Application of glow discharge mass spectrometry to multielement ultra-trace determination in ultrahigh-purity copper and iron: a calibration approach achieving quantification and traceability

Abstract

A new approach was developed for quantitative calibration in GD-MS which can afford reliable and metrologically traceable results for many trace elements and was exemplified for pure copper and pure iron. It can be assumed that the technique can be further improved and applied to the analysis of other pure metals. Pressed copper and iron powder samples were used to calibrate the glow discharge mass spectrometry applied to the analysis of pure copper and iron. The new type of glow discharge mass spectrometer--the Element GD (Thermo Electron Corporation)--was used with a Grimm-type discharge cell for flat samples. Two series of powder samples were prepared for each of the copper and iron matrixes. The powders were quantitatively doped with solutions of graduated and defined concentrations of 40 or 20 analytes, respectively. The mass fractions of the analytes in the dried and homogenized metal powder samples ranged from microg/kg levels up to 10 mg/kg levels. A special technique was developed to press the samples and to form mechanically stable pellets with low risk of contamination. Ion beam ratios of analyte ions to matrix ions were used as measurands. The calibration curves were determined and the linear correlation coefficients were calculated for different intervals of the curves. The linear correlation coefficients are very satisfactory for most of the calibration curves, which include the higher segments of mass fractions; however, they are less satisfactory for the lower segments of the calibration curves. Nevertheless, in many cases rather acceptable and rather promising values were achieved even for these lower segments, representing mass fractions of analytes at ultra-trace level. The comparison of the certified values of different reference materials with the measured values based on calibrations with the pressed powder samples led to deviations less than 30% for most of the considered examples.

High-Purity Fixed Points of the ITS-90 with Traceable Analysis of Impurity Contents

“…The basic principle of the new methodology for the instrument calibration is to replace the current semi-quantitative approach by a quantitative one based on sets of doped samples with well-known impurity content whose values are directly traceable to the International System of Units (SI) and that provides measurement results with small uncertainty down to the ng · g −1 level ( Fig. 1) [9]. Such a methodology is the most accurate procedure to obtain small uncertainties using GD-MS. To date, calibration sets of high-purity zinc doped with eight different impurity fractions between 5 ng· g −1 and 10 µg · g −1 have been established.…”

Glow Discharge Mass Spectrometry

“…With the aim of achieving highly accurate quantification with GDMS for rare elements and matrices, the calibration strategy with self-prepared synthetic standards was developed by Matschat et al 92 and then further improved, including evaluation of uncertainties, within the PhD thesis of Gusarova. 79 A similar concept has been applied to LA-ICP-MS quantitative analysis, as well.…”

RF-pulsed glow discharge time-of-flight mass spectrometry for glass analysis: Investigation of the ion source design

“…GDs have been successfully coupled for analytical purposes to mass analysers such as quadrupoles [4] and double-focusing [5,6] spectrometers; however, the sequential nature of such mass analysers make them not ideal for depth profiling with high depth resolution. This sequential operation can be overcome using timeof-flight mass spectrometry (TOFMS) [7], capable of fast collection of a complete mass spectrum within one single extraction of the packet of ions (one extraction pulse of the analyser) with high precision and sensitivity.…”