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。     

Determination of nickel by anodic adsorptive stripping voltammetry with a cation exchanger-modified carbon paste electrode

The behavior of a modified carbon paste electrode (CPE) for nickel determination by anodic adsorptive stripping voltammetry (AAdsSV) was studied. The electrode was built incorporating the Dowex 50W x 12 (H(+) form) ion exchanger to a Nujol-graphite base paste. Ni(2+) was preconcentrated on the electrode surface in open circuit conditions, with the reduction (-1300 mV)/reoxidation step carried out in HCl solution (pH 3). During deposition time (5 min), the hydrogen evolution did not present obstacle in the quantification of nickel. For 12 min of accumulation and 5 min of deposition, nickel can be quantified up to 600 mug l(-1). The detection limit was 0.005 mug l(-1) at a linear potential scan rate of 200 mV s(-1). Interferences from Hg(2+) and Ag(2+) up to a concentration of 1 and 0.6 mg l(-1), respectively, were eliminated with the aid of the anion exchanger Dowex-2 (mesh 200-400) which was added to the sample in the preconcentration step. The tolerance for some metal ions such as Cu(2+), Cd(2+), Fe(3+), Zn(2+), Co(2+) and Pb(2+) was improved in the same way. The method was applied for the determination of nickel in samples of tap and mineral water. At the concentration level of 50 mug l(-1) of Ni (2+), the results were in good agreement with those obtained using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). For a Ni(2+) concentration of 5 mug l(-1), the results obtained showed better accuracy than those obtained by ICP-AES.     

Determination of trace amount of bismuth(III) by adsorptive anodic stripping voltammetry at carbon paste electrode

A sensitive method is described for the determination of trace bismuth based on the bismuth-bromopyrogallol red (BPR) adsorption at a carbon paste electrode (CPE). The overall analysis involved a three-step procedure: accumulation, reduction, and anodic stripping. Optimal conditions were found to be an electrode containing 25% paraffin oil and 75% high purity graphite powder, a 0.30 mol l⁻¹ HCl solution containing 2.0×10⁻⁵ mol l⁻¹ BPR as supporting medium; accumulation potential and time, −0.10 V, 3 min; reduction potential and time, −0.35 V, 60 s; scan rate 100 mV s⁻¹; scan range from −0.35 to 0.15 V. It was found that the Bi(III)-BPR complex could be accumulated on the electrode surface during the accumulation period. Then the Bi(III) in the Bi(III)-BPR complex on the CPE surface was reduced to Bi(0) during reduction interval and finally reoxidized during the anodic stripping step for voltammetric quantification. Factors affecting the accumulation, reduction, and stripping steps were investigated. Interferences by other ions were studied as well. The detection limit was found to be 5×10⁻¹⁰ mol l⁻¹ with a 3 min accumulation time. The linear range was from 1.0×10⁻⁹ to 5.0×10⁻⁷ mol l⁻¹. Application of the procedure to the determination of bismuth in water and human hair samples gave good results.     

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%。     

Determination of folic acid by adsorptive stripping voltammetry at the static mercury drop electrode

Folic acid can be determined at nanomolar concentrations by controlled adsorptive accumulation of folic acid on a static mercury drop electrode held at ?0.3 V vs. Ag/AgCl followed by reduction of the surface species. In 0.1 M sulfuric acid, a cathodic scan gives peaks at ?0.47 v and ?0.75 V vs. Ag/Agcl; the latter peak provides greater sensitivity. Differential-pulse stripping is shown to be superior to normal-pulse and d.c. stripping. After a 5-min preconcentration, the detection limit is about 1 × 10^?10 M folic acid. The adsorptive stripping response is evaluated with respect to concentration dependence, preconcentration time and potential, solution acidity and the presence of gelatin and bromide. The relative standard deviation at the 5 × 10^?8 M level is 1.2%. This method is applied to the determination of folic acid in pharmaceutical tablets.     

Determination of uranium by adsorptive stripping voltammetry at a lead film electrode

An adsorptive stripping voltammetric procedure for the determination of U(VI) at an in situ plated lead film electrode is described. The U(VI) complex with cupferron was accumulated from an acetate buffer solution of pH 4.2 at the potential −0.65 V. The measurements were carried out from undeaerated solutions. The calibration graph for an accumulation time of 180 s was linear from 5 × 10⁻¹⁰ to 2 × 10⁻⁸ mol L⁻¹. The detection limit was 2 × 10⁻¹⁰ mol L⁻¹, the relative standard deviation for 2 × 10⁻⁸ mol L⁻¹ U(VI) was 4.3%. The proposed procedure was validated in the course of U(VI) determination in water certified reference materials.     

Determination of copper ion by square wave anodic stripping voltammetry at antimony trioxide-modified carbon nanotube paste electrode

In this work, an antimony trioxide-modified multi-walled carbon nanotube paste electrode (Sb₂O₃/CNTPE) was employed for determination of Cu²⁺ ions by using square wave anodic stripping voltammetry (SWASV) in the presence of 8-hydroxy-7-iodo-5-quinoline sulfonic acid (HIQSA) as a chelating agent. The field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS) and electrochemical impedance spectroscopy (EIS) methods were applied to estimate the morphology and properties of the modified electrode. Measurements related to SWASV were taken in 0.6 M HCl at ?1.0 V versus Ag|AgCl|KCl (3 M) for 90 s (deposition step). After equilibrium time of 15 s, an ASV appeared at 0.0 V versus Ag|AgCl|KCl (3 M) (stripping step). The sensor depicted a fairly linear response for Cu²⁺ in the concentration range of 2–100 ppb with appropriate detection limit about 0.39 ppb and limit of quantification about 1.3 ppb. The stability of the modified electrode during 7 weeks and its behavior in the presence of some metal ions was evaluated. The practical applicability of the Sb₂O₃/CNTPE was established on the voltammetric determination of Cu²⁺ in tap water as a sample.     

A detailed investigation for determination of tannic acid by anodic stripping voltammetry using porous electrochemical sensor

The electrochemical responses of tannic acid have been obtained at porous pseudo-carbon paste electrode (PPCPE), polypyrrole modified carbon paste electrode (PCPE), SBA-15 modified CPE (SBA-MCPE) and carbon paste electrode (CPE) under same conditions, respectively. The results show that the sensitivity of PPCPE is the highest among all the checked electrodes. The detection limit at PPCPE is 0.01 μM, which is about 10 times lower than that at CPE and is about 5 times lower than that at PCPE or SBA-MCPE. The developed electrode PPCPE possesses a few obvious advantages and no binding reagents are needed. The surface area of PPCPE is 59.26 m² g⁻¹ with pores ranging from 2 to 5 μm in diameter. The PPCPE is easy to preserve and has good reusability, which affords a nice electrochemical platform for detecting tannic acid.     

Trace determination of vardenafil hydrochloride in commercial formulation and human serum by adsorptive anodic stripping voltammetry at a carbon paste electrode

The electrochemical behavior of vardenafil HCl (VRL) at a carbon paste electrode (CPE) was investigated by cyclic voltammetry, and the mechanism of its oxidation was suggested and discussed. A simple Nujol-based CPE in combination with a sensitive square-wave adsorption anodic stripping voltammetry method was described for trace determination of VRL. The described method showed excellent performance for trace determination of VRL in its formulation “Levitra® tablets” without interference from excipients. The results were statistically compared with those obtained with an established HPLC method; nonsignificant differences were found between the described voltammetric and HPLC methods. The described stripping voltammetric method is highly sensitive (limit of detection?=?3?×?10^?10?mol?L^?1 and limit of quantitation?=?1?×?10^?9?mol?L^?1). It was successfully applied for the determination of VRL in spiked human serum without the necessity for pretreatment and/or time-consuming extraction steps prior to the analysis.     

Use of adsorptive square-wave anodic stripping voltammetry at carbon paste electrode for the determination of amlodipine besylate in pharmaceutical preparations

The antihypertensive drug amlodipine has been characterized voltammetrically in a carbon paste electrode by means of anodic stripping voltammetry. An adsorptive stripping method in a carbon paste electrode for trace determination of amlodipine has been described. Cyclic voltammetric studies indicated the oxidation of amlodipine besylate at the electrode surface through a single two-electron irreversible step fundamentally controlled by adsorption. A study of the variation in the peak current with solution variables such as pH, ionic strength, concentration of amlodipine, possible interference, and instrumental variables, such as preconcentration time and accumulation potential, has resulted in the optimization of the oxidation signal for analytical purposes. By anodic adsorptive anodic stripping voltammetry, the calibration plot was linear in the range 9.9 × 10^?9 ? 1.4 × 10^?7 M with a detection limit of 2 × 10^?10 M in a carbon paste electrode at pH 11.0. The procedure was successfully applied to the assay of amlodipine besylate in some commercial products in the market (Amlopres®, Amlodipine, and Norvasc®). The percentage recoveries were in agreement with those obtained by the reference method.     

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 ...     

Determination of levofloxacin in human urine by adsorptive square-wave anodic stripping voltammetry on a glassy carbon electrode

The adsorption behavior of levofloxacin on a glassy carbon electrode was explored by cyclic and square-wave voltammetry. The drug was accumulated on a glassy carbon electrode and a well-defined oxidation peak was obtained in acetate buffer pH 5.0. Using square-wave anodic stripping voltammetry and accumulation at +0.4 V versus Ag/AgCl (saturated KCl) for 300 s, linear calibration graph was obtained from 6.0x10(-9) to 5.0x10(-7) M levofloxacin. The detection limit was calculated to be 5.0x10(-9) M. The R.S.D. determined from ten determinations at the 1.0x10(-7) M level was 1.7%. The method was applied for the direct determination of levofloxacin in diluted urine samples. It was validated using high-performance liquid chromatography (HPLC) as a reference method.     

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.     

碳糊电极阳极吸附伏安法测定吡哌酸

吡哌酸（Pipmidic acid,简称PPA）,是吡喹酮类合成抗菌药物,目前的主要分析方法有分光光度法、交流示波滴定法、高效液相色谱法、阴极吸附溶出伏安法、单扫描示波极谱法、微分脉冲极谱法和循环伏安法。本文提出了在CPE上阳极吸附伏安法测定PPA的方法,并探讨了PPA在CPE上的伏安性质和电极反应机理。该法准确、简便、灵敏度高,应用于模拟尿样中痕量PPA的测定,得到满意的结果。     

Indirect measurement of brucine by adsorptive stripping voltammetry at mercury electrode

After reaction with nitric acid, brucine can be transformed into cacotheline, and then measured indirectly by adsorptive stripping voltammetry. This method is based on the adsorptive accumulation of cacotheline at a hanging mercury drop electrode, followed by cathodic linear sweep voltammetry. The cathodic peak potential is about -0.35 V (vs. saturated Ag AgCl ). The detection limit of 2.0 x 10(-9) M is obtained under optimized conditions. The electrochemical behaviour of cacotheline and the mechanism of the electrode reactions are discussed.     

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.     

Determination of uranium by adsorptive stripping voltammetry

A voltammetric method for the determination of uranium in natural waters in the concentration range from 0.4 μg 1⁻¹ to 0.2 mg 1⁻¹ is described. The method is based on adsorptive accumulation of the uranium(VI)—pyrocatechol complex on the hanging mercury drop electrode followed by the reduction of the absorbed complex.     

Determination of palladium by adsorptive stripping voltammetry

 Adsorptive accumulation of the Pd(II) complex with dimethylglyoxime was evaluated for stripping voltammetry with respect to different parameters. The sensitivity of the method and the linearity between the peak current and the concentration of Pd(II) depends on the ionic strength, the electrode area, the preconcentration time, the transport rate to the electrode, and the potential scan rate. The most appropriate medium was 0.1 mol/L acetate buffer between pH 3.5 and 4. Using 2 min of preconcentration at a 2.6 mm² electrode and the differential pulse mode, a detection limit of 0.05 μg/L Pd was achieved for liquid samples and 50 ng/g for solid samples. Different aqueous and solid samples were analysed and the recovery from biological and inorganic materials investigated. Received: 29 February 1996/Revised: 29 July 1996/Accepted: 1 August 1996     

Determination of azinphos-methyl by adsorptive stripping voltammetry

A very sensitive electrochemical stripping procedure for azinphos-methyl (Guthion) is reported. Accumulation is achieved by adsorption of the compound on a hanging mercury drop electrode. The adsorptive stripping response was evaluated with respect to accumulation time and potential, concentration dependence, electrolyte and other variables. The determination limit is 0.2 ng ml^?1 after 300 s accumulation and 0.4 ng ml^?1 after 180 s accumulation. The procedure was applied to spiked river water.