Background Equivalent Concentration Research Articles

ICP-AES detection of silicon carbide impurities volatilized in a graphite furnace with the use of carbon tetrachloride vapour

The analytical capability of high-temperature halogenation with carbon tetrachloride vapour in a graphite furnace was investigated for silicon carbide powder with known chemical composition and particle size. Intensity vs heating time curves were determined for analytical lines of Al, B, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Ti, V and Si constituents, volatilized with and without the presence of CCl4 vapour in the furnace atmosphere. Igniting 10 mg SiC at 2100 °C for 60 s in chlorinating atmosphere, the evaporated fraction of most of the constituents was higher than 90% (for Al about 50%). The line intensity vs sample mass (4–26 mg) relationships were linear for all impurities studied, while the intensity of silicon line showed a relatively small change with the sample mass. BEC (background equivalent concentration) values for this solid sampling technique (10 mg loaded sample) were 2–20 fold lower than those calculated for the conventional solution sample introduction method.

Detection of Fluorine with a Shock Wave Plasma Induced by a TEA CO2 Laser.

A new method is presented for detecting fluorine atoms with a shock wave plasma induced by bombardment of a TEA CO2 laser beam. Comparison is made between a fluorine neutral emission line (FI 685.6-nm) and a fluorine ionic emission line (FII 385.0-nm) on the pressure dependence and the spatial distribution. The detection limits of FI 685.6-nm line and FII 385.0-nm line are 100 ppm and 900 ppm, respectively. The background equivalent concentration (BEC ) are 0.015% for FI 685.6-nm and 0.02% for FII 385.0-nm. The present method is of great advantage to the direct measurement of solid samples and to reduce sample preparation procedures.

Determination of aluminium, titanium, niobium and vanadium in low-alloyed steels by spark ablation coupled with inductively coupled plasma atomic emission spectrometry

A medium-voltage spark at a high repetition rate, coupled with excitation in an argon inductively coupled plasma (ICP) was applied to the direct determination of Al, Ti, Nb and V in low-alloyed steels. Tests were conducted using Bureau of Analysed Samples reference materials, series 451/1–455/1 and 456/1–460/1. A comparative evaluation of the analytical performances obtained with spark optical emission spectrometry, ICP with pneumatic nebulization and spark ablation inductively coupled plasma atomic emission spectrometry is given. The analytical parameters evaluated are the limit of detection, signal to background ratio, background equivalent concentration and relative standard deviation.

ICP-AES analysis of nonconductive materials after spark ablation

Two modifications were applied to a commercial spark ablation system. A cyclone spray chamber system was installed between the spark device and the inductively coupled plasma (ICP) torch and as outer gas, a mixture of argon and 10% oxygen, was used at 1200 W incident power. The control of the aerosol particle size by the cyclone system leads to an improvement in the reproducibility of the method compared to a commercial system and prevents deposition of material on the torch injector. The modified system was tested for the analysis of nonconductive powders. The samples were briquetted into pellets with graphite and wax. The addition of wax (Höchstwachs C, Höchst, F.R.G.) enables a better ablation of the material. At the same time the mechanical properties of the pellets are improved. The optimum amounts of additives for preparation of the pellets were found to be 20% graphite and 2.4% wax. The applicability of the method was demonstrated using Siemens standard rock materials. For small amounts of powdered samples a graphite cup method was applied. Values of background equivalent concentrations (BEC) achieved for geological samples are comparable to the values achievable with a DC arc and even better than the BEC values for ICP solution analysis. For the elements determined (Sr, Co, Nb, Zn, Cu, Pb, Zr, Ni, Mn, P, Mg, and Cr) the detection limits range from 0.2 to 9 μg g .

Analyte volatilization procedure for continuous-flow determination of bromine by atmospheric pressure helium microwave-induced plasma atomic emission spectrometry

A simple method to generate a continuous flow of volatile bromine by oxidation of aqueous bromide is described for the determination of low concentrations of bromine by atmospheric pressure helium microwave-induced plasma atomic emission spectrometry. The bromine atom emission lines at 447.78 and 734.86 nm and the bromine ion emission line at 470.49 nm were selected as the analytical lines of interest. Of various oxidation reactions investigated, an oxidizing solution of 100 mmol dm–3 of potassium persulfate in 5.0 mol dm–3 sulfuric acid is the most appropriate for the generation of elemental bromine. The gaseous bromine is separated from the solution in a simple gas–liquid separator, dried with a desiccant of anhydrous calcium chloride and swept into the helium stream of a microwave-induced plasma for analysis. The best attainable detection limits (3σ criterion) for bromine at 447.78, 470.49 and 734.86 nm were found to be 29.5, 7.46 and 18.4 ng ml–1, respectively, with corresponding background equivalent concentrations for bromine of 5.05, 1.72 and 2.42 µg ml–1. Typical analytical calibration graphs obtained under the optimized experimental conditions are rectilinear over approximately three orders of magnitude of concentration.

Simulation of atomic spectra—I. Profiles and signal-to-background ratios of 350 prominent lines emitted from an inductively coupled plasma or whatever “customized” atomic emission lines

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 spectrosopic 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 profiles of 350 prominent lines of 65 elements emitted from an inductively coupled plasma in dependence on the spectral bandwidth of the spectrometer and the Doppler temperature of the source as optional variables. The physical characteristics of the lines, including specific values of the a-parameter of the Voigt profile and data on hyperfine structure (HFS) are stored in the database. A spectrum is displayed in terms of (SBR + 1) as a function of wavelength, where SBR = signal-to-background ratio. A spectral window of 80 pm is covered. Additionally: numerical data are displayed, encompassing, inter alia, the SBR and background equivalent concentration (BEC) in the maximum of the spectral structure, the full width at half maximum (FWHM) of the structure, and “standard” values of SBR, BEC, and detection limit, stored in the computer. The prime purpose of the program is to facilitate the conversion of data on SBRs, BECs, and detection limits between instruments of different spectral bandwidth and thus to ease unbiased comparisons between different ICPs or between ICPs and other sources. The database, which covers both simple lines and complex HFS composites, has been derived from the data reported by Boumans and Vrakking [ Spectrochim. Acta 41B, 1235 (1986)]. Vast improvements in the data resulted from the interactive development of the program and the database. The relevant studies as well as the development and testing of various models for handling HFS composites are detailed in the hardcopy text. These studies may be reworked using the program and an additional, small, dedicated database. The tutorial part of the 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. The approach leaves many possibilities for customization of spectral lines, since both the data files for the individual spectral lines as well as the umbrella files for all lines grouped in a database have a simple and transparent organization: users may thus easily add customized files to the existing databases or generate new databases for whatever purposes.

OES-Measurements on aluminium, copper and lead samples with a microwave-boosted glow discharge lamp

A microwave-boosted glow discharge lamp with argon as the plasma gas was used for optical emission spectroscopic (OES) measurements on aluminium, copper and lead samples. The shapes of the craters and the sputtering rates were investigated. Line profiles have been recorded for some elements and compared with those of a conventional lamp. For aluminium samples, the influence of a high zinc content on the signal obtained for magnesium was investigated. Background equivalent concentrations for a number of elements in Al, Cu and Pb were calculated and found to be in the range from 1 to 25 solμg g for aluminium samples, 0.4 to 110 solμg g for copper samples, and 0.4 to 11 solμg g for lead samples if the most sensitive spectral line for each element was used. In the case of copper samples the background equivalent concentrations were compared with those found for a conventional glow discharge lamp.

Continuous-Flow Determination of Trace Iodine by Atmospheric-Pressure Helium Microwave-Induced Plasma Atomic Emission Spectrometry Using Generation of Volatile Iodine from Iodide

A simple continuous-flow generation of volatile iodine by oxidation of aqueous iodide is described for the determination of low concentrations of iodine by atmospheric-pressure helium microwave-induced plasma atomic emission spectrometry (MIP-AES) in the normal ultraviolet (UV) and vacuum ultraviolet (VUV) regions of the spectrum. For measuring spectral lines in the VUV region, the monochromator and the enclosed external optical path between the MIP source and the entrance slit of the monochromator have both been purged with nitrogen to minimize oxygen absorption below 190 nm. Iodine atomic emission lines at 206.16 and 183.04 nm have been selected as the analytical lines. Of various oxidation reactions examined, an oxidizing solution of 1.0 mM sodium nitrite in 5.0 M sulfuric acid is the most favorable for the generation of elemental iodine. The gaseous iodine is separated from the solution in a simple gas/liquid separator and swept into the helium stream of a microwave-induced plasma for analysis. The best attainable detection limits (3 σ criterion) for iodine at 183.04 and 206.16 nm were 2.3 and 3.2 ng/mL, respectively, with the corresponding background equivalent concentrations of 60 and 118 ng/mL in iodine concentration. The typical analytical working graphs obtained under the optimized experimental conditions were rectilinear over approximately 4 and 3 orders of magnitude in concentration for the 206.16- and 183.04-nm iodine lines, respectively.

Determination of rare earth elements in yttrium, lanthanum, gadolinium and ytterbium matrices using an échelle-type spectrometer and inductively coupled plasma atomic emission

A high-resolution echelle spectrometer and inductively coupled plasma atomic emission spectrometry were used for the direct determination of 15 rare earth elements (REEs, except for Pm) in synthetic solutions containing an REE matrix. Yttrium, La, Gd and Yb were used as the REE matrices. Spectral interferences between REEs were investigated and the optimum analytical wavelengths selected with the echelle spectrometer, using wavelength modulation and detection of the second-derivative signals. Background equivalent concentrations and limits of detection were evaluated.

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. Acta 42B, 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.

Untersuchungen zur gleichzeitigen Bestimmung von Molybdän und Wolfram in Proben mit schwierigen Matrices mit induktiv gekoppeltem Plasma

Inaccurate values are often obtained in the determination of molybdenum and tungsten in difficult complex matrices — ores, processing and metallurgical products. The main reason for this effect is due to spectral interferences. Background equivalent concentrations caused by changes of background nearby the measured spectral line are calculated for the established interferent matrix elements. It is possible with the applied sample treatment to perform successful analyses of samples with very variable matrix composition.

A comparison of cloud chambers for use in inductively coupled plasma nebulisation systems

A comparison of the analytical performance of five cloud chambers of different geometry used in conjunction with a commercial concentric glass nebuliser is reported. The comparison was based on measurements of transport efficiency, background equivalent concentration, analyte emission stability, detection limit, equilibration time and memory effect. Significant variations in performance indicated the importance of cloud chamber geometry on the nebulisation system. Best results were obtained with a new design based on a cylindrical chamber with a central tangential inlet. Droplet size distribution measurements revealed that although the primary distribution of the nebuliser aerosol contained a substantial proportion of small droplets of similar size to those in the ultimate distributions of the nebulisation systems, a large number of droplets are removed from the aerosol by separation processes occurring in the chambers.

Analysis of Aluminum by Inductively Coupled Plasma-Atomic Emission Spectroscopy

Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) is applied in the determination of 21 elements in primary, refined, and alloy aluminum. Rapid and reliable sample preparation procedures are developed. Spectral lines are selected after examination of experimental wavelength scans at each analyte wavelength. The limits of detection, background equivalent concentration, and analytical figures of merit are determined. For high silicon-containing aluminum, HF solutions were analyzed by employing an inert nebulizer utilizing polytetrafluoroethylene (PTFE) capillary tubes, a PTFE spray chamber, and an ICP torch with a graphite injector tube.

Determination of Rare Earth Elements in Aluminum by Inductively Coupled Plasma-Atomic Emission Spectroscopy

Inductively coupled plasma-atomic emission spectroscopy is evaluated for the determination of 14 rare earth elements in aluminum. Spectral line interference, limit of detection, and background equivalent concentration values are evaluated, and quantitative recovery is obtained from aluminum samples spiked with rare earth elements. The procedure is simple and suitable for routine process control analysis.

Analysis of bauxite by inductively coupled plasma-atomic emission spectroscopy

Methods are described for the analysis of bauxite by inductively coupled plasma (ICP) emission spectroscopy. Bauxite samples were dissolved either in HCl, HNO 3, and HF at 160°C in all-PTFE bomb or fused with NaOH. Spectral lines were selected after examination of experimental wavelength scans at each potential analyte wavelength. Limits of detection, background equivalent concentration, and analytical figures of merit were established. The accuracy of the method was confirmed by determining 17 elements in NBS-SRM bauxite samples. Silicon in HF solutions was analyzed using a modified ICP torch with a graphite injector tube, an inert nebulizer using PTFE capillary tubes, and a PTFE spray chamber.

Determination of metals in fatty acid still bottom residues by inductively coupled plasma-atomic emission spectroscopy

Analysis of fatty acid still bottom residues for major, minor, and trace element content using inductively coupled plasma-atomic emission spectroscopy is described. A combination of isopropyl alcohol and nitric acid (IPA-HNO 3) provided the best solvent for the samples. Wavelength selection, ICP operating conditions, detection limits, background equivalent concentrations, and analytical figures of merit were established for the quantitative determination of Zn, Cd, Cu, and Ni. For the determination of trace levels of As, Se, and Hg, direct ICP analysis was found to be too insensitive. Hydride generation for As and Se, and elemental generation of Hg in the plasma were attempted. These elements were not detected in any of the samples.