Traceable analysis of impurities in metallic reference materials using glow discharge mass spectrometry
金属标准物质中杂质的辉光放电质谱法溯源分析

The traceability requirements for certification analyses of reference materials are much higher than for routine analysis,where certified matrix reference materials(CRM) can be used for calibration and to establish traceability.Although the ISO-Guides related to CRM production and certification are not fully clear concerning calibration,many CRM-producers do not accept matrix-CRMs for calibration in case of certification analyses.These requirements limit the methods used for certification to those that can be calibrated using standards of known high purity and stoichiometry or mixtures of such standards.Powerful solid sampling techniques such as glow-discharge mass-spectrometry(GD-MS) or spark-OES,where normally compact CRMs are used for calibration,seem not be applicable for certification analyses.Especially GD-MS is a powerful tool for trace element determination of solid samples.Beside metallic impurities the use of specific gas mixtures enables also the determination of interesting non-metallic impurities such as sulfur and phosphorus.Within BAM a calibration approach was developed which enables to use mixtures of standards of known high purity and stoichiometry also for GD-MS.Similar to matrix adaption in solution based techniques,the calibration approach is based on doped pressed powder pellets.It is presented and discussed together with results from certification analyses of copper and steel CRMs.