Atomic Absorption Spectrometry of Fire-Extinguishing Aerosols

The process of extinguishing a propane-air flame by aerosols of salt solutions has been investigated with the use of an atomic absorption spectrometer. The method of comparing aerosols in terms of the extinguishing efficiency has been evaluated. The changes in the flame temperature and spectra at different jet heights under the influence of aerosols of water and K₂CO₃ and Al(NO₃)₃ solutions have been shown.     

The Significance of Thermally-Assisted Processes in Atomic Absorption

The use of non-resonance lines in atomic absorption spectroscopy has been included in the theoretical treatment of the selection of lines for A.A.S.^1,2, and such lines are not infrequently used on an empirical basis in practical analyses. This aspect of the technique is invariably ignored in reviews and text-books on atomic absorption, however, and has only been given serious consideration in isolated cases^3,4. The object of this publication is to illustrate the significance of thermally-assisted absorption, and the difference between the use of thermally-assisted and resonance absorption lines.     

Flame Furnace Atomic Absorption Spectrometry: A Review

Abstract

Flame atomic absorption spectrometry (FAAS) is one of the most widespread traditional analytical techniques for trace element determination, but it often suffers from poor sensitivity due to the low nebulization efficiency and the short residence time of free atoms in the flame. On the basis of conventional FAAS, flame furnace atomic absorption spectrometry (FF-AAS) is developed with a tube (flame furnace) placed on top of the FAAS burner for the atomization. Sample is introduced via beam injection (BIFF-AAS) or thermospray (TS-FF-AAS). Due to the total sample introduction and prolonged residence time of free atoms in the flame furnace, marked sensitivity improvement is obtained for volatile and semivolatile elements over conventional FAAS. TS-FF-AAS can be employed as an element-selective detector for GC, HPLC, or CE for studying of metal speciation analysis and metallomics. In addition, three newly developed sample introduction methods, including ultrasonic nebulization, hydride generation, and pneumatic nebulization, are discussed. The analytical figures of merit and practical applications of FF-AAS in analytical atomic spectrometry are reviewed in this article.     

氢化物发生辅助雾化火焰原子吸收法测定人发中的铅

使用氢化物发生辅助雾化的火焰原子吸收法,在K₃Fe(CN)₆-HCl体系中,测定了头发中铅的含量。对酸度、氧化剂及浓度、NaBH₄的浓度及流速对Pb测定的影响分别进行了研究。与传统雾化火焰原子吸收法相比,本方法测铅的灵敏度提高了13.4倍。方法的检出限为2.8 μg·L-1,精密度(RSD)为1.4%。用于测定人发中的Pb,回收率达96%～99%。     

Evaluation of Carbon Rod Atomizer for Routine Analysis of Vanadium in Crude Oil by Atomic Absorption Spectroscopy

Abstract

The Carbon Rod Atomizer (CRA) was evaluated for routine trace analysis of vanadium in crude oil by atomic absorption spectroscopy with a carbon (graphite) tube as a micro-furnace. Two crude oil samples were analyzed, both by standard addition and standard working curve methods, and the results confirmed by analysis with flame atomic absorption spectroscopy using a fuel-rich nitrous oxide-acetylene flame. Because of the relative involatility of vanadium at the temperature of the CRA, quantitative recoveries of vanadium in crude oil occur only when the vanadium content of the sample injected into the CRA does not exceed the limit of about 1 × 10^?8 g. A sensitivity (weight/1% absorption) of 7.0 × 10^?11 g and detection limit (signal-to-root-mean-square-noise equal to two) of 6.9 × 10^?12 are reported.     

Indirect Amplification Determination of Thorium by Atomic Absorption Spectroscopy

Thorium may not be determined by direct atomic absorption spectroscopy in flame media with appreciable sensitivity because of inefficient atomisation. Earlier papers from this laboratory have described indirect amplification procedures for similarly difficult elements e.g. niobium¹ and titanium² by atomic absorption spectroscopy· Madison and Guyon³ have developed a solution spectrophotometric procedure for thorium in which the heteropoly acid complex of thorium with phosphomolybdic acid is formed and reduced to the ‘heteropoly blue’. Strict adherence to time of addition of reagents is required in this procedure, and. it is necessary to effect an initial separation of the thorium from most other cations present in the sample.     

The Use of a Triple Pass Optical Arrangement for the Determination of Arsenic and Selenium by Atomic Absorption Spectroscopy in an Inert Gas Shielded Nitrous Oxide-Acetylene Flame

The utility of the inert gas shielded nitrous oxide-acetylene flame for the determination of arsenic and selenium by atomic absorption spectrometry has been demonstrated elsewhere¹. The low background absorbance of the fuel-rich, 50 mm path-length flame (ca 4 and 5% at the As 193.7 and Se 196.0 nm lines respectively) permits the attainment of detection limits which are equal to, or somewhat superior to, those obtainable with the air-acetylene flame. The AAS sensitivity (that concentration producing 1% absorption), however, is decreased; this is the result of the shorter path length of this flame compared to that employed for air-acetylene (100 mm) and the lower concentration of analyte produced in the larger volume of gas used to support the flame.     

氢化物原子吸收与常规雾化火焰原子吸收法测定锑的几个问题

本文就氢化物原子吸收法与常规雾化火焰原子吸收法用于锑含量的测定中所存在的共存元素的干扰,"记忆效应"及锑的价态变化等几个方面的问题进行了试验考察和分析,对两种方法的灵敏度、精密度及测定线性范围进行了比较,结果表明:氢化物原子吸收法的最大优点是灵敏度高(可达pp～b级)能满足含有微量锑试样的分析要求。雾化火焰原子吸收法测定锑,由于不存在"记忆"效应,样品之间的更换瞬间即可完成,因而适宜大量样品的检测分析。     

Improved Performance of On-line Atom Trapping in Flame Furnace Atomic Absorption Spectrometry by Chemical Vapor Generation: Determination of Cadmium in High-Salinity Water Samples

ABSTRACT

On-line atom trapping inside a nickel flame furnace using chemical vapor generation for sample introduction was proposed for the determination of trace cadmium by flame atomic absorption spectrometry (AAS). Cadmium volatile species was generated upon reaction with potassium borohydride and then flushed into a flame furnace for on-line trapping by a flow of nitrogen carrier gas. The middle part of the flame furnace, where the carrier gas impacts, is cooled by the gas flow, and this provides a fine strategy for on-line atom trapping for the purpose of preconcentration. A stainless steel plate is put on the top of the flame burner in the middle to form a flame-free zone, which also greatly lowers the temperature of the flame furnace and facilitates the atom-trapping process. Due to the introduction of chemical vapor generation, matrix effect was greatly alleviated compared with direct pneumatic nebulization for on-line atom trapping in flame furnace AAS. With trapping time of 35 s, the current approach achieved an excellent limit of detection of 20 ng L^?1. The proposed method was successfully applied for the quantification of cadmium in high-salinity samples.     

Atomic Absorption Spectrophotometry with the Absorption Tube Technique

A device to increase the sensitivity of the atomic absorption spectrophotometric measurement by elongating the absorption path length has originally been developed by Fuwa and Vallee and the present authors called it “absorption tube technique”. Although the technique has been fully described in comparison with the flame photometry, and the behavior of the elements and the reactions in the tube were investigated for several elements, application of a newly designed ring burner to this technique and the detailed examination of the operating conditions have never beer, published.     

A New Source of Atomic Uranium for Absorption Spectroscopy and Other Applications

The absorption spectrum of atomic uranium has been observed in furnace¹ flash discharge² and flash photolysis² experiments. Furnace absorption requires high temperatures (ca. 2300°C), so that the lines are relatively wide and many levels are populated. More important, uranium liquid and vapor are extremely reactive, making furnace design and lifetime critical factors. For quantitative line intensity studies in a furnace, it is also difficult to determine the atomic uranium concentration. The flash discharge experiment in UF₆, while producing uranium quite suitable for high resolution absorption spectroscopy, is not well suited for quantitative studies of line strengths.     

He-Ne Laser for Intra-Cavity Enhanced Absorption Measurement

It has been shown recently that when a relatively weak absorber is placed within a laser cavity an enhacement of absorption occurs^1–3. This method has been succesfully used for trace analysis of Na^1,4, I₂ ^3,5, Sr and Ba^{+ 6}, Eu(NO₃)₃ ^2,8, Pr(NO₃)₃, NdCl₃ and HoCl₃.⁸ In these experiments the absorbing species were placed inside the cavity of: flashlamp-pumped dye lasers^1–4,6 continous wave dye lasers^3,5 and dye lasers pumped by a ruby laser⁸.     

Europium Oxychloride Absorption Spectroscopy as an Optical Probe of Temperature

The temperature dependence of the features which arise from the ⁷F_0,1 → ⁵D₃ absorption transitions in EuOCl as seen by diffuse-reflectance spectroscopy has been investigated. The transitions shift linearly to higher energy with increasing temperature. The ratio of the intensities of the transitions arising from the ⁷F₀ state to those arising from the ⁷F₁ state also appears to be a linear function of temperature.     

Determination of Silver by Chemical Vapor Generation with In Situ Trapping Flame Atomic Absorption Spectrometry

ABSTRACT

The hyphenation of chemical vapor generation with an integrated atom trap system for flame atomic absorption spectrometry (CVG-IAT-FAAS) was evaluated for determination of silver in real samples (coal fly ash, sediment, and nickel alloy). The volatile species of silver were formed by reaction with sodium tetrahydroborate(III) in the presence of nitric acid. A new CVG-IAT-FAAS design (versus a water-cooled single silica tube, double-slotted quartz tube) significantly improved the sensitivity and detection limits compared with conventional flame atomic absorption spectrometry (FAAS) for determination of silver. The concentration limit of detection was 0.7 ng mL^?1 for Ag. The overall efficiency of the vapor generation process was estimated to be ca. 12%. For a 2 min in situ preconcentration time, sensitivity was enhanced 143-fold for Ag using the vapor generation atom trapping technique, compared to conventional FAAS. Sensitivity can be further improved by increasing the collection time. The precision of measurement at 10 ng mL^?1 of Ag was 10% RSD. The accuracy of this method was validated by analyses of NRC GBW 07302 (Stream Sediment), BCS CRM No. 346 (Nickel Alloy), NIST SRM 2710 (Montana Soil), NRCC LUTS-1 (Lobster Hepatopancreas), and NIST SRM 1643e (Trace Element in Water) certified reference materials. The measured Ag contents in these five reference materials were in satisfactory agreement with the certified values (spanning the range of 0.066–35 µg g^?1).     

Continuum Source Atomic Absorption Spectrometry with Commercially Available Instrumentation. A Practical Solution

A calculating method is presented in this paper which may be used to correct for the curvature of the calibration curve in atomic absorption spectrometry due to the non-absorbed light within the monochromator bandpass when a continuum source of radiation is used. Thus a linear absorbance to concentration relationship is obtained. Cu, Cr and Ca have been determined using this method with a D₂ lamp as continuum source. The results agree with those obtained by the traditional method using hollow cathode lamps. The relative differences are below 6.2%. Earlier investigations concerning the use of continuum sources in atomic absorption spectrometry (aas) have shown that in some cases there are good results^1–4. However, there are two problems which are difficult to overcome in continuum source aas. First, a narrow slit must be used in order to obtain a bandpass of a width equivalent to the absorption line. However, in this case the light intensity transmitted to the monochromator and arriving to the detector is so small that the detection limits will be very poor. Of course the transmitted intensity may be increased if a wider slit is used. But in this case, the non-absorptive part on the two sides of the absorption line will also enter the monochromator and fall on the detector. As a result the sensitivity will be degraded and the calibration curve will bend towards the concentration axis. Problems such as those discussed above prevented the current use of continuum source aas. The whole field has been recently reviewd extensively^4a.

In this paper we consider a calculationg method which can overcome the influence of non-absorbed radiation and can also correct the non-linearity of the calibration curve. In the first part of the paper the calculating method is introduced and in the second part some factors affecting the method are discussed and the comparaison of some results obtained by this method and the traditional method are given.     

Determination of Trace Amounts of Zinc in Welding Fumes by Flow‐Injection Flame Atomic Absorption Spectrometry

A flow‐injection flame atomic absorption spectrometric method for the determination of zinc in welding fumes has been developed. The method is based on the continuous ultrasound‐assisted dissolution of the zinc oxide collected on the air filter. Variables such as sonication time, nature and concentration of the acid solution used as dissolving solution, dissolution temperature, flow rate of the continuous manifold, and dissolving solution volume were simultaneously studied by applying a Plackett–Burman design. Results showed that only the concentration of nitric acid solution used as dissolving solution was a statistically significant variable (confidence interval of 95%). Factors such as dissolution temperature and sonication time were finally optimized by using a central composite design. The detection limit was 1.1 µg/m³ and the repeatability of the overall method is 1.6% (n=11) for a zinc concentration of 75.4 µg/m³. The proposed method was applied to the determination of zinc in welders' workplace environments.     

Electronic Absorption Spectrum of Mesitylene Vapour

Abstract

The electronic absorption spectrum of mesitylene vapour has been photographed on a Q-24 Medium Quartz Spectrograph. The molecule belongs to D_3h symmetry and the transition is A→₁A₂ which is forbidden and due to that the (0,0) band does not appear in the spectrum. The position of (0,0) band in this case has been fixed at 36562 cm^?1 with the help of 0→1 and 1→0 transitions. There are 66 bands and most of them are assigned in terms of two ground state frequencies of magnitudes 278 and 519 cm^?1 and 7 excited state frequencies of magnitudes 267, 436, 554, 968, 1268, 1386 and 1575 cm^?1     

多光程吸收的频率调制光谱

采用可连续调谐的半导体二极管激光器作探测光源,将多光程吸收光谱技术、频率调制光谱技术和相敏检波技术相结合,建立了一套具有高检测灵敏度和分辨率的测量气态分子光谱和进行微量分析的研究装置并利用该装置研究了动态分压强为40Pa和120Pa时,H₂O分子在7462cm^-1和7473cm^-1附近的近红外吸收光谱,检测灵敏度远高于传统吸收光谱技术,为气态分子的光谱研究和微量分析提供了一种高灵敏度的光谱检测方法.     

The Influence of Flames on the Interference of Iron on Strontium in Atomic Absorption Spectrometry

The determination of strontium by atomic absorption spectrometry has been studied by several workers.^1-5Their papers reported that the alkali and alkaline earth metals, phosphorus, sulphur, silicon and aluminium caused interference.     

可调谐二极管激光吸收光谱法测量环境空气中的甲烷含量

可调谐二极管激光吸收光谱法是在二极管激光器与长光程吸收池技术相结合的基础上发展起 来的一种新的痕量气体检测方法.这种方法不仅精度较高、选择性强而且响应速度快.介绍了 一套可调谐二极管激光吸收光谱检测甲烷浓度的实验装置.这套装置具有灵敏度高、检测限 低（低于0087mg/m3³）、易于集成为便携式痕量气体检测仪等优点，利用 这套装置实现了对环境空气中甲烷含量的检测. 关键词： 可调谐二极管激光吸收光谱 多次回归 多次反射池