石墨烯修饰玻碳电极伏安法测定酪氨酸

制备了石墨烯修饰玻碳电极,研究了酪氨酸在修饰电极上的电化学行为.优化了包括支持电解质、溶液pH、修饰剂用量、富集电位及时间等测定条件.在0.1 mol·L-1pH 7.0的磷酸盐缓冲溶液中,峰电流与酪氨酸的浓度在3×10-6～1.2×10-4mol·L-1的范围内呈良好的线性关系,检出限为2 × 10-7 mol·L-...     

石墨烯修饰玻碳电极用于循环伏安法测定抗坏血酸

采用Hummers法制备了纳米石墨烯,并将该纳米材料分散在蒸馏水中得到悬浮液,取5μL的悬浮液滴涂在玻碳电极表面,制备石墨烯修饰电极。用循环伏安法研究了在pH 4.0磷酸盐电解质中,在-0.4～0.8V(vs.Ag/AgCl)电位范围内,抗坏血酸在修饰电极上的电化学行为。结果表明:抗坏血酸在修饰电极上在0.173V处可见明显的氧化峰,且氧化峰电流显著高于在裸玻碳电极上的氧化峰电流;并可有效排除肾上腺素、尿酸、多巴胺等物质的干扰。据此提出了用循环伏安法测定抗坏血酸的方法。抗坏血酸的线性范围为8.00×10-6～1.0×10-3 mol.L-1,检出限(3S/N)为1.0×10-7 mol.L-1。方法用于维生素C片的分析,回收率在96.3%～104.4%之间。     

Nafion—玻碳修饰电极阴极溶出伏安法测定痕量铋的研究

研究并提出在HNO_3-NaCl-硫脲(Tu)体系中,Nafion/玻碳(Gc)修饰电极阴极溶出伏安法测定痕量鉍的方法。表明Tu具络合协同作用,使Nation阳离子交换能力提高。本法检出限为5×10~(-9)mol/L Bi~(3+)(td:5min),电极表面易于再生,文中研究了电极过程机理,计算得[Bi(Tu)_6]~(3+)在Nafion膜中的分配系数(K_D),扩散系数(D)和选择性系数(K_H~[Bi(Tu)_6~+]~(3+))分别为7.57×10~5,5.9×10~(-11)cm~2/s及3.39。     

Nafion修饰玻碳电极伏安法测定痕量铟

报道了一种用Nafion修饰玻碳电极测定痕量铟的新方法。研究了Na-fion膜的有关特性和测定的条件,当富集时间为5 min时,峰电流与In(Ⅲ)浓度在1×10-9~1×10-7mol/L的范围呈良好的线性关系,检出限为1.46×10-10mol/L。该法用于实际水样中痕量铟的测定,平均回收率为98.4%。     

杯芳烃修饰玻碳电极吸附溶出伏安法测定微量铅

研究了以杯芳烃衍生物修饰玻碳电极,以其吸附溶出伏安法测定微量铅。对富集时间、铅的浓度、支持电解质、样品溶液pH值及部分离子干扰等进行了实验。实验发现以氢氧化钠溶液处理修饰电极可提高测定灵敏度,经过优化处理后,线性范围和检出限分别为5.0×10-7～1.0×10-5mol/L和1.0×10-8mol/L。应用本法对合成水样进行了测定,结果满意。本文还对吸附溶出机理进行了讨论。     

聚铬黑T修饰玻碳电极方波伏安法测定对羟基苯乙酮

建立了铬黑T修饰玻碳电极方波伏安法测定对羟基苯乙酮(p-hyd)的电化学方法。运用循环伏安法在含有0.5 mmol/L铬黑T的0.1 mol/L NaOH溶液中制备聚铬黑T膜,并用扫描电镜、红外光谱、电化学阻抗等技术进行了表征。在pH 4.5的磷酸盐缓冲溶液中,p-hyd在908 mV(vs.SCE)处的峰电流与其浓度在1~160μmol/L范围内呈良好的线性关系,检出限0.15μmol/L(S/N=3),相对标准偏差小于2%。     

双硫腙修饰玻碳电极阳极溶出伏安法测定痕量镉和铅

报道了双硫腙修饰玻碳电极同时测定痕量镉和铅的电分析方法。镉和铅离子通过与电极表面的双硫腙发生螯合作用而富集在电极表面 ,同时在 -1 .2 0V(vs.SCE)还原成零价镉和铅 ,当电极电势从 -1 .2 0V向 -0 .3 0V扫描时 ,被还原的镉和铅从电极表面溶出 ,分别于 -0 .78V和 -0 .4 8V左右形成灵敏的阳极溶出峰。优化了支持电解质及pH值、双硫腙用量、富集电位及时间等实验参数。利用该修饰电极测定镉、铅的线性范围分别为 1 .0×1 0 - 8～ 2 .5× 1 0 - 6 mol L和 5 .0× 1 0 - 9～ 2 .5× 1 0 - 6 mol L。检测限分别为 5 .0× 1 0 - 9mol L和7.0× 1 0 - 1 0 mol L。该法用于实际水样中镉和铅的测定 ,平均回收率分别为 99.3 0 %和 99.5 4 %。     

石墨烯修饰玻碳电极测定邻苯二酚

制备了用于测定邻苯二酚(CAT)的石墨烯修饰电极,并应用循环伏安法研究了CAT在该修饰电极上的电化学行为;用差分脉冲伏安法研究了测试底液的pH值对该修饰电极性能的影响,结果表明,此修饰电极在含不同浓度CAT的PBS溶液(pH=7.0)中测定,响应电流与CAT浓度在5.0×10-8～5.6×10-4mol/L范围内有良好的线性关系,相关系数r=0.9919,检出限为6.68×10-9mol/L(S/N=3)。与其它几种修饰电极相比,石墨烯修饰电极制备简单、响应时间快、操作简便,稳定性和重现性良好,有应用价值。     

Voltammetric determination of disinfectants at multiwalled carbon nanotube modified glassy carbon electrode

The voltammetric method for simultaneous determination of some disinfectants at glassy carbon electrode modified with multiwalled carbon nanotubes is presented. The examined compounds are: 2-phenylphenol, 4-chloro-3-methylphenol, triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol and 2-mercaptobenzothiazole. The measurements has been performed using cyclic voltammetry and differential pulse voltammetry in Britton-Robinson buffers as supporting electrolytes. The modification of electrode surface with multiwalled carbon nanotubes enhances the peak current. It is possible to measure mixtures of two compounds (2-phenylphenol and 2-mercaptobenzothiazole, 4-chloro-3-methylphenol and 2-mercaptobenzothiazole, triclosan and 2-mercaptobenzothiazole) in the solution of pH 9.9, which provides the best separation of oxidation peaks.     

Voltammetric determination of niclosamide at a glassy carbon electrode

A very sensitive and selective procedure was developed for the determination of niclosamide based on square-wave voltammetry at a glassy carbon electrode. Cyclic voltammetry was used to investigate the electrochemical reduction of niclosamide at a glassy carbon electrode. Niclosamide was first irreversibly reduced from NO2 to NHOH at -0.659 V in aqueous buffer solution of pH 8.5. Reversible and well defined peaks at -0.164 V and -0.195 V (vs. Ag/AgCl) were obtained that are responsible for two electron peaks between NHOH and NO. Following optimisation of the voltammetric parameters, pH and reproducibility, a linear calibration curve over the range 5 x 10(-8)-1 x 10(-6) mol dm(-3) was achieved. The detection limit was found to be 2.05 x 10(-8) mol dm(-3) niclosamide. For eight successive determinations of 5 x 10(-7) mol dm(-3) niclosamide, a relative standard deviation of 2.4% was obtained. This voltammetric method was applied to the direct determination of niclosamide in tablets. The results of the analysis suggest that the proposed method has promise for the routine determination of niclosamide in the products examined.     

Voltammetric determination of 4-nitrophenol at a sodium montmorillonite-anthraquinone chemically modified glassy carbon electrode

A new method for the determination of 4-nitrophenol(4-NP) by differential pulse voltammetry (DPV) based on adsorptive stripping technique was described. Cyclic voltammetry (CV) and linear scan voltammetry (LSV) were used in a comparative investigation into the electrochemical reduction of 4-NP at a Na-montmorillonite(SWy-2) and anthraquione (AQ) modified glassy carbon electrode. With this chemically modified electrode, 4-NP was first irreversibly reduced from phiNO(2) to phiNHOH at -0.78 V. A couple of well-defined redox peaks at +0.22 V (vs. SCE) were responsible for a two-electron redox peak between phiNHOH and phiNO. Studies on the effect of pH on the peak height and peak potential were carried out over the pH range 2.0-9.0 with the phosphate buffer solution. A pH of 3.4 was chosen as the optimum pH. The other experimental parameters, such as film thickness, accumulation time and potential etc. were optimized. Anodic peak currents were found to be linearly related to concentration of 4-NP over the range 0.3-45 mg l(-1), with a detection limit of 0.02 mg l(-1). The interference of organic and inorganic species on the voltammetric response have been studied. This modified electrode can be used to the determination of 4-NP in water samples.     

Voltammetric oxidation and determination of cinnarizine at glassy carbon electrode modified with multi-walled carbon nanotubes

We discovered a novel method to prepare a protein-based hydrogel, that is, a “Three-Dimensional Nanostructured Protein Hydrogel (3D NPH)”, which is composed of protein–polymer hybrid nanoparticles. In this study, we propose a novel protein microarray whose 3D NPH spots were prepared by dispensing a small volume of the solution of protein–polymer mixture on a substrate. The dispensed solution had a short time for cross-linking before its drying-up and the resulting 3D NPH had loosely cross-linked, thin spongy structure. Therefore, the reaction ratio between ligands and analytes was drastically improved in this system compared with the large volume system for Surface Plasmon Resonance (SPR) protein microarray.     

Voltammetric determination of phenylbutazone and oxyphenbutazone at a glassy carbon electrode

Linear-sweep and differential-pulse voltammetric methods are reported for the determination of phenylbutazone and oxyphenbutazone and of their pharmaceutical dosage forms. The methods are based on the electrochemical oxidation of phenylbutazone and oxyphenbutazone at a glassy carbon electrode in 0.1 M sodium acetate—0.1 M acetic acid in 98% ethanol. The mechanisms are discussed. The proposed methods show good reproducibility and are not subject to interference from common tablet excipients and from possible therapeutically active drug substances used in combination with phenylbutazone and oxyphenbutazone. A simple interrupted-sweep procedure can be used to determine phenylbutazone in the presence of oxyphenbutazone.     

聚L-丝氨酸修饰电极伏安法测定对乙酰氨基酚

对乙酰氨基粉(扑热息痛)为芳环对位取代的酰氨类药物,有解热、镇痛作用。临床上广泛用于感冒发烧、关节痛、神经痛及偏头痛、癌性痛及手术后止痛[1]。但过多服用对乙酰氨基酚对人体会造成伤害,对消化系统的影响主要表现为恶心、呕吐、压食、出汗、腹痛等症状;对泌尿系统、血液系统、呼吸系统都有影响,还能使对阿司匹灵过敏患者的支气管痉挛加重,严重时会抑制呼吸中枢。因此建立对乙酰氨基酚的灵敏检测方法是非常必要的。当前用于检测对乙酰氨基酚的方法主要有滴定法[2]、分光光度法[3]、高效液相色谱法[4]、毛细管电泳[5]、荧光法[6]以及电…     

聚磺胺嘧啶修饰电极伏安法测定对乙酰氨基酚

利用循环伏安法制备了聚磺胺嘧啶修饰电极, 研究了对乙酰氨基酚在该修饰电极上的电化学行为. 该电极对对乙酰氨基酚有较强的电催化作用. 在pH 9.0的PBS缓冲溶液中, 用循环伏安法和差分脉冲伏安法在该电极上测定了对乙酰氨基酚, 其线性范围分别为4.0×10-6～3.0×10-4 mol/L和2.0×10-7～1.0×10-5 mol/L, 检出限分别为9.0×10-7 mol/L和8.0×10-8 mol/L.