三辛基氧化膦化学修饰电极预富集-石墨炉原子吸收测定水中痕量锑的研究

本文研究了三辛基氧化膦(TOPO)化学修饰电极预富集石墨炉原子吸收法测定水样中痕量锑。水中痕量锑被电解还原蓝电积在TOPO修饰的钨电极上,然后放入石墨杯中直接原子化。锑的测定线性范围1.0—20ng/mL,含10ng/mL锑的溶液九次平行测定,变异系数为3.1％,捡出限为0.1ng/mL,24种共存离子及有机物不干扰测定。方法灵敏、简便、并用于一些水样的测定,得到满意的结果。     

TOPO修饰电极电位溶出法测定水中Sb(Ⅲ)

本文提出了TOPO化学修饰电极电位溶出分析法,研究了电极的修饰过程以及测定水中痕量锑的实验条件,探讨了修饰电极的作用机理,认为电极性能的改善主要是由电极表面上膜的络合吸附性所决定的。制作的修饰电极重复性好、灵敏度高。方法的变异系数为4.4％,Sb(Ⅲ)的检测下限为4×10~(-9)mol/L。     

应用锑膜修饰电极示差脉冲伏安法同时测定多巴胺和抗坏血酸

应用电化学还原法自制的锑膜修饰玻碳电极(GCE)研究了多巴胺(DA)和抗坏血酸(AA)在此修饰电极上的电化学性质.DA和AA在此修饰电极上的氧化电位依次为0.676 V和0.360 V,两者相差316 mV.此电位差值远大于两者在裸GCE电极上的差值(136 mV).据此,可用锑膜修饰的GCE,用示差脉冲伏安法同时测定DA和AA.测定DA和AA的线性范围分别为6.80×10-7～1.33×10-2,2.60×10-6～1.20×10-3mol·L-1,方法的检出限依次为1.50×10-7,6.70×10-7mol·L-1.应用所提出的方法分析了DA的针剂和AA的片剂样品,所得结果与标示值相符,并测得方法的回收率在97.9%～99.3%之间.     

Nafion修饰电极同位镀金膜阳极溶出伏安法测定痕量砷

金膜电极阳极溶出伏安法测定痕量砷已有报道,但铜、锑、铋存在严重干扰。本文采用Nafion修饰电极同位镀金膜阳极溶出伏安法测定痕量砷,大大提高了其选择性,铜、锑、铋分别为砷含量的6倍,3倍和6.5倍以下时,不干扰测定;测定灵敏度也较同位镀金膜电极时高。本法应用于标钢和黄河底泥中砷含量的测定,均获得满意结果。     

碳糊修饰电极吸附伏安法测定食品中的锑

研制了溴邻苯三酚红 (BPR)作修饰剂的碳糊修饰电极 ,并用此电极作工作电极建立了测定痕量锑的吸附伏安法。在选定的实验条件下 ,峰电流与Sb(Ⅲ )浓度在 8.0× 1 0 -9～ 2 .0× 1 0 -7mol L范围内呈线性关系 ,检出限为 2 .0×1 0 -9mol L ,1 0次测定相对标准偏差为 2 .0 % ,不用分离 ,可直接测定食品中痕量Sb(Ⅲ ) ,测定的回收率为 90 %～ 1 0 3%。     

纳米银粒子修饰电极法测定血红蛋白

报道了一种利用纳米材料修饰电极检测血红蛋白的新方法。制作了以纳米银粒子修饰的银电极,并研究了血红蛋白在该修饰电极上的直接电化学行为。实验结果表明,血红蛋白在该修饰电极上具有良好的电流响应。在2.0×10-7~1.0×10-5mol/L浓度范围内,血红蛋白的氧化峰电流与其浓度呈良好线性关系;检出限为7.4×10-8mol/L。研究了该修饰电极对血红蛋白的催化机理,利用该电极所建立的方法实现了对血红蛋白的分析测定。     

复合修饰电极测定p-硝基苯酚新方法的研究与探讨

将多壁碳纳米管分散在孔雀绿溶液中并滴涂在玻碳电极表面,再电聚合一层孔雀绿膜,制备了一种新型的聚孔雀绿/多壁碳纳米管复合膜修饰玻碳电极.用电化学方法对所制得的复合修饰电极进行了表征,并研究了p-硝基苯酚在该电极上的电化学行为.结果表明,所制备的复合修饰电极对P-硝基苯酚有良好的电催化作用,从而建立了一种直接测定P-硝基苯...     

纳米金/碳纳米管复合材料修饰电极催化鲁米诺电致发光体系的研究

制备了纳米金/多壁碳纳米管(MWNT)复合材料修饰电极,并将此电极应用于鲁米诺电化学发光体系.电化学发光实验表明,此复合材料修饰电极同时具备了纳米金和碳纳米管的催化性能.此外通过电极活性表面积测算、电化学交流阻抗实验等方法研究了纳米金和碳纳米管在此体系催化过程中的作用.纳米金/碳纳米管修饰电极具有良好的重现性,可以广泛应用于鲁米诺电化学发光测定体系.     

碳纳米管修饰电极离子色谱电化学法测定盐酸麻黄碱

采用阴离子交换分离,碳纳米管修饰电极安培检测离子色谱电化学法测定盐酸麻黄碱.在优化条件下,用碳酸钠溶液和甲醇溶液混合溶液为淋洗液,用碳纳米管修饰玻碳电极,在0.8 V电位处进行直流安培检测.结果发现在碳纳米管修饰玻碳电极后盐酸麻黄碱的电流响应值比未修饰前大大增加,方法的灵敏度比未修饰电极提高了10倍,用未修饰电极测定的检出限为2.4 μg·L-1,用修饰电极测定的检出限为0.2 μg·L-1,样品加标回收率为103.6%..     

痕量铅在Nafion修饰电极上的离子交换及其测定的研究

本文利用Nafion膜与试液中的痕量铅进行离子交換的特性,建立了Nafion修饰电极的富集及测定铅的方法,并探讨了Nafion修饰电极作用机理。本方法测定Pb~(2+)的线性范围为13～133ng/mL,变异系数为3.5％,检测下限为6ng/mL。     

Chemical Speciation of Antimony(III and V) in Water by Adsorptive Cathodic Stripping Voltammetry Using the 4‐(2‐Thiazolylazo) – Resorcinol

A simple adsorptive cathodic stripping voltammetry method has been developed for antimony (III and V) speciation using 4‐(2‐thiazolylazo) – resorcinol (TAR). The methodology involves controlled preconcentration at pH 5, during which antimony(III) – TAR complex is adsorbed onto a hanging mercury drop electrode followed by measuring the cathodic peak current (I_p,c) at ?0.39 V versus Ag/AgCl electrode. The plot of I_p,c versus antimony(III) concentration was linear in the range 1.35×10^?9–9.53×10^?8 mol L^?1.The LOD and LOQ for Sb(III) were found 4.06×10^?10 and 1.35×10^?9 mol L^?1, respectively. Antimony(V) species after reduction to antimony(III) with Na₂SO₃ were also determined. Analysis of antimony in environment water samples was applied satisfactorily.     

Determination of Lead(II) Using Screen‐Printed Bismuth‐Antimony Film Electrode

This work presents a disposable bismuth‐antimony film electrode fabricated on screen‐printed electrode (SPE) substrates for lead(II) determination. This bismuth‐antimony film screen‐printed electrode (Bi‐SbSPE) is simply prepared by simultaneously in situ depositing bismuth(III) and antimony(III) with analytes on the homemade SPE. The Bi‐SbSPE can provide an enhanced electrochemical stripping signal for lead(II) compared to bismuth film screen‐printed electrodes (BiSPE), antimony film screen‐printed electrodes (SbSPE) and bismuth‐antimony film glassy carbon electrodes (Bi‐SbGC). Under optimized conditions, the Bi‐SbSPE exhibits attractive linear responses towards lead(II) with a detection limit of 0.07 µg/L. The Bi‐SbSPE has been demonstrated successfully to detect lead in river water sample.     

A glassy carbon electrode modified with antimony and poly(p-aminobenzene sulfonic acid) for sensing lead(II) by square wave anodic stripping voltammetry

We have developed a sensor for the square wave anodic stripping voltammetric determination of Pb(II). A glassy carbon electrode was modified with a thin film of an antimony/poly(p-aminobenzene sulfonic acid) composite in air-saturated aqueous solution of pH 2.0. Compared to a conventional antimony film electrode, the new one yields a larger stripping signal for Pb(II). The conditions of polymerization, the concentration of Sb(III), the pH value of the sample solution, the deposition potential and time, frequency, potential amplitude, and step increment potential were optimized. Under the optimum conditions, a linear response was observed for Pb(II) in the range of 0.5 to 150.0 μg?L^?1. The detection limit for Pb(II) is 0.1 μg?L^?1.

A Coulometric Analysis Method and an Ion-exclusion Chromatographic Method for the Determination of Antimony(V) in Large Excess of Antimony(III)

A coulometric analysis method and an ion-exclusion chromatographic method were developed for the determination of antimony(V) in a large excess of antimony(III). Antimony(V) reacted with potassium iodide in a high concentration hydrochloric acid; the liberated iodine was determined by the standard-addition method using coulometrically generated iodine. Using a Dionex ICE-AS1 ion-exclusion column, antimony(V) was eluted with 40 mmol/L sulfuric acid; on the other hand, antimony(III) was strongly retained on the column. The content, expressed as the amount ratio of antimony(V) to antimony(III), was 0.035% in a 10 g/kg antimony(III) solution prepared from an antimony(III) oxide reagent by the coulometric analysis method and 0.036% in a 1 g/kg antimony(III) solution prepared from the same antimony(III) oxide by the ion-exclusion chromatographic method. The results of both methods were in good agreement with each other. The detection limit of antimony(V) in antimony(III) oxide by the former method was 0.004% of antimony(III), and that by the latter method was 0.002% of antimony(III).     

Anodic stripping voltammetry of antimony at unmodified carbon electrodes

Antimony is an element of significant environmental concern, yet has been neglected relative to other heavy metals in electroanalysis. As such very little research has been reported on the electroanalytical determination of antimony at unmodified carbon electrodes. In this paper we report the electrochemical determination of Sb(III) in HCl solutions using unmodified carbon substrates, with focus on non-classical carbon materials namely edge plane pyrolytic graphite (EPPG), boron doped diamond (BDD) and screen-printed electrodes (SPE). Using differential pulse anodic stripping voltammetry, EPPG was found to give a considerably greater response towards antimony than other unmodified carbon electrodes, allowing highly linear ranges in nanomolar concentrations and a detection limit of 3.9?nM in 0.25?M HCl. Furthermore, the sensitivity of the response from EPPG was 100 times greater than for glassy carbon (GC). Unmodified GC gave a comparable response to previous results using the bare substrate, and BDD gave an improved, yet still very high limit of detection of 320?nM compared to previous analysis using an iridium oxide modified BDD electrode. SPEs gave a very poor response to antimony, even at high concentrations, observing no linearity from standard additions, as well as a major interference from the ink intrinsic to the working electrode carbon material. Owing to its superior performance relative to other carbon electrodes, the EPPG electrode was subjected to further analytical testing with antimony. The response of the electrode for a 40?nM concentration of Sb(III) was reproducible with a mean peak current of 1.07?µA and variation of 8.4% (n?=?8). The effect of metals copper, bismuth and arsenic were investigated at the electrode, as they are common interferences for stripping analysis of antimony.     

Trace adsorptive voltammetric determination of antimony in hair

A very sensitive electrochemical procedure for trace determination of antimony is described. The complex of antimony with p-dimethyl-aminophenyl-fluorone (p-DMPF) is adsorbed on a hanging mercury drop electrode (HMDE), and the reduction current of the accumulated complex is measured by voltammetry. In linear sweep voltammetry, the reduction potential of the complex is more positive than that of the free dye. The peak height of the complex is proportional to the concentration of antimony in the range of 4.0 x 10(-9) to 4.0 x 10(-7) M, the detection limit is 1.0 x 10(-9) M Sb(III) for a 5 min preconcentration time. The relative standard error for the determination of 8.0 x 10(-8) M Sb(III) is 2.9%.     

Determination of Antimony(III) by Differential Pulse Voltammetry Using a Gold Nanoparticle–Ionic Liquid–Graphene-Modified Selenium-Doped Carbon Paste Electrode

A simple and sensitive differential pulse stripping voltammetric method was developed for the determination of antimony(III) using a selenium-doped carbon paste electrode modified with an ionic liquid, graphene, and gold nanoparticles. The conditions, including the mass of graphene, concentration of hydrochloric acid, deposition potential, and deposition time were optimized by single-factor experiments. Under the optimal conditions, a linear equation of I_Sb(III) (µA)?=??16.9882???11.0929 c (µmol/L) (R?=?0.9965) and a detection limit of 2.7?×?10^?8?mol/L were obtained for 8.0?×?10^?8 to 4.8?×?10^?6?mol/L antimony(III). The response shows that the sensor enhances the sensitivity of antimony due to the high conductivity and large surface areas of the ionic liquid, graphene, and gold nanoparticles. This electrode may provide a new sensing platform for the determination of antimony.     

Construction and Evaluation of a Gold Tubular Electrode for Flow Analysis: Application to Speciation of Antimony in Water Samples

A tubular gold electrode (TGE) is described for the first time by summarizing the important aspects of its construction and evaluation. Applicability of the TGE is evaluated in the speciation of Sb(III) and Sb(V) using anodic stripping voltammetry in a single flow manifold. Studies with surface active interferences and metallic cations were performed. The proposed conditions for antimony determination showed good tolerance towards cationic, anionic and nonionic surface active substances. A linear response for antimony was obtained for solutions containing significant amounts of several metallic cations. Linear calibration curves for Sb(III) were obtained in the range 1–10 ppb with a detection limit of 0.19 ppb (CV=2.91%, n=5, [Sb(III)]=5 ppb). For Sb(V), linear calibration curves were in the range 1–15 ppb with a detection limit of 0.32 ppb (CV=1.41%, n=5, [Sb(V)]=5 ppb). The figures of merit achieved sustain for the good applicability of the proposed method as it allows the determination of antimony at levels below maximum values permitted in consuming waters. Results of antimony concentration determined in water samples were validated against the ICP‐MS reference procedure or compared with reference water samples.     

Antimony speciation by inductively coupled plasma mass spectrometry using solid phase extraction cartridges

A novel and simple method for inorganic antimony speciation is described based on selective solid phase extraction (SPE) separation of antimony(III) and highly sensitive inductively coupled plasma mass spectrometric (ICP-MS) detection of total antimony and antimony(V) in the aqueous phase of the sample. Non-polar SPE cartridges, such as the Isolute silica-based octyl (C8) sorbent-containing cartridge, selectively retained the Sb(III) complex with ammonium pyrrolidine dithiocarbamate (APDC), while the uncomplexed Sb(V) remained as a free species in the solution and passed through the cartridge. The Sb(III) concentration was calculated as the difference between total antimony and Sb(V) concentrations. The detection limit was 1 ng L(-1) antimony. Factors affecting the separation and detection of antimony species were investigated. Acidification of samples led to partial or complete retention of Sb(V) on C8 cartridge. Foreign ions tending to complex with Sb(III) or APDC did not interfere with the retention behavior of the Sb(III)-APDC complex. This method has been successfully applied to antimony speciation of various types of water samples.     

Electrochemical Sensors for the Stripping Voltammetric Determination of Antimony(III)

The conditions of the modification of a glassy-carbon electrode with various polyphenols were studied by multicyclic voltammetry over a wide range of pH. The state of the electrode surface was additionally monitored by measuring cyclic voltammograms of ferrocyanide ions in the presence of a phosphate buffer solution (pH 7.0). It was found that the electrooxidation of all the studied polyphenols at the electrode surface resulted in the formation of a water-insoluble film which is capable of accumulating antimony(III) from aqueous solutions. The surface concentration of chemically active cites was of the order n × 10^–9 M/cm². The electrochemical sensors thus prepared were found to be suitable for the selective determination of antimony(III) by adsorption stripping voltammetry. The maximum signals of antimony(III) were obtained at electrodes modified with pyrocatechol and pyrogallol upon metal deposition from acetate buffer solutions (pH 4.5). The detected peak areas S (A · s) were directly proportional to the deposition time t _d (min) and the concentration of antimony(III). The analytical range was 10–250 g/L at t _d = 5.0 min, and the detection limit was 6 g/L. It was found that a sensor based on a pyrogallol film can selectively determine antimony(III) in the presence of Sb(V), Cu(II), and Pb(II), and can be used for the analysis of natural water.