APPLICATION OF SUB-ATMOSPHERIC PRESSURE NEGATIVE ION MASS SPECTROMETRY FOR MONITORING TRACE LEVELS OF SF6, AND C1 - C2 FREONS

Authors
  1. Pagotto, J.G.
  2. Sewell, L.
Corporate Authors
Defence Research Establishment Ottawa, Ottawa ONT (CAN);Guelph Univ, Guelph ONT (CAN) Dept of Chemistry
Abstract
Sub-atmospheric pressure negative ion mass spectrometry is capable of providing sensitivity limits for some highly electronegative species, that are the lowest ever reported. This technique can provide selective real time monitoring of compounds, such as SF6 in humid air, at levels as low as 10 parts per trillion. This paper describes the use of a custom designed mass spectrometer that employs a unique variation of the well known atmospheric pressure ionization sources used in commercial instruments. Characteristic of the corona discharge ion source used in this novel instrument, and an important factor allowing its high sensitivity, is the relatively limited ion fragmentation and water clustering that occurs, in comparison with classical atmospheric pressure mass spectrometery techniques. This study examines the use of a unique sub-atmospheric pressure (10 Torr) pulsed negative ion mass spectrometer to detect trace levels of SF6 and a selection of C1 and C2 halocarbons. One objective of this work was to identify the potential for using this technique in combination with an innocuous tracer gas for studying the performance of chemical protective equipment. Pulsed negative ion mass spectra are provided and ion fragmentation patterns proposed from data collected using various carrier gases.
Keywords
SF6;Tracer gas;Fit testing;Protection factor;Negative ions;Chemical protection;Freon
Report Number
DREO-1206 —
Date of publication
01 Apr 1993
Number of Pages
67
DSTKIM No
94-03646
CANDIS No
142972
Format(s):
Hardcopy;Originator's fiche received by DSIS

Permanent link

Document 1 of 1

Date modified: