Selective kinetic spectrophotometric determination of copper at nanograms per milliliter level

A sensitive and selective kinetic method is proposed for the determination of nanogram amounts of copper. The method is based on the catalytic effect of copper on the reduction of Ponceau S by sodium sulfide in an alkaline media. The rate of the reaction is monitored spectrophotometrically at 560 nm. The method allows determination of copper concentrations in the range 2-400 ng ml(-1) with a relative standard deviation of approximately 2%. The proposed method, which is highly selective to copper, has been applied satisfactory to its determination in real samples.     

Sequential determination of trace amounts of iron and copper in water samples by flow injection analysis with catalytic spectrophotometric detection.

A simple flow injection analysis (FIA) method is described for the sequential determination of iron and copper. The detection method for iron and copper is based on their catalytic activities in the oxidation reaction of N,N-dimethyl-p-phenylenediamine (DPD) with hydrogen peroxide. The sequential determination of iron and copper can be carried out by injecting two sample plugs into the FIA system, sequentially. One injection does not contain triethylenetetramine (TETA), and is used for the sum of iron and copper concentration; the other which contains TETA is used only for the iron concentration. For iron determination, TETA is used as a masking agent of copper. The difference in peak height can be used for the calculation of copper concentration. Under the optimal conditions, the detection limits (3sigma) of 0.01 and 0.07 microg L(-1) were obtained for iron and copper, respectively. The proposed method can be applied to the determination of iron and copper in tap water and bottled-drinking mineral water samples. Good recoveries of the method, 98-103% for iron and 98-106% for copper, were achieved.     

Determination of Ephedrine via the Formation of Metal Complexes

Abstract

The reaction of ephedrine with carbon disulphide and metals'reagents (nickel, copper and cobalt has been studied. Various methods are accordingly introduced for the determination of ephedrine in pure form and in pharmaceutical formulations. Direct spectrophotometric method determines 0.24-1.21, 0.61-5.45 and 6.05-60.5 μ moles. of epherdrine with a mean accuracy (P'=0.05) of 100.24± 1.48%,99.65±1.68% and 99.73±0.59% using nickel, copper and cobalt respectively. Indirect determinations- through the metals' content- include atomic absorption method, which is suitable for the determination of 0.73-8.5, 1.82-6.66 and 3.63-24.2 μ moles. of ephedrine with a mean accuracy of 99.49±1.18%, 100.13±1.65% and 99.68±0.63% on using nickel, copper and cobalt respectively. The corresponding data on determining the metals by the oxalyldrazide method are : 1.45-16.94, 0.61-1.57 and 0.73-17.54 μ moles. of epherdrine, 99.13±0.6%, 99.35±0.71% and 99.54±0.73% on using nickel, copper and cobalt respectively.     

Flow-injection determination of copper(II) based on its catalysis on the redox reaction of cysteine with iron(III) in the presence of 1,10-phenanthroline

A redox reaction of cysteine with iron(III) proceeds slowly in the presence of 1,10-phenanthroline (phen). However, this reaction is accelerated in the presence of copper(II) as a catalyst, producing an iron(II)-phen complex (lambda(max)=510 nm). A sensitive spectrophotometric flow-injection method is proposed for the determination of copper(II) based on its catalytic action on this redox reaction. The dynamic range was 0.1-10 ng ml(-1) of copper(II) with a relative standard deviation of 1.0% (n=10) for 1.0 ng ml(-1) of copper(II) at a sampling rate of 30 h(-1). The detection limit (S/N=3) is 0.04 ng ml(-1). The proposed method was successfully applied to the determination of copper in river water as a certified reference material.     

铜合金中铜的示波滴定—四苯硼钠法

本文报道了铜合金中铜的示波滴定方法。样品酸溶后，用抗坏血酸还的Ｃｕ＾２＋为Ｃｕ＾＋，加入过量的四苯硼钠，在ＰＨ５－６的ＨＡｃ－ＮａＡｃ缓冲溶液中，定量形成Ｃｕ－ＴＰＢ沉淀，过量的ＴＰＢ＾－，以Ｔｌ＾＋标准溶液进行示波滴定，铜合金中共存元素不干扰测定。铜的测定回收率９９．８％－１００．１％。进行了多种铜合金中铜含量的测定，结果令人满意。     

Rapid determination of copper in plants by neutron activation analysis

A rapid and simple neutron-activation analysis method has been developed for the determination of copper in plant leaves. Irradiated samples are dissolved in a mixture of fuming nitric acid, 70% perchloric acid and concentrated sulphuric acid in the presence of copper carrier solution. The copper in the resulting solution is extracted as copper cupferronate into chloroform and back-extracted into concentrated ammonia solution. The copper is precipitated as sulphide with 3% aqueous thioacetanude solution and the precipitate is dissolved in nitric acid. The induced activity of copper-64 in the resulting solution is counted with a 400-channel analyser. The photopeak of the annihilation energy of copper-64 at 0.51 MeV is compared with that of a copper standard processed in the same manner. After counting, the chemical yield of the separated copper is found by re-irradiating aliquots of the copper nitrate solution and comparing the induced activity of coppcr-66 at 1.04 MeV with that of another standard processed in a similar manner. The time required to complete the analysis, including the second irradiation and all radioactivity measurements, is about 25 min. The accuracy of the method was checked by analysing a biological standard of known copper content. The proposed method was successfully applied to the determination of copper in the leaves of 10 different plants (copper content 4-30 ppm).     

Spectrophotometric determination of copper in plutonium metal with 2,9-dimethyl-1,10-phenanthroline

A spectrophotometric method for the determination of copper plutonium has been developed. The copper is complexed with neocuproine, extracted into chloroform, and the absorbance read at 457 mmu. The average relative error of the method is -1.4% with an average relative standard deviation of 4%.     

Catalytic flow-injection determination of sub-ppb copper(II) using the redox reaction of cysteine with iron(III) in the presence of 2,4,6-tris(2-pyridyl)-1,3,5-triazine.

A kinetic-catalytic spectrophotometric flow-injection method was developed for the rapid and sensitive determination of trace amounts of copper(II). The method is based on the catalytic effect of copper(II) on the redox reaction of cysteine with iron(III). Iron(II) produced by the catalytic reaction reacts with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ) to form the iron(II)-TPTZ complex (lambda(max) = 593 nm). By measuring an absorbance of the complex, one could determine 0.05-8 ppb copper(II) with the relative standard deviations (n = 10) of 1.6%, 1.3%, and 0.8% for 0.5 ppb, 1 ppb, and 2 ppb copper(II), respectively. The limit of detection (S/N = 3) was 0.005 ppb. The sample throughput was 30 h(-1). The proposed method was successfully applied to the determination of copper in natural water and serum samples.     

Preconcentration of bismuth(III) and copper(II) by solid-phase extraction and subsequent determination by differential pulse polarography

A differential pulse polarographic method is proposed for the trace determination of bismuth and copper from large volumes of aqueous samples after adsorption of their 1-(2-thiazolylazo)-2-naphthol complexes onto microcrystalline naphthalene in the pH ranges of 7.2-9.0 and 4.0-7.8, respectively. Bismuth and copper are desorbed from microcrystalline naphthalene with 9 mL 1M HCl. Well-defined peaks are obtained at Ep = -0.09 and -0.20 V versus a saturated calomel electrode, in an HCl-isoquinoline medium as the supporting electrolyte, for bismuth and copper, respectively. Bismuth is reduced reversibly with a 3-electron change, whereas copper is reduced irreversibly under these conditions. The detection limits are 55 ng/mL for bismuth and 91 ng/mL for copper. Linearity is maintained in the concentration ranges of 0.18-13.5 and 0.30-17.3 microg/mL for bismuth and copper, respectively, with corresponding correlation coefficients of 0.9996 and 0.9885. The relative standard deviations are 1.0% for bismuth at 2.0 microg/mL and 1.4% for copper at 5.0 microg/mL. Various parameters were optimized to develop conditions for the determination of these metal ions in various samples.     

Rapid spectrophotonietric determination of copper in steel with zinc dibenzyldithiocarbamate

A rapid spectrophotometric method employing zinc dibenzyldithiocarbamate is described for determining copper in a wide variety of steels. The acidity is not critical (0.5-2N) and the colour of the complex is stable for > 1 hr. The range of the method is 0.005-5% copper and 6 samples can be analysed in about an hour.     

Selective determination of trace copper(II) by cathodic adsorptive stripping voltammetry with a naphthol-derivative Schiff's base

A selective and sensitive stripping voltammetric method for the determination of trace amounts of copper(II) with a recently synthesized naphthol-derivative Schiff's base (2,2'-[1,2-ethanediylbis(nitriloethylidyne)]bis(1-naphthalene)) is presented. The method is based on adsorptive accumulation of the resulting copper-Schiff's base complex on a hanging mercury drop electrode, followed by the stripping voltammetric measurement at the reduction current of adsorbed complex at -0.15 V (vs. Ag/AgCl). The optimal conditions for the stripping analysis of copper include pH 5.5 to 6.5, 8 microM Schiff's base and an accumulation potential of -0.05 V (vs. Ag/AgCI). The peak current is linearly proportional to the copper concentration over a range 2.3-50.8 ng ml(-1) with a limit of detection of 1.9 ng ml(-1). The accumulation time and RSD are 90 s and (3.2-3.5)%, respectively. The method was applied to the determination of copper in some analytical grade salts, tap water, human serum and sheep's liver.     

Determination of copper and zinc in serum by derivative atomic absorption spectrometry using the microsampling technique

A method has been developed for the determination of copper and zinc in the serum of rats by derivative microsampling flame atomic absorption spectrometry (D-MFAAS). The microsampling volume, solution uptake rate and other figures of merit of the proposed methodology were studied. For a 100 microl volume, the characteristic concentrations and detection limits (3s) of D-MFAAS were 0.023 and 0.013 microg ml(-1) for copper and 0.0066 and 0.0080 microg ml(-1) for zinc, which were 4.5-6.5-fold better than those of microsampling flame atomic absorption spectrometry (MFAAS). The detection limits and sensitivities of D-MFAAS were 6.4- and 16-fold for 300 microl volume for copper, 14- and 13-fold for 250 microl volume for zinc, better than those of MFAAS. The method demonstrates high tolerance to interferences, and the analytical results obtained for a certified reference material, GBW 08551 Pork Liver, were in good agreement with the certified values. The recovery with the standard additions method was good, in the range 97.6-101.5%, and precisions (relative standard deviations) obtained for a diluent sample containing 0.5 microg ml(-1) copper and 0.7 microg ml(-1) zinc were 4.0% and 3.5% (n = 15) for copper and zinc, respectively.     

Spectrophotometric determination of trace copper in water samples with thiomichlersketone

A simple and sensitive spectrophotometric method for determination of trace copper in water samples is proposed. In the presence of pH 4.6 HAc-NaAc buffer solution and surfactant polyethylene octyl phenyl ether (OP) medium, copper reacts with thiomichlersketone (TMK) to form a stable 1:4 complex. The complex Cu(II)-TMK-OP shows maximum absorbance at 500 nm with a molar absorptivity value of 5.7x10(4) l mol-1 cm-1. Beer's law is obeyed for copper concentrations in the range of 0-15 microg/25 ml. The average recovery of copper is between 95.8 and 106%. The method has been applied for determination of trace copper in different water samples with satisfactory results.     

Successive determination of copper and iron by a flow injection-catalytic photometric method using a serial flow cell.

A flow injection-catalytic spectrophotometric method using a serial flow cell was proposed for the successive determination of trace amounts of copper and iron. This method is based on the oxidation coupling of p-anisidine with N,N-dimethylaniline in the presence of hydrogen peroxide to form a dye, which has an absorption maximum at 740 nm. In this indicator reaction, ligands such as 1,10-phenanthroline (phen) and diphosphate were achieved to improve the sensitivity and selectivity. Under the optimal experimental conditions, the determinable ranges were 0.05-5 ppb for copper and 0.5 - 100 ppb for iron, respectively. The RSDs (n = 10) were 0.78% for 0.5 ppb copper(II) and 0.5% for 200 ppb iron(III). The sample throughput was 30 h(-1). The present flow-injection method was applied to the determination of copper and iron in standard river water, tap water, and other natural water samples, and also to the analysis of labile and inert complexes in synthesized samples containing humic acid with copper(II) or iron(III).     

Simultaneous determination of copper and iron by second derivative spectrophotometry using mixtures of ligands

A highly sensitive and selective second derivative spectrophotometric method has been developed for the determination of copper and iron in mixtures. The method is based on the separation of the analytes by liquid-liquid extraction as picrate ion pairs. Iron-picrate, reacts in the organic phase of DCE with 5-phenyl-3-(4-phenyl-2-pyridinyl)-1,2,4-triazine (PPT). Similarly the copper-picrate reacts with 2,9-dimethyl-4,7-diphenyl-1,10-phenantroline (bathocuproine). The extracts were evaluated directly by derivative spectrophotometric measurement, using the zero-crossing approach for determination of copper and graphic method for iron. Iron and copper were thus determined in the ranges 8-120 ng ml(-1) and 8-125 ng ml(-1), respectively, in the presence of one another. The detection limits achieved (3sigma) were 2.9 ng ml(-1) of iron and 2.8 ng ml(-1) of copper. The relative standard deviations were in all instances less than 2.1%. The proposed method was applied to the determination of both analytes in river and tap water and the results were consistent with those provided by the AAS standard method.     

Cu(Ⅱ)-抗坏血酸-三氯偶氮胂体系催化动力学光度法测定痕量铜的研究

在乙酸-乙酸钠缓冲溶液(pH4.4)中,以Cu(Ⅱ)催化抗坏血酸还原三氯偶氮胂褪色为指示反应,建立了测定痕量Cu(Ⅱ)的新方法.测定了反应级数和表观活化能.在70℃水浴中加热6min,测定的灵敏度为3.1×10~(-12)g·ml~(-1),线性范围为0～70ng/25ml.用于测定几种中草药样品中的铜,结果满意,相对标准偏差小于3%.     

Spectrophotometric extractive titrations-III Simultaneous determination of silver and copper in high purity lead

A procedure for the simultaneous determination of silver and copper in high-purity lead is given. After dissolution of the sample the majority of the lead is removed by precipitation with ammonium sulphate. Silver and copper are then determined by spectrophotometric extractive titration at pH 4.3-5.5 with dithizone. Changes of absorbance are measured at 550 mmu. The procedure has been checked by the method of standard additions and by comparison with conventional methods. The procedure is highly selective. The limit of determination is 2.5 x 10(-5)% of silver and 1.1 x 10(-5)% of copper.     

Speciation of protein-binding zinc and copper in human blood serum by chelating resin pre-treatment and inductively coupled plasma mass spectrometry

A method for the speciation of zinc and copper binding with proteins in human serum was explored by chelating resin (Chelex-100) pre-treatment and inductively coupled plasma mass spectrometry (ICP-MS). It was shown by a SEC (size-exclusion chromatography)-ICP-MS system that albumin-zinc and albumin-copper (loosely-bound species) could be selectively removed from serum by adsorption on the Chelex-100 resin after the chelating resin pre-treatment, while alpha 2-macroglobulin-zinc and ceruloplasmin-copper (firmly-bound species) remained in the serum. The zinc and copper bound with alpha 2-macroglobulin and ceruloplasmin, respectively, were then determined by ICP-MS after batch treatment of the serum samples with the Chelex-100 resin. In addition, the total concentrations of zinc and copper were also determined by ICP-MS after a 20-fold dilution with 0.1 M HNO3. The albumin-zinc and -copper were estimated as the differences between the concentrations of total and firmly-bound species. The present batch pre-treatment method was applied to the speciation analysis of zinc and copper binding with proteins in sera donated from 25 healthy volunteers as well as from a pregnant woman and a myelodysplastic syndrome patient. The observed concentrations of alpha 2-macroglobulin-zinc and ceruloplasmin-copper were in the ranges 109-202 ng ml-1 (12.4-31.3% of total zinc) and 513-880 ng ml-1 (90.6-99.7% of total copper), respectively. The present method is simple (only addition of the chelating resin and centrifugation is required) and reproducible (average RSD = 2% for alpha 2-macroglobulin-zinc and 1% for ceruloplasmin-copper in intra-assay measurements, and 5% for alpha 2-macroglobulin-zinc and 4% for ceruloplasmin-copper in inter-assay measurements), and there is less risk of contamination during separation.     

火焰原子吸收光谱法测定粗锌中的铜

建立火焰原子吸收光谱法测定粗锌中的铜含量。采用硝酸–酒石酸溶解样品,并以其为测定溶液介质,检测波长为324.7 nm,以水为参比,采用空气–乙炔火焰以原子吸收光谱仪进行测定。在优化的实验条件下,铜的质量浓度在0.10~2.50μg/m L范围内与吸光度有良好线性关系,相关系数为0.999 7,方法检出限为0.01μg/m L。测定结果的相对标准偏差为1.0%~3.0%(n=11),样品加标回收率为97%~102%。该方法具有灵敏度高,干扰少,重现性好等优点,适用于铜含量在0.001%~0.50%之间的粗锌中铜的测定。     

Simultaneous third-derivative spectrophotometric determination of copper and nickel in iron alloys and aluminium alloy

A method is proposed for the simultaneous determination of copper and nickel by third-derivative spectrophotometry based on the absorption spectra of their complexes with cyanide ion in the ultraviolet range. The method allows the determination of 0.55-5.8 mug/ml of copper and 0.55-6.8 mug/ml of nickel. The relative standard deviation for 11 determinations of 1.5 mul/ml of copper and nickel were 0.78 and 0.72%, respectively. The detection limits were 0.10,mug/ml for nickel and 0.13 mug/ml for copper. The method has been applied to direct determination of copper and nickel in iron alloys and an aluminium alloy without any separation.