Determination of sulfur,nickel and vanadium in fuel and residual oils by x-ray fluorescence spectrometry

The determination of sulfur, nickel and vanadium in fuel and residual oils by wavelength-dispersive x-ray fluorescence spectrometry is reported. Calibration is initially established with matrix-matched synthetic standards, and maintained free of instrumental drift by daily normalization to a reference standard. An epoxy-cast reference standard pellet offers mechanical rigidity and chemical stability for at least nine months. Matrix effects of sulfur and carbon are studied and corrected. Results for NBS SRM oils fall within the NBS certified values, with imprecision (% RSD) for S, Ni, and V of 1.1, 1.5 and 1.0%, respectively. Detection limits (3 s.d.) are 20 μg g^?1 for sulfur and 0.8 μg g^?1 for Ni and for V.     

X射线荧光光谱法测定铀钼合金中钼

建立铀钼合金中钼的X射线荧光光谱测定方法.用硝酸–盐酸混合酸溶解样品,调节样品溶液pH值为1～2,在选定的仪器工作条件下进行测定,采用α校正消除干扰.钼的质量分数在1.0％～16.0％范围内与X荧光强度呈良好的线性关系,线性相关系数为0.9999,检出限为0.039％.样品加标回收率为99％,测定结果的相对标准偏差为0...     

The determination of vanadium,molybdenum and tungsten by infrared spectroscopy

The infrared spectra of the 8-hydroxyquinolinates of molybdenum, vanadium and tungsten in the region 3–15 μ were investigated. It was found possible to determine the elements quantitatively, singly or in pairs, with an error of about 3%. Molybdenum was determined at 10.80 μ and 10.93 μ, vanadium at 10.50 μ, and tungsten at 10.61 μ or 10.90 μ.     

Determination of molybdenum and tungsten at trace levels in rocks and minerals by solvent extraction and X-ray fluorescence spectrometry

Separation by solvent extraction followed by X-ray fluorescence spectrometry has been used for determination of molybdenum and tungsten in rocks and minerals. Samples are decomposed either by heating with a mixture of hydrofluoric acid and perchloric acid or by fusion with potassium pyrosulphate, followed by extraction of molybdenum and tungsten with N-benzoylphenylhydroxylamine in toluene from 4-5M sulphuric acid medium. The extract is collected on a mass of cellulose powder, which is dried in vacuum, mixed thoroughly and pressed into a disc for XRF measurements. The method is free from all matrix effects and needs no mathematical corrections for interelement effects. The method is suitable for determination of molybdenum and tungsten in geological materials down to ppm levels, with reasonable precision and accuracy.     

Determination of total sulphur in coal by x-ray fluorescence spectrometry

A precise x-ray fluorescence method for the determination of sulphur in coat. The sample is mixed with calcium oxide and active carbon and is gradually heated to 900°C. After coding, lithium tetraborate and lead oxide are added and a prepared. The Pb M_α line is used as an internal standard for the KK_α line. The results for coal have a relative standard deviation of approximately 1% and exhibit.     

Determination of vanadium, molybdenum and tungsten in complex matrix samples by chelation ion chromatography and on-line detection with inductively coupled plasma mass spectrometry

In this work, two kinds of chelating resin, bis(2-aminoethylthio)methylated resin (BAETM) and γ-aminobutyrohydroxamate resin (γ-ABHX) were synthesized. Of these, the former has a hydrophobic skeleton, and the latter a hydrophilic skeleton. The functionalities of each were 0.91 and 2.21 mmol g⁻¹, respectively. The chelating behavior of these resins towards vanadium, molybdenum and tungsten as a function of pH was studied. To perform trace metals analysis in complex matrices, a hyphenated method-chelation ion chromatography (CIC) coupled on-line detection with inductively coupled plasma mass spectrometry (ICP-MS) was developed. With a BAETM resin column (5×0.4 cm i.d.) as the separator, a sample volume of 20 μl, nitric acid (pH 1.5) as the eluent and a flow rate of 1 ml min⁻¹, the detection limits for the determination of vanadium, molybdenum and tungsten were lower than 0.05 ng ml⁻¹and the linear ranges were up to 100 ng ml⁻¹ for each element. By increasing the injected sample volume to 250 μl, the resin concentrator improved the detection limit to 0.01 ng ml⁻¹. For the determination of these elements (5 ng ml⁻¹ for each) spiked in artificial sea water samples, γ-ABHX resin column (3×0.6 cm i.d.) demonstrated well resolved peak separation between the analytes and the matrix elements—calcium and magnesium, by using sodium nitrate (10 ml, 10⁻⁴ M) as the eliminator.     

Determination of tungsten in niobium-tantalum, vanadium and molybdenum bearing geological samples using derivative spectrophotometry and ICP-AES

Two different procedures, one using derivative spectrophotometry and another using inductively coupled plasma atomic emission spectrometry (ICP-AES) have been developed for the determination of tungsten in niobate-tantalates, tin slag samples, ores, concentrates and vanadium and molybdenum bearing geological materials. In the first method involving derivative spectrophotometry, 0.05-0.5 g of the sample is fused with sodium hydroxide, the tungsten is extracted by leaching the melt with distilled water and estimated as thiocyanate using a second derivative spectrophotometric method in the presence of interferents, i.e. Nb, Mo and V, without separating them. Mixtures of tungsten with V, Nb and Mo are used for standardizing the various parameters like zero-crossing wavelength, wavelength range, etc. Tolerance limits for V, Nb and Mo have also been evaluated. In the second method involving ICP-AES, 0.05-0.5 g of sample is fused with KHSO(4) to a clear melt and dissolved in ammonium oxalate solution. Ammonium hydroxide precipitation is then carried out to separate Nb and Ta as hydroxides and the filtrate is boiled with nitric acid to destroy the oxalates before aspiration into the plasma for measurement of tungsten values by ICP-AES using the 207.911 nm emission line. Both methods have been applied to niobate-tantalate and tin slag samples and the results obtained are reported in this paper. The values obtained by both methods are in good agreement with each other. The proposed methods have also been applied to the determination of tungsten in two Canadian Certified Reference Standards (CT-1 and MP-2) and the values obtained are in good agreement with the certified values and the R.S.D.% in case of the ICP-AES method varied from 1-2% at >1000 mug g(-1) level to 9.4% at the 20 mug g(-1) level whereas the R.S.D.% in case of the derivative method varied from 1 to 7.8%.     

Determination of vanadium and molybdenum by atomic-absorption spectrophotometry

A method is described for the determination by atomic-absorption spectrophotometry of vanadium and molybdenum, up to the milligram level, in samples of yellow cake, uranium-bearing minerals and geochemical standards. After attack with acids these two elements are separated from each other and from matrix elements by means of anion-exchange in 6M hydrochloric acid on the strongly basic anion-exchange resin Dowex 1, X8 (chloride form). Vanadium is unadsorbed and passes into the effluent while molybdenum is adsorbed on the resin. For the elution of molybdenum a mixed aqueous-organic solvent system consisting of methanol and 6M hydrochloric acid (9: 1 v/v) is used. After evaporation of the 6M hydrochloric acid effluent and of the mixed aqueous-organic eluate vanadium and molybdenum are determined by atomic-absorption spectrophotometry. The method was tested by analysing numerous samples with contents ranging from a few ppm to milligram amounts of vanadium and molybdenum. For comparison, the concentrations of these two elements were determined in a large number of samples by spectrophotometric and titrimetric procedures. In all cases very good agreement of results was obtained.     

Determination of trace metals in water using x-ray fluorescence spectrometry

A simple, rapid and accurate method for water analysis is proposed. The analytical procedure for the determination of Fe, Mn, Zn, Cu, Cd, As, Pb and Se in water in concentrations as low as a few ppM involves precipitation with a carrier of the metals by diethyldithiocarbamate (DDTC) or 1-(2-pyridylazo)-2-naphthol (PAN) and filitration through a Millipore filter. The precipitates collected on the filter disc are examined by X-ray fluorescence analysis. PAN is excellent for the determination of several metal ions at the ppM level, and DDTC can be used with tartrate as a masking agent if water samples contain large amounts of iron(III).     

Determination of trace elements in the water cycle by total-reflection x-ray fluorescence spectrometry

The determination of trace elements in the various stages of the water cycle is very important. Economic procedures for multi-element determinations of trace elements in various matrices are needed. The applications of total-reflection x-ray fluorescence spectrometry in this general area are reviewed briefly, with examples relating to rain, river and sea waters, sediments, particulate matter and manganese nodules and crusts, as well as mussel tissue. Up to 25 elements can be determined; these are S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Pb, Se, Rb, Sr, Y, Zr, Mo, Ag, Cd, Sb and Ba. Preliminary treatments of the various matrices are described. Accuracy checks by analysis of reference standards and by application of independent techniques are reported.     

Chromatographic separation of vanadium, tungsten and molybdenum with a liquid anion-exchanger

In acidic solution only molybdenum(VI), tungsten(VI), vanadium(V), niobium(V) and tantalum(V) form stable, anionic complexes with dilute hydrogen peroxide. This fact has been used in developing an analytical method of separating molybdenum(VI), tungsten(VI) and vanadium(V) from other metal ions and from each other. Preliminary investigations using reversed-phase paper chromatography and solvent extraction led to a reversed-phase column Chromatographic separation technique. These metal-peroxy anions are retained by a column containing a liquid anion-exchanger (General Mills Aliquat 336) in a solid support. Then molybdenum(VI), tungsten(VI) and vanadium(V) are selectively eluted with aqueous solutions containing dilute hydrogen peroxide and varying concentrations of sulphuric acid.     

Ion-exchange separation of vanadium, zirconium, titanium, molybdenum, tungsten and niobium

Schemes for the separation of two or more of the elements vanadium, zirconium and/or titanium, molybdenum and tungsten from each other and from relatively large amounts of niobium have been developed, a strongly basic anion-exchange resin being used. Interference from niobium is avoided by using hydrofluoric acid to elute vanadium, zirconium, titanium and molybdenum. The application of coupled columns to improve the efficiency of separation of multicomponent mixtures is demonstrated. The use of an "interval" equation defining the volume interval between successively eluted solutes is proposed for calculating the column length required for a particular separation. This equation is especially useful for determining the extent to which a column must be lengthened when overlapping occurs because of high column loading.     

Determination of lead in fly-ash from a garbage incinerator by atomic-absorption and x-ray fluorescence spectrometry

The lead content in fly-ash collected by an electrostatic precipitator has been determined by atomic-absorption spectrometry (AAS) after decomposition by four different leaching/dissolution techniques, and also determined by X-ray fluorescence spectrometry (XRFS) by the standard-addition method. The XRFS data were evaluated by non-linear regression since the standard additions affected the attenuation coefficient of the sample. Good agreement was obtained between the results obtained with AAS and XRFS. It is concluded that lead is quantitatively extracted by hot 1M nitric acid or treatment with hydrofluoric acid/nitric acid. Direct measurement of briquetted samples by XRFS is suggested for rapid monitoring of the lead content in fly-ash from garbage incineration.     

Analysis of tungsten carbides by X-ray fluorescence spectrometry

Five sample presentation techniques were examined for the X-ray fluorescence spectrometric analysis of tungsten carbide alloys in powder and cemented forms. Powder samples may be oxidized by air at 600° before fusion (I), or preferably by lithium nitrate during fusion (II); the fusion is effected with lithium-lanthanum tetraborate followed by briquetting with graphite. Powder samples may also be blended with wax and briquetted (III). Cemented carbides are surface-prepared with silicon carbide before analysis (V). Briquettes prepared by blending carbide powder, lithium-lanthanum tetraborate and graphite (IV), give poor reproducibility, however, owing to micro-absorption effects the technique is not recommended. The determination of eight common elements in tungsten carbide is discussed and the relative standard deviations are 0.002–0.004 for major and 0.008–0.01 for minor elements.     

Determination of trace amounts of vanadium(IV) and (V) in water by energy-dispersive x-ray fluorescence spectrometry combined with preconcentration and separation

A method is described for the separation, preconcentration and quantitation of V(IV) and V(V) in water. Vanadium(V) is precipitated with diethyldithiocarbamate (DDTC) at pH 1.8 and V(IV) is precipitated with DDTC at pH 4. The precipitates are collected by vacuum filtration on a membrane filter for quantitation by energy-dispersive x-ray fluorescence spectrometry. Multi-element and single-element calibration curves are prepared and used to evaluate the matrix and mass effects of diverse ions such as Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Pb(II). The total amount of metal ions should not exceed about 100 μg. The V(IV) and V(V) are separated completely and recovered quantitatively.     

Determination of small amounts of titanium in pure molybdenum,tungsten, vanadium and their oxides after separation on silica gel

A new method for the separation of titanium from molybdenum, tungsten and vanadium is described, based on sorption of the titanium complex with hydrogen peroxide on silica gel under dynamic conditions. The eluted titanium is determined spectrophotometrically with diantipyrylmethane. The method can be applied to the determination of small amounts of titanium in tungsten, molybdenum and vanadium metals and in their oxides.     

The determination of molybdenum and tungsten in solutions by thin-film X-ray-fluorescence spectrometry

Thin-film X-ray-fluorescence spectrometry was applied to the analysis of solutions containing Mo and W in concentrations ranging from 50 mgl^?1 to 6 gl^?1. The diameter of the sample and its corresponding effect on minimizing errors due to a differential chromatographic effect are discussed. The effect of sample loading was also investigated. The precision of analysis varies from 0.7 to 5.6%, and the limit of detection for Mo is 0.63 μg of element on the filter paper.     

Analysis of cast iron by x-ray fluorescence spectrometry

It is shown that a wide range of cast irons can be analysed on one calibration if the sample surfaces are prepared to a mirror finish with diamond paste. Polishing the samples with any abrasive material results in preferential removal of the softer constituents from the sample matrix. If coarser abrasives than diamond paste are used, the increased depth of the introduced sample inhomogeneity leads to unacceptable error limits for the determination of light elements.     

熔片X射线荧光光谱法测定钼精矿中多种元素

建立了用波长色散X射线荧光光谱测定钼精矿中多元素分析方法.采用Li2B4O7:LiBO2混合熔剂(67:33),加入氧化剂LiNO3,减少钼和硫的挥发并保护铂-金坩埚免受腐蚀,且严格控制脱模荆LiBr和NH4I加入量,熔融制备样片.对熔融制样温度和时间进行了讨论,并对钼的分析线作了仔细的选择.用经过多次化学分析的钼精矿...