Modular sampling and inlet systems for mobile environmental mass spectrometry

Abstract

Sampling systems and gas Chromatographic separators based on a modular concept have been developed for a mobile/portable quadrupole mass spectrometer. A special quick connector, designed to easily mount and remove the gas Chromatograph from the mass spectrometer, allows the operator to switch between different GC modules within minutes. A polysiloxane inlet membrane seals the vacuum chamber and prevents it from being vented, even during the exchange of GC modules. Since the GC's injector modules are designed as separate units, diverse injector systems can also be removed and swapped using similar quick interfaces, while the GC module remains connected to the mass spectrometer. Fast GC runs with short-capillary GC modules accelerate measurements dramatically. Using a spray extractor, volatile organic compounds in water can be sampled and trapped in the sorbent tube of the automatic air sampler for GC-MS analysis. A quick analysis can be made using the transfer-line GC with the sniffer probe. Examples are given of applications involving the analysis of polycyclic aromatics and other contaminants in soil samples, and analytical results on volatile organic compounds in air, in indoor atmospheres and in water. The concept of this modular system makes the whole instrumentation flexible, and permits a wide variety of mass spectrometry applications by using the right combination of sampling modules.