碳糊电极阳极吸附伏安法测定洛美沙星

报道了碳糊电极阳极吸附伏安法测定洛美沙星的新方法。在0.096mol L的KHP NaOH(pH5.4)缓冲液中,用碳糊电极为工作电极,在0.3V(vs.SCE)富集一定时间,然后从0.3～1 3V以300mV s扫速线性扫描,记录其在1 02V的二次导数阳极溶出峰。溶出峰电流与洛美沙星浓度在8.0×10-9～8.0×10-8mol L(富集90s)和8.0×10-8～8.0×10-7mol L(富集30s)范围内呈良好的线性关系,相关系数分别为0.9844和0.9967,检出限为9.0×10-10mol L(S N=3)。探讨了洛美沙星在碳糊电极上的伏安性质和电极反应机理,并且成功地应用于人体尿液中洛美沙星的测定,结果与紫外光度法基本吻合。     

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%。     

掺杂硒碳糊电极阳极溶出法测定铋

建立了一种测定痕量铋的新方法,即利用掺杂硒碳糊电极作为工作电极的阳极溶出法.在0.1 mol/L的HCl底液中,Bi3+于+0.05V(vs.Ag/AgCl)出现灵敏的氧化溶出峰,铋离子的浓度在1.0×10-5～1.0×10-9 mol/L范围内其对数值lgc与铋的氧化峰电流值呈线性关系,检出限达1.0×10 -10 ...     

Adsorptive anodic stripping voltammetry of zirconium(IV)-alizarin red S complex at a carbon paste electrode

A sensitive adsorptive anodic stripping procedure for the determination of trace zirconium at a carbon paste electrode (CPE) has been developed. The method is based on adsorptive accumulation of the Zr(IV)-alizarin red S(ARS) complex onto the surface of the CPE, followed by oxidation of adsorbed species. The optimal experimental conditions include the use of 0.10 mol · L⁻¹ ammonium acetate buffer (pH 4.3), ARS, an accumulation potential of 0.20 V (versus SCE), an accumulation time of 2 min, a scan rate of 200 mV · s⁻¹ and a second-order derivative linear scan mode. The oxidation peak for the complex appears at 0.69 V. The peak current is proportional to the concentration of Zr(IV) over the range of 1.0 × 10⁻⁹–2.0 × 10⁻⁷ mol · L⁻¹, and the detection limit is 3 × 10⁻¹⁰ mol · L⁻¹ for a 2 min adsorption time. The relative standard deviations (n = 8) for 5.0 × 10⁻⁸ and 5.0 × 10⁻⁹ mol · L⁻¹ Zr(IV) are 3.3 and 4.8%, respectively. The proposed method was applied to the determination of zirconium in ore samples with satisfactory results.     

Catalytic adsorptive stripping determination of trace chromium (VI) at the bismuth film electrode

A sensitive adsorptive stripping voltammetric protocol at a bismuth-coated glassy-carbon electrode for trace measurements of chromium (VI) in the presence of diethylenetriammine pentaacetic acid (DTPA) is described. The new protocol is based on accumulation of the Cr-DTPA complex at a preplated bismuth film electrode held at −0.80 V, followed by a negatively-going square-wave voltammetric waveform. Factors influencing the stripping performance including the film preparation, solution pH, DTPA and nitrate concentrations, deposition potential and deposition time, have been optimized. The resulting performance compares well with that observed for analogous measurements at mercury film electrodes. A preconcentration time of 7 min results in a detection limit of 0.3 nM Cr(VI) and after 2 min a relative standard deviation at 20 nM of 5.1% (n = 25). Applicability to river water samples is demonstrated. The attractive behavior of the new “mercury-free” chromium sensor holds great promise for on-site environmental and industrial monitoring of chromium (VI). Preliminary data in this direction using bismuth-coated screen-printed electrodes are encouraging.     

Determination of lead and cadmium using a polycyclodextrin-modified carbon paste electrode with anodic stripping voltammetry

This work reports the use of and -cyclodextrin-modified carbon paste electrodes (CPE_-CD and CPE_-CD) to determine simultaneously Pb(II) and Cd(II) by means of the electrochemical technique known as anodic stripping voltammetry (ASV). Both modified electrodes displayed good resolution of the oxidation peaks of the said metals. Statistic analysis of the results strongly suggests that the CPE_-CD exhibited a better analytical response that the CPE_-CD, while the detection limits obtained for Pb(II) were 6.3×10^–7 M for the CPE_-CD and 7.14×10^–7 M for the CPE_-CD, whereas for Cd(II) they were 2.51×10^–6 M for the CPE_-CD and 2.03×10^–6 M for the CPE_-CD.     

Catalytic adsorptive stripping voltammetric determination of copper(II) on a carbon paste electrode

A catalytic adsorptive stripping voltammetric method for the determination of copper(II) on a carbon paste electrode (PCE) in an alizarin red S (ARS)-K₂S₂O₈ system is proposed. In this method, copper(II) is effectively enriched by both the formation and adsorption of a copper(II)-ARS complex on the PCE, and is determined by catalytic stripping voltammetry. The catalytic enhancement of the cathodic stripping current of the Cu(II) in the complex results from a redox cycle consisting of electrochemical reduction of Cu(II) ion in the complex and subsequent chemical oxidation of the Cu(II) reduction product by persulfate, which reduces the contamination of the working electrode from Cu deposition and also improves analytical sensitivity. In Britton-Robinson buffer (pH 4.56±0.1) containing 3.6×10⁻⁵ mol L⁻¹ ARS and 1.6×10⁻³ mol L⁻¹ K₂S₂O₈, with 180 s of accumulation at −0.2 V, the second-order derivative peak current of the catalytic stripping wave was proportional to the copper(II) concentration in the range of 8.0×10⁻¹⁰ to ∼3.0×10⁻⁸ mol L⁻¹. The detection limit was 1.6×10⁻¹⁰ mol L⁻¹. The proposed method was evaluated by analyzing copper in water and soil.     

Determination of Trace Tin by Anodic Stripping Voltammetry at a Carbon Paste Electrode

A sensitive and selective procedure for the determination of trace tin at a carbon paste electrode was described. Each measurement cycle consisted of three steps: accumulation, reduction and stripping. The tin complex with bromopyrogallol red (BPR) was accumulated on the electrode surface in 0.10 mol/L acetate buffer (pH 4.5). After electrochemical reduction of Sn(II) had been carried out, the reoxidation wave of Sn(0) appeared at ?0.69 V (vs. SCE) on scanning the potential in the positive direction in 4.0 mol/L HCl. For a preconcentration time of 2 min, the detection limit was 0.06 μg/L (5×10^?10 mol/L ) and the linear range was from 0.1 to 50 μg/L. The proposed method was applied to the determination of tin in canned food and waste water samples with satisfactory results.     

Determination of subnanomolar concentrations of cobalt by adsorptive stripping voltammetry at a bismuth film electrode

Procedures for trace cobalt determinations by adsorptive stripping voltammetry at in situ and ex situ plated bismuth film electrodes are presented. These exploit the enhancement of the cobalt peak obtained by using the Co(II)–dimethylglyoxime–cetyltrimethylammonium bromide–piperazine-N,N-bis(2-ethanesulfonic acid) system. The calibration graph for an accumulation time of 120 s was linear from 2 × 10^–10 to 2 × 10^–8 mol L^–1. The relative standard deviation from five determinations of cobalt at a concentration of 5 × 10^–9 mol L^–1 was 5.2%. The detection limit for an accumulation time of 300 s was 1.8 × 10^–11 mol L^–1. The proposed procedure was applied to cobalt determination in certified reference materials and in tap and river water samples.     

Determination of medecamycin by adsorptive stripping voltammetry with an activated electrode

The adsorptive and electrochemical behaviors of medecamycin were investigated on a glassy carbon electrode (GCE) pretreated by anodic oxidation at +1.8 V for 5 min in 0.025 mol l^–1 NH₃-NH₄Cl (pH 8.6) solution. An adsorptive stripping voltammetric method for the determination of medecamycin at the pretreated glassy carbon electrode has been developed. Medecamycin was accumulated in NH₃-NH₄Cl buffer (pH 9.0) at a potential of –0.7 V (vs. saturated calomel electrode (SCE)) for a certain time, and then determined by second-order differential anodic stripping voltammetry. The second-order differential anodic stripping peak current at +0.72 V was proportional to the concentration of medecamycin in the range 2.0 g ml^–1 to 50.0 g ml^–1. The detection limit (three times the signal-to-noise) was 1.0 g ml^–1 and the relative standard deviation of the results was 3.28% for eight successive determinations of 10.0 g ml^–1 medecamycin. This method has been applied to the direct determination of medecamycin in commercial tablets and spiked urine samples with satisfactory results.     

依诺沙星在碳糊电极上的阳极吸附伏安法研究

在0.40 mol/L的NaAc-HAc(pH 4.5)缓冲液中,使用JP-303极谱分析仪,依诺沙星在碳糊电极(CPE)上有一灵敏的吸附伏安氧化峰,峰电位为1.17 V(vs.SCE).该氧化峰的二阶导数峰电流与依诺沙星的浓度在4.0×10-9～4.0×10-7 mol/L(富集90 s)范围内呈良好的线性关系,相关系数为0.995,检出限为2.0×10-9 mol/L(S/N=3,富集110 s).探讨了依诺沙星在碳糊电极上的伏安性质和电极反应机理,并且用于诺佳胶囊中依诺沙星的测定.     

Determination of trace aluminium by adsorptive stripping voltammetry on a preplated bismuth-film electrode in the presence of cupferron

This work reports the use of adsorptive stripping voltammetry (AdSV) for the determination of aluminium on a rotating-disc bismuth-film electrode (BiFE). Al(III) ions in the non-deoxygenated sample were complexed with cupferron and the complex was accumulated by adsorption on the surface of the preplated BiFE. The stripping step was carried out by using a square-wave (SW) potential-time voltammetric excitation signal. The experimental variables as well as potential interferences were investigated and the figures of merit of the method were established. Using the selected conditions, the 3σ limit of detection for aluminium was 0.5 μg l⁻¹ at a preconcentration time of 240 s and the relative standard deviation was 4.2% at the 5 μg 1⁻¹ level for a preconcentration time of 120 s (n = 8). The accuracy of the method was established by analysing water and metallurgical samples.     

茜素红S/多壁碳纳米管修饰碳糊电极阳极溶出伏安法测定痕量铜

制备了茜素红S/多壁碳纳米管修饰碳糊电极,提出了一种灵敏的溶出伏安法测定痕量铜的新方法.在极谱分析仪上采用二阶导数线性扫描伏安法进行分析,在0.1 moL/L的HAc-NaAc缓冲溶液(pH 4.1)中,Cu与修饰电极表面的茜素红S(ARS)形成Cu(Ⅱ)-ARS络合物而富集于电极表面,于-400 mV处还原后,再进行阳极化扫描,于64 mV处获得一灵敏的铜的阳极溶出峰,峰电流与Cu(Ⅱ)浓度在2×10-11 mol/L～6×10-7 mol/L范围内呈良好的线性关系,检出限(S/N=3) 为8.0×10-12 mol/L(富集时间240 s).方法应用于人发中铜含量的测定,回收率为98%～102%.     

Determination of linuron in water and vegetable samples using stripping voltammetry with a carbon paste electrode

A carbon paste electrode was used for the electrochemical determination of linuron concentrations in water and vegetable extracts. Optimal conditions were established with respect to electrode activation (electrochemical pretreatment), time accumulation, potential accumulation, scan rate, and pH. The limit of detection achieved with a pre-concentration step was 23.0 μg L⁻¹. Recovery measurements in vegetable extract and natural water samples were in the range of 98-103%, indicating that the proposed electrochemical method can be employed to analyze linuron in these matrices. The determination results were in good agreement with HPLC results.     

Determination of trace metoclopramide by anodic stripping voltammetry with nafion modified glassy carbon electrode

A novel method is described for determination of metoclopramide (MCP) by second-derivative adsorptive anodic stripping voltammetry with a nafion-modified electrode. The stripping peak current is proportional to the concentration of MCP over the range 1.2×10⁻⁹–4.6×10⁻⁷ M. The detection limit is 8.0×10⁻¹¹ M with 4-min accumulation. The method has been successfully applied to the determination of MCP in human serum.     

Study on the adsorptive catalytic voltammetry of aloe-emodin at a carbon paste electrode

Recently, the studies and applications for the pola-rographic catalytic waves of organic compounds at dropping mercury electrode made considerable head-way. Tovopova et al.[1―4] reported the polarographic catalytic waves of the organic compounds containi…     

Determination of trace amounts of morphine in human plasma by anodic adsorptive stripping differential pulse voltammetry

New adsorptive anodic differential pulse stripping voltammetry method for the direct determination of morphine at trace levels in human plasma of addicts is proposed.The procedure involves an adsorptive accumulation of morphine on a HMDE,followed by oxidation of adsorbed morphine by voltammetry scan using differential pulse modulation.The optimum conditions for the analysis of morphine are pH 10.5,Eacc of -100 mV（vs.Ag/AgCl）,and tacc of 120 s.The peak current is proportional to the concentration of morphine,and a Linear calibration graph is obtained at 0.01-3.10μg mL^-1.A relative standard deviation of 1.06%（n=5）was obtained,and the limit of detection was 3 ng mL^-1.The capabiLity of the method for the analysis of real samples was evaluated by the determination of morphine in spiked human plasma and addicts human plasma with satisfactory results.     

Linear scan stripping voltammetry of copper(II) at the chemically modified carbon paste electrode

A new chemically modified electrode (CME), -benzoinoxime (CUPRON) modified carbon paste electrode, for determining copper(II) is reported because of its excellent selectivity and sensitivity. The electrode is made by mixing a quantity of CUPRON (25%, w/w) with graphite powder (50%, w/w) and paraffin oil (25%, w/w). The CME preferentially deposits copper from the pH 8.5 NH₃-NH₄Cl buffer solution containing copper(II) under an open circuit and most of metal ions do not interfere with the measurements. The detection limit (S/N of three) for determining Cu(II) is 3 × 10^–10 g/ml after 10 min accumulation in fast linear scan stripping voltammetric measurement. Linear calibration curves are obtained for Cu(II) concentration ranged from 1 × 10^–8 M to 1 × 10^–6 M. The response can be maintained with relative standard deviation of 6.0% in a 5 × 10^–6 M Cu(II) solution after eight accumulation/measurement/ regeneration cycles at the same electrode surface. The effect resulted from carbon paste preparation, reduction potential, electrode renewal, electrolyte and solution pH, preconcentration time, concentration dependence, possible interference and other variables has been evaluated. As for application, the CME demonstrates its high sensitivity and copper-selectivity in complex composition samples, such as anodic mud and polluted water.     

MCM-41 mesoporous material modified carbon paste electrode for the determination of cardiac troponin I by anodic stripping voltammetry

An anodic stripping voltammetric method for the determination of cardiac troponin I (cTnI) at a MCM-41 mesoporous material modified carbon paste electrode (MCM-MCPE) was investigated. The test was based on the dual monoclonal antibody “sandwich” principle using colloidal gold as a labeled substrate. Four main steps were carried out to obtain the analytical signal, i.e. electrode preparation, immunoreaction, silver enhancement, and anodic stripping voltammetric detection. The anodic stripping peak current increased linearly with the concentration of cTnI over the range of 0.8-5.0 ng/ml. A detection limit of 0.5 ng/ml was obtained. The established method was applied to detect cTnI in acute myocardial infarction (AMI) samples using routine enzyme-linked immunoadsorbent assay (ELISA) for comparison analysis, and good results were obtained.     

Anodic stripping voltammetry at a new type of disposable bismuth-plated carbon paste mini-electrodes

A new type of disposable carbon paste mini-electrodes (CPmEs), with dimensions in the 50-300 μm range, have been fabricated by heat-shrinking the end-tip of plastic micropipette tips and filling them with carbon paste. The CPmEs have been characterized by microscopic and electrochemical means and tested as substrates for in situ plated Bi film electrodes (BiF-CPmEs), used in the determination of heavy metals by square wave anodic stripping voltammetry (SWASV). It was found that this new class of CPmEs combines the advantages of carbon paste electrodes (readily renewable surface and high surface area) with those of near-microelectrode behaviour (no stirring or electrolyte excess needed). During SWASV experiments in unstirred Pb(II) and Cd(II) solutions well-shaped stripping peaks were obtained whose height varied linearly with analyte concentration in the wide 1 × 10⁻⁸ to 10⁻⁶ M range, both in acetate buffer and unbuffered solutions. Under optimal conditions detection limits of 8 × 10⁻¹⁰ and 1.3 × 10⁻⁹ M were achieved for Pb(II) and Cd(II), respectively and in a trial application, these metal ions have been determined in a spiked tap water sample using a BiF-CPmE.