INORGANIC TRACE ANALYSIS BY MASS-SPECTROMETRY

Mass spectrometric methods for the trace analysis of inorganic materia ls with their ability to provide a very sensitive multielemental analy sis have been established for the determination of trace and ultratrac e elements in high-purity materials (metals, semiconductors and insula tors), in different technical samples (e.g. alloys, pure chemicals, ce ramics, thin films, implanted semiconductors), in environmental sample s (waters, soils, biological and medical materials) and geological sam ples. Whereas such techniques as spark source mass spectrometry (SSMS) , laser ionization mass spectrometry (LIMS), laser ablation inductivel y coupled plasma mass spectrometry (LA-ICP-MS), glow discharge mass sp ectrometry (GDMS), secondary ion mass spectrometry (SIMS) and inductiv ely coupled plasma mass spectrometry (ICP-MS) have multielemental capa bility, other methods such as thermal ionization mass spectrometry (TI MS), accelerator mass spectrometry (AMS) and resonance ionization mass spectrometry (RIMS) have been used for sensitive mono- or oligoelemen tal ultratrace analysis (and precise determination of isotopic ratios) in solid samples. The limits of detection for chemical elements using these mass spectrometric techniques are in the low ng g(-1) concentra tion range. The quantification of the analytical results of mass spect rometric methods is sometimes difficult due to a lack of matrix-fitted multielement standard reference materials (SRMs) for many solid sampl es. Therefore, owing to the simple quantification procedure of the aqu eous solution, inductively coupled plasma mass spectrometry (ICP-MS) i s being increasingly used for the characterization of solid samples af ter sample dissolution. ICP-MS is often combined with special sample i ntroduction equipment (e.g. flow injection, hydride generation, high p erformance liquid chromatography (HPLC) or electrothermal vaporization ) or an off-line matrix separation, and enrichment of trace impurities (especially for characterization of high-purity materials and environ mental samples) is used in order to improve the detection limits of tr ace elements. Furthermore, the determination of chemical elements in t he trace and ultratrace concentration range is often difficult and can be disturbed through mass interferences of analyte ions by molecular ions at the same nominal mass. By applying double-focusing sector fiel d mass spectrometry at the required mass resolution-by the mass spectr ometric separation of molecular ions from the analyte ions-it is often possible to overcome these interference problems. Commercial instrume ntal equipment, the capability (detection limits, accuracy, precision) and the analytical application fields of mass spectrometric methods f or the determination of trace and ultratrace elements and for surface analysis are discussed. (C) 1998 Elsevier Science B.V. All rights rese rved.