聚多巴胺/多壁碳纳米管/玻璃碳电极上多巴胺的电分析

基于多巴胺（DA）在多壁碳纳米管（MWCNTs）修饰玻璃碳（GC）电极上的电聚合,制得聚多巴胺(PDA)/MWCNTs/GC电极,并对该修饰电极进行了电化学阻抗谱 (EIS)和循环伏安法(CV)表征。 在该修饰电极上,DA呈现良好的电化学行为。在pH=7.4磷酸缓冲溶液中其氧化电流显著高于在裸电极上的响应,且能有效地抑制2.0 mmol/L抗坏血酸(AA)或K4Fe(CN)6的直接电化学响应,表明MWCNTs可增敏信号,且阳离子选择透过性PDA膜可抑制阴离子的电化学干扰。 采用CV实验检测DA,DA氧化的半微分伏安峰高(ipa-sd)与多巴胺浓度在0.08～1.76 μmol/L范围内呈线性关系,在无抗坏血酸和有0.5 mmol/L抗坏血酸共存时的线性回归方程分别为ipa-sd(μA/s1/2)=0.107+0.405c(μmol/L)（r2=0.986）和ipa-sd(μA/s1/2)=0.628+0.649c(μmol/L)(r2=0.992),检测限均为8.0×10-8 mol/L(S/N=3)。 该法用于盐酸多巴胺注射液中多巴胺的快速测定,结果满意。     

A Boron Doped Diamond Electrode Modified with Nano‐carbon Black for the Sensitive Electrochemical Determination of Chlorogenic Acid

An electrochemical method was developed for the sensitive determination of chlorogenic acid using a boron doped diamond electrode (BDDE) modified with nano‐carbon black (nano‐CB). The active surface areas were found to be 0.059 and 0.146 cm² for the unmodified BDDE, and nano‐CB/BDDE, respectively. Compared with a BDDE, the nano‐CB/BDDE exhibited a well‐defined redox couple for chlorogenic acid. In addition, the plot of the peak current response changing from a square root to a linear dependence on scan rate is attributed to the transition from planar diffusion to surface behaviour. The anodic and cathodic peak separations (ΔE_p) were 97 mV and 14 mV at BDDE and nano‐CB/BDDE, respectively. The decrease in ΔE_p at the proposed electrode indicated that the process of chlorogenic acid was greatly accelerated. Square wave voltammetry (SWV) exhibited a dynamic range in which the current versus the concentration of chlorogenic acid were linear from 2.0×10^?8 to 2.0×10^?6 M with a LOD of 4.1×10^?9 M (based on 3S_b/m). The nano‐CB modified BDDE provided improved electrochemical behavior, high electrocatalytic activity, high sensitivity and good reproducibility.     

超声波-微分脉冲伏安法测定超痕量铜

以循环伏安和微分脉冲伏安法研究了超声作用下铜在铂电极上的电沉积行为,建立了超痕量铜的超声波-微分脉冲伏安法。超声波增加了铜的阳极溶出峰电流近一个数量级,提高了方法的灵敏度。在优化实验条件下,铜的微分脉冲阳极溶出峰电流与铜离子浓度在两个范围内呈线性关系。在5.00~200nmol/L的浓度范围内,线性方程为I=0.0453 0.00101c(nmol/L,R=0.9963,SD=0.0078);检出限为0·20nmol/L(13ng/L);在0.200~8.00μmol/L浓度范围内,线性方程为i=0.243 0.0864c(μmol/L,R=0·9983,SD=0.0188)。常见金属离子一般不干扰。方法简便快速,直接用于自来水实际样品的测定,加标回收率为95.4%~104.6%;RSD为3.36%,结果令人满意。     

Black Phosphorene Modified Electrochemical Sensor for Fast Determination of 5-Hydroxymethyl-2-furfural in Milk

The fast detection of 5-hydroxymethyl-2-furfural (HMF) in food industry is vital because of its toxicity and mutagenicity. A glassy carbon electrode (GCE) modified with black phosphorene (BP) nanosheets was prepared and coated with Nafion to improve stability. The electrode has excellent electrochemical stability and current response for HMF electroreduction. The good linear relationship is in the concentration range of 0.1–10 μg/mL with the detection limit of 0.012 μg/mL. HMF electroreduction is a diffusion-controlled process involving two electrons and two protons. The sensor was successfully applied to the measurement of HMF in milk with the recovery values of 92.92 %–96.33 %.     

纳米材料修饰电极及其在电分析化学中的应用

综述了纳米材料修饰电极的特性及其在电分析化学领域的一些研究成果。重点介绍了碳纳米管、纳米二氧化钛和钠米金修饰电极的修饰,表征方法及其作为一类新型电极在电分析化学中的应用前景。     

Modified carbon paste electrode for the electrochemical sensing of 3,5,6-trichloro-2-pyridinol

An electrochemical sensor for the determination of 3,5,6-trichloro-2-pyridinol (TCP), the main metabolite of the pesticide chlorpyrifos, was herein developed. TCP has greater solubility than the source pesticide, and its occurrence in ground and surface water is more frequent and more dangerous. The sensor was fabricated using carbon paste modified with the inorganic complex chloro-5,10,15,20-tetrakis-(pentafluorophenyl)-21 H,23 H-porphyrin iron(III) (FeTPPCl); this metallic complex has a chemical core structure similar to the heme cofactor of the cytochrome P450 (CYPs). Measurements were performed with square-wave voltammetry. Using the optimised voltammetric parameters and without any sample preparation, the sensor showed a limit of detection of 2.8 mg L^?1 (14 μmol L^?1), recoveries ca. 102%, suitable selectivity and long durability (over 1 month).     

Disposable and Flexible Electrochemical Paper-based Analytical Devices Using Low-cost Conductive Ink

In this work, a simple procedure for construction of disposable electrochemical paper-based analytical devices (ePADs) by screen-printing using low-cost materials and a home craft electronic printer is proposed. The devices were constructed using liner paper as a substrate and carbon ink prepared with graphite powder and wood glue. The ePAD was evaluated as an electrochemical sensor and biosensor. The proposed conductive carbon-based ink can be easily prepared and is an eco-friendly and non-toxic material. The developed ePAD was simple to produce and can be used as a low-cost electrochemical sensor, at less than US $0.20 per device.     

Electroanalytical Determination of Estrone in Seawater Samples Using Functionalized Multiwalled Carbon Nanotubes

In this work, a glassy carbon electrode (GCE) modified with multiwalled carbon nanotubes functionalized with carboxylic groups (MWCNT−COOH) was used to determine the hormone estrone in seawater samples. Modification of the electrode was optimized using three successive 10-μL aliquots of the MWCNT−COOH dispersion in ethanol (1 : 5 mL). The cyclic voltammetry results showed an oxidation peak at 0.59 V with characteristics of an irreversible process, pH dependent and controlled by adsorption of species. The results of square-wave voltammetry showed that the intensities of peak currents for the MWCNT−COOH/GCE were about 2.5 times higher than for GCE. The calibration curve showed a linearity of 0.9981 and a sensitivity of 0.1521 μA/mol L⁻¹. The limits of detection and quantification were 0.117 and 0.392 μmol L⁻¹, respectively. The recovery obtained using seawater samples was 91%, indicating the applicability of the method in marine environments.     

Determination of Ni with Electrodes Modified with Mordant Violet 5

Abstract

The utility of electrodes modified with the dye Mordant Violet 5 (MV-5) for the determination of Ni is demonstrated. The method is based on the coordination of Ni from solution by an immobilized layer (via ion exchange) of the dye. Upon coordination the redox response of the dye is shifted in the negative direction by about 250 mV (from ?0.74 to ?0.97 V). The height of this peak is used as the analytical signal which is related to the concentration of Ni in solution. Linear calibration curves were obtained for Ni concentrations ranging from about 10^?4 to 2×10^?3M. Although this reflects only moderate sensitivity, a basic concept is established; this method allows for the determination of the metal via the redox response of the dye. Thus, with appropriate choice of reagents, metal ions difficult to determine by direct reduction can be determined by this method. The use of other reagents may result in enhanced sensitivity.