Spectral interferences in the determination of traces of scandium, yttrium and rare earth elements in “pure” rare earth matrices by inductively coupled plasma atomic emission spectrometry-I. Cerium, neodymium and lanthanum matrices

The present paper deals with spectral interferences from cerium, neodymium and lanthanum on prominent lines of scandium, yttrium and rare earth elements (REE). The “true detection limit” criterion was used for rational wavelength line selection as proposed by boumans and vrakking [Spectrochim. Acta 42B, 819 (1987); 43B, 69 (1988)]. Analysis lines selected for cerium and neodymium matrices suffered both wing and line interferences. In the case of a lanthanum matrix, it is possible to choose mostly analysis lines that are free of line interference and negligible wing interference. The high degree of spectral interferences with a cerium or neodymium matrix significantly worsens the true detection limits. This article is an electronic publication in Spearochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hardcopy text is accompanied by a disk with data and text files. The data files comprise in particular the tabular material of this article in electronic form.     

Spectral interferences in the determination of traces of scandium, yttrium and rare earth elements in “pure” rare earth matrices by inductively coupled plasma atomic emission spectrometry. Part IV. Lutetium and yttrium

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), a section of Spectrochimica Acta Part B (SAB). The hardcopy text is accompanied by an electronic archive, stored on the SAE homepage at http://www.elsevier.nl/locate/sabe. The archive contains data files and text files. The present article is the fourth part of a series of papers discussing the spectral interferences of rare earth elements (REEs) in inductively coupled plasma atomic emission spectrometry (ICP-AES). The spectral interferences for 200-pm wide windows centred (±100 pm) around the prominent lines of the analytes, due to matrix lines and oxide radicals (LuO or YO) that emit band spectra depending on the excitation temperature (T_exc.) in ICP were investigated. The main result is that for T_exc.=7200 K, LuO and YO band components can be eliminated so that prominent analysis lines of La, Ce, Pr, Nd, Eu and Sm were observed on a smooth background. T_exc..=7200 K was chosen as the optimal excitation temperature in the determination of traces of REEs in Lu₂O₃ and Y₂O₃, respectively. The quantification of the interferences in terms of Q-value was used in accordance with Boumans and Vrakking [Spectrochimica Acta Part B 42 (1987) 819; 43 (1188) 69]. The “best” analysis lines are free of line interferences and negligibly influenced by wing interferences and Lu₂O₃ and Y₂O₃ as matrices do not raise the real detection limits.     

Spectral interferences in the determination of traces of scandium, yttrium and rare earth elements in “pure” rare earth matrices by inductively coupled plasma atomic emission spectrometry: Part VII — Terbium, Dysprosium, Holmium and Thulium

This article is the seventh part of a series of papers discussing the spectral interferences of rare earth elements (REEs) in ICP-AES. Radial viewing 27.12 MHz inductively coupled plasma atomic emission spectrometry (ICP-AES) was used in the determination of scandium, yttrium and rare earth elements in Tb₂O₃, Dy₂O₃, Ho₂O₃ and Tm₂O₃ as “pure” rare earth matrices. The quantification of the interferences in terms of Q-values for line interference Q_I(_a) and wing background interference Q_W(Δλ_a) were used in accordance with Boumans and Vrakking [Spectrochim. Acta Part B 43 (1988) 69]. The “best” analysis lines from point of view of spectral interferences were selected. The true detection limits by using the “best” analysis lines were calculated.     

Simulation of atomic spectra—II. Mutual spectral interferences of rare earth elements in the inductively coupled plasma

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta B (SAB). The hardcopy text, comprising the main article and an appendix, is accompanied by a diskette with a program, data files, and a manual. The text details the purpose of the work, with emphasis on the spectroscopic aspects, and the appendix provides the essential information for accessing the diskette and using program and data. Additional tutorial guidance is provided by the manual.

The program primarily concerns the simulation of the spectra of rare earth elements (REE) as interferents in 80-pm wide spectral windows centred about the wavelengths of 26 prominent lines of Ce, La, Nd, Pr, and Sm. The program essentially covers the model described in Spectrochim. Acta 43B, 1365 (1988) and the database is identical to the experimental database published in Spectrochim. Acta 44B, 31 (1989). Accordingly, the data are for an inductively coupled plasma (ICP). The program enables the user to simulate spectra with the spectral bandwidth as an optional variable. The user may then generate spectra of both single REEs, without or with analyte, and mixtures of REEs of any composition, also without or with analyte, whereby for spectra with analyte the display includes the blank spectrum. Displays are accompanied by legends providing a set of essential numerical data. In addition, particular program options allow the generation of numerical data only, one of them being the calculation of true detection limits. This option permits it to perform, within the limited scope of the database, line selection for complex REE samples in a rational way.

The program operates, in principle, with the default values of the ICP Doppler temperature (6800 K) and “average” ICP a-parameter of the Voigt profile (0.5), but these values may be optionally modified. Similarly, the user may add new data files to the base and thus also apply the program for other purposes and outside the REE environment, such as model studies in general, and for learning or teaching, as explained in the manual on the diskette. The tutorial part of this manual provides the user not only with elementary instructions for using the program as a practical tool, but also incorporates a variety of instructive examples, including a brief “course” on spectral line profiles and spectral interferences.     

Spectral interferences in the determination of traces of scandium,yttrium and rare earth elements in “pure” rare earth matrices by inductively coupled plasma atomic emission spectrometry Part III. Europium

This paper is the third part of a series of papers dealing with spectral interferences of rare earth elements (REEs) in inductively coupled plasma atomic emission spectrometry (ICP-AES). The present article shows: (a) the spectral data of europium interferent for 200 pm wide windows centred (±100 pm) about prominent lines of scandium, yttrium and REEs; (b) the database of Q values for line interference (Q_l) and Q values for (wing) background interference (Q_w); (c) the detection limits measured by using the “true detection limit” criterion as proposed by P.W.J.M. Boumans and J.J.A.M. Vrakking (Spectrochim. Acta Part B, 42 (1987) 819; 43 (1988) 69). Different possibilities for improvement of the true detection limits are discussed: the use of equipment of high resolving power, the application of multicomponent analysis (MCA) techniques and preliminary separation of the matrix component combined with preconcentration of trace REEs. This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hard copy text is accompanied by a disk with data and text files. The data files comprise in particular the tabular material of this article in electronic form.     

Cumulative indices for Spectrochima Acta, Part A and Spectrochimica Acta, Part B

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), a section of Spectrochimica Acta, Part B (SAB). The hardcopy text is accompanied by an electronic archive, stored on the SAE homepage at http://www.elsevier.nl/locate/sabe. The archive contains data, index and program files. The main article discusses the bibliographical purpose of the program and data files. A collective index for Spectrochimica Acta for volumes since it was split into Parts A and B, and continuing through 1991 for SAA and 1997 for SAB, is presented in DBF format, along with rudimentary data entry and access software.     

Methods of calibration in the direct analysis of solid samples by electrothermal atomic absorption spectrometry

One of the major problems involved in the direct analysis of solid samples by electrothermal atomic absorption spectrometry (ETAAS) lies in the calibration step because non-spectral interference effects are often pronounced. Three standardization techniques have been described and used in solid sampling-ETAAS: (i) standard additions method; (ii) calibration relative to a certified reference material; and (iii) calibration curve technique. However, an adequate statistical evaluation of the uncertainty in the analyte concentration in the solid sample is most frequently neglected, and reported errors may be seriously underestimated. This can be attributed directly to the complexity of the statistical expressions required to accurately account for errors in each of the calibration techniques mentioned above, and the general lack of relevant reference literature. The object of this work has been to develop a computer package which will perform the necessary statistical analyses of solid sampling-ETAAS data; the result is the program “SOLIDS” described here in the form of an electronic publication in Spectrochimica Acta Electronica, the electronic section of Spectrochimica Acta Part B. The program could also be useful in other analytical fields where similar calibration methods are used. The hard copy text, outlining the calibration models and their associated errors, is accompanied by a diskette containing the program, some data files, and a manual. Use of the program is exemplified in the text, with some of the data files discussed included on the diskette which, together with the manual, should enable the reader to become familiarized with the operation of the program, and the results generated.     

An electronic aid for line selection for scanning inductively coupled plasma atomic emission spectrometers

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). Accompanying this hard copy text is a disk containing the program, source flies, data files and a brief manual along with a few programming notes. The main article discusses the purpose of this work, and the Appendix provides brief instruction on the use of the program, manipulation of the data, and source code. An automatic file selection system for the control of a rapid scanning spectrometer performing atomic emission spectrometry has been developed using the PROLOG language. The system can be “taught” the elemental composition of a given sample type. It uses this information (when available) to generate a linear search strategy which minimizes the number of lines that need to be measured. The rules used by the system can be observed during system operation to allow a trace of the logic. Reading of the initial data base takes no more than 6 s and then decisions are made in less than 1 s per line.     

Computer modeling of fluorescence dip spectroscopy with pulsed laser excitation

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hard copy text is accompanied by a disk with a demonstration program, block libraries, demonstration files, and ancillary files. The article discusses the computer modeling of fluorescence dip spectroscopy, a relatively new and powerful atomic diagnostic technique. The models were found to agree essentially perfectly with previously published photostationary results and to extend those results to the more realistic laser temporal profiles encountered in actual experiments.

The fluorescence dip parameters were found to be robust so long as the system under study approached saturation conditions. Short, noisy laser pulses were found to be acceptable, for determination of the fluorescence dip parameters, provided the laser pulses were sufficiently intense to cause near saturation of the three level system. Conversely, steady state excitation was not found to be crucial to the determination of accurate fluorescence dip parameters. For a five level model of the silver atomic system, “negative fluorescence dips” were readily found in the simulations, even though some of the relevant parameters were rough estimates of the actual, unknown parameters.     

Tomographically resolved ionization temperatures and electron densities in the inductively coupled plasma determined by the line-to-continuum method

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hardcopy text is accompanied by three disks with data files with the hardcopy paper in Word 5.0 and ASCII format, and a disclaimer. The text details the purpose of the work and the structure of the three-dimensional Ar ionization temperature and electron number density data files. The line-to-continuum method was used to evaluate the spatial distribution of Ar ionization temperatures, T_ion, and electron number densities, n_e, within a dry Ar inductively coupled plasma (ICP). The emission measurements were spatially resolved in three dimensions by reconstruction algorithms for computed tomography. The 40.68 MHz Ar ICP was operated at applied r.f. power levels of 0.75 and 1.0 kW. The reconstructed distributions of Ar I line emission (430.0 nm) and continuum emission (428.6 nm) show good reproducibility over a series of five replicate runs. Argon ionization temperatures remain within a 6500–8500 K range throughout the continuum-emission cone of the plasma. Deviations from this temperature range occur in the central channel and around the outer edge of the plasma. Low in the plasma, the central-channel T_ion is cooler than 6000 K. Along the outer edge of the plasma, the line-to-continuum ratio becomes small; this low ratio results in erroneously high temperatures (> 12000 K). The errors in T_ion appear to be due to reproducible artifacts in the reconstruction process that lead to low Ar I line-emission readings along the outer edge of the plasma. Electron densities show a maximum of 8.5 × 10¹⁴ cm⁻³ and 1.2 × 10¹⁵ cm⁻³ at 0.75 and 1.0 kW, respectively. Electron number densities were much better behaved than T_ion due to their dependence on the square-root of continuum measurements and only the fourth-root of T_ion.     

Selective accumulation of light or heavy rare earth elements using gram-positive bacteria

The accumulation of samarium from a solution only containing samarium by Arthrobacter nicotianae was examined. The amount of accumulated samarium was strongly affected by the concentration of samarium and pH of the solution. The accumulation of samarium by the strain was very rapid and reached equilibrium within 3 h. The accumulation of samarium-europium or europium-gadolinium from the solution containing the two metals using various actinomycetes and gram-positive bacteria was also examined. Most of the tested strains could accumulate similar amounts of samarium and europium; however, most of the tested strains could accumulate a greater amount of europium than gadolinium. Especially, the amounts of accumulated europium using gram-positive bacteria were higher than those using actinomycetes. The selective accumulations of light or heavy rare earth elements (REEs) using A. nicotianae and Streptomyces albus were also examined. The amounts of accumulated samarium and europium were higher than those of the other light REEs using both microorganisms. S. albus can accumulate greater lutetium than other REEs from a solution containing yttrium and eight heavy REEs. On the other hand, A. nicotianae can accumulate higher amounts of terbium and ytterbium than that of the other heavy REEs from the same solution. A. nicotianae can also accumulated higher amounts of Sm than other REEs from a solution containing six light REEs.     

MS Interview: An elemental mass spectrometry spectral interference data base

A graphically-oriented data base of spectral interferences dut occur in inductively coupled plasma-mais spectrometry and glow discharge-mass spectrometry has been developed. The program is called “MS Interview” and runs on a Macintosh computer. The program allows one to specify which technique (ICP or GD) the various interferences will be presented for, and for the case of the ICP, the acid matrix background. Bated on these parameters the program provides a listing of interferences broken down into the following categories: Isobarics, Oxides, Doubly Charged Species, Background Dependent, and Matrix Dependent. For the glow discharge case there are two additional categories: Argides and Dimers. Interference information is provided for all masses of all elements and is easily accessed via mouse operations from a periodic table window and element mass spectral windows. The program is expandable to include other ion sources and interferences can be added or deleted as required by the user. Finally, the program also includes a small library of typical background spectra that can be displayed and manipulated. This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta B (SAB). The hardcopy text is accompanied by a disk containing the program MS Interview, a manual, a reference list, and a bar graph format mass spectral library of the elements.     

An electronic spectroscope for classroom displays of visible spectra

This article is an electronic publication in Spectrochimica Acta Electronica (SAE), a section of Spectrochimica Acta Part B (SAB). The hardcopy text is accompanied by an electronic archive, stored on the SAE homepage at http://www.elsevier.nl/locate/sabe. The archive contains program, data and text files. The hardcopy text describes a program that has been developed to accept data from a compact electronic spectrograph and translate the data into a display on a computer screen. The computer display mimics the view seen through a direct vision spectroscope. Atomic spectra appear as vertical lines of the appropriate color dispersed on a black field. A conventional plot of intensity versus wavelength is simultaneously displayed. The update of the display is sufficiently rapid that the image on the screen is essentially a real-time representation of the light entering the spectrograph. The system was designed for use in conjunction with video projection equipment in demonstrations to large groups of students.     

Mutual spectral interferences of rare earth elements in inductively coupled plasma atomic emission spectrometry: I. Rational line selection and correction procedure

This paper is the first part of a series of three papers dealing with mutual spectral interferences of rare earth elements (REE). The present paper reports the measurement of the partial sensitivities of all REEs at the peak wavelengths of 30 prominent lines of Ce, La, Nd, Pr, Sm, and Yb, the most abundant REEs in geological samples. These sensitivities are split into line and wing contributions and are ratioed with respect to the analyte sensitivities. The “Q-values” thus obtained, along with the numerical values of the background equivalent concentrations for the pure solvent and the relative standard deviation of the background, permit a rational selection of analysis lines for REE mixtures of whatever composition using as a criterion the “true detection limit” as proposed by Boumans and Vrakking [Spectrochim. Acta42B, 819 (1987)]. The effectiveness of this approach is illustrated with examples. The data listed are likely to be also appropriate for other spectrometers having a spectral bandwidth of approximately the same magnitude as that used in the experiments, i.e. 17 pm. Therefore the paper includes brief instructions for applying the data. The article finally demonstrates the use of the same data for multielement interference corrections.     

Dynamic ion-exchange chromatography with post-column reaction detection for the determination of the rare earth elements in monazites

Summary Separation and determination of lanthanum, cerium, praseodymium, neodymium and samarium in monazites have been achieved by dynamic ion-exchange chromatography. The ore samples are decomposed by sulfuric acid and the rare earths are separated in a group as oxalates. The rare earth elements are then separated from each other on a column of bonded phase silica by gradient elution with 0.05 to 0.5 M lactic acid (pH 3.5) in the presence of 0.01 M sodium 1-octanesulfonate. Post-column reaction with Arsenazo III is used for detection and quantification of the individual rare earth elements. Results are quoted for lanthanum, cerium, praseodymium, neodymium and samarium in monazites. Detection limit is 1 μg ml⁻¹ with a S/N ratio of 3. The separation is complete within 27 min valley to valley resolution. Precision of better than 1% can usually be obtained.     

Determination of rare earth impurities in cerium dioxide and oxalate by X-ray fluorescence technique

A method for the determination of lathanum, praseodymium, neodymium and samarium oxides in cerium dioxide has been developed. The sample in the oxalate form is mixed with the binding material (boric acid) in the ratio 1∶1 pressed to form a double layer pellet over a boric acid backing pellet and irradiated by X-rays from a tungsten tube. The secondary X-rays are dispersed with a LiF (200) crystal in a Philips PW 1220 semiautomatic X-ray fluorescence spectrometer. The intensity of fluorescent X-rays is measured by a flow proportional counter. The minimum determination limit is 0.01% for lanthanum and samarium oxides and 0.02% for praseodymium and neodymium oxides. The precision at each concentration of the standards and theoretical minimum determination limit for each element have been calculated.     

Spectral interferences in the determination of trace elements in environmental materials by inductively coupled plasma atomic emission spectrometry

This paper deals with spectral interferences in inductively coupled plasma atomic emission spectrometry (ICP-AES) encountered with environmental materials. These samples normally contain high concentrations of aluminium, calcium, magnesium, iron, titanium, potassium and sodium. The investigations cover: (a) spectral data for Al, Ca, Mg, Fe, Ti, K and Na as interferents for 200 pm wide windows centred (±100 pm) around the prominent lines of As, B, Ba, Be, Cd, Cr, Cu, Hg, Mn, P, Pb, Sb, Se, Sn, Tl, U and Zn; (b) a data base of Q-values for line interference [Q_Ij(λ_a)] and Q-values for wing background interference [Q_Wj(Δλ_a)] for two values of the excitation temperature 6200 K and 7200 K. The lines free or negligibly influenced by line interference were selected for analyte determination. Q-values were used for calculation of correction factors under a spectral line without the measurement of a reference blank at the wavelength of the prominent analysis lines. The accuracy of ICP-AES with the Q-concept as a basic methodology is checked by the analysis of a certified reference material IAEA/Sediment SD-N-1/2/. The precision of the method is characterised by an RSD of 0.6–1.7%. Extraction of trace elements soluble in aqua regia was used as a decomposition method. This article is an electronic publication in Spectrochimica Acta Electronica (SAE), a section of Spectrochimica Acta, Part B (SAB). The hardcopy text is accompanied by an electronic archive, stored on the SAE homepage at http://www.elsevier.nl/locate/sabe. The archive contains the tabular material of this article in electronic form.     

Determination of stability constants for rare earth elements and fulvic acids extracted from different soils

Fulvic acids (FAs) were extracted by alkali extraction from different soil samples in China, then purified using resins and characterized by Fourier transform infrared spectroscopy. The complexing ability of FAs was investigated by measuring the stability constants of rare earth elements (REEs) (La³⁺, Ce³⁺, Sm³⁺, Gd³⁺, Y³⁺) with FAs by the ion exchange technique. The results indicated that maximum binding ability forY³⁺ (4.414.44) was higher than other REEs (La³⁺, Ce³⁺, Sm³⁺, Gd³⁺) (0.721.03). There were two types of binding sites in the functional groups of fulvic acids. The complexing reaction followed two steps. The stability constants (K₁ and K₂) of REEs with FAs were calculated from experimental data by division of Scatchard plots into two straight-line segments. Y³⁺ (log K₁=5.72±0.05, log K₂=4.83±0.01) also has higher stability constants than the other four REEs (log K₁=4.37±0.16, log K₂=3.62±0.28).     

Some recent studies of inductively coupled plasmas involving the measurement or use of physical line widths: a tutorial discussion with retrospects and extensions

This paper summarizes a series of studies dealing with the measurement and use of physical line widths, and with related topics such as spectral resolution, spectral interferences, spectrum simulation, and detection limits, with particular reference to inductively coupled plasma atomic emission spectrometry and with emphasis on recent work in Philips Research Laboratories. The article tutorially reviews the essentials of those studies from a uniform and consistent point of view and incorporates additional data not covered in earlier papers. In connection with spectrum simulation and spectral interferences the author points out two crucial questions in a future perspective: (a) the potentials of electronic publications in spectroscopy as a most efficient way for disseminating the results of research, and (b) the promising application of chemometric methods to a “definitive” solution of the spectral interference problem in emission spectroscopy, as evidenced by recent literature, and the need for an effective cooperation between spectroscopists working along this line in order to make the collected data as much as possible universally usable.     

O-TOF-ICP-MS analysis of rare earth elements,noble elements,uranium and thorium in river-relating species

The determination of rare earth elements (REEs), Au, Pt, Ir, Pd, Th and U in various river species was performed by the orthogonal time-of-flight inductively coupled plasma mass spectrometry (o-TOF-ICP-MS). The method working conditions were optimised in order to minimise the presence and possible spectral interferences of oxides. Ratios MO⁺/M⁺ as well as interference of light REE and Ba oxides/hydroxides with high REEs were evaluated and confirmed to be insignificant. Using the internal standard Re, non-spectral matrix effects (originally decreasing of intensities up to 15%) were overcome and recoveries were found from 92 to 105% for all matrices analysed. For solutions, limits of detection (3σ) were 0.14–0.82 for REEs, Th, U and Y, 1.18 for La, 4.3–5.6 for Au, Pt, Ir and Pd 11 for Sc (all in ng L^?1). The Principal component analysis was used for classification of samples according to their places of origin successfully. The o-TOF-ICP-MS was proved to be a very sensitive and suitable technique for bio-monitoring purposes and was employed in the analysis of biota samples (fish, insect, profiles, benthal growths) originated from five different places in the river Elbe (Czech Republic).