Selective detection of volatile nickel,vanadium, and iron porphyrins in crude oils by gas chromatography-atomic emission spectroscopy

This report describes the selective detection of volatile nickel, vanadium, and iron metalloporphyrins in crude oil samples. An atomic emission detector (AED) was used for simultaneous detection of these metals using the Ni 301.2 nm, V 292.4 nm, and Fe 302.1 nm emission lines. Detection limits for these metals range from 0.05 to 5 pg/sec. The presence of volatile forms of these metals in several crude oil samples has been confirmed.     

Determination of vanadium and titanium in steel by inductively coupled plasma atomic emission spectrometry with modified use of a tungsten boat furnace atomizer for atomic absorption spectrometry

For electrothermal sample introduction, a commercially available tungsten boat atomizer for atomic absorption spectrometry (AAS) was transferred to a vaporizer for inductively coupled plasma atomic emission spectrometry (ICP-AES). The modification retained as much of the original design of the atomizer as possible, so that the apparatus could be switched easily between conventional tungsten boat furnace (TBF)-AAS and TBF-ICP-AES. By using this system, a procedure for the determination of vanadium and titanium in steel was investigated. The detection limits (S/N=3) of vanadium and titanium were 3.9 and 1.5 ng ml^?1, respectively. The relative standard deviations for five replicate determinations were ca. 3% for both elements. The calibration graphs were linear up to 100 μg ml^?1 vanadium(V) and 10 μg ml^?1 titanium(IV). Results of analyses of some low-alloy steel samples are given.     

New method for removal of spectral interferences for beryllium assay using inductively coupled plasma atomic emission spectrometry

Beryllium (Be) has been used widely in specific areas of nuclear technology. Frequent monitoring of air and possible contaminated surfaces in U.S. Department of Energy (DOE) facilities is required to identify potential health risks and to protect U.S. DOE workers from beryllium-contaminated dust. A new method has been developed to rapidly remove spectral interferences prior to beryllium measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES) that allows lower detection limits. The ion exchange separation removes uranium (U), plutonium (Pu), thorium (Th), niobium (Nb), vanadium (V), molybdenum (Mo), zirconium (Zr), tungsten (W), iron (Fe), chromium (Cr), cerium (Ce), erbium (Er) and titanium (Ti). A stacked column consisting of Diphonix Resin and TEVA Resin reduces the levels of the spectral interferences so that low level Be measurements can be performed accurately. If necessary, an additional anion exchange separation can be used for further removal of interferences, particularly chromium. The method has been tested using spiked filters, spiked wipe samples and certified reference material (CRM) standards with high levels of interferences added. The method provides very efficient removal of spectral interferences with very good accuracy and precision for beryllium on filters or wipes. This new method offers improvements over other separation methods that have been used by removing large amounts of all the significant spectral interferences with greater simplicity and effectiveness. The effective removal of spectral interferences allows lower method detection limits (MDL) using inductively coupled atomic emission spectrometry. A vacuum box system is employed to reduce analytical time and reduce labor costs.     

火花放电原子发射光谱法测定钛及钛合金中主要元素

采用火花放电原子发射光谱法测定了钛及钛合金中碳、铁、铝和钒的含量。通过对钛合金样品的表面处理方式、氩气流量和压力、类型标准化等参数的摸索,确立了一套系统的分析方法。结果表明,4种元素测定的相对标准偏差在0.40%~6.8%,测定结果和化学湿法分析结果相比基本一致,比较适合批量检测。     

火花放电原子发射光谱法测定钛及钛合金中主要元素

采用火花放电原子发射光谱法测定了钛及钛合金中碳、铁、铝和钒的含量。通过对钛合金样品的表面处理方式、氩气流量和压力、类型标准化等参数的摸索,确立了一套系统的分析方法。结果表明,4种元素测定的相对标准偏差在0.40%～6.8%,测定结果和化学湿法分析结果相比基本一致,比较适合批量检测。     

电感耦合等离子体原子发射光谱法(ICP-OES)测定含钒尾渣中钒的含量

以氢氟酸、硝酸消解样品,然后加入硫酸络合钛避免其在低酸度介质中水解,并且加热至产生三氧化硫烟以驱赶氢氟酸,以水稀释定容后采用电感耦合等离子体原子发射光谱法（ICP-OES）直接测定含钒尾渣中钒的含量。实验考察了在共存含有铁、钛、铝、铬、锰、钒等元素的含钒尾渣复杂基体中,基体效应、光谱干扰以及背景噪音等影响因素对钒测定的干扰,方法通过优选元素分析谱线、背景校正区域以及光谱仪工作条件,并且采用基体匹配法和同步背景校正法相结合的方式,消除了构成复杂且变化无常的样品基体对测定的影响。结果表明,方法可用于测定0.01%~6.0%的钒,并且样品基体在含20%~40%铁,5%~30%钛时,铝、铬、锰、钠、硅、钙、镁各元素1%~10%的变化对测定无影响,检测下限可达0.0009%;精密度RSD〈3%,加标回收率94%~106%,与高锰酸钾氧化-硫酸亚铁铵滴定化学分析法的测定结果对照一致。     

Determination of elements in lithium potassium niobate and lithium niobate containing vanadium by ICP-AES

The elements in lithium potassium niobate and lithium niobate containing vanadium (such as aluminum, lithium, niobium, potassium and vanadium) were determined by inductively coupled plasma atomic emission spectrometry after fusion of the sample with ammonium hydrogensulfate. The samples were completely decomposed and high precision results were obtained for the metallic elements. Oxygen has been determined by a helium carrier fusion thermal conductivity method using both a nickel capsule and tin as a melting flux in a graphite crucible.     

Capillary Electrophoresis Coupled On-Line with Inductively Coupled Plasma Atomic Emission Spectrometry for Elemental Speciation

Capillary electrophoresis (CE) has become a powerful analytical technique for the separation of a variety of analytes ranging from small inorganic ions to large biomolecules such as proteins and nucleic acids. A selective and sensitive detector for CE has been one of the most important and challenging prerequisites for the growth of CE. On-column UV-Vis detectors are commonly used to determine the analytes separated by CE. However, these detectors are often not very selective. Other detection techniques such as mass spectrometry, laser induced fluorescence, amperometry, and inductively coupled plasma spectrometry have been investigated to provide a more sensitive and selective detection for the target analytes. However, relatively few studies have been published on the use of inductively coupled plasma atomic emission spectrometry (ICP-AES) as a means of detection in CE separation.     

Investigation of a coaxial boosted-output hollow-cathode lamp for atomic absorption

A version of the boosted-output, hollow-cathode lamp has been studied as a possible light source for atomic absorption. Our version of this lamp utilizes a secondary electrical discharge to enhance the emission. passing axially through the center of an open cylindrical cathode. Eventually the increase in intensity is accompanied by a decrease in the absorbance of test solutions due to line-broadening in the lamp. Using the criterion of equivalent absorbance, lamps of this design provided ten to twenty times the intensity of commercial hollow-cathode lamps for the elements studied: aluminum, molybdenum, titanium vanadium and copper.     

Selective detection and identification of Se containing compounds--review and recent developments

The complexity of selenium (Se) chemistry in the environment and in living organisms presents broad analytical challenges. The selective qualitative and quantitative determination of particular species of this element is vital in order to understand selenium's metabolism and significance in biology, toxicology, clinical chemistry and nutrition. This calls for state-of-the-art analytical techniques such as hyphenated methods that are reviewed with particular emphasis on interfaced separation with element-selective detection and identification of the detected selenium compounds. Atomic spectral element specific detection for monitoring chromatographic eluent enabled quantitative determination of selenium species in selenized yeast and qualitative measurement for breath samples. Gas chromatography with atomic emission detection (AED) of ethylated species and fluoroacid ion pair HPLC applied to the analysis of currently produced or archived selenized yeast and Brassica juncea have revealed the presence of a previously unrecognised Se-S amino acid, S-(methylseleno)cysteine.     

NH3 TPD study and thermal behaviour of vanadium-exchanged titanium phosphates as catalysts

The ion exchange technique was employed for the preparation of VO²⁺ modified titanium phosphates as catalysts for the selective reduction of NO with NH₃. The samples were prepared by contacting with a vanadyl sulphate solution different precursor materials, amorphous, crystalline or sodium half exchanged titanium phosphate. The vanadium contents of modified phosphates were in the range 0.08–2.3 wt%. XRD and thermal analysis TG/DTA showed that vanadium loading does not cause structural modification in hydrogen titanium phosphate. A vanadyl containing phase was obtained when half sodium titanium phosphate was employed. The NH₃ TPD measurements indicated the presence of a wide distribution of NH₃ adsorbing sites with medium-high strength. Catalytic activity measurements were performed under dilute conditions. It was found that the presence of vanadium even in low amounts strongly promote the catalytic activity.     

Effect of the organic ligand on the response for vanadium in flame atomic emission spectrometry

Flame emission intensities from vanadium in the forms of chelates with N-nitroso-phenylhydroxylamine and 8-quinolinol in methyl isobutyl ketone were measured. Although differences in atomic absorption characteristics for vanadium bound by different ligands have been reported, significant differences were not found in the emission intensities of these two chelates after signals for the appropriate blanks had been subtracted.     

First-derivative spectrometric analysis of mixtures of peroxo complexes of titanium,vanadium, and molybdenum for respective metals

The application of first-derivative spectrometry to the simultaneous determination of titanium and vanadium; titanium and molybdenum; and vanadium and molybdenum in their mixtures with varying mass ratios has been described with hydrogen peroxide as color developing reagent. At a first-derivative isosbestic point for the peroxo complex of one constituent, the derivative absorbance of the other constituent is read and used for quantitation. The procedure does not require the solution of simultaneous equations. The first-derivative spectrometry is also feasible at 450.0 nm for the selective determination of titanium in the presence of vanadium, molybdenum, and tungsten.     

Applications of gas chromatography with an atomic emission detector

An atomic emission detector for gas chromatography has been developed which is, in principle, capable of detecting selectively any element (except helium) which can elute from a gas chromatographic column. Software methods have been developed so far for 23 elements and on isotope, including all of the organic elements along with mercury, lead, tin, silicon, and deuterium. Element-specific analyses are shown for several petroleum, environmental, and aroma samples. A table for the detector's element-specific detection limits, selectivities, and linear dynamic ranges is given for 12 elements and deuterium.     

DTA-EGA determination of carbides chemically extracted from steel

Differential thermal analysis-effluent gas analysis (DTA-EGA) techniques have been applied to the determination of specific metal carbides in residues which are isolated from steels by chemical methods. In this method, a weighed portion of sample residue is transferred to the DTA sample-holder and subjected to programmed heating in a dynamic oxygen atmosphere. When combustion of the carbide occurs, a differential temperature response is recorded over a specific temperature range. The temperature range is used as an aid in identifying the specific carbide present. The thermal conductivity of the effluent gas is recorded and the signal resulting from the presence of carbon dioxide in the effluent gas is then used for the quantitative determination of the carbide. The DTA-EGA method has been applied to several experimental steels for determination of the carbides of zirconium, vanadium or titanium individually and for the determination of vanadium and zirconium carbides in mixtures of the two. Results for these metal carbides obtained by DTA-EGA agreed within 15% with those obtained by the lengthy chemical methods. The lower limits of detection, based on the original steel sample weight, were 0.02% for the vanadium and titanium carbides and 0.01% for zirconium carbide.     

地球化学样品中钒检测方法的对比

地球化学样品中钒的测定方法主要有原子吸收光谱法、等离子体发射光谱法(ICP-AES)、电感耦合等离子体质谱法(ICP-MS)和X射线荧光光谱法.选用国家一级标样,分别用4种方法测定样品含量值,依次对方法检出限、准确度、精密度、加标回收率作比较.经对比,4种方法测定值与推荐值都基本吻合.等离子体发射光谱法检出限低,线性范围更宽,准确度与精密度更好,更适用于地球化学样品中钒批量的测试.     

In situ formation of heterobimetallic salen complexes containing titanium and/or vanadium ions

A combination of high-resolution electrospray mass spectrometry and (1)H NMR spectroscopy has been used to prove that when a mixture of [(salen)TiO]2 complexes containing two different salen ligands (salen and salen') is formed, an equilibrium is established between the homodimers and the heterodimer [(salen)TiO2Ti(salen')]. Depending upon the structure and stereochemistry of the two salen ligands, the equilibrium may favor either the homodimers or the heterodimer. Extension of this process to mixtures of titanium(salen) complexes [(salen)TiO]2 and vanadium (V)(salen') complexes [(salen')VO] (+)Cl (-) allowed the in situ formation of the heterobimetallic complex [(salen)TiO2V(salen')] (+)X (-) to be confirmed for all combinations of salen ligands studied except when the salen ligand attached to titanium contained highly electron-withdrawing nitro-groups. The rate of equilibration between heterobimetallic complexes is faster than that between two titanium complexes as determined by line broadening in the (1)H NMR spectra. These structural results explain the strong rate-inhibiting effect of vanadium (V)(salen) complexes in asymmetric cyanohydrin synthesis catalyzed by [(salen)TiO]2 complexes. It has also been demonstrated for the first time that the titanium and vanadium complexes can undergo exchange of salen ligands and that this is catalyzed by protic solvents. However, the ligand exchange is relatively slow (occurring on a time scale of days at room temperature) and so does not complicate studies aimed at using heterobimetallic titanium and vanadium salen complexes as asymmetric catalysts. Attempts to obtain a crystal structure of a heterobimetallic salen complex led instead to the isolation of a trinuclear titanium(salen) complex, the formation of which is also consistent with the catalytic results obtained previously.     

Vanadium in Italian waters: monitoring and speciation of V(IV) and V(V)

In this work, a highly sensitive method was developed to separate vanadium (IV) from vanadium (V), which are both contained in water at trace levels. A suitable strong anionic exchange column (SAX) loaded with disodium ethylendiaminetetraacetic acid (Na₂EDTA) was used to trap both vanadium species dissolved in 10–100 ml of water at pH 3. The vanadyl ion was selectively eluted by means of 15 ml of an aqueous solution containing Na₂EDTA, tetrabutylammonium hydroxide (TBA⁺OH⁻), and isopropanol (ⁱPr-OH) and was subsequently determined by atomic absorption spectroscopy with electrothermal atomization. The concentration of vanadate ion was calculated by subtracting the vanadyl concentration from the total concentration of vanadium. The optimal conditions for a selective elution were evaluated. The recovery of vanadium (IV) was 95% or better. The proposed method provides a simple procedure for the speciation of vanadium in aqueous matrices. The collection of the two forms could easily be carried out at the sampling site. Therefore, the risk of changing the concentration ratio between vanadium species was widely reduced. The detection limits were 1 μg/l for both species, when a 10-ml sample was eluted through the column. The method was applied successfully to vanadium speciation on different kinds of Italian volcanic water: Mount Etna (Sicily), Lake Bracciano and Castelli Romani (Latium).     

微波消解－ICP-OES测定钛渣中常量或微量杂质

钛渣样品采取高压密闭微波加热方式以HF、HNO3进行消解,采用电感耦合等离子体原子发射光谱法(ICP-OES)直接同时测定常量、微量杂质铁、铅、砷、铬、铜、磷、锰、钒、镁、钙。考察了消解条件、基体钛以及共存元素之间的干扰影响、等离子体参数等测定条件,通过优选元素分析谱线、以及采用基体匹配与同步背景校正相结合的方式消除光谱干扰和基体效应。测定50、60、70、80、90等不同品位钛渣中杂质元素的结果表明:方法检测范围涵盖了0.005%～10.0%的钙、镁、铁,以及0.005%～2.0%的铅、砷、铬、铜、磷、锰、钒,校准曲线相关系数大于0.999 2;背景等效浓度0.002%～0.0015%,检测限0.0009～0.0038%;含量不小于1.0%的RSD低于0.677%,在0.010%～0.10%含量范围内RSD低于3.85%;回收率为90.0%～108.0%。以本法对70、80、90 3个高钛渣标准样品的定值分析结果与传统化学方法对照一致。     

Cross-correlation masks for automatic detection of spectral information

Cross-correlation masks based on spectral intensities and binary spectral peak positions are evaluated for detection and quantitation of atomic emission spectra. The inductively coupled plasma emission spectra of nickel and vanadium as acquired with a photodiode array spectrometer were utilized to test and illustrate the cross-correlation procedures.