Simultaneous determination of trace uranium and vanadium in biological samples by radiochemical neutron activation analysis

Summary A radiochemical neutron activation analysis (RNAA) for simultaneous determination of uranium and vanadium in a single sample at trace levels is described. The method is based on post-irradiation wet-ashing and solvent extraction of vanadium with N-benzoyl-N-phenyl-hydroxylamine reagent. From the remaining aqueous phase, uranium is extracted into a toluene solution of tri-n-butyl phosphate. The chemical yields are determined spectrophotometrically for vanadium and by gamma-counting of the added natural uranium carrier for uranium. The method was evaluated by the analysis of reference materials and the results showed a good agreement with the certified values. The method was applied to the determination of vanadium and uranium in five military total diet samples in Slovenia.     

Flow injection electrogenerated chemiluminescence determination of vanadium and its application to environmental water sample

A selective flow injection electrogenerated chemiluminescence(CL) method for the determination of vanadium is described in this paper. It was based on the chemiluminescence reaction of luminol with vanadium(II), which was on-line electrogenerated from vanadate using a flow-through carbon electrolytic cell. Under the optimal conditions, the CL intensity was linear to the concentration of vanadium in the range of 5.0x10(-10)-1.0x10(-7) gml(-1) with a detection limit of 2x10(-10) gml(-1) vanadium. The relative standard deviation was 4% for 5.0x10(-8) gml(-1) vanadium in 11 repeated measurements. The method has been successfully applied to the determination of vanadium in environmental water samples.     

Direct Determination of Vanadium in Water Samples,Human Hairs,Vegetables, and Foods by Graphite Furnace Atomic Absorption Spectroscopy

At present,the considerable attention was greatly paid to the determination of vanadium from the point of vanadium as a kind of biological nutrient element or one kind of industrial sources of pollution. In the paper,we employed graphite furnace AAS (GFAAS) method to determine directly the vanadium in samples, using optically controlled raising temperature combining with pyrolytic coating tube to atomize vanadium under the conditions of stable temperature for the determination of vanadium in samples.     

钒(Ⅴ)-桑色素-溴化十六烷基三甲铵胶束增敏荧光光度法的研究和应用

研究了在 p H 2 .5的 HCl- Na Ac介质中 ,溴化十六烷基三甲铵( CTMAB)对桑色素 ( morin)和钒 ( )配合物荧光的增敏作用 ,建立了利用钒 ( ) - morin- CTMAB胶束增敏荧光反应测定痕量钒的荧光光度新方法。方法的检出限为 0 .92μg/L ,荧光强度与钒的含量在 0 .0 1 0～ 6.0μg/1 0 m L范围内呈线性关系 ,配合物中钒 ( )与桑色素的组成比为 :V( )∶ morin=1∶ 1。方法可应用于天然水和食品中微量钒的测定     

Simultaneous spectrophotometric determination of iron and vanadium by H-point standard addition method and partial least squares regression in micellar medium

Simultaneous determination of total iron and vanadium by H-point standard addition method (HPSAM) and partial least squares (PLS) is described. Gallic acid (GA) in a cationic micellar solution of CTAB was used for determination of iron and vanadium in different oxidation states at pH 5. The presence of a micellar system enables total iron and vanadium to be determined with improved sensitivities. The total relative standard error for applying the PLS method to 15 synthetic samples in the ranges 0.20–15.00 μg ml⁻¹ iron and 0.20–8.00 μg ml⁻¹ vanadium was 2.2%. The results of applying the H-point standard addition method showed that iron and vanadium can be determined simultaneously with the concentration ratios of iron to vanadium from 10:1 to 1:20 in the mixed sample. Both HPSAM and PLS methods showed suitable abilities to resolve accurately overlapped absorption spectra of the compounds. Both proposed methods were successfully applied to the determination of Fe and V in several synthetic alloy solutions.     

Determination of vanadium in biological and environmental samples by RNAA with emphasis on quality control

Summary In the present work an improvement of radiochemical neutron activation analysis for determination of nanogram levels of vanadium is described. The method is based on post-irradiation wet ashing and solvent extraction of vanadium with N-benzoyl-N-phenyl-hydroxylamine (BPHA) forming a violet chelate complex in strongly acidic medium. For quality assurance purposes a procedure for determination of the overall chemical yield using spectrophotometry of the V-BPHA complex is described, and possible interferences are evaluated. The procedure was applied to the determination of vanadium in reference materials and selected food samples from Slovenia.     

Catalytic determination of trace amounts of vanadium by means of the chromotropic acid-bromate reaction

A catalytic reaction-rate method is described for the determination of trace amounts of vanadium; the method is based on the vanadium-catalysed oxidation of chromotropic acid by bromate. The reaction was followed spectrophotometrically by measuring the rate of change in absorbance of chromotropic acid at 430 nm. The method is sensitive, rapid and simple, and allows determination of as little as 5 ng of vanadium. Of the many ions examined, iron(III), copper and tungsten(VI) interfered seriously at 100-fold concentrations. The relative standard deviation for 20 ng of vanadium (10 determinations) was 2.5%.     

Kinetic-spectrophotometric determination of trace amounts of vanadium

A simple and sensitive kinetic-spectrophotometric method is described for the determination of vanadium and the possible mechanism of catalytic reaction is proposed. The method is based on the vanadium(V)-catalyzed oxidation of 1,8-diaminonaphthalene (DNA) by potassium bromate (Tiron as activator) at pH 3.8 and 40 degrees C. The reaction was monitored spectrophotometrically by measuring the increase in absorbance of oxidation products at 505 nm after a fixed time (6 min). The proposed method allowed the determination of vanadium in the range 0.025-15 ng ml(-1) with good precision and accuracy and the detection limit was down to 0.01 ng ml(-1). The method was found to be relatively selective and was applied successfully to the determination of vanadium in food and hair samples without previous separations. Recovery experiments have also been performed; excellent results were obtained.     

ICP-OES测定钒矿石中五氧化二钒的测量不确定度评定

介绍了电感耦合等离子体发射光谱法(ICP-OES)测定钒矿石中五氧化二钒测重不确定度的评定万法.建立了测量过程中各不确定度分量的数学模型,对不确定度来源进行了分析,并对不确定度分量进行量化.当钒矿石中五氧化二钒含量为0.419％时,其扩展不确定度为0.0070％(k=2).     

Spectrophotometric determination of vanadium(v) and its application to vanadium steels containing chromium, molybdenum, tungsten and manganese

A newly synthesized reagent, N-o-toluoyl-N-o-tolylhydroxylamine is used in a sensitive and selective spectrophotometric method for determination of vanadium(V). The method has been successfully applied to vanadium determination in Mn-Mo-Cr-V steels. The system in 2-6M hydrochloric acid medium obeys Beer's law at 510 nm in the range of vanadium concentration from 0.5 to 10.0 mug ml .     

动力学分析法研究(Ⅲ)——BKrO3-钒(Ⅴ)-柠檬酸-溴酚蓝体系催化光度法测定痕量钒

钒对许多均相反应都有催化作用,但利用催化光度法测定痕量钒国内研究较少。作者发现钒(Ⅴ)对稀硫酸介质中溴酸钾氧化溴酚蓝褪色的反应有催化作用,通过条件试验,建立了利用这一新指示反应催化光度法测定痕量钒的方法。     

Elimination of the interferences of anions in the kinetic spectrophotometric determination of vanadium (V) solution

Accurate determination of vanadium (V) in industrial waste water is of great importance in environmental, biological and toxicological studies. Most of kinetic spectrophotometric methods based on the catalytic effect of vanadium (V), when applied to real samples for determination of trace levels of vanadium (V) lack the satisfactory sensitivity and selectivity. This may be attributed to the serious interferences of various anions which are common pollutants in industrial waste water. The oxidation of gallic acid by ammonium persulphate, catalysed by vanadium (V) was chosen for our study. The effect of the serious interferences of various anions such as chloride, bromate, bromide, chromate, iodide, iodate, molybdate, carbonate and sulphate on the net absorbance given by 4 microg l(-1) of vanadium (V) solution were studied. The minimum concentrations of citric acid, EDTA, ascorbic acid and oxalic acid as leveling off agents required to level off interfering effects due to the aforementioned anions in the kinetic determination of vanadium (V) were 50, 70, 80 and 120 microg ml(-1), respectively. In the presence of optimum concentrations of effective leveling off agents, the dynamic range can be extended and sensitivity increased as compared with the proposed method without levelling off agents. The proposed method is a rapid, sensitive and selective method for the determination of ultra trace amounts of vanadium (V) in real samples with satisfactory results.     

Spectrophotometric determination of micro-amounts of vanadium with 5,7-di-iodo-8-hydroxyquinoline

A precise spectrophotometric method for the determination of 2.5-25 mug of vanadium in volumes of up to 500 ml of water was developed. The method is based on the simultaneous concentration (100-1000 fold) and complexation of vanadium(V) with di-iodo-oxine in a water-immiscible phase. Interference from iron is eliminated by masking with phosphoric acid. The standard deviation evaluated was +/-0.04 mug for solutions containing 5 mug vanadium.     

Ion-exchange separation and spectrophotometric determination of vanadium in environmental samples

A selective and sensitive method for the extraction and spectrophotometric determination of vanadium(V) in microgram quantities is described. The molar absorptivity of the yellow vanadium(V)-caffeic acid-Aliquat 336 extract is 1.3 x 10(4) 1.mole(-1).cm(-1) at 370nm. The method is compared with the atomic-absorption spectrometric method and applied to the trace determination of vanadium in steel, alloys, a rock and environmental samples.     

KBrO3氧化甲基紫褪色动力学光度法测定食品中痕量钒

基于0.004 mol/L的柠檬酸介质中,痕量V(Ⅴ)催化KBrO3氧化甲基紫的褪色反应,建立了测定痕量V(Ⅴ)的动力学光度法。方法的检出限为1.23μg/L,线性范围为0～0.16μg/mL。讨论了酸度、反应物浓度、温度、反应时间、干扰离子等因素的影响,确定了该体系反应的最佳条件。在25 mL溶液中,测定2.0μg V(Ⅴ)的RSD为1.9%(n=11)。方法可用于测定小麦和苹果中的痕量V(Ⅴ),RSD为1.1%～2.7%,标准加入回收率为97.6%～99.0%。     

Solid-phase spectrophotometric determination of trace amounts of vanadium at sub-ng/ml level with 4-(2-pyridylazo)resorcinol

Solid-phase spectrophotometry has been applied to analysis for trace amounts of vanadium. Vanadium was sorbed in a styrene-divinylbenzene-type anion-exchanger Dowex 1-X8 as a vanadium-4-(2-pyridylazo)resorcinol complex. Resin phase absorbances at 562 and 800 nm were measured directly which allowed the determination of vanadium in the range of 0.1-2.4 ng/ml with a RSD of 1.5%. The method has been applied to the determination of vanadium in different samples, namely toadstool tissue, mussel tissue, petroleum crudes and swamp water.     

Speciation analysis of vanadium in natural water samples by electrothermal vaporization inductively coupled plasma optical emission spectrometry after separation/preconcentration with thenoyltrifluoroacetone immobilized on microcrystalline naphthalene

A sensitive and simple method for low temperature electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP-OES) determination of V(IV) and V(V) after separation/preconcentration by a micro-column packed with immobilized thenoyltrifluoroacetone (TTA) on microcrystalline naphthalene has been developed. Thenoyltrifluoroacetone was used as both a chelating agent for micro-column separation/preconcentration and a chemical modifier for ETV-ICP-OES determination of vanadium. Both vanadium species could be trapped by micro-column at pH 4.0, and the vanadate (VO₂⁺) ion could be collected selectively at pH 2.4. Solid material loaded with analyte in the micro-column was dissolved with 100 μL of acetone containing 2.0 mmol L⁻¹ TTA and the vanadium was determined subsequently by ETV-ICP-OES. The concentration of vanadyl (VO²⁺) ion was calculated by subtracting the vanadate concentration from the total concentration of vanadium. Under the optimized experimental conditions, the detection limit (3σ) for the preconcentration of 5 mL of aqueous solution is 0.068 μg L⁻¹ for both species and the relative standard deviations were 4.3% for vanadium(V) and 4.8% for vanadium(IV) (c=10 μg L⁻¹, n=7), respectively. The method was applied successfully to the determination of vanadium(IV) and vanadium(V) in natural water samples.     

Spectrophotometric determination of vanadium(V) with oxine in isoamyl alcohol

A new method for the spectrophotometric determination of vanadium(V) with 8-hydroxyquinoline in isoamyl alcohol is described. The spectra show broad absorption maxima between 450 and 490 nm. The effects of amount of reagent, acidity, time, and temperature were also studied. The optimal interval of Beer's law application is 0.75–3.50 μg vanadium/ml. The nature of the complex in solutions, as well as the interference, reproducibility, and precision of the method, was investigated. The method has been applied to the determination of vanadium in foods.     

Determination of Trace Amounts of Vanadium by Kinetic-Catalytic Spectrophotometric Methods

Kinetic-catalytic spectrophotometric methods were proposed for the determination of trace amounts of vanadium element as vanadium（Ⅳ） and/or V（Ⅴ） ions. The vanadium（Ⅳ） as VO^2＋ ion and/or vanadium（Ⅴ） as VO3^- ion showed a catalytic effect on the kinetic reactions between a color reagent such as methylthymol blue （MTB） or SPADNS and bromate in acidic media. The rate of decrease in the absorbance of the reagent MTB at 440 nm or SPADNS at 510 nm was proportional to concentration of V（Ⅳ） and/or V（Ⅴ） ions in the solution. The linear ranges for determination of vanadium were obtained in the range of 1.0-150 and 5.0-100.0 μg/L by the fixed-time and slope methods, respectively, with using MTB as reagent. In the presence of SPADNS as reagent, the calibration curves were made in the amplitude 1.0-200.0 and 5.0-150 μg/L of vanadium ion by the fixed-time and slope methods, respectively. Using fixed-time method, the limits of detection were obtained to be 0.5 and 0.7 μg/L of vanadium in the presence of MTB and SPADNS as reagents, respectively. Detection limits of vanadium by slope method and reagents of SPADNS and MTB were obtained to be 3.5 and 3.8 μg/L of vanadium, respectively. The proposed methods were applied successfully to determination of vanadium in synthetic and real samples.     

电感耦合等离子体质谱(ICP-MS)法测定钒银矿中硒

提出了电感耦合等离子体质谱(ICP-MS)法测定钒银矿中硒的含量。样品经逆王水加高氯酸溶解,并采用内标法消除了可能存在的质谱干扰。实验结果表明,方法检出限为0.066ng/mL,加标回收率为94%~104%,测定值的相对标准偏差(n=7)均小于5.0%。方法简单、快速、准确,适用于钒银矿中硒含量的测定。