The use of a wavelength scanning technique for multi-element determinations by atomic fluorescence spectroscopy

Summary The simple modification necessary to a conventional atomic absorption spectrometer to enable it to be used for a wavelength scanning technique for multi-element atomic fluorescence determinations is described. Both a xenon arc lamp continuum and some dual-element electrodeless discharge lamps have been used as spectral sources. Results have been obtained for the rapid-sequential multi-element determination of several combinations of elements, and these show that the sensitivity and selectivity are the same by the scanning technique as by conventional atomic fluorescence.

---

Wellenlängen-Scanning zur Multi-Elementbestimmung durch Atomfluorescenz-Spektroskopie

Zusammenfassung Eine einfache Modifikation eines konventionellen Atomabsorptions-Spektrometers wird beschrieben, die die Ausführung von atomfluorescenzspektrometrischen Bestimmungen mit Hilfe des Wellenlängen-Scanning gestattet. Als Lichtquellen dienen das Xenon-Bogenkontinuum sowie elektrodenlose Bielement-Entladungslampen. Die Ergebnisse der Bestimmung verschiedener Elementkombinationen zeigen, daß Empfindlichkeit und Selektivität der konventionellen Atomfluorescenzmethode entsprechen.

Lecture presented at Euroanalysis I Conference, 28. 8.–1, 9. 1972 in Heidelberg, Germany.     

原子吸收法测定中草药中钙、镁、铁、锌、铜和锰

钙、镁、铁、锌、铜、锰都是人体必不可少的元素 ,而中草药中这些元素的测定 ,无论是从中医药学还是营养卫生学的角度而言 ,都显得极其重要和必不可少[1 ,2 ] 。本文采用原子吸收分光光度法连续测定中草药中的钙、镁、铁、锌、铜、锰。1　实验部分1 .1　仪器与试剂Ｚ 80 0 0偏振塞曼原子吸收分光光度计 ,配火焰和石墨炉原子化器 (日本日立公司 )。ＬａＣｌ3溶液( 1 0 0ｇ/Ｌ) ;ＳｒＣｌ2 溶液 ( 5 0ｇ/Ｌ) ;钙、镁、铁、锌、铜、锰混合标准储备液 (Ｃａ、Ｍｇ、Ｆｅ 2ｇ/Ｌ ,Ｍｎ 1ｇ/Ｌ ,Ｚｎ、Ｃｕ 0 5ｇ/Ｌ)。1 .2　样品液的制备准确称…     

Measurement of relative atomic transition probabilities using flame atomic absorption spectroscopy

A simple and straightforward technique has been developed to measure relative atomic transition probabilities (A_ji) using flame atomic absorption spectroscopy (FAAS). A_ji values for Cu, Ag, Mn and Mo are calculated from absorption measurements in an air—acetylene flame using both line emission (AAL) and continuum excitation (AAC) sources. For Mn and Mo, large discrepancies for A_ji are found between AAL and AAC, which may be attributed to hyperfine structure (hfs). For continuum source measurements the absorbance is independent of the absorption line profile thus eliminating the problems associated with hfs. Therefore, AAC provides a more accurate method for relative A_ji measurements, with determinations of better than 10% relative standard deviation for all elements.     

Analytical atomic spectroscopy using ion trap devices

Investigations using ion trap devices for analytical atomic spectroscopy purposes have focused on the use of an inductively coupled plasma (ICP) ion source with ion trap mass spectrometric (ITMS) detection. Initial studies were conducted with an instrument assembled by simply appending an ion trap as the detector to a fairly conventional ICP/MS instrument, i.e. leaving an intermediate linear quadrupole between the plasma source and the ion trap. The principal advantages found with this system include the destruction of nearly all problematic and typical ICP/MS polyatomic ions (e.g., ArH(+), ArO(+), ArCl(+), Ar(2)(+), etc) and a dramatic reduction of the primary plasma source ion, Ar(+). These results prompted the development of a second-generation plasma source ion trap instrument in which direct coupling of the ICP and ion trap has been effected (i.e. no intermediate linear quadrupole); the same performance benefits have been largely preserved. Initial operation of this instrument is described, characterized, and compared to the originally described ICP/ITMS and conventional ICP/MS systems. In addition, experiments aimed at improving ICP/ITMS sensitivity and selectivity using broadband resonance excitation techniques are described. Finally, the potential for laser optical detection of trapped ions for analytical purposes is speculated upon.     

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.     

Analytical atomic spectroscopy using ion trap devices

Investigations using ion trap devices for analytical atomic spectroscopy purposes have focused on the use of an inductively coupled plasma (ICP) ion source with ion trap mass spectrometric (ITMS) detection. Initial studies were conducted with an instrument assembled by simply appending an ion trap as the detector to a fairly conventional ICP/MS instrument, i.e. leaving an intermediate linear quadrupole between the plasma source and the ion trap. The principal advantages found with this system include the destruction of nearly all problematic and typical ICP/MS polyatomic ions (e.g., ArH⁺, ArO⁺, ArCl⁺, Ar₂⁺, etc) and a dramatic reduction of the primary plasma source ion, Ar⁺. These results prompted the development of a second-generation plasma source ion trap instrument in which direct coupling of the ICP and ion trap has been effected (i.e. no intermediate linear quadrupole); the same performance benefits have been largely preserved. Initial operation of this instrument is described, characterized, and compared to the originally described ICP/ITMS and conventional ICP/MS systems. In addition, experiments aimed at improving ICP/ITMS sensitivity and selectivity using broadband resonance excitation techniques are described. Finally, the potential for laser optical detection of trapped ions for analytical purposes is speculated upon.     

Preliminary study of metals in proteins by high-performance liquid chromatography-inductively coupled plasma mass spectrometry using multi-element time-resolved analysis.

The feasibility of multi-element and multi-isotope determinations during the on-line chromatographic separation of protein matrices was investigated using time-resolved software with inductively coupled plasma mass spectrometry. Size-exclusion chromatography was used to separate a mixture of known proteins and the behaviour of associated elements was monitored. It was possible to scan either the entire mass range or a selected number of isotopes. Reversed-phase chromatography was used to separate Zn-containing species in chicken meat that had been intrinsically and extrinsically labelled with stable isotopes of Zn. The ratio obtained for the intrinsic label agreed with that obtained by other workers using thermal ionization mass spectrometry. Time-resolved analysis permitted rapid data acquisition, thus reducing the number of chromatographic runs required. However, at present, data handling can be time consuming. Further software developments will add to the advantages that this technique offers.     

Simultaneous multi-element analysis of some edible pulses using neutron activation analysis

This paper comprises the application of instrumental neutron activation analysis (INAA) for multi-element determination in some edible pulse samples. These edible pulses are usually daily used in the Egyptian kitchen. These were: anise, cumin, coriander, caraway, black cumin, white kidney bean, lupine, lentil, chickpea, broad bean, peanut, almond, and fenugreek. The pulses have been analyzed as dehulled pulses, in the case of legume and oil pulses with simultaneous analysis of their respective skins. The determined elements were: Ce, Co, Cr, Cs, Eu, Fe, Hf, Rb, Sb, Sc, Sr, Th and Zn. The element content in the dehulled pulses and their respective skins has been compared. Some elements were major or minor elements where others were trace elements. Standard reference materials were used to assure quality control, accuracy and precision of the technique.     

Simultaneous multi-element analysis for trace metals in sea water by inductively-coupled plasma/atomic emission spectrometry after batch preconcentration on a chelating resin

Batch treatment with Chelex-100 resin was investigated for preconcentration of trace metals in sea water followed by determination by inductively-coupled plasma atomic emission spectrometry. The preconcentration conditions such as resin weight, stirring time, and amount of ammonium acetate buffer solution were carefully examined for effective multi-element preconcentration from sea water. The resin weight could be decreased to 0.5 g (dry weight) for 1 l of sea water, which was much less than that required in the column method, and a preconcentration factor of 100 was achieved. Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Mo, Cd and Pb in sea water were measured with good precision. The detection limits ranged from 6 to 180 ng l^?1. The time required for one sample by the batch method was only 3 h.     

Mono-standard calibration approach to multi-element XRF analysis of thin films using polychromatic excitation

Summary A reliable method is described for the calculation of slopes of calibration lines for thin-film samples using polychromatic excitation. Theoretically calculated slopes for elements within one series, e.g. the K-series, are normalized using one or two known slopes for elements in the series. The mathematical equations used to interpolate slopes as a function of atomic number are based on the fundamental relationship between fluorescent intensity and atomic number, fluorescent yield, detector efficiency, concentration and mass absorption coefficients. Kramer's formula is used to approximate the shape of the primary radiation spectrum. The method was applied to the analysis of thin films.     

Construction and performance of a time-multiplex multiple-slit flame atomic fluorescence spectrometer for multi-element analysis

The design and performance characteristics of a new multi-element flame atomic fluorescence spectrometer are presented. Radiation from four hollow-cathode tubes is directed onto an unsheathed air—hydrogen flame. The resulting atomic fluorescence is viewed by a special monochromator with a separate exit slit for each element. The light exiting from all slits is directed to a single photomultiplier tube. The fluorescence signals from different elements are distinguished by a time multiplex approach. Single-element detection limits for ten elements and multi-element detection limits for four elements are presented. The degradation of detection limits by flame background emission noise and effect of flame composition on performance are discussed. Better than 1% precision is obtained for moderate analyte concentrations.     

Simultaneous multi-element determination of trace metals in sea water by inductively-coupled plasma atomic emission spectrometry after coprecipitation with gallium

Coprecipitation with gallium hydroxide is studied for the preconcentration of trace metals in sea water before multi-element analysis by inductively-coupled plasma/atomic emission spectrometry. Gallium precipitates at pH 9 only when magnesium is present. Optimum conditions are established for multi-element preconcentration and removal of matrix elements. The method is almost free from contamination because of the use of highly pure gallium meetal and only a small amount of sodium hydroxide for pH adjustment. Spectral interferences from gallium are negligible and a concentratioin factor of more than 200 can be obtained. Detection limits range from a few ng l^?1 to 150 ng l^? for Al, Co, Cr, Fe, La, Mn, Ni, Ti, V, Zn, Y and Pb. Artificial and natural sea-water samples can be analyzed with adequate precision.     

Serum lithium determinations using flameless atomic absorption spectroscopy

The use of lithium salts and lithium carbonate in particular, in the control and treatment of certain types of psychiatric patients requires a means of monitoring lithium levels in serum. The currently accepted theraputic concentrations cover the range 0.5–1.5 milliequiv-alents of lithium per liter (mEq/l.) of serum with toxic symptoms reported above 1.5–2.0 mEq/l. Atomic absorption spectroscopy has been the method of choice for this analysis for several years and with the development of flameless methods the smaller samples may be used and multiple determinations made in about the same time required for a single determination using an air-acetylene flame and aspiration technique. The standard deviation of the flameless method is approximately 5% relative over the range of interest, 0.5–2.0 mEq/l. A comparison of results is made using a Perkin-Elmer Model 303 AA unit and a Varian Model AA5 with Model 63 Carbon Rod Atomizer.     

Differentiation of black,green, herbal and fruit bagged teas based on multi-element analysis using inductively-coupled plasma atomic emission spectrometry

In the present paper, multi-element characterisation of 26 bagged teas was carried out using inductively-coupled plasma atomic emission spectrometry. Na, K, Ca and Mg were the metals with major contents. Among the essential elements, Fe and Zn were the most abundant, followed by Se, Cu, Mo and Cr. The tea bag samples also contained significant contents of Mn and Al. The chemometric techniques of linear correlation analysis, principal component analysis (PCA) and cluster analysis (CA) were used for differentiation of the tea bag samples according to their metal content. The samples analysed were classified into four groups by PCA and CA. The first group includes hibiscus, nettle, mint, rtanj tea, thyme, bearberry and sage. Green and black teas are in the second group. The third group contains strawberry, lime, pineapple, pomegranate, elder, blueberry, milfoil, apricot and chamomile. Exotic fruits, sweet cherry, forest fruits, apple, St John’s wort, rose hips, cherry and raspberry are in the fourth group.     

Quantitative analysis of immobilized metalloenzymes by atomic absorption spectroscopy

A new, sensitive assay for the quantitative determination of immobilized metal containing enzymes has been developed using atomic absorption spectroscopy (AAS). In contrast with conventionally used indirect methods the described quantitative AAS assay for metalloenzymes allows more exact analyses, because the carrier material with the enzyme is investigated directly. As an example, the validity and reliability of the method was examined by fixing the iron-containing enzyme catalase on cotton fabrics using different immobilization techniques. Sample preparation was carried out by dissolving the loaded fabrics in sulfuric acid before oxidising the residues with hydrogen peroxide. The iron concentrations were determined by flame atomic absorption spectrometry after calibration of the spectrometer with solutions of the free enzyme at different concentrations.     

Determination of metals in heavy oil residues by inductively coupled plasma atomic emission spectroscopy

A method is proposed for the sample preparation of heavy oil residues characterized by viscosity of more than 700 mm²/sec at 100°C to study their elemental composition. It is shown that a wide range of elements can be determined in heavy oil residues by inductively coupled plasma atomic emission spectrometry (IC-AES) when the sample dissolved in an organic solvent is injected into the instrument. The optimal parameters for the determination of metals in heavy oil residues by ICP-AES are selected, including an organic solvent and the method of sample dilution. The results of elemental analysis of heavy residues of oils from Chernigovskoe, Shpakovskoe, and Samarskoe deposits are compared. The developed method for determining metals in heavy oil residues significantly reduces the analysis time and does not require complex sample preparation.     

Combined furnace—flame non-dispersive atomic fluorescence spectrometry for direct simultaneous multi-element analysis of air filters

Furnace volatilization followed by atomization in the flame of a non-dispersive atomic fluorescence spectrometer is used for the direct, simultaneous, multi-element determination of Zn, Cd, Pb and Fe on air filter papers. Standardization is done by using blank filter papers impregnated with standard metal solutions. The results agree well with those obtained by a standard atomic absorption procedure.     

A contribution to the solution of the problem of quantification in surface analysis work using glow discharge atomic emission spectroscopy

The emission intensity from spectral lines has been studied in a Grimm-type glow discharge lamp (GDL). The variation in intensity of Ar I lines was investigated in order to exclude the influence of the sample sputtering rate. The variations in intensity of several analytical lines were then studied and compared with the sample sputtering rate. It was concluded that the sample atom number density in the plasma saturates with increasing voltage. An empirical intensity expression, taking into account the current, voltage and sample composition is presented. This expression was used for the determination of elemental concentrations in Cu based alloys, using a single steel reference sample as standard. An application of this procedure to a surface analysis problem is presented, and the results are compared with atomic absorption measurements. Good agreement was obtained, indicating that surface analysis data can be quantified in a simple and straightforward manner.     

Multielement atomic absorption analysis using Hadamard transform spectroscopy with a new computation and superposition procedure

The application of Hadamard transform spectroscopy (HTS) to analytical atomic spectroscopy has been investigated. A theoretical examination of the signal to noise ratio indicates that HTS offers a slight multiplex advantage over single slit scanning of the spectrum for the measurement of intense lines, as in atomic absorption, but is disadvantageous for measuring small signals in atomic emission and fluorescence. Using a simple HT spectrometer Mg and Pb were determined simultaneously by flame atomic absorption spectrometry. Sensitivities similar to those of conventional systems were obtained but, owing to instrumental imperfections and a short data collection time, detection limits were worse. Optimum system performance was obtained when the mask interval width was equal to the width of the image of the spectrometer entrance slit. Greater spectral detail was revealed by superposition of a set of computed spectra in which the starting point of each spectrum was displaced from the others by a distance less than the interval width of the Hadamard mask. This approach gave improved spectra without increased instrumental complexity.