溴酸钾氧化酸性铬深蓝催化动力学极谱法测定痕量钒

在0.15mol·L~(-1)H_2SO_4介质中,以酒石酸作活化剂,Ⅴ(Ⅴ)对溴酸钾氧化酸性铬深蓝的反应具有强烈的催化作用,以极谱法监测催化反应过程中酸性铬深蓝浓度的变化,建立了测定痕量钒的催化动力学新方法。钒的线性范围为0.10～7.0ng·ml~(-1),检出限为0.05ng·ml~(-1),应用于人发中痕量钒的测定,结果满意。并对酸性铬深蓝的极谱特性进行了初步的探讨。     

Determination of Copper by an Adsorption Differential Pulse Stripping Method with Naphthol Derivative

ABSTRACT

A simple, sensitive and selective method is proposed for the determination of copper(II) by adsorption-differential pulse stripping method. This method is based on the selective accumulation of the complexes of Cu(II) with l-(2-pyridylazo)-2-Naphthol and then reduction of the complex on a HMDE. The reduction current of the complex is about 0.0V vs. Ag/AgCl reference electrode at p8543146=4.0. The influences of various experimental parameters on the current peak were completely studied. The calibration graph was linear up to 50.0 ng/ml for a deposition time of 60 sec. The relative standard deviation was 2.3% (n=5) for Cu(II) concentration of 10.0 ng/ml, with a limit of detection of 0.2 ng/ml. The influence of potentially interfering ions was completely studied. The method has been applied for the determination of Cu(II) in water samples.     

铜催化抗坏血酸还原酸性铬深蓝动力学光度法测定痕量铜

在乙酸-乙酸钠介质中,以邻菲罗啉为活化剂,铜对抗坏血酸还原酸性铬深蓝具有强烈的催化作用,测定了反应的表观活化能,探讨了反应机理,建立了测定痕量铜的催化动力学新方法,测定的线性范围为2.5～60ng·ml~(-1),直接用于食品及人发中铜的测定。结果满意。     

Constant-potential pulse polarographic detection in flow-injection analysis without deaeration of solvent or sample

A constat-potential pulse waveform is applicable for the polacographic analysis of buffered solutions (pH ?= 7) of cathodically active metal ions without voltammetric interference from dissolved oxygen. The technique is demonstrated at a dropping mercury electrode for detection of lead(II) and cadmium(II) in a conventional polarographic Cell (ca. 75 ml) as well as for small samples (2 ml) in a flow-injection system. The flow-injection polarographic technique is recommended for higher sample throughout than conventional polagraphy and is demonstrated for an electroless copper plating solution containing about 1.5 × 10^–2 M copper(II).     

A Highly Sensitive Method for Determination of Copper (II) in Water Samples for Field Screening

Abstract

A new method has been developed for field screening of copper (II) in water samples, which is based on an enzyme inhibition reaction between copper (II) and nitrate reductase. The concentration of copper (II) was acquired by indirect determination the reaction product (nitrite) with a mini optical reflection sensor. Under the optimum conditions, the calibration graph was linear in the range of 5.0–50 ng mL^?1. The limit of detection was 0.5 ng mL^?1. This method has been used for the field screening of copper (II) with satisfactory results.     

Polarographic Determination of Inorganic Phosphorus in Phytic Acid

Abstract

A method for the determination of inorganic phosphorus in phytic acid by polarography was developed. The mechanism of Mo/Sb/P polarographic behaviour has been studied. It is one of the most sensitive analytical methods of phosphorus at present. The limit of detection is 8x10^?9 g/ml. This method has been used in the determination of inorganic phosphorus in phytic acid and result is found satisfactory.     

Catalytic Kinetic Determination of Trace Amounts of Iron(III) With Polarographic Detection

Abstract

This method is based on the catalytic effect of Fe³⁺ on the oxidation reaction between Acid Chrome Blue K and potassium bromate in sulfuric acid medium at 100deg;C, and in 0.08 mol/L NH₄OH - 0.01 mol/L (NH₄)₂ SO₄ supporting electrolyte, Acid Chrome Blue K exhibits a sensitive polarographic wave at -0.55V vs. SCE, and change of concentration is traced by a polarographic detection technique. The linear range of Fe³⁺ is 10–100ng/mL. This new catalytic method has been applied to the determination of iron in natural water and food with satisfactory results.     

A New catalytic reaction for determination of nanogram amounts of copper

Summary A simple and very sensitive new catalytic method is proposed for determination of copper(II). The method is based on the oxidation of sulphanilic acid with H₂O₂ at pH 7 in the presence of pyridine as activator. The sensitivity of the method is 5 ng/ml. Cobalt(II) interferes at concentrations of the same order as copper(II). The method is suitable for determination of copper in biological materials.

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Zusammenfassung Eine einfache und sehr empfindliche katalytische Methode zur Bestimmung von Kupfer(II) wurde vorgeschlagen. Sie beruht auf der Oxydation von Sulfanilsäure mit Wasserstoffperoxid bei pH 7 in Gegenwart von Pyridin als Aktivator. Ihre Empfindlichkeit beträgt 5 ng/ml. Kobalt(II) stört in Konzentrationen der gleichen Größenordnung wie Kupfer(II). Das Verfahren eignet sich zur Kupferbestimmung in biologischem Material.

     

A Polarographic Method Determing Cu(II), Cu(I) and Metallic Copper Contents in Copper Oxide Samples

Abstract

A polarographic procedure was developed which permits the analysis of powdered cupric and cuprous oxides in the presence of metallic copper. To determine CuO, Cu₂O and metallic copper content in the sample two weight aliquots were used. The first aliquot was dissolved in medium of 50 % ethanol + 3 M hydrochloric acid + saturated ascorbic acid solution. Insoluable metallic copper was determined polarographically after its' separation and additional dissolving in concentrated nitric acid.

The second sample aliquot was dissolved in 6 M hydrochloric acid and the ratio of Cu(I) / Cu(II) in the solution was determined from the polarographic curves. To calculate CuO, Cu₂O and Cu content in a sample the proposed procedure was applied. The developed method provides the accurate results of the determination of CuO, Cu₂O and Cu content in a powdered mixture. The reproducibility expressed as the relative standard deviation is from 1 % to 5 %.     

A New Method for the HPLC Analysis of Pt(II) in Urine

Abstract

An analytical method has been developed to measure Pt(II) in urine via derivatization and UV or HPLC analysis. A measured quantity of urine is heated briefly with diethyl ammonium diethyl-dithiocarbamate, and the resulting Pt(Et₂NCS₂)₂ is extracted into a measured volume of chloroform. Concentrations of Pt(II) are determined by UV absorption at 346 nm or by reverse phase HPLC analysis. The detection limit for Pt(II) as its dithiocarbamate is ～ 1 ng by HPLC; the concentration limit for HPLC analysis by direct extraction was ～ 25 ng/ml. Chromatographic response was linearly related to Pt(II) concentration over the range 100-4, 000 ng/ml; dilution of more concentrated samples has extended this range to at least 30, 000 ng/ml. This method has been applied to the analysis of Pt(II) in the urine of patients who have received cis-dichlorodiamniineplatinum(II) (CDDP) chemotherapy.     

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.     

Spectrophotometric and derivative spectrophotometric determination of nickel with hydroxynaphthol blue

The reaction of nickel(II) cation with hydroxynaphthol blue (HNB) in aqueous media at pH 5.2–6.0 results in a red complex that is stable for at least 2h. Beer's Law is obeyed up to 3.2 g/ml of nickel(II) with an apparent molar absorptivity of 1.38 × 10⁴l/mol/cm at 563 nm. This paper proposes procedures for nickel determination by ordinary and first-derivative spectrophotometry. The results demonstrate that the linear dynamic range is 0.08–3.20 g/ml with a limit of detection of 23 ng/ml for ordinary spectrophotometry, compared with 21–800 ng/ml and 6 ng/ml, respectively, for first-derivative spectrophotometry. Calcium(II), magnesium(II), barium(II), strontium(II), cadmium(II), lead(II), manganese(II), bismuth(III) and molybdenum(VI) ions do not interfere for at least 1001 mass ratios. The main interferents are cobalt(II), titanium(IV), aluminium(III), mercury(II) and copper(II). The interferences of titanium(IV), aluminium(III), zirconium(IV) and iron(III) can be masked by fluoride and mercury(II) and copper(II) with thiosulfate or thiourea. The derivative method is applied to nickel determination in standard brasses and the results demonstrate that there is no significant difference between the results and certified values at the 95% confidence level.     

Pulse Polarographic: Determination of Nanogram Amounts of Ortho-Phosphate

Abstract

A procedure has been developed for the pulse polarographic determination of nanogram amounts of ortho-phosphate based on the reduction of molybdenum blue formed from 12-molydophosphate. The molybdenum blue is extracted into iso-amyl alcohol from acid solution, and the extract is then washed free of excess molybdate with dilute sulphuric acid. Finally, the molybdenum blue is back-extracted into a tartrate buffer and is pulse polarographed. Precise determinations can be made on 10 ng of PO₄ ³ ml^?11 in the polarographed solution. Determinations have been made on standard and sample ortho-phosphate solutions at the 2 ng of PO₄ ³ ml^?11 level by effecting a five-fold concentration at the extraction step.     

Flow Injection Analysis for Beryllium Determination With Chrome Azurol S as Chromogenic Agent

Abstract

A flow injection analysis system which employs a visible absorption detector is used for the determination of beryllium. Be(II) ions are detected by means of a complexation reaction between Be(II) and chrome azurol s as the chomogenic reagent. The reaction forms a stable 1:1 complex which appears dark red-violet. The optimum conditions for the determination are pH 4.15, 35% chrome azurol s, 3% buffer, 62% HCI and 1,3-phenylenediamine, flow rate of 1.0 mL/min, and wavelength at 570 nm. A concentration limit of 0.1 μg/mL (or 2 ng in 25 μ of a sample injected) of Be(II) can be detected, and the linear dynamic range extends to 100 μg/mL. Some interference limits are established in the presence of EDTA and thiosulfate which are used as masking agents.     

Chemiluminescence Flow Injection Determination of Copper (II)

ABSTRACT

A sensitive and selective flow injection chemiluminescence method for the determination of copper over the range of 0.5-7.5 ng is described. The method is based on quenching effect of copper (II) on the chemiluminescent reaction of dichlorofluorescein and hydrogen peroxide in alkaline media. Method development includes optimization of reagent concentrations and flow conditions. The optimized method yielded a detection limit (3σ) of 0.2 ng. The method is simple, fast, selective and precise and was used for the determination of copper in blood sera.     

Polarographic and Voltammetric Study of the Sc(III)-Acid Chrome Blue K Complex and Determination of Trace Scandium

Abstract

A new system of polarographic adsorptive wave for determining trace scandium was proposed. In 0.2 mol/L NH₄OAc, the Sc(III)- ACBK [1,8- dihydroxy- 2- (2- hydroxy- 5- sulfo- 1- phenylazo)- 3,6- disulfo- naphthalene, called acid chrome blue K] complex emerged a sensitive adsorptive complex wave(Ep′ = -0.67V). The molar ratio of Sc(III) to ACBK in the complex was established as 1: 2 and the apparent stability constant β₂ = 2.7 × 10¹⁵. But for Y(III), the molar ratio was 1: 1 and β = 1.5 × 10⁵. Because of the particularity of Sc complex, the sensitivity and the selectivity of determination Sc are much better than that of other rare earth ions. The detection limit is 1.1 × 10^?7 mol/L for oscillopolarography and 2.0 × 10^?8 mol/L for adsorptive stripping voltammetry.     

Ion paired chromatography of iron (II,III), nickel (II) and copper (II) as their 4,7-Diphenyl-1,10-phenanthroline chelates

A reversed phase ion-paired chromatographic method that can be used to determine trace amounts of iron (II,III), nickel (II) and copper (II) was developed and applied to the determination of iron (II) and iron (III) levels in natural water. The separation of these metal ions as their 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline) chelates on an Inertsil ODS column was investigated by using acetonitrile-water (80/20, v/v) containing 0.06 M perchloric acid as mobile phase and diode array spectrophotometric detection at 250-650 nm. Chromatographic parameters such as composition of mobile phase and concentration of perchloric acid in mobile phase were optimized. The calibration graphs of iron (II), nickel (II) and copper (II) ions were linear (r > 0.991) in the concentration range 0-0.5, 0-2.0 and 0-4.0 mug ml(-1), respectively. The detection limit of iron (II), nickel (II) and copper (II) were 2.67, 5.42 and 18.2 ng ml(-1) with relative standard deviation (n = 5) of 3.11, 5.81 and 7.16% at a concentration level of 10 ng ml(-1) for iron (II) and nickel (II) and 25 ng ml(-1) for copper (II), respectively. The proposed method was applied to the determination of iron(II) and iron(III) in tap water and sea water samples without any interference from other common metal ions.     

A New Polarographic Adsorptive Catalytic Wave for the Determination of Trace Tellurium in Smog Dust and Wheat Flour

Linear-sweep polarography of tellurium in sulfuric acid solution containing methylene blue produces a wave at −0.82 V (vs SCE). In a cathodic sweep, the derivative peak current is directly proportional to the concentration of tellurium over the range 4 × 10⁻⁹to 1 × 10⁻⁷g/ml, and the detection limit is 2 × 10⁻⁹g/ml. The polarographic wave is an adsorptive catalytic hydrogen wave. This method has been applied to the determination of trace amounts of tellurium in smog dust and wheat flour, with satisfactory results.     

Flow-Through Photometric Sensor for the Determination of Cadmium at the Nanogram per Millilitre Level

Abstract

A sensor for the determination of cadmium based on retention of the CdI₄ ^? complex on a QAE Sephadex resin located in the flow-cell of a conventional photometric detector and on subsequent complex displacement reaction with 4-(2-pyridylazo)-resorcinol is proposed. Formation of the colored chelate and detection take place simultaneously. The method features a determination range between 30 and 500 ng/ml of Cd(II) with relative standard deviations of 1.8% and 3.4% for 200 and 50 ng/ml of Cd(II), respectively. The selectivity involved in the use of the proposed sensor is shown in the study of interference.     

Determination of Germanium in Zinc by Differential Cathode Ray Polarography

Abstract

A differential cathode ray polarographic method is described for determining traces of germanium in zinc and its compounds. The germanium was previously extracted with carbon tetrachloride from the sample solution in hydrochloric acid. After reextraction with water the germanium content was determined polarographically in 1.4 M perchloric acid ? 5.10^?2 M pyrogallol. The detection limit was 0.0012 μg/ml, allowing to detect about 4 ppb of germanium in zinc using 5 g samples.