电热进样微波等离子体原子吸收光谱法的性能研究

本文将L形放电-吸收管与电热进样微波诱导等离子体原子吸收光谱法相结合,考察了各种实验参数对分析性能的影响.给出了利用该方法测定一系列元素的特征浓度,讨论了共存元素等因素对检测结果的影响.将本法用于实际样品分析,结果较好.     

N—2—羟基苯胺—N—2—羟基—1—环丁烯—3，4—二酮与Fe^3＋的显色反应的研究和应用

研究了N-2-羟基苯胺-N-2-羟基-1-环丁烯-3.4-二酮与Fe3+的显色反应,在pH≈1的盐酸缓冲体系中,它与Fe3+反应生成棕黄色水溶性化合物,其最大吸收波长在455nm处,ε为1.7×103L·mol·cm-1。此显色反应可用于铁的吸光光度测定。     

7—（苯偶氮）—8—羟基喹啉—5—磺酸钠—溴化十六烷基三甲基铵与铜的显色反应研究

研究了铜与 7- (苯偶氮 ) - 8-羟基喹啉 - 5-磺酸钠 ( PAHQS)的显色反应 ,发现 Cu( )与PAHQS形成棕黄色配合物 ,在表面活性剂溴化十六烷基三甲基铵 ( CTMAB)存在下 ,对配合物及PAHQS有明显的增溶增敏作用。在 p H3.3的邻苯二甲酸氢钾 -盐酸缓冲溶液中 ,配合物最大吸收峰位于 460 nm处 ,其表观摩尔吸光系数为 6.0 4× 1 0 4 L·mol-1· cm-1,铜浓度在 0～ 50 μg/2 5ml范围内符合比耳定律 ,方法应用于中药和环境水样中痕量铜的分析 ,结果满意     

非平衡等离子体放电模式及反应器结构对氨气分解制氢的影响

在常压下研究了不同等离子体放电模式及反应器结构对氨分解制氢反应的影响.实验中调节反应器结构分别产生了介质阻挡放电和交流弧放电两种放电模式.通过对两种放电模式的放电图像、电压-电流波形和氨分解过程中等离子体区活性物种的发射光谱(OES)研究发现,与介质阻挡放电相比,交流弧放电为局部强放电,具有更高的电源效率和电子密度.因此,在介质阻挡放电中氨气分子大部分通过生成电子激发态物种NH3*,再与载能电子碰撞断裂N―H键进行氨分解反应;而在交流弧放电中载能电子具有更高的平均电子能量,可直接断裂氨气分子的N―H键生成NH2和NH等高活性物种,促进氨分解反应的进行.结果表明,交流弧放电的氨分解效果要明显优于介质阻挡放电.在交流弧放电模式下不同类型反应器对氨气分解转化率由高到低的顺序为:管-管管-板针-板板-板.在输入功率为30 W,气隙间距为6 mm时,管-管交流弧放电的氨气转化率达到60%左右,而板-板介质阻挡放电的氨气转化率仅为4%.     

5—（2—苯并噻唑偶氮）—8—氨基喹啉作为镍的光度分析试剂及应用研究

研究了新试剂 5- (2 -苯并噻唑偶氮 ) - 8-氨基喹啉与镍的显色反应。在弱碱性介质中 ,阳离子表面活性剂溴化十六烷基三甲基铵存在下 ,试剂与镍形成 3∶ 1的蓝色配合物 ,其最大吸收波长位于 61 0 nm处 ,表观摩尔吸光系数为 1 .2 6× 1 0 5L· mol-1· cm-1,镍的浓度在 0～ 8.0μg/2 5ml范围内 ,符合比耳定律。应用于铝合金中微量镍的测定 ,获得了满意的结果。     

2—（5—溴—2吡啶偶氮）—5—二乙氨基酚在光度分析应用中的新进展

2-(5溴-2吡啶偶氮)-5-二乙氨基酚(简称5-BrPADAP)系吡啶基偶氮化合物中最典型的高灵敏显色剂。自70年代末,我国分析工作者就开始研究了在光度分析中的应用。有关该试剂的性能及其至80年代初期的应用现状已有专题综述。此后,近十年期间,随着表面活性剂的广泛应用,以及各种消除干扰途径的开拓,使其扩大了在光度分析中的应用范围。本文就1984年以来国内的一些工作状况加以归纳。 1 在有色合金、环境样品分析中的应用 铁 在pH 5.0HOAc-NaOH缓冲介质中,在Tri-ton X-100存在下,Fe(Ⅱ)与试剂所形成的紫红色配合物有两个吸收峰。分别为558nm与746nm,746nm为特征吸收,s=2.63×10~4,虽然,在此波长下灵敏度要降低些,但其他能与试剂显色的金属离子均无吸收。因此,在无任何掩蔽剂存在下,可选择性地用于镁、铝合金中微量铁的测定。容庆新等在pH 6 HOAc-NaOAc缓冲介质中,选择乙醇作增溶剂,用硫脲、四乙烯五胺及EDTA掩蔽Cu、M、Co等离子的干扰,该法用于铜合金、铝、镁合金中微量铁的测定,同时也可用于电炉渣、白云石、镁砂等样品中铁的测定。 锰 在pH 9.7～10.4 NH_4OH-NH_4Cl缓冲介质中,在CTMAB存在下,Mn(Ⅱ)与试剂瞬间形成紫红色配合物,λ_(max)=568nm,ε=1.21×10~5,0～17.5μg/     

5，5—二甲基—2—氧代—2—（N，N‘—对苯二胺基—二苄基）—二—1，3，2—氧磷杂环已烷的合成及表征

以新戊二醇、三氯化磷和乙醇为原料制得中间体5,5-二甲基-1,3,2-二氧磷杂环已烷-2-氧（DPDO）,用DPDO与由芳醛和对苯二胺缩合制得的席夫碱SBⅠ-SBⅡ加成,合成了膨胀型阻燃剂5,5-二甲基-2-氧代-2-（N,N‘-对苯二胺基-二苄基）-二-1,3,2-氧磷杂环已烷（DPPOⅠ-DPPOⅡ）,通过元素分析,IR,NMR和MS对其结构进行表征,并对其在醇酸清漆中的应用进行了讨论。     

Fe（Ⅲ）—5—Br—PADAP—EGTA—胶束体系显色反应的研究及应用

研究了Fe(Ⅲ)-5-Br-PADAP-EGTA-胶束体系的吸光光度特性和最适宜的显色条件。在pH9.0～10.0氨性介质中及85℃水浴条件下,显色体系最大吸收波长为555nm,摩尔吸光系数达7.2×10~4,Fe(Ⅱ)0.2～20μg/25ml符合比耳定律。应用于国家标准物质桃叶、小麦粉、食品和水样中Fe(Ⅱ)的测定,结果令人满意。     

3，5—环—孕甾—6—甲氧基—20—S—22—醛的立体选择性合成

油菜甾醇内酯(brassinolide)(1)是一种高效植物生长激素,一些实验室曾成功地进行了合成(图1)。这些合成路线不少是以20-S-22-甾醛为关键中间体,再分步接上侧链的,而C_(20)-S-22-甾醛大都由豆甾醇为原料制得。考虑到豆甾醇来源困难,我们采用国内资源丰富、价格低廉的薯蓣皂甙元为起始原料,立体选择性地合成了C_(20)-S-22-甾醛化合物7(见图2),对1及其     

meso—四（3—氯—4—磺酸苯基）卟啉与钴（Ⅱ）显色反应的光度法测定

研究了弱碱性介质中新试剂 meso-四 ( 3-氯 - 4磺酸苯基 )卟啉 ( m - Cl TPPS4 )与钴 (Ⅱ)的显色反应条件。不加任何辅助试剂 ,沸水浴中加热 ,m- Cl TPPS4 与 Co(Ⅱ)形成检测灵敏度很高的 1∶ 1 ( M∶ L)配合物 ,其最大吸收波长为 42 6nm,表观摩尔吸光系数达 4.0× 1 0 5L· mol- 1·cm- 1。钴 (Ⅱ)含量在 0～ 5 .0 μg/2 5 m L范围内符合比耳定律。该方法应用于维生素 B12 中钴 (Ⅱ)的测定 ,结果满意     

Direct determination of selenium in a wild fruit juice by electrothermal atomic absorption spectrometry

A matrix modifier composed of platinum and nickel is proposed for the determination of selenium in a wild fruit juice made from Lantingguo (Vuccinium uliginosam). Five matrix modifiers (copper/nickel, palladium/magnesium, platinum/magnesium, platinum/nickel and platinum/copper) for suppressing the interference effects of seven co-existing elements (potassium, phosphorus, calcium, magnesium, manganese, zinc and iron) in a wild juice were studied and a matrix modifier composed fro;m 10 mug of platinum and 200 mug of nickel was found to give the best performance. Selenium in three juices was determined by electrothermal atomic absorption spectrometry employing the proposed matrix modifier without matrix preseparation. The relative standard deviation was 14% for 0.20 mg l(-1) of selenium. The recoveries were 95-110%. A characteristic mass was 28 pg.     

Atom-trapping absorption spectrometry with water-cooled metal collector tubes

Water-cooled metal collector tubes for atom-trapping atomic absorption spectrometry in air—acetylene flames are discussed, particularly for the more volatile elements such as cadmium and selenium which may be less efficiently trapped at the hotter surface of a silica tube. It was found that a nickel tube gave 3 times greater sensitivity than silica for the determination of cadmium but was oniy half as sensitive for the determination of selenium. No atomic absorption signal for copper could be obtained with a nickel collector tube. A copper tube was 3–4 times more sensitive than nickel for cadmium and selenium. Similar effects were observed for cadmium solutions containing 1000 ppm copper or nickel, and for selenium solutions containing 1000 ppm copper, with silica atom-trap tubes, but in both cases better results were obtained when the analyte solution of cadmium or selenium contained the co-element (1000 ppm) than when the cadmium or selenium was measured with a silica tube previously metallized with the co-element.     

Les possibilités et limitations de l'atomisation électrothermique en spectrom/'etrie d'absorption atomique lors de l'analyse directe des metaux lourds dans l'eau de mer

This work shows the analytical possibilities of an electrothermal atomizer for the direct determination of trace metals in sea-water.The high background signals generated by the matrix perturb in particular volatile elements because of the low decomposition temperature allowed. In the case of cadmium, addition of ascorbic acid to the sample permits the modification of the atomization mechanism and the reduction of the optimum temperature. Under these conditions, absorption peak of the cadmium precedes the background absorption and consequently the analysis is no longer limited by the magnitude of the matrix signal: the determination of cadmium concentrations far below the μg^?1 level is easily possible. Although the direct determination of the other elements should be in principle less disturbed by the background, the analytical performance is poorer than for cadmium. Limits of determination of the order from 0.1 to 1 μg^?1 can be reached for chromium, copper and manganese. Lead and nickel appeared to be the most difficult elements; their direct determination is only possible in polluted coastal or estuarine waters.The injection of the sample as an aerosol into hot graphite tube showed to be well adapted to this kind of investigations. The simultaneous visualization of specific and background signals allows interpretations which until now were impossible with commercially available apparatus.     

Simultaneous Preconcentration of Copper,Nickel and Cobalt In Water By Coprecipitation-Flotation For Electrothermal Atomic Absorption Spectrometry

Abstract

A method is described for the simultaneous flotation separation and determination of μg-levels of copper (II), nickel (II) and cobalt (II) in water. Copper, nickel and cobalt in a 1000-ml sample of water are coprecipitated with hydrated zirconium oxide at pH 9.1±0.1. The precipitate is floated with the aid of a surfactant solution and small air bubbles, separated and dissolved in dilute hydrochloric acid. The contents of these elements are determined by electrothermal atomic absorption spectrophotometry. The method is applied to the determination of low μg/1 levels of copper, nickel and cobalt in fresh water.     

Determination of nickel in water by electrothermal atomic absorption spectrometry with preconcentration on a tungsten foil

A preconcentration method for nickel in waters involving adsorption on tungsten foil, followed by electrothermal atomic absorption spectrometry (ETAAS) with a tungsten tube atomizer is described. The most suitable pH for nickel adsorption was 5 and the optimum immersion time was 2 min. Severe interferences from co-existing elements (Al, Ca, Cu, Fe, K, Mg, Na, Pb and Zn) on the Ni AA signal were observed. Under optimal conditions, the preconcentration of nickel on W foil could eliminate interferences from these elements. The detection limit of nickel by preconcentration-ETAAS was 0.1 ng/ml (3S/N). The method with preconcentration on tungsten foil was applied to the determination of nickel in river water. The recovery of spiked nickel was 93–102%. The tungsten foil preconcentration method is sensitive, simple, and convenient. This adsorption method can be utilized inin situ-sampling of ultra-trace nickel in environmental samples (water). Furthermore, after sampling it is easy to carry and store the W-foil without contamination for long time.     

Determination of trace impurities in some nickel compounds by flame atomic absorption spectrometry after solid phase extraction using Amberlite XAD-16 resin

A simple flame atomic absorption spectrometric (FAAS) procedure for the determination of lead, bismuth, gold, palladium and cadmium as impurities in Raney nickel and nickel oxide was developed using a preconcentration step on an Amberlite XAD-16 resin packed column. Lead, bismuth, gold, palladium and cadmium were quantitatively recovered and separated from a solution containing 1 M HCl and 0.3 M NaI by the column system. Effects of the various parameters such as reagent concentrations, sample volume, matrix effects, etc. have been investigated. Under optimized conditions, the relative standard deviation of the combined method of sample treatment, preconcentration and determination with FAAS (n = 7) is generally lower than 12%. The limit of detection (3s, n = 20) was between 10–270 ng/g. The results were used for separation and preconcentration of five trace elements from nickel matrices.     

Analysis of mixtures of compounds of copper using K-edge X-ray absorption spectroscopy

Summary A determination is described of copper metal, oxide, and hydroxide in samples containing both nickel and copper. The analysis was based on K-edge x-ray absorption spectra of the copper. This allowed us to consider the chemical states of copper and ignore the nickel also present. The method involved fitting linear combinations of copper standard spectra to the spectrum from copper in the sample. The fit composition that minimized the variance gave the sample composition. The work demonstrated that K-edge x-ray absorption spectra are sufficiently characteristic to allow their use for quantification of components in mixtures. This method of analysis is complemented by diffraction and less general techniques. It is a strength of x-ray absorption edge analysis that it is element-specific and applicable to most elements maintained under any conditions of temperatures, pressure, and atmosphere.     

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.     

Determination of traces of calcium, magnesium, iron and nickel in aluminium salts by atomic-absorption spectrophotometry with a microwave-excited source and hollow-cathode lamps

The determination of trace amounts of calcium and magnesium in solutions containing large concentrations of aluminium salts may be accomplished by co-precipitating their hydroxides on iron(III) hydroxide, dissolving the precipitate, and extracting the 8-hydroxyquinolates of calcium and magnesium into methyl isobutyl ketone at about pH 11. The extract may be sprayed into the airpropane flame of a simple unmodulated spectrophotometer and atomic-absorption measurements for calcium and magnesium made at 4227 and 2852 A respectively. The limits of determination correspond to 10 and 1 ppm of calcium and magnesium in solid alumina. Iron and nickel may be co-precipitated on hydrated manganese(IV) oxide and their 8-hydroxyquinolates extracted at pH 4.5. Measurements of atomic absorption for these elements at 2483 and 2320 A respectively yield limits of determination corresponding to 10 ppm in alumina. Hollow-cathode lamps may be used for calcium, magnesium and nickel, but a simple microwave-excited discharge tube gives much better sensitivity than a hollow-cathode lamp for iron.     

Determination of Nickel,Manganese, Copper and Zinc in Blood Serum by Atomic Absorption Spectrometry after Deproteinization by Microwave Irradiation

ABSTRACT

Deproteinization of serum was performed by microwave irradiation combined with a small volume of diluted trichloracetic acid. The procedure reduced the protein level of the samples to less than 99% of the total with a small dilution factor (1+1) and allowed the determination of nickel and manganese by electrothermal atomic absorption spectrometry and copper and zinc by flame atomic absorption spectrometry directly without modifiers or matrix interferences. As metallic ions are normally bonded to serum proteins they must be released during protein precipitation. Spiked serum samples were submitted, before the deproteinization, to an incubation treatment to bond the added ions to the proteins. To check the efficiency of the incubation time for each ion, serum samples were ultrafiltered at set time intervals and the metals determined in the ultrafiltrate. The proposed method was compared with the common deproteinization by acids for the separation of the proteins. The reduction of proteins allowed a small dilution of the sample and the use of faster temperature programmes for the determination of nickel and manganese by electrothermal atomic absorption spectrometry and the aspiration of samples more similar to aqueous standards for copper and zinc determination by flame atomic absorption spectrometry. Recoveries from spiked, incubated and deproteinized samples compared to only diluted samples show that the method can satisfactorily be used for atomic absorption spectrometric determination of these elements.