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Three methods for direct solid sampling of bulk material namely IR laser ablation, glow discharge and spark OES, were compared with respect to analytical figures of merit obtained for elemental analysis with atomic spectrometry. Matrices investigated were copper, pressed doped copper powder, and magnesium alloys. For the vast majority of analytes, statistical equivalence regarding precision (usually ≤ 5%) and the performance of the calibrations between the compared methods was demonstrated.
An intercomparison study of analytical methods for the determination of magnesium in low alloy steel
(2012)
In an intercomparison study three low alloy steel materials were analyzed on their content of the trace element Mg, and five different analytical techniques were used, namely spark-OES, inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma time of flight mass spectrometry (ICP-TOFMS), inductively coupled plasma quadrupole mass spectrometry (ICP-QMS), and glow discharge mass spectrometry (GD-MS). Solid steel discs were used for analysis with spark-OES and GD-MS. For the analyses with ICP-OES, ICP-TOFMS, and ICP-QMS steel chips were wet-digested in aqua regia, and the wet-digestion was performed either in polypropylene tubes placed in a heating block or in Teflon pressure vessels using a microwave assisted system. The Mg concentrations obtained for the three steel materials were: 2.0, 2.8, and 10.3 µg g-1, respectively, and the spread in results was acceptable, giving RSD values in the range of 2030%.
Direct current (DC) fast flow glow discharge mass spectrometry is an important and versatile tool for multielemental trace analysis of conductive solid materials down to the µg/kg level. Special benefits are minimum demands on sample preparation, avoiding losses and contamination, and only short analysis time.
For fast flow GD sources, the quantification strategy based on relative standard sensitivity factors (Standard RSFs) which are independent of matrix is not sufficiently satisfying regarding accuracy for each matrix and element [1]. Therefore matrix-matched calibration samples (MMCS) are required to achieve reliable quantification. In fact, the list of existing certified reference materials (CRM) appropri-ate for calibration in trace analysis is rather short.
Convenient synthesis of homogeneous MMCS, as e.g. easily obtained in liquid sampling spectrometry, can facilitate the application of fast flow GD-MS for quantification of impurities in a variety of matrices.
Pressing of metal powders for the preparation of MMCS for GD-MS was suggested earlier [2], the method was further modified by use of analyte solutions for doping of rather pure metal powders such as Cu and Zn [3], but has not yet been applied Ni matrix.
In the present work we describe the determination of matrix-dependent relative sensitivity factors (RSFs) for Mg, Al, Cr, Mn, Fe, Co, Cu, Zn, Ag, Cd, Tl, Pb and Bi in pure Ni by using the liquid doping approach for the preparation of synthetic pressed Ni-powder samples. A four point-calibration was used applying the fast flow glow discharge mass spectrometer, Element GD (Thermo Fisher). The determined RSF were verified against suitable CRM and compared with the standard RSF given by the supplier of the instrument.
The obtained results demonstrate a satisfying Agreement with the certified values of the CRM and a significant improvement for the quantification of most of the determined elements in comparison with standard RSF.
Mixed copper and titanium hydride powder was hot-pressed and characterized by Carrier Gas Hot Extraction, XRay Diffraction, Thermal Gravimetric Analysis coupled with Mass Spectrometry, and Scanning Electron Microscopy.
The hot-pressed and five conventional samples were applied for calibration of hydrogen in Glow Discharge Optical Emission and Mass Spectrometry. Up to the introduction of 15 ng/s hydrogen the Emission yield model is useful in Glow Discharge Optical Emission Spectrometry. A correlation between saturation and even reversal of the emission yield of the spectral lines H121, H486 and H656 and low sputtering rates was found. Hydrogen effects exist for the spectral lines of Cu(II) 219 and Ti(I) 399. In Glow Discharge Mass Spectrometry, a linear dependency of the 1H ion current on the sputtered mass per time exists over the total range of hydrogen content investigated. Hydrogen effects also exist for the sensitivity of 48Ti and 63Cu. The sputtering rate of two-phase materials depends linearly on the sputtered mass per time of one phase, which allows the sputtering rate of two-phase materials with known composition to be predicted.