2．5次微分溶出伏安法测定水中痕量铜

报告了测定痕量铜的一种新方法。在０．０１ｍｏｌ／ＬＨＡｃ－ＮａＡｃ溶液中，铜和乙醛酸缩氨基硫脲（ＧＡＴＳＣ）形成的配合物产生一很灵敏的还原峰，峰电位是－０．３３Ｖ（ｖｓ·ＳＣＥ），铜的浓度在１．０×１０－８～２．０×１０－６ｍｏｌ／Ｌ范围内成直线关系，检测限为３．０×１０－９ｍｏｌ／Ｌ，该法用于测定水中痕量铜，结果令人满意。     

Depletive Stripping Chronopotentiometry: A Major Step Forward in Electrochemical Stripping Techniques for Metal Ion Speciation Analysis

A comparative evaluation of the utility of the various modes of stripping chronopotentiometry (SCP) for trace metal speciation analysis is presented in the broad context of stripping voltammetric techniques. The remarkable fundamental advantages of depletive SCP at scanned deposition potential (SSCP) are highlighted, and the rigorous underpinning theory is described. The distinctive features of SSCP include: i) an effective getting around part of the Nernstian extension of the reoxidation process, leading to ii) greater resolution than conventional stripping voltammetries; iii) a certain insensitivity to electrochemical irreversibility, especially at a microelectrode; iv) in principle, freedom from induced metal ion adsorption interferences; v) no requirement for excess ligand during stripping; and vi) ability to provide a certain measure of any chemical heterogeneity in the metal speciation that is easily distinguishable from effects of electrochemical irreversibility.     

Sensitive Anodic Stripping Voltammetric Copper Ions Determination Performed in Double Deposition and Double Stripping Steps System for Real Water Samples Analysis

The article reports on utilization of double deposition and stripping steps for increasing sensitivity of Cu(II) determination by anodic stripping voltammetry (ASV) at two lead film working electrodes. A significant preconcentration of copper was achieved thanks to utilization of a simple design of four electrodes system that gives possibility to perform one measurement cycle consisting of two deposition and two stripping steps. Due to the fact that deposition step is doubled, the concentration of Pb(II) needed to lead film electrodes formation was significantly reduced as compared to traditional procedures using three electrodes system. The analytical procedure of Cu(II) determination was optimized. The experimental factors: supporting electrolyte's pH and its concentration, lead ions concentration, potential and time of deposition at both working electrodes were studied. The Cu(II) peak current was linearly dependent on its concentration from 5×10^?10 to 2×10^?8 mol L^?1 (deposition time of 270 and 160 s at the first and the second working electrode, respectively). The obtained detection limit for copper ions determination was 2.1×10^?10 mol L^?1. The described procedure was validated by analysis of two water certified reference materials. The described procedure was also utilized for real water sample analysis.     

Copper Sensing in Alkaline Electrolyte Using Anodic Stripping Voltammetry by Means of a Lead Mediator

Anodic stripping voltammetry (ASV) is an analysis technique that permits the selective and quantitative analysis of metal ion species in solution. It is most commonly applied in neutral to acidic electrolyte largely due to inherent metal ion solubility. Bismuth (Bi) is a common film used for ASV due to its good sensitivity, overall stability and insensitivity to O₂. ASV, utilizing a Bi film, along with cadmium (Cd) and lead (Pb) as the plating mediators, has recently been adapted to determine zinc (Zn) concentrations in highly alkaline environments (30 % NaOH or 35 % M KOH). Successful analysis of Zn in alkaline relies on the ability of the hydroxide to form soluble metal anion species, such as Bi(OH)₄⁻ and Zn(OH)₄²⁻. Here, we look to extend this technique to detect and quantify copper (Cu) ions in these highly basic electrolytes. However, in general, the use of ASV to detect and quantify Cu ion concentrations is notoriously difficult as the Cu stripping peak potential overlays with that of Bi from the common Bi film electrode. Here, an ASV method for determining Cu concentration in alkaline solutions is developed utilizing Pb as a deposition mediator. As such, it was found that when analyzing Cu solutions in the presence of Pb, the stripping voltammetry curves present separate and defined Cu stripping peaks. Different analyzes were made to find the best stripping voltammetry performance conditions. As such, an accumulation time of 5 minutes, an accumulation potential of≤−1.45 V vs. Hg/HgO, and a concentration of 35 wt% KOH were determined to be the conditions that presented the best ASV results. Utilizing these conditions, calibration curves in the presence of 5.0 ppm Pb showed the best linear stripping signal correlation with an r‐squared value of 0.991 and a limit of detection (LOD) of 0.67 ppm. These results give way to evaluating Cu concentrations using ASV in aqueous alkaline solutions.     

用溶出伏安法测定蛋白胨细胞生长液中易变形态铜

采用阳极阶梯溶出伏安法 ,测定了蛋白胨细胞生长液中的易变形态铜 ,并获得了总铜量中易变形态的摩尔分数以及易变形态的表观稳定常数。通过使用交换介质法 ,较好消除了由于蛋白胨细胞生长液中各种氨基酸或其它组分吸附在汞膜表面而引起的干扰     

Silver Amalgam Film Electrode of Prolonged Application in Stripping Chronopotentiometry

The utility of the cylindrical silver‐based mercury film electrode of prolonged analytical application in stripping chronopotentiometry (SCP) was examined. This electrode allowed us to obtain good reproducibility of results owing to the special electrode design, which enables regeneration of the thin layer before each measurement cycle. The accessible potential window in KNO₃ (pH 2), acetate and ammonia buffers was defined, and the optimal conditions (i.e., stripping current, deposition potential and deposition time) for the determination of Cd and Pb traces were selected. The detection limits, obtained for an accumulation time of 60 s, were 0.023 μg/L for Cd and 0.075 μg/L for Pb. The response increases linearly with Cd, Pb and Zn concentration, up to at least 100 μg/L. It was also shown that the proposed procedure ensures excellent separation of the In and Tl, Pb and Tl or the In and Cd signals. The method was tested with dolomite and lake sediment samples, and good agreement with reference values was achieved. The obtained results showed good reproducibility (RSD=5–6%) and reliability.     

泡沫塑料吸附—溶出计时电位法测定地质物料中痕量铊

本文提出了泡沫塑料吸附解脱新体系，建立了泡沫塑料吸附－溶出计时电位法测定地质物料中痕量铊的新方法。方法检出限０．０３μｇ／ｇ；铊的含量水平分别为０．７１μｇ／ｇ和１．６μｇ／ｇ时的测定精密度为３．４５％和３．２８％；工作曲线线性范围为５￣１５００ｎｇ／ｍＬ；回收率为９７．５％￣９８．０％。     

用色谱膜法富集阴极吸附溶出伏安法测定空气中的镍铜铅镉

在色谱膜池中,用１．０ｍｏｌ／ＬＨＮＯ３溶液吸收富集空气中的镍、铜、铅和镉,以８－羟基喹啉络合物吸附阴极溶出伏安法测定其含量。在ｐＨ７．５０的醋酸铵溶液中,８－羟基喹啉与镍、铜、铅及镉络合物的峰电位分别为－０．３８、－０．５２、－０．６２和－０．８０Ｖ,线性范围分别为０．５～３００、０．３～５０、０．０８～１００和０．０２～１００ｎｍｏｌ／Ｌ。     

Simultaneous Determination of Iron and Copper in Ethanol Fuel Using Nafion/Carbon Nanotubes Electrode

This work presents the analytical method development for iron and copper determination in ethanol fuel. This method was developed using stripping voltammetry with a glassy carbon electrode modified with Nafion/Carbon‐nanotubes. With linear sweep stripping voltammetry was achieved a limit of detection of 7.1×10^?7 mol L^?1 for Fe³⁺ and 5.1×10^?8 mol L^?1 for Cu²⁺. The amperometric sensitivities were 2.0×10⁶ µA mol^?1 L for Fe³⁺ and 2.8×10⁷ µA mol^?1 L for Cu²⁺. The recovery study showed that the method has good accuracy and repeatability, with recovery of 108 and 103 % for Fe³⁺ and Cu²⁺ respectively.     

Medium Exchange Stripping Potentiometry for the Measurement of Labile Copper in White Wine

An efficient and effective procedure is described for the determination of the labile copper concentration in untreated white wine using medium exchange stripping potentiometry. Two rinse steps between the enrichment and stripping steps allowed measurement of labile concentration with good repeatability and reproducibility. The fraction of labile copper ranged from 13% to 91%, for 16 white wines, indicating the highly variable copper complexing character of the wine matrix. The methodology was applied to labile copper measurement during the oxidation of white wines.     

Determination of chloride by stripping chronopotentiometry with silver-film electrode

The experimental parameters of cathodic stripping chronopotentiometry of chloride at a silver-film electrode are investigated and optimized. The chloride preconcentration is achieved in the form of silver chloride by a controlled potential oxidation of the working electrode under vigorous stirring. Cathodic stripping of the deposit is obtained by the constant current, under the condition of diffusive mass transfer. Deaeration of the solution is not necessary. A detection limit of 35 μ dm⁻³ (10⁻⁶ mol dm⁻³) is obtained at a deposition time of 180 s, with a reproducibility of 6.7 % (expressed as relative standard deviation, RSD).     

Double Deposition and Stripping Steps for Trace Determination of Au(III) Using Anodic Stripping Voltammetry

A new way of decreasing the detection limit ‐ double deposition and stripping steps was proposed to determine trace amounts of gold(III) by anodic stripping voltammetry. Two carbon composite electrodes that differed drastically in their surface areas were used for the measurements. The calibration graph was linear from 1×10^?9 to 1×10^?8 mol L^?1 following deposition time of 300 s at the first and the second electrode. The detection limit was found to be 2.3×10^?10 and 1.4×10^?11 mol L^?1 for deposition time 600 and 2400 s, respectively. It is the lowest detection limit obtained so far for gold(III) determination in stripping voltammetry.     

Renewable Copper and Silver Amalgam Film Electrodes of Prolonged Application for the Determination of Elemental Sulfur Using Stripping Voltammetry

New, renewable copper (Hg(Cu)FE) and silver (Hg(Ag)FE) based amalgam film electrodes applied for the determination of elemental sulfur using differential pulse cathodic stripping voltammetry are presented. With surface areas adjustable from 1 to 12 mm², both electrodes are characterized by very good surface reproducibility (≤2%) and long‐term stability (a few thousand measurement cycles). The mechanical refreshing of the amalgam film takes about 1–2 seconds. The effects of various factors such as instrumental parameters and the supporting electrolyte composition were optimized. Interferences from sulfides are easily removed by the addition of acid, and bubbling with argon, for Hg(Ag)FE. In the case of Hg(Cu)FE, sulfides did not interfere. The calibration graph is linear within the studied range from 16 ng L^?1 to 4.8 μg L^?1 for Hg(Cu)FE, and up to 6.4 μg L^?1 for Hg(Ag)FE (t_acc=15 s). The correlation coefficients for the two electrodes were at least 0.997. The detection limits for a low concentration of S(0) and t_acc=60 s are as low as 14 ng L^?1 for Hg(Cu)FE and 4 ng L^?1 for Hg(Ag)FE. The proposed method was successfully applied and validated by studying the recovery of S(0) from spiked river water.     

食品中铜、铅、锡的微分电位溶出法同时测定

用微分电位溶出分析法,以pH2.4的0.06mol·L     

Determination of Copper by Adsorptive Stripping Voltammetry in the Presence of Calcein Blue

An electrochemical adsorptive stripping approach is presented for the trace measurement of copper in some real samples. The method is based on the reduction of Cu²⁺ at pH 5.5 calcein blue (CB) containing solution at ?250 mV (vs. Ag/AgCl), adsorption of Cu? CB complex on hanging mercury drop electrode (HMDE) and the voltammetric determination by further reduction to Cu⁺ at HMDE. Experimental optimum conditions were determined in the fundamental studies. At the experimental optimum conditions the adsorbed complex of Cu²⁺ and calcein blue gives a well defined cathodic stripping peak current at ?0.135 V, which has been used for the determination of copper in the concentration range of 0.02 to 15 ng/mL with accumulation time of 90 s. The relative standard deviation (RSD) for the determination of 0.5 and 6.0 ng mL^?1 were 2.60 and 1.94% respectively. (n=10). The method has been applied to the analysis of copper in analytical reagent grade salts and tap water, mineral water and drug samples with satisfactory results.     

Determination of Trace Amounts of Copper by Adsorptive Stripping Voltammetry

ABSTRACT

A technique is presented for the determination of trace amounts of copper(II) by adsorptive cathodic stripping voltammetry. The procedure is based on adsorptive accumulation of copper(II)-Alizarin Red S (ARS) complex on a hanging mercury drop electrode, followed by a stripping voltammetric measurement of the reduction current of the adsorbed complex at -0.16 V (vs. Ag/AgCl). The height of the copper -ARS reduction peak is linearly dependent upon the copper(II) concentration between 0.2-15 and 15-500 ng.ml^?1. The detection limit of the technique is 0.05 ng.ml^?1 copper(II) for a collection time of 1 minute. The method is free from most interferences. The procedure has been successfully applied to the determination of trace amounts of copper(II) in some analytical grade salts.     

Determination of Trace Amounts of Indium in Sphalerites by Potentiometric Stripping Analysis

Abstract

A simple procedure for the determination of trace amounts of indium in sphalerites has been developed. the sample is dissolved by combined action of concentrated HC1 and HNO₃. Indium is separated by ether extraction from a 4 M HBr solution. the organic phase is evaporated and the residue is dissolved in acetate-bromide ionic medium, where indium is directly measured by stripping potentiometry.     

Stripping Potentiometry of Lead,Cadmium and Copper at a Nafion Coated Glassy Carbon Electrode with Encapsulated Mercury Acetate

Abstract

The stripping potentiometric determination of lead, cadmium and copper with mercury film glassy-carbon electrodes coated with a Nafion membrane was investigated. The mercury film was plated using either mercury(II) acetate encapsulated within the Nafion membrane or a mercury(II) solution. Dissolved dioxygen was used as the stripping agent. The electrodes showed promising properties, particularly robustness and response repeatability. A linear dependence of the stripping time on concentration was found in the μg l^?1 concentration range (s.d. of intercept ≤ 0.3 μg l^?1, r.s.d. of slope ≤ 1%, for both lead and cadmium).     

Voltammetric Determination of Zinc,Copper, and Selenium in Selected Raw Plant Material

The objective of this work was to determine zinc, copper, and selenium content in selected plant raw materials used as pharmaceuticals, foodstuffs, or spices. The study included: Chamomillae anthodium, Anisi fructus, Menthae piperitae folium, Equiseti herba, Urticae folium, quinoa seeds (Chenopodium quinoa), amaranth seeds (Amaranthus cruentus), clove (Syzygium aromaticum), and oregano (Origanum vulgare). Stripping voltammetry with differential pulse step was used for zinc, copper, and selenium determination after microwave digestion procedure for organic matrix decomposition. Obtained results showed that proposed methods were suitable in determination of selenium, copper, and zinc. Selenium content varied from 11.6 µgkg^?1 of dry weight of oregano up to 1031.2 µg kg^?1 for amaranth. Zinc content ranged from 11.1 to 42.1 mgkg^?1 and copper content was between 0.7 and 12.0 mg kg^?1. The proposed method was successfully applied and validated by studying the certified reference material (INCT-MPH-2, bovine liver BCR-185), with recovery 94%–102%; 92%–97%; and 97%–108% for copper, zinc, and selenium, respectively.     

Determination of dissolved sulphides in waste water samples by flow-through stripping chronopotentiometry with a macroporous mercury-film electrode

Sulphides in water samples were determined by stripping chronopotentiometry in a computer controlled flow system with a flow-through electrochemical cell. The working electrode was a porous glassy carbon electrode coated with Nafion and mercury. The sample was diluted with 0.1 mol L⁻¹ NaOH and analysed. Sulphides in the sample were collected in the porous electrode as mercury sulphide and then stripped by a current of −500 μA. The limit of detection was found to be 1.6 μg L⁻¹ and 0.5 μg L⁻¹ for 1 mL and 5 mL of preconcentrated sample, respectively. The linear range for 1 mL sample was found to be 5-400 μg L⁻¹. The repeatability and reproducibility was found to be 2.6% and 4.8%, respectively. The method was applied to analyses of waste water samples from a tannery.