Uncertainty of atomic absorption spectrometer

The uncertainty of the flame atomic absorption spectrometer was studied. Drift of signal, noise, and nonlinearity of the calibration curve were found to be main sources of uncertainty for the absorbance measurement, and factors affecting these sources of uncertainty were evaluated using Cd as a typical element. The combined uncertainty was 0.00133 absorbance units at a Cd concentration of 0.5 mg/l (0.078 absorbance units). The relationship between the flame conditions and the burner optics contributed strongly to the uncertainty. Therefore, the matrix effect of the sample must to be taken into consideration in actual analyses.     

Interfacing an analogue infrared spectrometer to a microcomputer

An Apple microcomputer has been interfaced to a Perkin-Elmer model 577 infrared spectrometer. The spectral data are digitized with the aid of an in-house designed 12-bit analogue-to-digital interface unit. Control and status signals are obtained from the spectrometer and an optical encoder unit is used to provide an accurate wavenumber marker for the conversion and data recording. The digital data are formatted by the microcomputer and then can be manipulated by programs already developed for handling spectral data recorded from digital spectrometers.     

Optimization of a simultaneous multi-element atomic absorption spectrometer

A variable-size simplex procedure was used to optimize the overall response of a simultaneous multi-element flame atomic absorption spectrometer. Seven factors (air to fuel ratio, slit width, height above the burner head, and four hollow cathode lamp currents) were optimized for copper, iron, manganese, and zinc atomic absorption. A univariate search procedure was used to determine the effect of individual factors on response. The results of the optimization showed that a comprise set of operating conditions must be used when performing multi-element determinations. The atomic absorption sensitivity of the multi-element determination as compared to single-element determination was reduced by a factor of no more than two.     

A simple,inexpensive computer-controlled slew-scan atomic fluorescence flame spectrometer for multi-element determinations

The system consists of a continuum xenon arc lamp source, a chopper, an argon-separated separated air/acetylene flame atomizer, a high-throughput, medium-resolution grating monochromator under Apple II+ wavelength control, a photomultiplier detector, and a photon counter with an Apple II+ for data collection and statistical treatment. The computer-controlled system is shown to give semiquantitative results (within ±50%) for 19 elements at two wavelengths each (one wavelength for 7 elements) in less than 15 min; quantitative results (within ± 5%) for each element at a selected wavelength were obtained in about 5 min. The system was characterized by determining 10 and 14 elements in synthetic mixtures and by determining a number of elements in NBS standard reference materials (orchard leaves and two steels).     

A Rowland Circle,multielement graphite furnace atomic absorption spectrometer

A simultaneous, multielement atomic absorption spectrometer utilizing a graphite furnace atomizer was constructed and evaluated. The optical arrangement employs a concave grating to combine the spectral output from a deuterium lamp and four hollow cathode lamps that are placed on the perimeter of a Rowland Circle. A graphite furnace atomizer is positioned on the circle at the point of convergence of the five light sources. Background correction is performed by the continuum source method. Simultaneous detection of the analyte absorption signals is accomplished with a charged-coupled device. Four test elements were used for evaluation purposes: cadmium, lead, copper and chromium. Even though the elements differ greatly in volatility, the detection limits approach the values published for single element GFAAS: 4, 12, 14 and 12 pg for Cd, Pb, Cu and Cr, respectively. The characteristic masses (integrated absorbance) for the four metals are 3, 24, 14 and 7 pg, respectively. Three drinking water reference materials are analyzed: NIST SRM #1643b (Trace Elements in Water), Fisher Scientific “Metals Drinking Water Standard,” and High Purity Standards “Drinking Water Metals Solution A and B”. The determined amounts were within 10% of the certified values for each of the four elements for all three reference materials.     

火焰原子吸收光谱法测定废旧二次电池中钴的含量

建立了火焰原子吸收光谱(FAAS)法测定废旧二次电池中钴的方法。确定了最佳溶样方法和仪器测定的最佳条件,在选定的操作条件下,钴的检出限0.015μg/mL,相对标准偏差为0.98%～1.9%,加标回收率为98.0%～105%。用来测定废旧二次电池中的钴,操作简单、快速、灵敏度高,结果令人满意。     

基于国产仪器研究钨丝原子吸收光谱

用标准的150 W幻灯灯泡的钨丝作原子化加热材料,设计制作了一种新颖的、结构简单的钨丝电热原子化器,同时还设计了该原子化器的电源电路和信号的数据采集电路.该原子化器能的最高原子化温度可达3100 K左右;编写了硬件的控制软件和信号处理的应用软件.用该原子化器将实验室一台火焰原子吸收光谱仪改装成钨丝原子吸收光谱仪,并以铜元素标准溶液和PerkinElmer公司多元素标准溶液对仪器性能作了研究.仪器对铜的检出限为0.0133 μg/mL,线性范围为0.10～4.0 μg/mL;对1.0 μg/mL的铜标准溶液测试的相对标准偏差为RSD=4.1%(测试次数n=10),每次分析所需样品量20 μL.     

Analytical characteristics of a continuum-source tungsten coil atomic absorption spectrometer.

A continuum-source tungsten coil electrothermal atomic absorption spectrometer has been assembled, evaluated, and employed in four different applications. The instrument consists of a xenon arc lamp light source, a tungsten coil atomizer, a Czerny-Turner high resolution monochromator, and a linear photodiode array detector. This instrument provides simultaneous multi-element analyses across a 4 nm spectral window with a resolution of 0.024 nm. Such a device might be useful in many different types of analyses. To demonstrate this broad appeal, four very different applications have been evaluated. First of all, the temperature of the gas phase was measured during the atomization cycle of the tungsten coil, using tin as a thermometric element. Secondly, a summation approach for two absorption lines for aluminum falling within the same spectral window (305.5-309.5 nm) was evaluated. This approach improves the sensitivity without requiring any additional preconcentration steps. The third application describes a background subtraction technique, as it is applied to the analysis of an oil emulsion sample. Finally, interference effects caused by Na on the atomization of Pb were studied. The simultaneous measurements of Pb and Na suggests that negative interference arises at least partially from competition between Pb and Na atoms for H2 in the gas phase.     

Determination of alkylmercury compounds in fish tissue with an atomic absorption spectrometer used as a specific gas chromatographic detector

Atomic absorption spectrometry is used as a specific gas chromatography detector in the determination of alkylmercury compounds in fish. An electrical furnace “cracks” the organic mercury molecules in the Chromatographic effluent. An extraction procedure has been developed which improves the precision of the method. The detection limit is 0.3 ppm of mercury for 0.5-g samples.     

Determination of lead in sea-water with a graphite furnace atomic absorption spectrometer and an improved automatic on-line pre-concentration system

An improved automatic on-line pre-concentration system for graphite furnace atomic absorption spectrometry (GFAAS) for the determination of trace metals in sea-water was developed. This system was modified from a Perkin-Elmer AS-40 autosampler by mounting a silica gel C₁₈ microcolumn near the tip of the autosampler capillary. The pre-concentration procedure was performed by using a four-way distribution valve and controlled by a programmable controller. The pre-concentration system developed previously was improved by using a peristaltic pump to replace the reciprocating pumps, a newly designed tube bed adjuster to release the back-pressure in the pre-concentration system, and a better control program, such that on-line pre-concentration became more reliable and fully automatic. The chelating agent ammonium pyrolidinedithiocarbamate (APDC) and a miniature column packed with 5 mg of C₁₈ silica gel were used for pre-concentration. This system was tested by analyzing the lead content in reference standard sea-water samples. A sample volume of only 2 ml was required to determine lead in sea-water. The relative limit of detection of lead was 3.5 pg/ml.     

Validation of a computer program for atomic absorption analysis

 The approach to validation of a computer program for an analytical instrument as a component of the analytical method (using this instrument with the program) is discussed. This approach was used for validating a new program for atomic absorption analysis. The validation plan derived from this approach was based on minimising the influence of all steps of the analytical procedure on the analytical results obtained by the method. In this way significant changes in the results may be caused only by replacement of the previous program by the new one. The positive validation conclusion was based on the comparison of the results of the analysis of suitable reference materials obtained with the new program and with its precursor in the same conditions, and also on comparison of their deviations from the accepted reference values for these materials, with the corresponding uncertainties. Received: 25 January 1997 Accepted: 14 March 1997     

Spectrophotometric determination of flotation collectors and organic reagents in ore treatment process liquors and effluents with an atomic absorption spectrometer

An atomic absorption spectrometer has been adapted to measure the absorbance of solutions of flotation reagents (e.g. xanthate, mercaptobenzothiazole, dithiophosphate, and Z-200) in the concentration range 0–10 mg l^-1 in aqueous and non-aqueous solvents in the u.v. and visible regions. The absorbance values obtained are similar to those from a u.v.—visible spectrophotometer and straight-line calibration graphs are obtained. Hollow-cathode lamps emitting the desired wavelengths can be selected from wavelength tables of atomic lines. This technique allows a metallurgical analytical laboratory to extend its range of determinations without additional cost by the use of an a.a.s. unit as a u.v.—visible spectrometer.     

A simple,low cost,multielement atomic absorption spectrometer with a tungsten coil atomizer

An inexpensive, multielement atomic absorption spectrometer utilizing a tungsten coil atomizer has been developed. The novel optical arrangement employs three 60° beam combiners to blend the spectral output from four light sources such as electrodeless discharge lamps, or hollow cathode lamps, and then direct that output over an atomizer. This instrument uses an inexpensive tungsten coil atomizer that is extracted from a standard 150 W projector bulb. The temperature of the coil is computer-controlled by changing the voltage across the coil. A low voltage is first used to dry the sample then a higher voltage is used to atomize the sample. Simultaneous detection of the analyte absorption signals is accomplished using a charge-coupled device. The elements of interest in this study were Cd, Pb, and Cu. Near-line background correction was used to correct for nonspecific analyte absorption.     

Evaluation and characterization of a commercial zeeman-modulated tungsten-strip electrothermal atomic absorption spectrometer

The operating parameters and the quantitative of an AAZ-2 Zeeman-modulated tungsten-strip atomic absorption spectrometer are reported. The figures of merit for Ag, Au, Cd, Co, Cu, Fe, Mn, Ni, Pb, Tl, and Zn are reported. Detection limits obtained with the AAZ-2 were comparable to those obtained with other metal atomizers reported in the literature. A maximum heating rate of 12 K ms^?1 was measured for the tungsten-strip atomizer.