Extended range Zeeman atomic absorption spectrometry based on a 3-field a.c. magnet

The dynamic range of a.c. Zeeman atomic absorption (ZAA) analytical curves can be extended 10 times when intensity measurements are performed at three different field strengths, i.e. zero, maximum and intermediate field strength during each modulation cycle of the magnet, rather than at zero and maximum field strength only.The conventional ZAA analytical curve and the extended range curve are obtained simultaneously from one series of standards.The power supply of the magnet is described. In the extended range system the background correction frequency is 50 Hz, whereas the system operates at 100 Hz in the conventional ZAA mode.     

Construction and performance of an a.c. modulated magnet for Zeeman atomic absorption spectroscopy

A Zeeman atomic absorption spectroscopy system has been constructed utilizing a 50 Hz sine wave modulated magnetic field that can be directed either parallel or perpendicular to the optical axis. The amplitude of the magnetic field strength is adjustable up to 10 kG at a maximum power consumption of 0.7 kW.The readout system allows normal atomic absorption as well as d.c. and a.c. Zeeman atomic absorption measurements. Plots of experimental sensitivity vs magnetic field strength and analytical curves are in agreement with theoretical predictions.Experiments in the presence of filter simulated and real background absorbance show that the described Zeeman instrument is capable of correcting background absorption up to two absorbance units.     

Theory of Zeeman atomic absorption spectrometry

A theoretical analysis is presented of the signals observed with different systems that employ the Zeeman effect for background correction in analytical atomic absorption spectrometry.Magnetic modulation of the primary source of radiation offers basically the same possibilities as the deuterium background correction system. Correction for wavelength dependent background absorption is possible only when the magnetic field is applied to the absorbing vapour. Similar expressions are obtained for constant or variable magnetic fields directed either perpendicular or parallel to the optical axis. However, mere magnetic modulation of either the source or the atomizer cannot correct for non-absorbed lines.It is demonstrated that simultaneous correction for non-absorbed lines and background absorption can be attained with a variable magnetic field applied to the atomizer, by taking measurements at three discrete, different field strengths.     

An improved power supply for the magnet in a.c. modulated Zeeman atomic absorption spectrometry

This note describes a simple power supply for a magnet to be used in a.c. ZAA spectrometry. The modified sine wave shape of the 50 Hz 10 kG magnetic field allows a 0.5 ms period at zero field to perform the zero field intensity measurement. At lower maximum field strength, the zero field period can be extended.     

Roll-over of analytical curves in atomic absorption spectrometry arising from background correction with pulsed hollow-cathode lamps

A theoretical analysis of background correction systems in atomic absorption spectrometry reveals the interdependence of three phenomena: analytical sensitivity, roll-over of the analytical curve, and wavelength proximity of the background correction. The deuterium lamp system sacrifices wavelength proximity and the Zeeman technique is subject to roll-over. For the newly introduced correction technique using pulsed hollow-cathode lamps roll-over has also been observed, although the effect is reduced by sacrifices of both wavelength proximity and analytical sensitivity.     

Zeeman atomic absorption spectrometry

The shift of atomic spectral lines in a magnetic field (the Zeeman effect) forms the basis for three novel developments in atomic absorption spectrometry: (i) greatly improved background correction; (ii) the use of forward scattering techniques as an analytical tool; (iii) the determination of small gaseous molecules.     

Laser-excited atomic-fluorescence spectrometry in an electrothermal atomizer with Zeeman background correction

A pulsed excimer-pumped dye laser was used to excite atomic flourescence in graphite tube electrothermal atomizer. A 60-Hz ac magnitude field was applied around the atomizer and parallel to the excitation beam, for Zeeman background correction. The correction system was found to degrade the detection limits for silver, cobalt, indium, manganese, lead, and thallium by a factor of between 1 and 10. An increase in magnetic field strength, or a decrease in laser linewidth, should improve the detection limits, but was not possible here. For copper, the application of Zeeman background correction was unsuccessfull because the instrumentation was unable to resolve the sigma components from the laser emission profile sufficiently during the background correction measurement. For elements that exhibit sufficient Zeeman splitting, the linear dynamic range was the same with or without background correction Zeeman background correction was used to correct for scatter, in the resonance flourescence determination of manganese in a zinc chloride matrix and in mouse brain tissue.     

An application of the Zeeman effect to atomic absorption spectrometry: a new method for background correction

A new Zeeman method for background correction in atomic absorption spectrometry was studied. The light source was operated in a steady magnetic field,     

Spectral interferences using the Zeeman effect for furnace atomic absorption spectroscopy

Using a transverse, a.c. Zeeman system, with the magnet on the analyte, background correction is performed at the exact analyte wavelength. As a result, nearly all of the spectral interferences associated with continuum correction are eliminated. Errors may occur, though, using Zeeman correction if coincident or nearby absorption lines or molecular absorption bands exhibit Zeeman splitting.We have found an example of overcorrection in the determination of Cd at the alternate 326.1-nm line that we believe is due to splitting of PO bands. We have also confirmed errors from Ft in the determination of Fe at the alternate 271.9-nm line and from Co in the determination of Hg at 253.6 nm.     

A novel method for atomic absorption spectroscopy based on the analyte-Zeeman effect

A new type of atomic absorption spectrometry using the Zeeman effect of sample materials is proposed. A magnetic field was applied to the sample vapor in the direction perpendicular to the propagation of light emitted from an atomic spectral source. Absorption of radiation polarized perpendicular and parallel to the magnetic field was observed alternatively. The absorption difference was proportional to the true atomic absorption, and was not interfered with by any other molecular absorption and light scattering, i.e., background absorption. The background absorption could be monitored at exactly the same wavelength as an atomic absorption line. Suitable magnetic field strength was found for each line of the various elements.     

An application of the Zeeman elect to atomic absorption spectrometry: Development of spectral-line sources stable in magnetic field

A new atomic-absorption spectrophotometer using the Zeeman effect, in which the magnetic field is applied to the light source, is described. A steady magnetic field of 3.8 kG was applied to conventional hollow-cathode lamps, which were operated using a high frequency power of 100 MHz.The π-and σ-components of the Zeeman split atomic lines were observed alternatively after traversing a flame. The absorbance difference between of the two Zeeman components was proportional to the atomic-absorption and was not influenced by background absorption. Dependences of atomic absorption signals on magnetic field strengths which were in close relation to profiles of absorption lines were measured for elements Cd, Mg, Pb, Cr, Cu and Mn by scanning of magnetic field strength.     

Zeeman atomic absorption spectrometry using high frequency modulated light polarization

This paper reports the novel use of Zeeman atomic absorption spectrometry using high frequency modulated light polarization (ZAAS-HFM), its theoretical basis and experimental validation. Due to the high frequency modulation of the analytical and reference signals, the temporal background correction error is reduced below 10⁻⁵ absorbance units. In addition, the use of ZAAS-HFM enables the operator to increase the apparatus transmittance and therefore to reduce the detection limits and to broaden the dynamic range of the analytical curves.     

Application of the zeeman effect to analytical atomic spectroscopy-III Extension of calibration curves

An application of the Zeeman effect is described by which calibration curves applicable to high analyte concentrations may be obtained. The procedure uses single-beam measurements on the displaced σ-components of the Zeeman multiplet, and thus permits controlled desensitization of an atomic-absorption signal to be obtained, simply by increasing the magnetic field strength, while leaving the monochromator permanently set on the optimum analytical line for the element considered. Calibration curves for Ca, Cd and Cu are given for applied field strengths from 0 to 16kG.     

Spectral interferences and background overcompensation in zeeman-corrected atomic absorption spectrometry : Part 1. The effect of iron on 30 elements and 49 element lines

The background compensation performance of a Zeeman corrector with the magnetic field acting on the graphite atomization cell was assessed for 30 elements and 49 element lines in an iron matrix. Two of the elements studied, gallium and zinc, are influenced by background overcompensation which introduces serious negative systematic errors. The overcompensation is due to the presence of iron lines close to the 287.4-nm gallium line and the 213.9-nm zinc line; when the magnetic field is on, the σ-components of the adjacent iron lines overlap at the position of the analyte line and a background, which is not present when the magnetic field is off, is recorded. When gallium and zinc are measured under the same conditions but with deuterium arc background correction, the adjacent iron lines cause positive systematic errors. These spectral interferences for gallium in the presence of iron can be avoided by doing the measurements at the 294.4-nm gallium line; the two lines have about the same sensitivity. When zinc is to be measured at the 213.9-nm line, with either type of background correction, the spectral interferences from iron can be avoided by careful selection of the graphite-furnace parameters. In addition to spectral interferences, iron also affects the sensitivity for both gallium and zinc.     

Zeeman原子吸收光谱分析法中谱线轮廓的研究(Ⅳ)──Te 214.3 nm和Te 225.9 nm谱线

Te214．3nm和Te225．9nm谱线分别是原子吸收光谱分析（AAS）法中Te的灵敏线和非灵敏线．在Zeeman原子吸收光谱分析（ZAAS）法中,尤其当Zeeman调制方式不同时,分析性能的差异非常明显,颇为典型．本文从原子吸收光谱法的基本原理,即原子发射（AE）、原子吸收（AA）和Zeeman原子吸收（ZAA）谱线轮廓间重叠关系留［‘］来研究其分析特性差异的原因以及在实际分析工作中的应用．1理论部分在原子吸收光谱法中吸光度值A和原子吸收系数间的关系式为：普通AAS法：AN一043K“（1）偏振调制方式ZAAS法：AZ（。;一0．43［K：一大：］…     

Investigation of artifacts caused by deuterium background correction in the determination of phosphorus by electrothermal atomization using high-resolution continuum source atomic absorption spectrometry

The artifacts created in the measurement of phosphorus at the 213.6-nm non-resonance line by electrothermal atomic absorption spectrometry using line source atomic absorption spectrometry (LS AAS) and deuterium lamp background correction (D₂ BC) have been investigated using high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). The absorbance signals and the analytical curves obtained by LS AAS without and with D₂ BC, and with HR-CS AAS without and with automatic correction for continuous background absorption, and also with least-squares background correction for molecular absorption with rotational fine structure were compared. The molecular absorption due to the suboxide PO that exhibits pronounced fine structure could not be corrected by the D₂ BC system, causing significant overcorrection. Among the investigated chemical modifiers, NaF, La, Pd and Pd + Ca, the Pd modifier resulted in the best agreement of the results obtained with LS AAS and HR-CS AAS. However, a 15% to 100% higher sensitivity, expressed as slope of the analytical curve, was obtained for LS AAS compared to HR-CS AAS, depending on the modifier. Although no final proof could be found, the most likely explanation is that this artifact is caused by a yet unidentified phosphorus species that causes a spectrally continuous absorption, which is corrected without problems by HR-CS AAS, but which is not recognized and corrected by the D₂ BC system of LS AAS.     

The use of the Zeeman effect for the background correction in atomic absorption analysis of biological fluids

The analytical technique based on the Zeeman effect for the correction of non-specific absorptions is used for the quantitative analysis of lead traces in human blood plasma. The analysis of lead traces in biological fluids by means of flameless atomic absorption is usually rather difficult to perform, owing to the presence of background absorptions in the atomization step. Tests carried out on real matrices with additions of known lead concentrations have often shown the impossibility of getting a sufficient accuracy and characteristic mass necessary for the application of the method as a clinical test. On the other hand, the background correction technique by the Zeeman effect appears to be the most convenient. To check the effectiveness of this correction method, standard solutions with compositions suitable for the production of very strong molecular absorption and light scattering phenomena were analysed; the various results obtained are reported and compared. The investigation was performed on the whole atomic absorption spectral range normally used in spectroscopy by means of different wavelength resonance lines.     

Determination of serum aluminum by electrothermal atomic absorption spectrometry: A comparison between Zeeman and continuum background correction systems

Excessive exposure to aluminum (Al) can produce serious health consequences in people with impaired renal function, especially those undergoing hemodialysis. Al can accumulate in the brain and in bone, causing dialysis-related encephalopathy and renal osteodystrophy. Thus, dialysis patients are routinely monitored for Al overload, through measurement of their serum Al. Electrothermal atomic absorption spectrometry (ETAAS) is widely used for serum Al determination. Here, we assess the analytical performances of three ETAAS instruments, equipped with different background correction systems and heating arrangements, for the determination of serum Al. Specifically, we compare (1) a Perkin Elmer (PE) Model 3110 AAS, equipped with a longitudinally (end) heated graphite atomizer (HGA) and continuum-source (deuterium) background correction, with (2) a PE Model 4100ZL AAS equipped with a transversely heated graphite atomizer (THGA) and longitudinal Zeeman background correction, and (3) a PE Model Z5100 AAS equipped with a HGA and transverse Zeeman background correction. We were able to transfer the method for serum Al previously established for the Z5100 and 4100ZL instruments to the 3110, with only minor modifications. As with the Zeeman instruments, matrix-matched calibration was not required for the 3110 and, thus, aqueous calibration standards were used. However, the 309.3-nm line was chosen for analysis on the 3110 due to failure of the continuum background correction system at the 396.2-nm line. A small, seemingly insignificant overcorrection error was observed in the background channel on the 3110 instrument at the 309.3-nm line. On the 4100ZL, signal oscillation was observed in the atomization profile. The sensitivity, or characteristic mass (m₀), for Al at the 309.3-nm line on the 3110 AAS was found to be 12.1 ± 0.6 pg, compared to 16.1 ± 0.7 pg for the Z5100, and 23.3 ± 1.3 pg for the 4100ZL at the 396.2-nm line. However, the instrumental detection limits (3 SD) for Al were very similar: 3.0, 3.2, and 4.1 μg L^− 1 for the Z5100, 4100ZL, and 3110, respectively. Serum Al method detection limits (3 SD) were 9.8, 6.9, and 7.3 μg L^− 1, respectively. Accuracy was assessed using archived serum (and plasma) reference materials from various external quality assessment schemes (EQAS). Values found with all three instruments were within the acceptable EQAS ranges. The data indicate that relatively modest ETAAS instrumentation equipped with continuum background correction is adequate for routine serum Al monitoring.     

Spectral interferences and background overcompensation in inverse zeeman-corrected atomic absorption spectrometry : Part 2. The effects of cobalt,manganese and nickel on 30 elements and 53 elements lines

The background compensation performance of a transversal alternating-current Zeeman corrector system with the magnet acting on the graphite atomization cell was assessed for 30 elements and 53 element lines in the presence of relatively large amounts of cobalt, manganese or nicke. The study reveaaled three cases of background overcompensation, all being caused by a cobalt line adjacent to the analytical line. When the magnetic field is on (and the background is measured), a σ-component of the cobalt lines overlaps the emission lines of boron (249.7 nm), mercury (253.7nm) and gold (267.6 nm). The interfering effect on boron is small, but mercury and gold are more seriously affected; for both elements a serious negative systematic error is introduced. Manganese and nickel did not give any overcompensation effects on the elements and lines studied. When gold and mercury were measured with the use of the same experimental parameters and a conventional deuterium-arc background corrector, only mercury suffered from spectral interference. The spectral interference of cobalt on mercury, with either type of background correction, can be avoided by selecting a proper furnace program. When gold is tobe measured in the presence of cobalt and with the present Zeeman background-correction system, the 267.6.-nm line should not be used; the more sensitive 242.8 nm line is recommended.