Portable double-focusing mass-spectrometer system for field gas monitoring

Abstract

Traditional mass-spectrometry (MS) instruments have been confined to laboratory usage because of their large size, power and high-vacuum requirements, which make them unsuitable for use in most field environments. Developments in mass spectrometers and small vacuum pump systems have now made possible the development of transportable mass-spectrometer instruments. A portable MS device based on a miniature double-focusing (ExB) sector-field mass spectrometer has been developed for in situ gas analysis and monitoring applications. The device (acronym Portable-CDFMS) uses a 1.1-Tesla NdFeB permanent magnet, a lithographically defined electric sector, a molecular-flow frit inlet, a spiral filament in a closed ion source, and a miniature channeltron detector. The high vacuum is provided with the use of a very compact hybrid turbomolecular and diaphragm pump combination. This MS system weighs 18 lb., is able to detect atmospheric species at the part-per-million (ppm) level, and has a mass range up to 200 amu, which makes this miniature mass spectrometer well suited for field applications. © 2001 John Wiley & Sons, Inc. Field Analyt Chem Technol 5: 156–167, 2001