCNTs/GCE sensor exhibits larger binding to functionalized capacity, larger affinity, faster binding kinetics and higher selectivity to template Hg(II). The differential pulse anodic stripping voltammetry (DPASV) response of the Hg(II)-imprinted PMBT/AuNPs/SWCNTs/GCE sensor to Hg(II) is ca. 3.7- and 10.5-fold higher than that at the non-imprinted PMBT/AuNPs/SWCNTs/GCE and the imprinted PMBT/AuNPs/GCE, respectively, and the detection limit for Hg(II) is 0.08 nM (S/N=3, which is well below the guideline value given by the World Health Organization) and a sensitivity of 0.749 µA nM(-1) was obtained. Excellent wide linear range (0.4-96.0 nM) and good repeatability (relative standard deviation of 2.6%) were obtained for Hg(II). The interference experiments show that Ag(I), Pb(II), Cd(II), Zn(II) and Cu(II) had little or no influence on the Hg(II) signal. These values, particularly the high sensitivity and excellent selectivity in contrast to the values reported previously in the area of electrochemical Hg(II) detection, demonstrate the analytical performance of the Hg(II)-imprinted PMBT/AuNPs/SWCNTs/GCE toward Hg(II) is superior to the existing electrodes and could be used for efficient determination of Hg(II) in natural water samples.

Stripping voltammetric detection of mercury(II) based on a surface ion imprinting strategy in electropolymerized microporous poly(2-mercaptobenzothiazole) films modified glassy carbon electrode.

This work reports a surface ion imprinting strategy in electropolymerized microporous poly(2-mercaptobenzothiazole) (MPMBT) films at the surface of glassy carbon electrode (GCE) for the electrochemical detection of Hg(II). The Hg(II)-imprinted MPMBT/GCE exhibits larger binding to functionalized capacity, faster binding kinetics and higher selectivity to template Hg(II) due to their high ratio of surface-imprinted sites, larger surface-to-volume ratios, the complete removal of Hg(II) templates and larger affinity to Hg(II). The square wave anodic stripping voltammetry (SW ASV) response of the Hg(II)-imprinted MPMBT/GCE to Hg(II) is ca. 3.0 and 5.9 times larger than that at the direct imprinted poly(2-mercaptobenzothiazole) modified GCE and non-imprinted MPMBT/GCE sensor, respectively; and the detection limit for Hg(II) is 0.1nM (which is well below the guideline value given by the World Health Organization). Excellent wide linear range (1.0-160.0nM) and good repeatability (relative standard deviation of 2.5%) were obtained for Hg(II). The interference experiments showed that mercury signal was not interfered in the presence of Pb(II), Cd(II), Zn(II), Cu(II) and Ag(I), respectively. These values, particularly the high sensitivity and excellent selectivity compared favorably with previously reported methods in the area of electrochemical Hg(II) detection, demonstrate the feasibility of using the prepared Hg(II)-imprinted MPMBT/GCE for efficient determination of Hg(II) in aqueous environmental samples.

Chemiluminescence sensor for sulfonylurea herbicide using molecular imprinted microspheres as recognition element.

Uniform molecular imprinting microspheres were prepared using precipitation polymerization with thifensulfuron-methyl (TFM) as template, acrylamide as functional monomer and ethylene glycol dimethacrylate as cross-linker. TFM could be selectively adsorbed on the molecularly imprinted polymers (MIPs) matrix through the hydrogen bonding interaction and the adsorbed TFM could be sensed by its strikingly enhancing effect on the weak chemiluminescence (CL) reaction between luminol and hydrogen peroxide. On this basis, a novel CL sensor for the determination of TFM using MIPs as recognition elements was established. The logarithm of net CL intensity (ΔI) is linearly proportional to the logarithm of TFM concentration (C) in the range from 1.0 × 10(-9) to 5.0 × 10(-5) mol L(-1) with a detection limit of 8.3 × 10(-10) mol L(-1) (3σ). The results demonstrated that the MIP-CL sensor was reversible and reusable and that it could strikingly improve the selectivity and sensitivity of CL analysis. Furthermore, it is suggested that the CL enhancement of luminol-H(2)O(2) by TFM might be ascribed to the enhancement effect of CO(2), which came from TFM hydrolysis in basic medium.

Determination of tannic acid in industrial wastewater based on chemiluminescence system of KIO4-H2O2-Tween40.

The oxidation reaction of H2O2 with KIO4 can produce chemiluminescence (CL) in the presence of the surfactant Tween40 and the CL intensity of the CL system KIO4-H2O2-Tween40 can be strikingly enhanced after injection of tannic acid. On this basis, a flow injection method with CL detection was established for the determination of tannic acid. The method is simple, rapid and effective to determine tannic acid in the range of 7.0 × 10(-9) to 1.0 × 10(-5) mol/L with a determination limit of 2.3 × 10(-9) mol/L. The relative standard deviation is 2.6% for the determination of 5.0 × 10(-6 )mol/L tannic acid (n = 11). The method has been applied to determine the content of tannic acid in industrial wastewater with satisfactory results. It is believed that the CL reaction formed singlet oxygen (1)O(2)* and the emission was from an excited oxygen molecular pair O2(¹Δ(g))O2(¹∑⁻(g)) in the KIO4-H2O2-Tween40 reaction. Tween40 played an important role in enhancing stabilization of the excited oxygen molecular pair O2(¹Δ(g))O2(¹∑⁻(g)) and in increasing CL intensity.

[Determination of phloroglucinol by a new flow injection chemiluminescence method].

Chemiluminescence reaction of phloroglucinol with potassium permanganate in the presence of formaldehyde as an enhancer was investigated. A new chemiluminescence method for the determination of phloroglucinol with flow injection technique was developed. The linear range for phloroglucinol is 5.0 x 10(-9)-5.0 x 10(-5) mol x L(-1) with a detection limit of 3.0 x 10(-9) mol x L(-1). The relative standard deviation is 2.5% for 1.0 x 10(-6) mol x L(-1) phloroglucinol in 11 repeated measurements. The method has been used to determine the content of phloroglucinol in simulated water with satisfactory results.

A novel chemiluminescent method for determination of phloroglucinol.

It was found that the inhibition and enhancement by phloroglucinol of the chemiluminescence from the luminol-K3Fe(CN)6 system were dependent on the pH of luminol solution and the concentration of phloroglucinol. In Na2CO(3)-NaHCO3 buffer, phloroglucinol exhibited strong chemiluminescent enhancement at pH 9.4. On this basis, a flow injection method was developed for the determination of phloroglucinol. The method was simple, rapid, convenient and sensitive, with a detection limit of 2.0 x 10(-9) mol/L. It is effective for determining phloroglucinol in the range of 1.0 x 10(-5)-5.0 x 10(-9) mol/L. The relative standard deviation is 1.3% within one day and 3.2% between days for the determination of 5.0 x 10(-7) mol/L phloroglucinol. The method has been successfully used to determine phloroglucinol in environmental water, with satisfactory results.