A radiofrequency glow-discharge-time-of-flight mass spectrometer for direct analysis of glasses (original) (raw)
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Analytica Chimica Acta, 2009
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for quantitative analysis of ancient/historic glasses is subject to calibration issues which have been addressed in this work. Since ancient/historic glasses have widely ranging matrix compositions, a complementary analysis by an alternative method is generally employed to determine at least one major element which can be used as an internal standard. We demonstrate that such a complementary analysis is unnecessary using a so-called sum normalization calibration technique (mathematically formulated) by simultaneous measurement of 54 elements and normalizing them to 100% [w/w] based on their corresponding oxide concentrations. The crux of this approach is that by assuming a random internal standard concentration of a particular major oxide, e.g. SiO 2 , the normalization algorithm varies the internal standard concentration until the cumulated concentrations of all 54 elemental oxides reach 100% [w/w]. The fact that 54 elements are measured simultaneously predetermines the laser ablation mode to rastering. Nine glass standards, some replicating historic compositions, were used for calibration. The linearity of the calibration graphs (forced through the origin) represented by the relative standard deviations in the slope were between 0.1 and 6.6% using SiO 2 as an internal standard. This allows high-accuracy determination of elemental oxides as confirmed by good agreement between found and reported values for major and minor elemental oxides in some synthetic glasses with typical medieval composition (European Science Foundation 151 and 158). Also for trace elemental concentrations of lanthanides in a reference glass (P&H Developments Ltd. DLH7, a base glass composition with nominally 75 g g −1 elements added) accurate data were obtained. Interferences from polyatomic species and doubly charged species on the masses of trace elements are possible, depending on the base composition of the glass, with Ba and Sb glasses showing potential interferences on some lanthanides. We showed that they may be reduced to a great extent by using an Octopole Reaction System although the overall sensitivity decreases which may be a problem for some low-level determinations.
Archaeometry 51, 6, 966-986, 2009
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used, for the first time, for the characterization of opaque ancient glasses. Isotope-specific chemical imaging with sub-micron resolution enabled the separate analysis of opacifiying inclusions and the surrounding glass matrix. Phase identification has been demonstrated and quantification of the matrix composition has been investigated by use of Corning Glass Standard B as a model. Trace element detection limits are typically in the range 0.5–5.0 ppm atomic—in favourable cases down to 0.01 ppm. For the analysis of inclusions in particular, this has the potential to provide new information of use in establishing provenance and trade routes by ‘fingerprinting’ as well as the investigation of manufacturing techniques, as demonstrated by comparisons between glasses and with EDX data from the same samples.
Journal of Analytical Atomic Spectrometry, 2009
The analytical potential of a radiofrequency glow discharge orthogonal time-of-flight mass spectrometer (RFGD-TOFMS) has been evaluated in both pulsed and non-pulsed modes. A certified reference steel was selected for this study. The operating conditions of the GD plasma (pressure and applied power) were optimized in terms of sensitivity. Additionally, duty cycle and pulse width parameters were investigated in the pulsed RF mode. In this case, high analyte ion signals and improved signal to background ratios were measured after the end of the pulse, in the so-called afterglow domain. The analyte ion signals were normalized to sputtering rates to compare different operating conditions. It was found that the sensitivity in the pulsed mode was improved in comparison to the non-pulsed mode; however, the factor of enhancement is element dependent. Moreover, improved analytical performance was obtained in terms of ion separation capabilities as well as in terms of accuracy and precision in the evaluation of the isotopic ratios, using the pulsed RFGD-TOFMS. Additionally, depth profile analyses of a Zn/Ni coating on steel were performed and the non-pulsed and pulsed RFGD-TOFMS analytical performances were compared.
Analytical Chemistry, 1993
A glow discharge source has been adapted for use with a commercial external ion source Fourier transform ion cyclotron resonance mass spectrometer. This combination, with improvements in detection limits and accuracy, should be analytically useful for a variety of samples. Results on National Institute of Standards and Technology stainless steel standards showed that peaks due to nominally isobaric atomic isotopes can be observed with high mass resolution (m/AmlIz 2 290000). Detection limits in the high parts per billion to low parts per million range were achieved for analysis of trace metals in the standards, and concentrations of the trace elements were determined with good accuracy (average error of 14%).
Journal of Forensic Sciences, 2008
Advances in the technology employed for the manufacture of glass have resulted in a final glass product with little variability in terms of its physical and optical properties. For example, the refractive index of Australian float glass tends to lie between 1.5189 and 1.5194. It has therefore become necessary to complement physical and optical methods for forensic glass comparison with instrumental elemental analyses. In a previous study, time-of-flight secondary ion mass spectrometry has been shown to offer potential for the analysis of glass particles as small as a few tens of microns across. In this study, the three-dimensional homogeneity of a sheet of float glass is described, and consequences for forensic elemental analysis of glass particles of such size are explored. Variation in Si, Ca, Mg, and Na levels immediately under the nonfloat surface was observed, with the variance accompanied by a decrease in refractive index.
Present and future of glow discharge — Time of flight mass spectrometry in analytical chemistry
Spectrochimica Acta Part B: Atomic Spectroscopy, 2011
The coupling of glow discharges (GDs) as ion sources for time of flight mass spectrometry (TOFMS) chemical analysis has been extensively investigated during the last two decades. However, important instrumental advances in GD-TOFMS as well as demonstration of unique analytical applications (particularly quasisimultaneous production of elemental, structural and molecular information from organics in gas phase, multielemental depth profile analysis with high depth resolution of layered materials, direct speciation in solid samples and identification of polymers) are rocketing in the last years. In the present review, instrumental developments and recent applications of GD-TOFMS are presented, both for the elemental and molecular direct solid analyses of materials and for analytes in gaseous phase (including permanent gases, vaporized compounds and GD-TOFMS uses as detector for gas chromatography). Also, GD-TOFMS analytical potential in important fields of modern research is critically discussed.
Applied Spectroscopy, 1995
The use of different secondary cathodes is evaluated for the analysis of solid, nonconducting samples by means of dc glow discharge mass spectrometry. Optimum discharge conditions and analytical characteristics are reported for the analysis of a compacted iron ore sinter and a solid glass sample, both with known composition. These conditions seem to differ significantly for the two samples under consideration. This difference is assumed to be caused mainly by the electrical characteristics of the sample. The electrical resistivity of the sample is indeed found to be an important factor, determining the capabilities of the technique, especially with respect to the detection power.
International Journal of Mass Spectrometry, 1998
The combination of a glow discharge ionization source with a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer provides several advantages for elemental analysis; among these is an isotope ratio measured at the highest possible mass resolving power. In this report, lead ratios (206 Pb/ 208 Pb, 207 Pb/ 208 Pb, and 207 Pb/ 206 Pb) in a sample composed of 10% lead oxide, 10% mercuric oxide, and 80% silver powder (w/w) were observed to be precise to better than Ϯ3% relative standard deviation (RSD at 1) in a commercial FTICR instrument that used a conventional elongated cell. Upon incorporation of a cell whose excitation voltages approximated those in an ideal cell of infinite length, the precision improved to better than Ϯ0.4% RSD. The isotopic bias between measured and known values was also evaluated. Using a cathode composed of 5% National Institute of Standards and Technology (NIST) SRM 987 SrCO 3 in silver powder, biases that averaged less than 2.5% were detected using the cell of improved design. These results compared favorably with those obtained using a commercial magnetic sector glow discharge mass spectrometer, although it is still unclear how glow discharge mass spectrometry biases vary in general.